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|Year : 2020 | Volume
| Issue : 2 | Page : 305-306
Commentary on Surgical Treatment of Scoliosis-Associated with Syringomyelia: The Role of Syrinx Size
Richard Menger1, Anthony Sin2
1 Chief of Complex Spine Surgery, Assistant Professor of Neurosurgery, Assistant Professor of Political Science, University of South Alabama, AL 36688, United States
2 Vice-Chair and Director of Complex Spinal Disorders, Professor Department of Neurosurgery, Louisiana State University Health Sciences Center-Shreveport, LA 71101, United States
|Date of Web Publication||15-May-2020|
Chief of Complex Spine Surgery, Assistant Professor of Neurosurgery, Assistant Professor of Political Science, University of South Alabama, AL 36688
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Menger R, Sin A. Commentary on Surgical Treatment of Scoliosis-Associated with Syringomyelia: The Role of Syrinx Size. Neurol India 2020;68:305-6
Spinal deformity surgery in the setting of syringomyelia can be directly linked with higher post-operative deficits and frustrating intraoperative monitoring challenges. Scoliosis is found in 20% of patients with Chiari malformation Type 1 and up to 60% of patients with syringomyelia.
Those with syrinx of at least half of spinal cord diameter are at a risk for the motor loss during surgery. Those with an absolute syrinx of 10mm tend to have challenges related to neuromonitoring. The debate has existed regarding the timing and mechanism of intervention related to patients with scoliosis.
Here, the authors illustrate an interesting retrospective series of 26 patients reviewed over a six-year period through a single institution. Their study revealed no correlation between syrinx size and curve severity in sygrinomyeliga scoliosis (SMS) patients. The author's findings centred on the potential benefit of prophylactic neurosurgery in decreasing the risk of spinal correction surgery in SMS patients with large syrinx (S/C ratio > 0.7). The premise being that patients with large syrinx could obtain similar clinical and radiographic outcomes of treatment with pedicle-screw-based spinal instrumentation and fusion compared to patients with small syrinx (S/C ratio ≤0.7).
Authors separate Chiari magnitude on the basis of a maximal syrinx (S)/spinal cord (C) ratio (the maximal diameter of the syrinx divided by the diameter of the spinal cord at the same level) Small syrinx is an S/C ratio ≤0.7 and a large syrinx, S/C ratio >0.7. They note that after a prophylactic neurosurgical procedure, large syrinx patient obtains similar clinical and radiographic outcomes for scoliosis instrumentation and fusion.
A crucial element of the authors' study is the inclusion criteria. Patients in their cohort presented with age ≤18 years, the Cobb angle of the primary curve was more than 50°, diagnosis of syringomyelia, more than one year of clinical and radiographic follow-up after the last surgery, and no congenital spinal deformity.
Several understandings underpin this discussion. First is the traditional importance of ordering screening spine MRIs on patients with seemingly idiopathic curves cannot be overstated. Neurological complaints such as headaches, sensory complaints, cranial nerve findings, hyperreflexia, or motor issues within a traditional pediatric orthopedic clinic should warrant a screening MRI even if scoliosis curves are not at an operative threshold. Nearly 10% of patients with idiopathic curves will have MRI findings, 2/3 of which are a syrinx. Indeed within the University of South Alabama Complex Spine Center, it is standard practice to get MRIs on all adolescent patients undergoing surgery for scoliosis. This slightly exceeds the traditional atypical concerns for apex left, sharp angular deformity, and hyperkyphosis. All early-onset scoliosis patients need a screening MRI.
In patients, less than ten years of age, data supports that Chiari decompression may alleviate the spinal deformity without any formal spinal intervention for curves less than 40 degrees. Ozerdemoglu, et al., noted that Chiari in the setting of scoliosis is benefitted most by suboccipital craniectomy not direct shunting of the syrinx. In the current study, it is somewhat vague as to which intervention was entertained prophylactically. There is also an issue of timing post neurosurgical intervention for CMI/syrinx to the definitive corrective surgery since posterior fossa decompression may or may not decrease the size of syrinx for many months. The potential benefit is negated if syrinx fails to respond prior to spinal fusion. Indeed in our respective institutions, the standard of practice is to intervene, with suboccipital decompression, on those patients with syrinx and Chiari I malformation even if their Cobb angle is below the traditional operative range prior to spinal instrumentation and fusion.
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