Nucleoplasty is a percutaneous disc decompression using radiofrequency energy. Bipolar radiofrequency coagulation denaturalizes proteoglycan and changes the internal environment of the diseased nucleus pulposus; especially, the organic molecules (collagen and collagen like long chain molecules) inside the disc is changed to liquid or gaseous state, which is absorbed and removed at the target site [2
]. Chen et al. proved that the decompression using Coblation® technique decreased the pressure in the disc with an experiment in a cadaveric specimen [6
]. The advantage of the Coblation® technique used in nucleoplasty is that exceptionally precise and targeted removal is possible while minimizing the thermal injury to the surrounding tissue [7
In proceeding with cervical nucleoplasty, the selection of a suitable patient is the most important. When Birnbaum's recommendations [8
] and indications of lumbar nucleoplasty are considered, they are as follows [5
]: 1) In the case of lateral herniation, presence of radicular/ axial pain while arm pain is severe than neck pain, MRI evidence of contained herniation, and failure of conservative treatment. 2) In the case of central herniation, presence of axial neck pain, unresponsive to 3 months of conservative treatment, MRI evidence of contained herniation, and the disc height more than 75%. Exclusion criteria include that the disc height less than 50%, extruded or sequestrated disc, spinal fracture or tumor, spinal stenosis, complete disruption of the annulus fibrosis, central myelopathy, instability from degeneration, and extrusion more than 1/3 of the spinal canal.
Nardi et al. [1
] argued that patient who can be a candidate for cervical nucleoplasty must have contained herniation or focal bulging proven on MRI, but Bonaldi et al. [2
] reported that the cervical nucleoplasty was performed in the patients who had a bulging, protruding, or soft extruded disc which was not sequestrated or migrated determined by MRI or CT studies. In our study, we performed cervical nucleoplasty on patients showing extrusion and stenosis in addition to protrusion on their MRI; who had no improvement from more than 3 months of conservative treatment including appropriate pain management; who keenly want non-surgical treatment over surgical treatment; and after adequate explanation on the possibility of failure, possible side-effects and costs of nucleoplasty. In MRI studies taken before the procedure, only 17 patients from the total 22 patients had disc protrusion suitable for indications, and from the 5 patients who had non-indication, 2 patients showed extrusion while the other 3 patients showed degenerative spinal stenosis. From these patients who had disc extrusion, one expressed 'excellent' according to the Modified McNab criteria after the cervical nucleoplasty and the other one was also satisfied and expressed 'good'. From the 3 patients who had degenerative spinal stenosis, one expressed 'excellent while the other 2 expressed 'fair'. Considering these results, although more clinical experience should be accumulated, nucleoplasty could be considered in disc disorders like soft disc extrusions and stenosis prior to surgical treatment if the patient wants non-surgical treatment; however, cautious application of cervical nucleoplasty should be taken after consideration of cost and possible side-effects [5
In this study, postprocedure MRI studies were acquired in 2 patients who had shown clinical improvement after 2 months follow up. MRI study in one patient showed a morphologic evidence of volume reduction of protruded disc material but the other did not. Nardi et al. [1
] had reported that regression of the herniated disc shown on the MRI has a correlation with clinical resolution, but Bonaldi et al. [2
] reported that clinical improvement did not always accompany the regression of the herniated disc on MRI. Even in cases where there seems to be no regression of the herniated disc material, a minute reduction in the disc adjacent to the nerve root can cause nerve root pressure to fall below the critical point. If the postprocedure MRI had been acquired in all patients, we could have gained more information from the results. However, it was not possible due to the economic circumstances of the patients.
Few side effects concerning the cervical nucleoplasty have been reported and no serious side effects have been known. Side effects reported in the study of Bonaldi et al. [2
] included 1 case of infectious discitis out of 55 patients, temporary side effects related to local anesthetic (bradycardia, Horner's syndrome, hoarseness, etc.), and retrosternal and retropharyngeal pain in patients treated on 3 levels but they responded well to conservative treatment [11
]. There was no significant complication related to the procedure within the first month in our study.
Nardi et al. [1
] and Birnbaum [8
] had proven the efficacy of nucleoplasty by comparing the cervical nucleoplasty group and the conservative treatment group. Bonaldi et al. [2
] performed cervical nucleoplasty on 55 patients and reported that it was successful in 85% of them. Li et al. [13
] reported that 83.73% from the 126 patients treated reported 'excellent' or 'good' according to the MacNab criteria. In our study, 76% of the patients expressed satisfaction by answering 'good' or 'excellent'. These results of cervical nucleoplasty appear to be much better than the results of lumbar nucleoplasty [3
]. However, the reasons that the nucleoplasty treatment may be more effective at the cervical level than at the lumbar level are not clear. One possible explanation could be anatomic: The cervical nerve root is confined to a relatively smaller space than its lumbar counterpart so the cervical nerve root respond more sensitively to even a minute reduction. For this reason, even if the pressure of the disc is reduced slightly, the decompression on the nerve root and reduction in clinical symptoms can be easily obtained. Another reason could be the topography of the lesion and direction from which it is approached for treatment. In lumbar nucleoplasty, we use a posterolateral approach from the lesion. But in cervical nucleoplasty, we use anterolateral approach to the disc, and so, the SpineWand™ could be accurately positioned in the lesion site posteriorly located. In other words, since symptomatic herniation is directed posterior, cervical nucleoplasty can effectively approach the lesion site because it uses the anterior approach [2
Another benefits of cervical nucleoplasty are that it does not have any influence on the stability of the cervical vertebrae compared to surgical treatment [13
]; it is minimally invasive since it uses a 19-gauge introducer needle, which is smaller compared to other percutaneous decompression; the Perc™ DC™ SpineWand that is handled by the surgeon is small and hard so it could be operated more precisely; it only takes a 10-12 minutes to treat one level of disc; and there is a markedly low possibility of damage to the surrounding tissue [5
Upon retrospective examination of the medical records of the 22 patients that were treated in our hospital, clinical improvement in symptoms within a month after cervical nucleoplasty were seen in most patients. Most of the patients reported the reduced subjective symptoms, such as radicular and axial pain, and an improved quality of life. Consequently, they expressed satisfaction with the cervical nucleoplasty.
In conclusion, in the treatment of cervical disc disorders, cervical nucleoplasty is minimally invasive, easy and has fewer complications than the surgical treatment. Therefore, when there is no response to conservative treatment, cervical nucleoplasty can be considered as a suitable alternative prior to open surgical treatment. However, to obtain good clinical results, appropriate selection of patients according to the indications of nucleoplasty must precede the procedure, and more experience and research should be accumulated for other indications such as extrusion and stenosis.