SURGICAL DECISION MAKING IN CERVICAL SPONDYLOTIC MYELOPATHY A PROSPECTIVE STUDY OF 135 CASES

Abstract

Introduction: Formulation of surgical protocol in CSM is marred by the diversity in clinico-radiological presentation. Prospective data that assigns a specific surgery with identifiable similarities in clinico-radiological attributes is sparse.

Objectives:

• To identify radiological patterns of compression (POC) of the spinal cord

• To develop a surgical protocol based on POC and determine its efficacy.

• To identify parameters predicting outcome of surgery

Methods: 135 consecutive patients aged 32–75 yrs (mean 48.1yr) operated for CSM from 1999–2005 formed the study group for this prospective series. The objectives were to identify radiological patterns of compression (POC), develop a surgical algorithm based on POC and evaluate outcome. Four POC were identified on MRI.

• Pattern I – predominant one/two level compression in normal/narrow canal

• Pattern II – anterior & posterior compression at one/ two levels (pincer cord)

• Pattern III – Three or more levels of predominant anterior compression with a normal canal

• Pattern III(A) – Pattern III in a patient with multiple medical co-morbidities

• Pattern IV – Three/more levels of anterior compression in narrow canal +/− posterior compression (beaded cord)

• Pattern IV(A) – Pattern IV with one/two level severe compression amongst the multiple anterior compressions.

Mean follow-up was 3 yrs (2–8). ACDF was performed for patterns I, II & III and posterior decompression for pattern IV and III(A). For pattern IV(A), a two stage primary posterior decompression followed by targeted ACDF at the site of maximal compression was performed. The clinical outcome was measured by modified JOA (mJOA) score, Hirayabashi Recovery Rate (HRR) and functional outcome by modified Neck Disability Index (NDI).

Results: The mean pre & post-op mJOA score was 10.40±3.33 & 15.76±1.45 respectively with average HRR of 80.10 ± 26.38. The difference in the mJOA scores was statistically significant (unpaired t test) for each POC. In multilevel CSM, anterior surgery in POC type III had statistically better post op mJOA as compared to those who underwent posterior surgery viz POC types IV and III & IV variants although the difference in their HRR and NDI were not statistically significant.

Conclusion: Anterior surgery has better neurological outcome in judiciously selected patients with multilevel CSM. Surgical decision-making guided by patterns of compression (POC) is pivotal for optimal functional outcome.