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1.  Anatomic Feasibility of Posterior Cervical Pedicle Screw Placement in Children: Computerized Tomographic Analysis of Children Under 10 Years Old 
To evaluate the anatomical feasibility of 3.5 mm screw into the cervical spine in the pediatric population and to establish useful guidelines for their placement.
A total of 37 cervical spine computerized tomography scans (24 boys and 13 girls) were included in this study. All patients were younger than 10 years of age at the time of evaluation for the period of 2007-2011.
For the C1 screw placement, entry point height (EPH) was the most restrictive factor (47.3% patients were larger than 3.5 mm). All C2 lamina had a height larger than 3.5 mm and 68.8% (51/74) of C2 lamina had a width thicker than 3.5 mm. For C2 pedicle width, 55.4% (41/74) of cases were larger than 3.5 mm, while 58.1% (43/74) of pedicle heights were larger than 3.5 mm. For pedicle width of subaxial spine, 75.7% (C3), 73% (C4), 82.4% (C5), 89.2% (C6), and 98.1% (C7, 1/54) were greater than 3.5 mm. Mean lamina width of subaxial cervical spine was 3.1 (C3), 2.7 (C4), 2.9 (C5), 3.8 (C6), and 4.0 mm (C7), respectively. Only 34.6% (127/370) of subaxial (C3-7) lamina thickness were greater than 3.5 mm. Mean length of lateral mass for the lateral mass screw placement was 9.28 (C3), 9.08 (C4), 8.81 (C5), 8.98 (C6), and 10.38 mm (C7).
C1 lateral mass fixation could be limited by the morphometrics of lateral mass height. C2 trans-lamina approach is preferable to C2 pedicle screw fixation. In subaxial spines, pedicle screw placement was preferable to trans-lamina screw placement, except at C7.
PMCID: PMC4303722  PMID: 25628806
Anatomical morphometrics; Cervical spine; Pediatric population; Screw placement
2.  Intraoperative Monitoring of Motor-Evoked Potentials for Supratentorial Tumor Surgery 
The purpose of this study was to assess the feasibility and clinical efficacy of motor evoked potential (MEP) monitoring for supratentorial tumor surgery.
Between 2010 and 2012, to prevent postoperative motor deterioration, MEP recording after transcranial stimulation was performed in 84 patients with supratentorial brain tumors (45 males, 39 females; age range, 24-80 years; median age, 58 years). MEP monitoring results were correlated with postoperative motor outcome compared to preoperative motor status.
MEP recordings were stable in amplitude (<50% reduction in amplitude) during surgery in 77 patients (91.7%). No postoperative motor deficit was found in 66 out of 77 patients with stable MEP amplitudes. However, postoperative paresis developed in 11 patients. False negative findings were associated with edema in peri-resectional regions and postoperative bleeding in the tumor bed. MEP decrease in amplitude (>50%) occurred in seven patients (8.3%). However, no deficit occurred postoperatively in four patients following preventive management during the operation. Three patients had permanent paresis, which could have been associated with vascular injury during tumor resection.
MEP monitoring during supratentorial tumor surgery is feasible and safe. However, false negative MEP results associated with postoperative events may occur in some patients. To achieve successful monitoring, collaboration between surgeon, anesthesiologist and an experienced technician is mandatory.
PMCID: PMC4200373  PMID: 25328645
Brain tumor; Intraoperative monitoring; Motor-evoked potentials; Supratentorial; Surgery
3.  Analysis of Measurement Accuracy for Craniovertebral Junction Pathology : Most Reliable Method for Cephalometric Analysis 
This study was designed to determine the most reliable cephalometric measurement technique in the normal population and patients with basilar invagination (BI).
Twenty-two lateral radiographs of BI patients and 25 lateral cervical radiographs of the age, sex-matched normal population were selected and measured on two separate occasions by three spine surgeons using six different measurements. Statistical analysis including intraclass correlation coefficient (ICC) was carried out using the SPSS software (V. 12.0).
Redlund-Johnell and Modified (M)-Ranawat had a highest ICC score in both the normal and BI groups in the inter-observer study. The M-Ranawat method (0.83) had a highest ICC score in the normal group, and the Redlund-Johenll method (0.80) had a highest ICC score in the BI group in the intra-observer test. The McGregor line had a lowest ICC score and a poor ICC grade in both groups in the intra-observer study. Generally, the measurement method using the odontoid process did not produce consistent results due to inter and intra-observer differences in determining the position of the odontoid tip. Opisthion and caudal point of the occipital midline curve are somewhat ambiguous landmarks, which induce variable ICC scores.
On the contrary to other studies, Ranawat method had a lower ICC score in the inter-observer study. C2 end-plate and C1 arch can be the most reliable anatomical landmarks.
PMCID: PMC3841268  PMID: 24294449
Cephalometric measurement; Basilar invagination; Odontoid process; Opisthion; C2 end plate; C1 arch
4.  Split Cord Malformation Combined with Tethered Cord Syndrome in an Adult 
Split cord malformations (SCMs) usually present in childhood, and are rarely reported in adults. And also, a cervicothoracic SCM associated with tethered cord syndrome has very rarely been reported in the literature. We report a case of SCM associated with tethered cord and spina bifida in an adult. This report describes the case of a 34-year-old woman who presented for evaluation of neck pain, back pain, and intermittent paraparesis of several months duration. The MRI and CT showed a SCM at the cervicothoracic level and a fibrous septum at the thoracic level. She underwent surgery for the SCM and tethered cord syndrome, and was followed for 7 years. Patient presented complete recovery in the follow-up. The authors discuss this unusual lesion and describe the anatomical relationship of the level of cord duplication and fibrous septum.
PMCID: PMC3841284  PMID: 24294465
Split cord malformation; Adult; Tethered cord syndrome
5.  Position Change of the Neurovascular Structures around the Carpal Tunnel with Dynamic Wrist Motion 
The purpose of this study was to determine the anatomic relationships between neurovascular structures and the transverse carpal ligament so as to avoid complications during endoscopic carpal tunnel surgery.
Twenty-eight patients (age range, 35-69 years) with carpal tunnel syndrome were entered into the study. We examined through wrist magnetic resonance imaging in three different positions (neutral, radial flexion, and ulnar flexion) and determined several anatomic landmark (distance from the hamate hook to the median nerve, ulnar nerve, and ulnar vessel) based on the lateral margin of the hook of the hamate. The median nerve and ulnar neurovascular structure were studied with the wrist in the neutral, ulnar, and radial flexion positions.
The ulnar neurovascular structures usually passed just over or ulnar to the hook of the hamate. However, in 12 hands, a looped ulnar artery coursed 0.6-3.3 mm radial to the hook of the hamate and continued to the superficial palmar arch. The looped ulnar artery migrates on the ulnar side of Guyon's canal (-5.2-1.8 mm radial to the hook of the hamate) with the wrist in radial flexion. During ulnar flexion of the wrist, the ulnar artery shifts more radially beyond the hook of the hamate (-2.5-5.7 mm).
It is appropriate to transect the ligament greater than 4 mm apart from the lateral margin of the hook of the hamate without placing the edge of the scalpel toward the ulnar side. We would also recommend not transecting the transverse carpal ligament in the ulnar flexed wrist position to protect the ulnar neurovascular structure.
PMCID: PMC3243843  PMID: 22200022
Carpal tunnel syndrome; Ulnar neurovascular structures; Wrist position
6.  A Computed Tomography-Based Anatomic Comparison of Three Different Types of C7 Posterior Fixation Techniques : Pedicle, Intralaminar, and Lateral Mass Screws 
The intralaminar screw (ILS) fixation technique offers an alternative to pedicle screw (PS) and lateral mass screw (LMS) fixation in the C7 spine. Although cadaveric studies have described the anatomy of the pedicles, laminae, and lateral masses at C7, 3-dimensional computed tomography (CT) imaging is the modality of choice for pre-surgical planning. In this study, the goal was to determine the anatomical parameter and optimal screw trajectory for ILS placement at C7, and to compare this information to PS and LMS placement in the C7 spine as determined by CT evaluation.
A total of 120 patients (60 men and 60 women) with an average age of 51.7±13.6 years were selected by retrospective review of a trauma registry database over a 2-year period. Patients were included in the study if they were older than 15 years of age, had standardized axial bone-window CT imaging at C7, and had no evidence of spinal trauma. For each lamina and pedicle, width (outer cortical and inner cancellous), maximal screw length, and optimal screw trajectory were measured, and the maximal screw length of the lateral mass were measured using m-view 5.4 software. Statistical analysis was performed using Student's t-test.
At C7, the maximal PS length was significantly greater than the ILS and LMS length (PS, 33.9±3.1 mm; ILS, 30.8±3.1 mm; LMS, 10.6±1.3; p<0.01). When the outer cortical and inner cancellous width was compared between the pedicle and lamina, the mean pedicle outer cortical width at C7 was wider than the lamina by an average of 0.6 mm (pedicle, 6.8±1.2 mm; lamina, 6.2±1.2 mm; p<0.01). At C7, 95.8% of the laminae measured accepted a 4.0-mm screw with a 1.0 mm of clearance, compared with 99.2% of pedicle. Of the laminae measured, 99.2% accepted a 3.5-mm screw with a 1.0 mm clearance, compared with 100% of the pedicle. When the outer cortical and inner cancellous height was compared between pedicle and lamina, the mean lamina outer cortical height at C7 was wider than the pedicle by an average of 9.9 mm (lamina, 18.6±2.0 mm; pedicle, 8.7±1.3 mm; p<0.01). The ideal screw trajectory at C7 was also measured (47.8±4.8° for ILS and 35.1±8.1° for PS).
Although pedicle screw fixation is the most ideal instrumentation method for C7 fixation with respect to length and cortical diameter, anatomical aspect of C7 lamina is affordable to place screw. Therefore, the C7 intralaminar screw could be an alternative fixation technique with few anatomic limitations in the cases when C7 pedicle screw fixation is not favorable. However, anatomical variations in the length and width must be considered when placing an intralaminar or pedicle screw at C7.
PMCID: PMC3218172  PMID: 22102943
Intralaminar screw; Pedicle screw; Lateral mass screw; Anatomic study
7.  Is Computerized Tomography Angiographic Surveillance Valuable for Prevention of Tracheoinnominate Artery Fistula, a Life-Threatening Complication after Tracheostomy? 
The aim of this study was to evaluate the utility of volume-rendered helical computerized tomography (CT) angiography focusing tracheostomy tube and innominate artery for prevention of tracheoinnominate artery fistula.
The authors retrospectively analyzed 22 patients with tracheostomy who had checked CT angiography. To evaluate the relationship between tracheostomy tube and innominate artery, we divided into three categories. First, proximal tube position based on cervical vertebra, named "tracheostomy tube departure level (TTDL)". Second, distal tube position and course of innominate artery, named "tracheostomy tube-innominate artery configuration (TTIC)". Third, the gap between the tube and innominate artery, named "tracheostomy tube to innominate artery gap (TTIG)". The TTDL/TTIC and TTIG are based on 3-dimensional (3D) reconstruction around tracheostomy and enhanced axial slices of upper chest, respectively.
First, mean TTDL was 6.8±0.6. Five cases (23%) were lower than C7 vertebra. Second, TTIC were remote to innominate artery (2 cases; 9.1%), matched with it (14 cases; 63.6%) or crossed it (6 cases; 27.3%). Only 9% of cases were definitely free from innominate artery injury. Third, average TTIG was 4.3±4.6 mm. Surprisingly, in 6 cases (27.3%), innominate artery, trachea wall and tracheostomy tube were tightly attached all together, thus have much higher probability of erosion.
If low TTDL, match or crossing type TTIC with reverse-L shaped innominate artery, small trachea and thin TTIG are accompanied all together, we may seriously consider early plugging and tube removal.
PMCID: PMC3079095  PMID: 21519499
Tracheoinnominate artery fistula; Tracheostomy; Computerized tomography angiography; Imaging study; Complication
8.  Noncommunicating Spinal Extradural Meningeal Cyst in Thoracolumbar Spine 
Spinal extradural meningeal cyst has been rarely reported, whose etiologies are assumed to be the communication of cerebrospinal fluid (CSF) between intradural subarchnoid space and cyst due to the congenital defect in dura mater. Although the CSF communication due to this defect can be found, in most case, few cases in which there is a lack of the communication have also been reported. We report a case of the huge extradural meningeal cyst occurring in the thoracolumbar spine (from T10 to L2) where there was a lack of the communication between the intradural subarachnoid space and cyst in a 46-year-old man who presented with symptoms that were indicative of progressive paraparesis and leg pain. The patient underwent laminectomy and cyst excision. On intraoperative findings, the dura was intact and there was a lack of the communication with intradural subarachnoid space. Immediately after the surgery, weakness and leg pain disappeared shortly.
PMCID: PMC3053550  PMID: 21430982
Meningeal cyst; Noncommunicating; Cerebrospinal fluid; Thoracolumbar spine
9.  Neurologic Complication Following Spinal Epidural Anesthesia in a Patient with Spinal Intradural Extramedullary Tumor 
Paraplegia following spinal epidural anesthesia is extremely rare. Various lesions for neurologic complications have been documented in the literature. We report a 66-year-old female who developed paraplegia after left knee surgery for osteoarthritis under spinal epidural anesthesia. In the recovery room, paraplegia and numbness below T4 vertebra was checked. A magnetic resonance image (MRI) scan showed a spinal thoracic intradural extramedullary (IDEM) tumor. After extirpation of the tumor, the motor weakness improved to the grade of 3/5. If a neurologic deficit following spinal epidural anesthesia does not resolve, a MRI should be performed without delay to accurately diagnose the cause of the deficit and optimal treatment should be rendered for the causative lesion.
PMCID: PMC3053553  PMID: 21430985
Spinal epidural anesthesia; Spinal intradural extramedullary tumor
10.  C7 Posterior Fixation Using Intralaminar Screws : Early Clinical and Radiographic Outcome 
The use of segmental instrumentation technique using pedicle screw has been increasingly popular in recent years owing to its biomechanical stability. Recently, intralaminar screws have been used as a potentially safer alternative to traditional fusion constructs involving fixation of C2 and the cervicothoracic junction including C7. However, to date, there have been few clinical series of C7 laminar screw fixation in the literature. Thus, the purpose of this study is to report our clinical experiences using C7 laminar screw and the early clinical outcome of this rather new fixation technique.
Thirteen patients underwent C7 intralaminar fixation to treat lesions from trauma or degenerative disease. Seventeen intralaminar screws were placed at C7. The patients were assessed both clinically and radiographically with postoperative computed tomographic scans.
There was no violation of the screw into the spinal canal during the procedure and no neurological worsening or vascular injury from screw placement. The mean clinical and radiographic follow up was about 19 months, at which time there were no cases of screw pull-out, screw fracture or non-union. Complications included two cases of dorsal breech of intralaminar screw and one case of postoperative infection.
Intralaminar screws can be potentially safe alternative technique for C7 fixation. Even though this technique cannot be used in the cases of C7 laminar fracture, large margin of safety and the ease of screw placement create a niche for this technique in the armamentarium of spine surgeons.
PMCID: PMC2941855  PMID: 20856661
Cervical spine; Posterior screw fixation; Intralaminar screw; C7
11.  Cerebellar Hemorrhage after Burr Hole Drainage of Supratentorial Chronic Subdural Hematoma 
Cerebellar hemorrhage is an unusual complication of supratentorial neurosurgery. To the best of our knowledge, only three case reports have described the occurrence of cerebellar hemorrhage after burr hole drainage for the treatment of chronic subdural hematoma (SDH). We present the case of a patient with this rare postoperative complication of cerebellar hemorrhage after burr hole drainage of a chronic SDH. Although burr hole drainage for the treatment of chronic SDH is rare complication, it is necessary to be aware of the possibility of cerebellar hemorrhage after supratentorial surgery, even with limited surgery such as burr hole drainage of a chronic SDH.
PMCID: PMC2803280  PMID: 20062580
Cerebral hemorrhage; Subdural hematoma; Craniotomy; Complication; Supratentorial
12.  Surgical Treatment of Orbital Tumors at a Single Institution 
The authors reviewed the experience of 19 patients with orbital tumors and summarize the clinical features, surgical treatment and outcomes.
The authors searched the database for all patients who underwent surgery for the treatment of orbital tumors at a single institution between 1999 and 2007. Data from clinical notes, surgical reports, and radiological findings were obtained for the analysis.
Orbital tumors constituted a heterogenous array of histopathology. The presenting symptoms were exophthalmos (52.6%), visual disturbance (26.3%) and pain (21.1%). The surgical approaches used were transcranial in 17 patients. Tumors located in the intraconal or perioptic space were surgically excised using a frontoorbital approach (8 cases), while pterional (3 cases), orbital (2 cases) and combined approaches (6 cases) were used for tumors in other sites. Total resection of tumors was achieved in 12 of 19 patients. In 4 patients with glioma and lymphoma only diagnostic biopsy was done. Three patients experienced visual deterioration postoperatively. Two patients had temporary diplopia, and one patient had temporary ptosis.
Surgical treatment could be the mainstay of therapy for the majority of symptomatic orbital tumors. Many orbital tumors can be treated safely via a transcranial approach. Frontoorbital approach allows the surgeon to reach both the intraorbital and intracranial structures. Knowledge of the microanatomy of the orbit and meticulous surgical skills are necessary to overcome the pitfalls of intraorbital surgery.
PMCID: PMC2588297  PMID: 19096665
Orbit; Tumor; Surgery; Approach; Exophthalmos
13.  Two Cases of Symptomatic Perineural Cysts (Tarlov Cysts) in One Family: A Case Report 
Symptomatic sacral perineural cysts are uncommon. Several hypotheses have been proposed to explain the etiologies of perineural cysts, but the accurate etiologies remain unclear. We experienced two cases of symptomatic sacral perineural cysts (Tarlov cysts) in one family, who presented with perianal paresthesia. Both of them were operated and postoperatively their symptoms were disappeared immediately. We experienced the excellent treatment outcome with the surgical management of symptomatic perineural cysts in the sacral region. We assume that the theory of congenital origin including a familial tendency is the most plausible of the hypotheses that have been proposed.
PMCID: PMC2588291  PMID: 19096672
Tarlov cyst; Sacrum; Congenital
14.  Posterior Epidural Migration of Thoracic Disc Fragment 
Migration of a disc fragment to the posterior epidural space is rare, especially in the thoracic spine. Only four such cases of posterior epidural migration of thoracic disc fragments have been reported. The authors report a case of 66-year-old man who presented with back pain and right leg weakness due to posterior epidural migration of thoracic disc fragment. The patient was successfully treated by laminectomy and partial facetectomy with disc removal.
PMCID: PMC2588224  PMID: 19096604
Thoracic disc herniation; Migration; Posterior epidural space; Magnetic resonance imaging

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