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1.  A new cervical nerve root avulsion model using a posterior extra-vertebral approach in rats 
The nerve root avulsion injury causes decrease of motor neurons in the spinal ventral horn. To investigate the motoneuron death after avulsion injury in rats, the intradural root avulsion procedure is usually used, although it is technically demanding and associated with a risk of unexpected spinal cord damage. We have developed a new cervical nerve root avulsion procedure in rats and investigated the validity of our procedure.
Our procedure is using a posterior approach and pulling the C6 nerve root outside the vertebral foramen without intradural procedures. The lateral third of the lateral mass is needed to be resected before pulling the nerve root. The accomplishment of our procedure is judged by confirmation of the bifurcated stump of the avulsed nerve root and the leakage of the spinal fluid from vertebral foramen. At first, four Sprague–Dawley (SD) rats were used for the examination of C6 motor neuron distribution in the normal spinal cord. Then, 40 SD rats were divided into following four groups and the survival rate of motor neuron was examined. (A) an intradural avulsion group, (B) an intradural rhizotomy group, (C) our extravertebral avulsion group, and (D) an extravertebral rupture group. Another 26 SD rats were used for the examination of histomorphorogic changes in the spinal cord after our extra-vertebral avulsion procedure.
At 28 days after injury, the percentage of surviving motor neurons in groups A (39.0 ± 2.1%) and C (47.5 ± 7.1%) were significantly lower than those in groups B (77.1 ± 12.3%) and D (98.9 ± 9.9%). Compared with other groups, our procedure was easier and associated with less unexpected spinal cord damage. Although the length of the distal stump of the extravertebrally avulsed ventral rootlets was varied between 1.5 and 3.2 mm, this difference did not affect motoneuron death. The extravertebral avulsion injury showed intraspinal bleeding along the motoneuron axons, glial reaction and macrophage infiltration in the lesioned side of the ventral horn.
Our extravertebral avulsion procedure is simple and reproducible. It would become a useful tool for the study of cervical nerve root avulsion injury.
PMCID: PMC3848685  PMID: 24020460
Animal models; Brachial plexus neuropathies; Motor neurons; Nerve root avulsion; Rats
2.  Intraoperative neurophysiological monitoring in spinal root surgical interventions 
Journal of Injury and Violence Research  2012;4(3 Suppl 1): Paper No. 84.
Surgical interventions around spinal roots may result in rootlets injury and neurological deficits. Multimodal introperative neurophysiological monitoring (MIOM) can allow for early detection and then reversal of nerve roots potential injuries. These utilities have been currently used to evaluate spinal sensorimotor pathways and nerve root function during posterior spinal approches for transpedicular screw fixations in a rotine base in our setting (Vali-e ASR Hospital, Arak, Iran) since 1998.
In three consecutive patients (1 male, 16 years old. and 2 female, 17 and 16 years old) kyphoscoliosis corrections, patient’s history, preoperative physical examination and MIOM were performed using a multimodal 40-channel electrophysiologic monitoring system (Nicolet Endeavor, VIASYS Healthcare, 2005, USA). In all cases somatosensory evoked potentials (SSEPs) and F-wave responses corresponding tothe related myotome, were recorded 2 days prior surgery. The SSEPs, bilateral EMGs of paravertebrals and related muscle, stimulus-evoked evoked EMGs by mid-dural spinal stimulation, stimulus-evoked EMGs through root stimulation (pre/post foraminal) were performed when required during different stages of operation procedure. The compound muscle action potentials (CMAPs) were recorded using a pair of 1 Cm2 golden cup surface electrode. A paired-pulse stimulation consisting of two pulses with 2 ms interstimulus interval (ISI), 100-300 µs duration and 10-40 mA intensity was applied through a surgical probe pair electrode touched to the intact dura, over the midline of dorsal column, 2 segments above the involved root, to evoke constant reproducible EMGs in paravertebrals and/or approperiate myotomes of the segment in both lower limbs. Latency of CMAPs were measured for dorsal culumn, foramen entrance and root exit site stimulations. Following the measurements of the F-wave latencies, the central root conduction time and foramenal segments were calculated and used for further monitoring.
The SSEPs of ascending valleis from medial tibial nerve stimulation were recorded at C7 spine and C3´ or C4´of the operation side. A unilateral, sustained loss of 50% of the SSEP amplitude and/or increase by 10% of latency from average values after anesthesia, and SSEP/CMAP waveform change to an asynchronous polyphasic wave, were considered to be pathologic. Drilling and screw positionings were evaluated intraoperatively with standard posteroanterior and lateral radiographs.
None of the 3 patients showed significant change in the SSEPsor post-operative radiculopathies distinct from their preoperative presentations. One hour after the start of surgery, when the spinal column was exposed to the operating theatre temperature, a minimal prolongation of latencies as well as amplitude reduction of SSEPs was observed. The SSEP waveforms were not affected subsequently. A reverse change appeared again after paravertebral muscles stitching at the final hour of surgery.
In our cases, latencies of different root segments were kept intact during the operation and also during the transfer to the recovery room. Propofol or Propofol/Ketamine mixture plus narcotic is suitable to obtain stable reproducible SSEPs and EMGs. Atracurium or other nondepolarizing skeletal muscle relaxants should be avoided. Muscle relaxants application or mean arterial pressure (MAP) below 70 mmHg may cause bilateral reduction or loss of SSEPs and EMGs. There was no postoperative clinically detectable complication.
Findings of our study demonstrated that MIOM should be used in all patients undergoing surgery around spinal roots. Monitoring can practically reduce possibilities of neurological deficit. Futhermore, it can be concluded that the use of SSEPs to evaluate the pedicle screw placement or similar interventions is not an appropriate tool itself, since, , it could be practically limited to sensory fibers of root. In these settings and similar procedures, if IOM is required, alternative multimodal methods with greater sensitivity and efficacy should be explored. To aquire MIOM modalities, close collaboration of an anesthesioloist is nessesary.
Spinal surgery, Transpedicular screw, Multimodal intraoperative monitoring
PMCID: PMC3571610
3.  Lateral Mass Fixation in Subaxial Cervical Spine: Anatomic Review 
Global Spine Journal  2012;2(1):39-46.
Introduction The cervical spine is a highly mobile segment of the spinal column, liable to a variety of diseases and susceptible to trauma. It is a complex region where many vital structures lie in close proximity. Lateral mass screw fixation has become the method of choice in stabilizing subaxial cervical spine among other posterior cervical fixation techniques whenever the posterior elements are absent or compromised.
Objective This study examined cervical specimens of cadavers and cervical computed tomography (CT) scans to minimize as much as possible complications of cervical lateral mass screw placement such as vertebral artery or nerve root injuries, facet joint violations, or inadequate placement.
Methods Forty normal cervical CT scans, obtained from the emergency unit as part of the trauma workup, were included in this study plus 10 cervical cadaveric specimens obtained from the Alexandria Neuro-anatomy laboratory. There were three fixed parameters for screw insertion in this study. First, the point of screw insertion was the midpoint of the lateral mass; it was the crossing point between the sagittal and axial planes of the posterior cortex of the lateral mass. Second, the direction of the screw in the craniocaudal plane was 30 degrees cranially to avoid facet joint penetration. Third, the exit point of the screw was located on the ventral cortex of the lateral mass just lateral to the root of the transverse process in the midaxial cut of each lateral mass, to make a sound bicortical fixation without injuring the vertebral artery or the nerve root. The selected screw trajectory in this study was the line drawn between the inlet and exit points. The depth and width of the lateral mass of the cervical vertebrae from C3 to C7 were measured as well as the angle of screw trajectory from the sagittal plane. All these measures were applied on the cadaveric specimens to make sure that no injury to the vertebral artery, nerve root, or facet joint occurred.
Results As regards the collected measurements of the lateral mass of all subaxial cervical vertebrae, the study revealed that the average depth of the lateral mass was 12.83 ± 1.28 mm. The average width of the lateral mass was 11.92 ± 0.96 mm. The average divergent angle of bicortical screw insertion without injury to the vertebral artery or the nerve root was 19.51 ± 1.83 degrees. As regard the cadaveric specimens, based on all the collected measurements taken from the CT scans, there was no reported injury to the vertebral arteries or nerve roots or penetration to the facet joints.
Conclusion Lateral mass fixation can be applied easily and safely for all levels of subaxial cervical spine from C3 to C6 with the following parameters: (1) the point of entry is the midpoint of the lateral mass; (2) the screw trajectory is directed 30 degrees cranially and 20 degrees laterally; (3) the screw length is 13 to 15 mm.
PMCID: PMC3864406  PMID: 24353945
lateral mass fixation; vertebral artery; nerve root; facet joint
4.  Functional Reinnervation of the Canine Bladder after Spinal Root Transection and Immediate Somatic Nerve Transfer 
Journal of neurotrauma  2008;25(3):214-224.
This study was performed to determine whether nerve transfer immediately after spinal root transection would lead to bladder reinnervation in a canine model. In one animal, the left T12 intercostal nerve was mobilized, cut and attached to the severed ends of sacral roots inducing bladder contraction using a graft from the T11 intercostal nerve. On the right side and bilaterally in two other dogs, coccygeal roots innervating tail musculature were cut and attached to the severed bladder sacral roots (coccygeal nerve transfer [CG NT]). In four other dogs, bladder sacral roots were transected in the vertebral column, and the genitofemoral nerve was transferred within the abdomen to the pelvic nerve (genitofemoral nerve transfer [GF NT]). After 14 months for CG NT and 4.5 months for GF NT, electrical stimulation of the pelvic nerve induced bladder pressure and urethral fluid flow on the intercostal nerve transfer side, in each of the five CG NT sites and bilaterally in three of the four GF NT animals. Reinnervation was further shown by retrograde labeling of spinal cord neurons following fluorogold injections into the bladder wall and by histological examination of the root/nerve suture sites. In all CG NT animals, labeled neuronal cell bodies were located in ventral horns in lamina IX of coccygeal cord segments. In the three GF NT animals in which pelvic nerve stimulation induced bladder contraction, abundant labeled cell bodies were observed in lamina IX and lateral zona intermedia of upper lumbar cord. These results clearly demonstrate that bladder reinnervation can be accomplished by immediate nerve transfer of intercostal nerves or coccygeal spinal roots to severed bladder sacral roots, or by transfer of peripheral genitofemoral nerves (L1,2 origin) to pelvic nerves.
PMCID: PMC3604734  PMID: 18352835
animal studies; axonal injury; neuroplasticity; peripheral nerve injury; regeneration
5.  The So-Called Anterior Meningeal Artery: an Anatomic Study for Treatment Modalities 
Interventional Neuroradiology  2005;10(4):293-299.
The so called anterior meningeal artery (AMA) is a branch of the vertebral artery (VA), which had been interpreted as a supplying vessel of the dura in the foramen magnum and upper cervical level.
In this study, we examined the anatomy of this artery and relationships to its surrounding structures for treatment modalities. With the aid of magnification, five adult cadaveric head and neck complex and five cervical spines were examined after perfusion of the vessels with colored silicone.
The AMA arose from the VA between the C2 and C3 level, and passed medially through the intrervertebral foramen anterior to the dural sheath of the third cervical nerve root. It ran upwards dorsal to the deep layer of the posterior longitudinal ligament (PLL) with anterior internal vertebral venous plexus. Rostrally, it formed an arcade above the apex of the odontoid process with its contralateral mate.
The AMA gave off several tiny branches to the deep layer of the PLL, ligaments and soft tissues above the apex of the odontoid process, and vertebral bodies of the axis. At the level of the foramen magnum, it ended in several small twigs to the dura. Anastomoses between the AMA system and adjacent vessels were observed. One was directed through the hypoglossal canal to the ascending pharyngeal artery and the other was with the V3 segment of the VA. The origin and course of the two AMA, and anastomoses were symmetric. Although the AMA feeds the ventral dura of the foramen magnum, the perfusion area is larger than its name suggests, including the bony and ligamentous structures in the craniovertebral junction.
Anatomical knowledge of the AMA, including its anastomoses and layer relationships to the surrounding structures, may help to perform treatment modalities in this region rationally.
PMCID: PMC3463288  PMID: 20587212
anatomy, anterior meningeal artery, craniovertebral junction, vertebral artery
6.  Complications of transpedicular screw fixation in the cervical spine 
European Spine Journal  2005;15(3):327-334.
Today, posterior stabilization of the cervical spine is most frequently performed by lateral mass screws or spinous process wiring. These techniques do not always provide sufficient stability, and anterior fusion procedures are added secondarily. Recently, transpedicular screw fixation of the cervical spine has been introduced to provide a one-stage stable posterior fixation. The aim of the present prospective study is to examine if cervical pedicle screw fixation can be done by low risk and to identify potential risk factors associated with this technique. All patients stabilized by cervical transpedicular screw fixation between 1999 and 2002 were included. Cervical disorders included multisegmental degenerative instability with cervical myelopathy in 16 patients, segmental instability caused by rheumatoid arthritis in three, trauma in five and instability caused by infection in two patients. In most cases additional decompression of the spinal cord and bone graft placement were performed. Pre-operative and post-operative CT-scans (2-mm cuts) and plain X-rays served to determine changes in alignment and the position of the screws. Clinical outcome was assessed in all cases. Ninety-four cervical pedicle screws were implanted in 26 patients, most frequently at the C3 (26 screws) and C4 levels (19 screws). Radiologically 66 screws (70%) were placed correctly (maximal breach 1 mm) whereas 20 screws (21%) were misplaced with reduction of mechanical strength, slight narrowing of the vertebral artery canal (<25%) or the lateral recess without compression of neural structures. However, these misplacements were asymptomatic in all cases. Another eight screws (9%) had a critical breach. Four of them showed a narrowing of the vertebral artery canal of more then 25%, in all cases without vascular problems. Three screws passed through the intervertebral foramen, causing temporary paresis in one case and a new sensory loss in another. In the latter patient revision surgery was performed. The screw was loosened and had to be corrected. The only statistically significant risk factor was the level of surgery: all critical breaches were seen from C3 to C5. Percutaneous application of the screws reduced the risk for misplacement, although this finding was not statistically significant. There was also a remarkable learning curve. Instrumentation with cervical transpedicular screws results in very stable fixation. However, with the use of new techniques like percutaneous screw application or computerized image guidance there remains a risk for damaging nerve roots or the vertebral artery. This technique should be reserved for highly selected patients with clear indications and to highly experienced spine surgeons.
PMCID: PMC3489301  PMID: 15912352
Cervical spine; Pedicle screw fixation; Complication; Posterior fusion
7.  Evaluation of normal appearing spinal cord by diffusion tensor imaging, fiber tracking, fractional anisotropy, and apparent diffusion coefficient measurement in 13 dogs 
Functional magnetic resonance (fMR) imaging offers plenty of new opportunities in the diagnosis of central nervous system diseases. Diffusion tensor imaging (DTI) is a technique sensitive to the random motion of water providing information about tissue architecture. We applied DTI to normal appearing spinal cords of 13 dogs of different breeds and body weights in a 3.0 T magnetic resonance (MR) scanner. The aim was to study fiber tracking (FT) patterns by tractography and the variations of the fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) observed in the spinal cords of dogs with different sizes and at different locations (cervical and thoracolumbar). For that reason we added a DTI sequence to the standard clinical MR protocol. The values of FA and ADC were calculated by means of three regions of interest defined on the cervical or the thoracolumbar spinal cord (ROI 1, 2, and 3).
The shape of the spinal cord fiber tracts was well illustrated following tractography and the exiting nerve roots could be differentiated from the spinal cord fiber tracts. Routine MR scanning times were extended for 8 to 12 min, depending on the size of the field of view (FOV), the slice thickness, and the size of the interslice gaps. In small breed dogs (< 15 kg body weight) the fibers could be tracked over a length of approximately 10 vertebral bodies with scanning times of about 8 min, whereas in large breed dogs (> 25 kg body weight) the traceable fiber length was about 5 vertebral bodies which took 10 to 12 min scanning time. FA and ADC values showed mean values of 0.447 (FA), and 0.560 × 10-3 mm2/s (ADC), respectively without any differences detected with regard to different dog sizes and spinal cord 45 segments examined.
FT is suitable for the graphical depiction of the canine spinal cord and the exiting nerve roots. The FA and ADC values offer an objective measure for evaluation of the spinal cord fiber integrity in dogs.
PMCID: PMC3648354  PMID: 23618404
Canine; Tractography; DTI; FA; ADC
8.  Anatomical Morphometric Study of the Cervical Uncinate Process and Surrounding Structures 
The purpose of this study is to elucidate the anatomic relationships between the uncinate process and surrounding neurovascular structures to prevent possible complications in anterior cervical surgery.
Twenty-eight formalin-fixed cervical spines were removed from adult cadavers and were studied. The authors investigated the morphometric relationships between the uncinate process, vertebral artery and adjacent nerve roots.
The height of the uncinate process was 5.6-7.5 mm and the width was 5.8-8.0 mm. The angle between the posterior tip of the uncinate process and vertebral artery was 32.2-42.4°. The distance from the upper tip of the uncinate process to the vertebral body immediately above was 2.1-3.3 mm, and this distance was narrowest at the fifth cervical vertebrae. The distance from the posterior tip of the uncinate process to the nerve root was 1.3-2.0 mm. The distance from the uncinate process to the vertebral artery was measured at three different points of the uncinate process : upper-posterior tip, lateral wall and the most antero-medial point of the uncinate process, and the distances were 3.6-6.1 mm, 1.7-2.8 mm, and 4.2-5.7 mm, respectively. The distance from the uncinate process tip to the vertebral artery and the angle between the uncinate process tip and vertebral artery were significantly different between the right and left side.
These data provide guidelines for anterior cervical surgery, and will aid in reducing neurovascular injury during anterior cervical surgery, especially in anterior microforaminotomy.
PMCID: PMC3488636  PMID: 23133716
Anterior cervical surgery; Foraminotomy; Uncinate process, Vertebral artery; Nerve root
The Journal of General Physiology  1949;32(4):409-443.
The "dorsal root potential" consists of five successive deflections designated for convenience, D.R.I, II, III, IV, and V. Of these, D.R.V alone constitutes the dorsal root potential of prior description. A study has been made of the general properties of those deflections not previously described. Dorsal root potentials are electrotonic extensions into the extramedullary root segment, the result of electrical interactions within the cord comparable to those that have been studied in peripheral nerve. Although the anatomical and electrical conditions of interaction are infinitely more complex in the cord than in nerve, it is seen that the fact of parallel distribution of primary afferent fibers pertaining to neighboring dorsal roots provides a sufficient anatomical basis for qualitative analysis in the first approximation of dorsal root potentials. An extension of the theory of interaction between neighboring nerve fibers has been made to include an especial case of interaction between fibers orientated at right angles to one another. The predictions have been tested in a nerve model and found correct. Given this elaboration, and the stated anatomical propositions, existing knowledge of interaction provides an adequate theoretical basis for an elementary understanding of dorsal root potentials. The study of general properties and the analysis of dorsal root potentials have led to the formulation of certain conclusions that follow. D.R.I, II, and III record the electrotonic spread of polarization resulting from the external field of impulses conducted in the intramedullary segment and longitudinal trajects of primary afferent fibers. D.R.IV arises in part as the result of activity in primary afferent fibers, and in part as the result of activity in secondary neurons. In either case the mode of production is the same, and the responsible agent is residual negativity in the active collaterals, or, more precisely, the external field of current flow about the collaterals during the period of residual negativity. Current flow about active primary afferent collaterals during the period of residual negativity is the agent for residual facilitation of monosynaptic reflex pathways. Since the changes in reflex threshold follow the course of residual negativity there is no need to postulate especial properties for prolonging action at regions the threshold of which is measured by means of monosynaptic test reflexes. D.R.V results from polarization of primary afferent fibers by current flow about secondary neurons. There is indication that somata rather than axons of secondary neurons generate the polarizing currents. Similarity between D.R.V and the positive intermediary potential further indicates that soma gradients established during the recovery cycle are responsible for D.R.V. Little or no net polarization of primary afferent fibers results from activity confined to the contralateral gray substance, the dorsal root potentials in contralateral recording resulting from interaction in the dorsal column or in the ipsilateral gray substance following decussation of contralaterally evoked activity. During the course of asphyxia the initial defect in reflex pathways is the failure of secondary neurons to respond to primary impulses. Subsequently block is established at the branching zone of primary afferent fibers. A relation exists between the sequence of dorsal root potentials and the cord potential sequence, the major departure from exact correspondence occurring in the region of D.R.IV and the negative intermediary potential and being of a nature to suggest that different aspects of internuncial activity are emphasized by the two methods of leading.
PMCID: PMC2147173  PMID: 18114558
10.  ATF3 upregulation in glia during Wallerian degeneration: differential expression in peripheral nerves and CNS white matter 
BMC Neuroscience  2004;5:9.
Many changes in gene expression occur in distal stumps of injured nerves but the transcriptional control of these events is poorly understood. We have examined the expression of the transcription factors ATF3 and c-Jun by non-neuronal cells during Wallerian degeneration following injury to sciatic nerves, dorsal roots and optic nerves of rats and mice, using immunohistochemistry and in situ hybridization.
Following sciatic nerve injury – transection or transection and reanastomosis – ATF3 was strongly upregulated by endoneurial, but not perineurial cells, of the distal stumps of the nerves by 1 day post operation (dpo) and remained strongly expressed in the endoneurium at 30 dpo when axonal regeneration was prevented. Most ATF3+ cells were immunoreactive for the Schwann cell marker, S100. When the nerve was transected and reanastomosed, allowing regeneration of axons, most ATF3 expression had been downregulated by 30 dpo. ATF3 expression was weaker in the proximal stumps of the injured nerves than in the distal stumps and present in fewer cells at all times after injury. ATF3 was upregulated by endoneurial cells in the distal stumps of injured neonatal rat sciatic nerves, but more weakly than in adult animals. ATF3 expression in transected sciatic nerves of mice was similar to that in rats. Following dorsal root injury in adult rats, ATF3 was upregulated in the part of the root between the lesion and the spinal cord (containing Schwann cells), beginning at 1 dpo, but not in the dorsal root entry zone or in the degenerating dorsal column of the spinal cord. Following optic nerve crush in adult rats, ATF3 was found in some cells at the injury site and small numbers of cells within the optic nerve displayed weak immunoreactivity. The pattern of expression of c-Jun in all types of nerve injury was similar to that of ATF3.
These findings raise the possibility that ATF3/c-Jun heterodimers may play a role in regulating changes in gene expression necessary for preparing the distal segments of injured peripheral nerves for axonal regeneration. The absence of the ATF3 and c-Jun from CNS glia during Wallerian degeneration may limit their ability to support regeneration.
PMCID: PMC400733  PMID: 15113454
11.  Spine surgery in neurological lesions of the cervicothoracic junction: multicentric experience on 33 consecutive cases 
European Spine Journal  2011;20(Suppl 1):13-19.
Surgical treatment of the cervico-thoracic junction (CTJ) in the spine require special evaluation due to the anatomical and biomechanical characteristics of this spinal section. The transitional zone between the mobile cervical and the relatively rigid thoracic spine can be the site of serious unstable traumas or neoplastic lesions. Frequently, injury is associated with neurological impairment due to the small caliber of the spinal canal and/or spinal cord vascular insufficiency. The authors considered 33 neurologic lesions of the CTJ (21 traumas, 10 tumors, 2 infections) treated by means of decompression, fixation, and fusion by different type of instrumentation. Surgical procedure was posterior in 26 cases, anterior in 1 and combined in 6. Major general complications were not found in patients undergoing anterior approach. Biomechanical failure was found in two patients operated by T1 body replacement and C7-T2 anterior plate. Serious cardio-respiratory complications were related to 2 polytrauma patients who underwent posterior surgery. Follow-up evaluation showed spinal stability and fusion in 88% of cases, improvement of the neurological deficits in 42% (19% improved to ASIA E), no or only occasional pain in 75% of patients. In the experience, recovery of spinal realignment and stability is essential to avoid disability due to back pain in trauma patients. In spinal tumors, back pain was related to local recurrence. Neurological outcomes can be unsatisfactory due to the initial serious impairment. There is no type of instrumentation more effective than other. In each single lesion, the most suitable type of instrumentation should be employed, considering morphology, biomechanics, and familiarity of the spinal surgeon with different implants and constructs. Therefore, we prefer to use posterior cervicothoracic fixation in T1 lesions with involvement of the vertebral body and subsequently replace the body with cage without anterior stabilization.
PMCID: PMC3087034  PMID: 21404033
Spine; Cervicothoracic junction; Instability; Operative treatment
12.  Lateral radiological evaluation of transarticular screw placement in the lower cervical spine 
European Spine Journal  2009;18(3):392-397.
This study assessed the ideal district of lateral radiograph in evaluation of transarticular screw placement in the lower cervical spine. To assess the ideal zone of lateral radiographs in determining the safe or hazardous locations of the screw tips during transarticular screw implantation in the lower cervical spine. Transarticular screw in the lower cervical spine had been used as an alternative technique to achieve posterior cervical spine stability. Injury to the spinal nerves caused by transarticular screws which are too long must be identified quickly to minimize the neurologic complication. No previous radiological study regarding evaluation of the transarticular screw placement using lateral radiographs has been reported. Twelve cervical spines were removed from embalmed cadavers. Four transarticular screw placements with Dalcanto’s technique under direct visualization, including placement of the screw tip staying the ventral cortex, 2, 4 and 6 mm over-penetration of the ventral cortex, were performed on each specimen. Following each placement, a lateral radiograph was taken. Each vertebral body was divided vertically into four equal zones, and another equal zone posterior to the posterior border of the vertebral body was defined as Zone pre-1. The numbers of screw tips seen in each zone were quantified for each placement. Partitions of χ2 method was used to evaluate the ideal zone on lateral radiograph for transarticular screw insertion. At C34 and C45, no significant difference was found between Zone pre-1 and Zone 1 (χ2 = 0.18, P > 0.50), while there was significant difference between Zones 1 and 2 (χ2 = 73.6, P < 0.005), as well as Zones 2 and 3 (χ2 = 13.2, P < 0.005). At C56 and C67, No significant difference was found between Zones 2 and 3 (χ2 = 0.25, P > 0.50), while there was significant difference between Zone pre-1 and Zone 1 (χ2 = 66.2, P < 0.005), as well as Zones 1 and 2 (χ2 = 10.5, P < 0.005). Ideal screw tip positions on lateral radiograph for transarticular screw by Dalcanto’s technique should be in Zone 1 at C34 and C45, in Zone pre-1 at C56 and C67. If the screw tip was in Zones 3 and 4, the safe rate will be decreased significantly and it might be too deep and be dangerous.
PMCID: PMC2899426  PMID: 19130097
Lower cervical spine; Transarticular screw placement; Cervical radiograph; Nerve root injury
13.  A new minimally invasive posterior approach for the treatment of cervical radiculopathy and myelopathy: surgical technique and preliminary results 
European Spine Journal  2003;12(3):268-273.
Degenerative cervical disorders predominantly lead to anterior spinal cord compression (by bony spurs at the posterior margin of the vertebral body or by degenerated disc), which may be central and/or foraminal. In a smaller percentage of cases, there is encroachment of the canal mainly from posterior by bulging yellow ligaments or bony appositions, resulting in compression syndromes of roots or spinal cord. The aim of this work is to present a minimally invasive posterior approach avoiding detachment of muscles for the treatment of cervical radiculopathy and myelopathy. Thirteen patients suffering from cervical radiculopathy (four patients) or myelopathy (nine patients) were operated according to this technique. In principle, the technique secures access to the diseased spinal segment via a percutaneously placed working channel (11 mm outer diameter and 9 mm inner diameter). The cervical paraspinal muscles are not deflected, but just spread between their fibres by special dilators. All further steps are performed through this channel under control of three-dimensional vision through the operating microscope. The mean follow-up period was 17 months (one patient died 9 months postoperatively), and patients were evaluated using a modified version of the Oswestry Index, called the Neck Disability Index (NDI), and the visual analogue scale (VAS) for neck and arm pain. The mean NDI (P<0.0001) improved from 13.2 (preoperatively) to 4.8 (postoperatively). The VAS for arm pain (P<0.001) and for neck pain (P<0.001) also showed marked postoperative improvement. Complete recovery of the preoperative neurological deficit was found in four patients, while the remaining eight patients showed improvement of the neurological symptoms during the follow-up period. There were no intra-operative or postoperative complications and no re-operation. The preliminary experience with this technique, and the good clinical outcome, seem to promise that this minimally invasive technique is a valid alternative to the conventional open exposure for treatment of lateral disc prolapses, foraminal bony stenosis and central posterior ligamentous stenosis of the cervical spine.
PMCID: PMC3615500  PMID: 12687439
Minimally invasive posterior approach Radiculopathy Myelopathy Foraminotomy Cervical spine
14.  Cervical Spine Stenosis Measures in Normal Subjects 
Journal of Athletic Training  2002;37(2):190-193.
Objective: To compare 2 methods of determining cervical spinal stenosis (Torg ratio, space available for the cord [SAC]); determine which of the components of the Torg ratio and the SAC account for more of the variability in the measures; and present standardized SAC values for normal subjects using magnetic resonance imaging (MRI).
Design and Setting: The research design consisted of a posttest-only, comparison-group design. The independent variable was method of measurement (Torg ratio and SAC). The dependent variables were Torg ratio and SAC scores.
Subjects: Fourteen men (age = 24.4 ± 2.5 years, height = 181.0 ± 5.8 cm, weight = 90 ± 13.5 kg) participated in this study. The C3 to C7 vertebrae were examined in each subject (n = 70).
Measurements: The Torg ratio was determined by dividing the sagittal spinal-canal diameter by the corresponding sagittal vertebral-body diameter. The SAC was determined by subtracting the sagittal spinal-cord diameter from the corresponding sagittal spinal-canal diameter. The Torg ratio and SAC were measured in millimeters.
Results: The SAC ranged from 2.5 to 10.4 mm and was greatest at C7 in 71% (10 of 14) of the subjects. The SAC was least at C3 or C5 in 71% (10 of 14) of the subjects. A Pearson product moment correlation revealed a significant relationship between the Torg ratio and SAC (r = .53, P < .01). Regression analyses revealed the vertebral body (r 2 = .58) accounted for more variability in the Torg ratio than the spinal canal (r 2 = .48). Also, the spinal canal (r 2 = .66) accounted for more variability in the SAC than the spinal cord (r 2 = .23).
Conclusions: The SAC measure relies more on the spinal canal compared with the Torg ratio and, therefore, may be a more effective indicator of spinal stenosis. This is relevant clinically because neurologic injury related to stenosis is a function of the spinal canal and the spinal cord (not the vertebral body). Further research must be done, however, to validate the SAC measure.
PMCID: PMC164344  PMID: 12937434
spinal stenosis; spinal cord; MRI
15.  Subdural spread of injected local anesthetic in a selective transforaminal cervical nerve root block: a case report 
Although uncommon, selective cervical nerve root blocks can have serious complications. The most serious complications that have been reported include cerebral infarction, spinal cord infarction, transient quadriplegia and death.
Case presentation
A 40-year-old Japanese woman with a history of severe right-sided cervical radicular pain was scheduled to undergo a right-sided C6 selective cervical nerve root block using a transforaminal approach under fluoroscopic guidance. An anterior oblique view of the C5-C6 intervertebral foramen was obtained, and a 23-gauge spinal needle, connected to the normal extension tube with a syringe filled with contrast medium, was introduced into the posterior-caudal aspect of the C5-C6 intervertebral foramen on the right side. In the anteroposterior view, the placement of the needle was considered satisfactory when it was placed no more medial than halfway across the width of the articular pillar. Although the spread of the contrast medium along the C6 nerve root was observed with right-sided C6 radiculography, the subdural flow of the contrast medium was not observed with real-time fluoroscopy. The extension tube used for the radiculography was removed from the spinal needle and a normal extension tube with a syringe filled with lidocaine connected in its place. We performed a negative aspiration test and then injected 1.5 mL of 1.0% lidocaine slowly around the C6 nerve root. Immediately after the injection of the local anesthetic, our patient developed acute flaccid paralysis, complained of breathing difficulties and became unresponsive; her respiratory pattern was uncoordinated. After 20 minutes, she regained consciousness and became alert, and her muscle strength in all four limbs returned to normal without any sensory deficits after receiving emergent cardiorespiratory support.
We believe that confirming maintenance of the appropriate needle position in the anteroposterior view by injecting local anesthetic is important for preventing central needle movement. Because the potential risk of serious complications cannot be completely eliminated during the use of any established selective cervical nerve root block procedure, preparation for an emergency airway, ventilation and cardiovascular support is indispensable in cases of high spinal cord anesthesia.
PMCID: PMC3414837  PMID: 22657834
16.  Expression of c-Fos and c-Jun in adjacent cervical spinal cord segments following C7 nerve root rhizotomy in rats: Indication of a neural pathway between adjacent cervical spinal cord segments 
Cervical radiculopathy is a common disease in clinical practice. However, the symptoms are not confined to the affected spinal cord segment indicated by magnetic resonance imaging (MRI) findings. In the present study, we measured c-Fos and c-Jun expression in ipsilateral and adjacent cervical spinal cord segments following C7 nerve root rhizotomy, to determine whether there is a neural pathway between adjacent cervical spinal cord segments. Forty-eight adult male Wistar rats were randomly divided into two groups: the C7 rhizotomy group (rhizotomy group, n=24) and the sham-operated group (sham group, n=24). The right C7 nerve root was completely cut off in the rhizotomy group, while it was exposed but not cut in the sham group. The expression of c-Fos and c-Jun in cervical spinal cord segments was detected by immunohistochemistry at 2 and 4 h after surgery. We observed that the number of c-Fos- and c-Jun-positive neurons in ipsilateral C5–7 segments were significantly increased at 2 and 4 h after C7 nerve root rhizotomy (P<0.05 vs. the sham group). The location of c-Fosand c-Jun-positive neurons in C5–7 gray matter was similar in the rhizotomy and sham groups, which was mainly in lamina IX of the anterior horn and laminae I–II of the dorsal horn of the spinal cord. However, the number of c-Fos- and c-Jun-positive neurons in the C5–7 gray matter was significantly reduced at 4 h after surgery compared with the number 2 h after surgery. The location of c-Fos- and c-Jun-positive neurons at 4 h was similar with that at 2 h. Therefore, there may be a neural pathway between ipsilateral adjacent cervical spinal cord segments. This may be one possible explanation as to why the radicular symptoms of cervical radiculopathy are not confined to the affected spinal cord segment shown by MRI.
PMCID: PMC3786826  PMID: 24137191
cervical radiculopathy; neural pathway; c-Fos; c-Jun; spinal cord
17.  Intracisternal Cranial Root Accessory Nerve Schwannoma Associated with Recurrent Laryngeal Neuropathy 
Intracisternal accessory nerve schwannomas are very rare; only 18 cases have been reported in the literature. In the majority of cases, the tumor origin was the spinal root of the accessory nerve and the tumors usually presented with symptoms and signs of intracranial hypertension, cerebellar ataxia, and myelopathy. Here, we report a unique case of an intracisternal schwannoma arising from the cranial root of the accessory nerve in a 58-year-old woman. The patient presented with the atypical symptom of hoarseness associated with recurrent laryngeal neuropathy which is noted by needle electromyography, and mild hypesthesia on the left side of her body. The tumor was completely removed with sacrifice of the originating nerve rootlet, but no additional neurological deficits. In this report, we describe the anatomical basis for the patient's unusual clinical symptoms and discuss the feasibility and safety of sacrificing the cranial rootlet of the accessory nerve in an effort to achieve total tumor resection. To our knowledge, this is the first case of schwannoma originating from the cranial root of the accessory nerve that has been associated with the symptoms of recurrent laryngeal neuropathy.
PMCID: PMC4200365  PMID: 25328655
Schwannoma; Accessory nerve; Intracisternal; Recurrent laryngeal neuropathy
18.  Medial Loop of V2 Segment of Vertebral Artery Causing Compression of Proximal Cervical Root 
It is rare that the medial loop in the V2 segment of the vertebral artery (VA) causes compression of the proximal cervical root of the spinal cord without leading to bony erosion and an enlarged foramen. We evaluated the clinical significance and incidence of the medial loop in the V2 segment of the VA.
We reviewed the records from 1000 consecutive patients who had undergone magnetic resonance imaging evaluation of the cervical spine between January 2005 and January 2008. The inclusion criteria were that over a third of the axial aspect of the VA located in the intervertebral foramen was inside the line between the most ventral points of the bilateral lateral mass, and that the ipsilateral proximal root deviated dorsally because of the medial loop of the VA. We excluded cases of bone erosion, a widened foramen at the medial loop of the VA, any bony abnormalities, tumors displacing VA, or vertebral fractures. The medical records were reviewed retrospectively to search for factors of clinical significance.
In six patients (0.6%), the VA formed a medial loop that caused compression of the proximal cervical root. One of these patients had the cervical radiculopathy that developed after minor trauma but the others did not present with cervical radiculopathy related to the medial loop of the VA.
The medial loop of the VA might have a direct effect on cervical radiculopathy. Therefore, this feature should be of critical consideration in preoperative planning and during surgery.
PMCID: PMC3550417  PMID: 23346321
Vertebral artery; Medial loop; Spine
19.  Computerized tomography myelography with coronal and oblique coronal view for diagnosis of nerve root avulsion in brachial plexus injury 
The authors describe a new computerized tomography (CT) myelography technique with coronal and oblique coronal view to demonstrate the status of the cervical nerve rootlets involved in brachial plexus injury. They discuss the value of this technique for diagnosis of nerve root avulsion compared with CT myelography with axial view.
CT myelography was performed with penetration of the cervical subarachnoid space by the contrast medium. Then the coronal and oblique coronal reconstructions were created. The results of CT myelography were evaluated and classified with presence of pseudomeningocele, intradural ventral nerve rootlets, and intradural dorsal nerve rootlets. The diagnosis was by extraspinal surgical exploration with or without spinal evoked potential measurements and choline acetyl transferase activity measurement in 25 patients and recovery by a natural course in 3 patients. Its diagnostic accuracy was compared with that of CT myelography with axial view, correlated with surgical findings or a natural course in 57 cervical roots in 28 patients.
Coronal and oblique coronal views were superior to axial views in visualization of the rootlets and orientation of the exact level of the root. Sensitivity and specificity for coronal and oblique coronal views of unrecognition of intradural ventral and dorsal nerve root shadow without pseudomeningocele in determining pre-ganglionic injury were 100% and 96%, respectively. There was no statistically significant difference between coronal and oblique coronal views and axial views.
The information by the coronal and oblique coronal slice CT myelography enabled the authors to assess the rootlets of the brachial plexus and provided valuable data for helping to decide whether to proceed with exploration, nerve repair, primary reconstruction.
PMCID: PMC1947985  PMID: 17651476
20.  Freehand determination of the trajectory angle for cervical lateral mass screws: how accurate is it? 
European Spine Journal  2011;20(6):972-976.
Different methods of lateral mass screw placement in the cervical spine have been described with separate trajectories for each technique in the sagittal and parasagittal planes. In the latter, plane 30° has been recommended in the modified Magerl’s technique as the optimum angle to avoid injury to the vertebral artery and nerve root. The estimation of this angle remains arbitrary and very much operator dependant. The aim of this study was to assess how accurately the lateral trajectory angle of 30° is achieved by visual estimation amongst experienced surgeons in a tertiary spinal unit and to determine the likelihood of neurovascular injury during the procedure. We chose an anatomical ‘sawbone’ model of the cervical spine with simulated lordosis. The senior author marked the entry points. Five spinal consultants and five senior spinal fellows were asked to insert 1.6-mm K wires into the lateral masses of C3 to C6 bilaterally at 30° to the midsagittal plane using the marked entry points. The lateral angulation in the transverse plane was measured using a custom protractor and documented for each surgeon at each level and side. The mean and standard deviation (SD) of the data were obtained to determine the inter observer variability. Utilising this data, measurements were then made on a normal axial computerised tomography (CT) scan of the cervical spine of an anonymous patient to determine if there would have been any neurovascular compromise. Among the 10 surgeons, a total of 80 insertion angles were measured from C3 to C6 on either side. The overall mean angle of insertion was 25.15 (range 20.4–34.8). The overall SD was 4.78. Amongst the 80 measurements between the ten surgeons, two episodes of theoretical vertebral artery violation were observed when the angles were simulated on the CT scan. A moderate but notable variability in trajectory placement exists between surgeons during insertion of cervical lateral mass screws. Freehand estimation of 30° is not consistently achieved between surgeons and levels. In patients with gross degenerative or deformed cervical spine anatomy, this may increase the risk of neurovascular injury. The use of the ipsilateral lamina as an anatomical reference plane is supported.
PMCID: PMC3099156  PMID: 21279393
Cervical spine; Lateral mass screw; Surgical technique; Reliability
21.  Extensive Neuronal Differentiation of Human Neural Stem Cell Grafts in Adult Rat Spinal Cord 
PLoS Medicine  2007;4(2):e39.
Effective treatments for degenerative and traumatic diseases of the nervous system are not currently available. The support or replacement of injured neurons with neural grafts, already an established approach in experimental therapeutics, has been recently invigorated with the addition of neural and embryonic stem-derived precursors as inexhaustible, self-propagating alternatives to fetal tissues. The adult spinal cord, i.e., the site of common devastating injuries and motor neuron disease, has been an especially challenging target for stem cell therapies. In most cases, neural stem cell (NSC) transplants have shown either poor differentiation or a preferential choice of glial lineages.
Methods and Findings
In the present investigation, we grafted NSCs from human fetal spinal cord grown in monolayer into the lumbar cord of normal or injured adult nude rats and observed large-scale differentiation of these cells into neurons that formed axons and synapses and established extensive contacts with host motor neurons. Spinal cord microenvironment appeared to influence fate choice, with centrally located cells taking on a predominant neuronal path, and cells located under the pia membrane persisting as NSCs or presenting with astrocytic phenotypes. Slightly fewer than one-tenth of grafted neurons differentiated into oligodendrocytes. The presence of lesions increased the frequency of astrocytic phenotypes in the white matter.
NSC grafts can show substantial neuronal differentiation in the normal and injured adult spinal cord with good potential of integration into host neural circuits. In view of recent similar findings from other laboratories, the extent of neuronal differentiation observed here disputes the notion of a spinal cord that is constitutively unfavorable to neuronal repair. Restoration of spinal cord circuitry in traumatic and degenerative diseases may be more realistic than previously thought, although major challenges remain, especially with respect to the establishment of neuromuscular connections.
When neural stem cells from human fetal spinal cord were grafted into the lumbar cord of normal or injured adult nude rats, substantial neuronal differentiation was found.
Editors' Summary
Every year, spinal cord injuries, many caused by road traffic accidents, paralyze about 11,000 people in the US. This paralysis occurs because the spinal cord is the main communication highway between the body and the brain. Information from the skin and other sensory organs is transmitted to the brain along the spinal cord by bundles of neurons, nervous system cells that transmit and receive messages. The brain then sends information back down the spinal cord to control movement, breathing, and other bodily functions. The bones of the spine normally protect the spinal cord but, if these are broken or dislocated, the spinal cord can be cut or compressed, which interrupts the information flow. Damage near the top of the spinal cord can paralyze the arms and legs (tetraplegia); damage lower down paralyzes the legs only (paraplegia). Spinal cord injuries also cause many other medical problems, including the loss of bowel and bladder control. Although the deleterious effects of spinal cord injuries can be minimized by quickly immobilizing the patient and using drugs to reduce inflammation, the damaged nerve fibers never regrow. Consequently, spinal cord injury is permanent.
Why Was This Study Done?
Scientists are currently searching for ways to reverse spinal cord damage. One potential approach is to replace the damaged neurons using neural stem cells (NSCs). These cells, which can be isolated from embryos and from some areas of the adult nervous system, are able to develop into all the specialized cells types of the nervous system. However, because most attempts to repair spinal cord damage with NSC transplants have been unsuccessful, many scientists believe that the environment of the spinal cord is unsuitable for nerve regeneration. In this study, the researchers have investigated what happens to NSCs derived from the spinal cord of a human fetus after transplantation into the spinal cord of adult rats.
What Did the Researchers Do and Find?
The researchers injected human NSCs that they had grown in dishes into the spinal cord of intact nude rats (animals that lack a functioning immune system and so do not destroy human cells) and into nude rats whose spinal cord had been damaged at the transplantation site. The survival and fate of the transplanted cells was assessed by staining thin slices of spinal cord with an antibody that binds to a human-specific protein and with antibodies that recognize proteins specific to NSCs, neurons, or other nervous system cells. The researchers report that the human cells survived well in the adult spinal cord of the injured and normal rats and migrated into the gray matter of the spinal cord (which contains neuronal cell bodies) and into the white matter (which contains the long extensions of nerve cells that carry nerve impulses). 75% and 60% of the human cells in the gray and white matter, respectively, contained a neuron-specific protein six months after transplantation but only 10% of those in the membrane surrounding the spinal cord became neurons; the rest developed into astrocytes (another nervous system cell type) or remained as stem cells. Finally, many of the human-derived neurons made the neurotransmitter GABA (one of the chemicals that transfers messages between neurons) and made contacts with host spinal cord neurons.
What Do These Findings Mean?
These findings suggest that human NSC grafts can, after all, develop into neurons (predominantly GABA-producing neurons) in normal and injured adult spinal cord and integrate into the existing spinal cord if the conditions are right. Although these animal experiments suggest that NSC transplants might help people with spinal injuries, they have some important limitations. For example, the spinal cord lesions used here are mild and unlike those seen in human patients. This and the use of nude rats might have reduced the scarring in the damaged spinal cord that is often a major barrier to nerve regeneration. Furthermore, the researchers did not test whether NSC transplants provide functional improvements after spinal cord injury. However, since other researchers have also recently reported that NSCs can grow and develop into neurons in injured adult spinal cord, these new results further strengthen hopes it might eventually be possible to use human NSCs to repair damaged spinal cords.
Additional Information.
Please access these Web sites via the online version of this summary at
The US National Institute of Neurological Disorders and Stroke provides information on spinal cord injury and current spinal cord research
Spinal Research (a UK charity) offers information on spinal cord injury and repair
The US National Spinal Cord Injury Association Web site contains factsheets on spinal cord injuries
MedlinePlus encyclopedia has pages on spinal cord trauma and interactive tutorials on spinal cord injury
The International Society for Stem Cell Research offers information on all sorts of stem cells including NSCs
The US National Human Neural Stem Cell Resource provides information on human NSCs, including the current US government's stance on stem cell research
PMCID: PMC1796906  PMID: 17298165
22.  Spinal shortening and monosegmental posterior spondylodesis in the management of dorsal and lumbar unstable injuries 
Patients with spinal injuries have been treated in the past by laminectomy in an attempt to decompress the spinal cord. The results have shown insignificant improvement or even a worsening of neurologic function and decreased stability without effectively removing the anterior bone and disc fragments compressing the spinal cord. The primary indication for anterior decompression and grafting is narrowing of the spinal canal with neurologic deficits that cannot be resolved by any other approach. One must think of subsequent surgical intervention for increased stability and compressive posterior fusion with short-armed internal fixators.
To analyze the results and efficacy of spinal shortening combined with interbody fusion technique for the management of dorsal and lumbar unstable injuries.
Materials and Methods:
Twenty-three patients with traumatic fractures and or fracture-dislocation of dorsolumbar spine with neurologic deficit are presented. All had radiologic evidence of spinal cord or cauda equina compression, with either paraplegia or paraparesis. Patients underwent recapping laminoplasty in the thoracic or lumbar spine for decompression of spinal cord. The T-saw was used for division of the posterior elements. After decompression of the cord and removal of the extruded bone fragments and disc material, the excised laminae were replaced exactly in situ to their original anatomic position. Then application of a compression force via monosegmental transpedicular fixation was done, allowing vertebral end-plate compression and interbody fusion.
Lateral Cobb angle (T10–L2) was reduced from 26 to 4 degrees after surgery. The shortened vertebral body united and no or minimal loss of correction was seen. The preoperative vertebral kyphosis averaged +17 degrees and was corrected to +7 degrees at follow-up with the sagittal index improving from 0.59 to 0.86. The segmental local kyphosis was reduced from +15 degrees to −3 degrees. Radiography demonstrated anatomically correct reconstruction in all patients, as well as solid fusion.
This technique permits circumferential decompression of the spinal cord through a posterior approach and posterior interbody fusion.
PMCID: PMC3122988  PMID: 21716869
Injury; laminoplasty; spine; shortening; spondylodesis
23.  Analysis of axonal regeneration in the central and peripheral nervous systems of the NG2-deficient mouse 
BMC Neuroscience  2007;8:80.
The chondroitin sulphate proteoglycan NG2 blocks neurite outgrowth in vitro and has been proposed as a major inhibitor of axonal regeneration in the CNS. Although a substantial body of evidence underpins this hypothesis, it is challenged by recent findings including strong expression of NG2 in regenerating peripheral nerve.
We studied axonal regeneration in the PNS and CNS of genetically engineered mice that do not express NG2, and in sex and age matched wild-type controls. In the CNS, we used anterograde tracing with BDA to study corticospinal tract (CST) axons after spinal cord injury and transganglionic labelling with CT-HRP to trace ascending sensory dorsal column (DC) axons after DC lesions and a conditioning lesion of the sciatic nerve. Injury to these fibre tracts resulted in no difference between knockout and wild-type mice in the ability of CST axons or DC axons to enter or cross the lesion site. Similarly, after dorsal root injury (with conditioning lesion), most regenerating dorsal root axons failed to grow across the dorsal root entry zone in both transgenic and wild-type mice.
Following sciatic nerve injuries, functional recovery was assessed by analysis of the toe-spreading reflex and cutaneous sensitivity to Von Frey hairs. Anatomical correlates of regeneration were assessed by: retrograde labelling of regenerating dorsal root ganglion (DRG) cells with DiAsp; immunostaining with PGP 9.5 to visualise sensory reinnervation of plantar hindpaws; electron microscopic analysis of regenerating axons in tibial and digital nerves; and by silver-cholinesterase histochemical study of motor end plate reinnervation. We also examined functional and anatomical correlates of regeneration after injury of the facial nerve by assessing the time taken for whisker movements and corneal reflexes to recover and by retrograde labelling of regenerated axons with Fluorogold and DiAsp. None of the anatomical or functional analyses revealed significant differences between wild-type and knockout mice.
These findings show that NG2 is unlikely to be a major inhibitor of axonal regeneration after injury to the CNS, and, further, that NG2 is unlikely to be necessary for regeneration or functional recovery following peripheral nerve injury.
PMCID: PMC2100060  PMID: 17900358
24.  Variations in Entrance of Vertebral Artery in Korean Cervical Spine: MDCT-based Analysis 
The Korean Journal of Pain  2014;27(3):266-270.
Knowledge of the anatomical variation of the vertebral artery has clinical importance not only for the performance of interventional or surgical procedures itself but also to ensure their safety. We conducted a study of the anatomical variation by reviewing multi-detector computed tomography (MDCT) images of the cervical spine from 460 Korean patients.
16-row MDCT data from 460 patients were used in this study. We observed 920 vertebral arteries. Examination points included level of entrance of the artery into the transverse foramen of the cervical vertebra, origin site of the vertebral artery, course of a vertebral artery with aberrant entrance.
The vertebral artery in 2 (0.2%) cases in this study entered into the transverse foramen of the 7th cervical vertebra from the left. In 45 (4.9%) cases, the vertebral artery entered into the transverse foramen of the 5th cervical vertebra. Of these, the entrance was on the right in 15 (1.6%) and on the left in 30 (3.3%). We found 17 (1.8%) cases in which the artery entered into the transverse foramen of the 4th cervical vertebra, 10 (1.1%) on the right and 7 (0.7%) on the left side. As is commonly acknowledged, the 6th cervical vertebra was the most common site of entry; the vertebral artery entered the transverse foramen of the 6th cervical vertebra in the remaining 855 (93.0%) cases, on the right in 434 (47.2%) and on the left in 421 (45.8%).
In conclusion, the possibility of an atypical course of the vertebral artery in segments V1 and V2 should be evaluated with magnetic resonance imaging (MRI) or CT images before carrying out procedures involving the anterior cervical vertebrae.
PMCID: PMC4099240  PMID: 25031813
cervical spine; multi-detector computed tomography; vertebral artery
25.  Operative treatment of unstable injuries of the cervicothoracic junction 
European Spine Journal  1999;8(4):279-283.
The authors present their experience in the operative treatment of unstable lesions at the cervicothoracic junction. Ten patients, six men and four women, underwent operative procedures at the cervicothoracic junction (C7-T1) between 1990 and 1997. Six patients had sustained fracture-dislocations, three patients had metastases and one patient had a primary malignant lesion. All the patients had significant cervical pain and neurologic deficit. The spinal cord and nerves were decompressed in all cases. Posterior stabilization was accomplished using various types of implants including hooks, wires and rods. Anteriorly, the spine was stabilized with plates and screws. Partial or complete vertebrectomy was performed in five cases and a titanium cylinder or an iliac autograft replaced the vertebral body. Five patients were submitted to a posterior operation only, and the other five to bilateral procedures. In four of these a one-stage operation was performed and in the last case a two-stage procedure. The anatomic and biomechanical characteristics of the cervicothoracic junction require a precise pre-operative analysis of the local anatomy and the selection of the proper implants for anterior and posterior stabilization.
PMCID: PMC3611184  PMID: 10483829
Key words Spine; Cervicothoracic junction; Instability; Operative treatment

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