Spinal cord expansion after decompression in cervical myelopathy. Investigation by computed tomography myelography and ultrasonography.

Abstract

This study analyzed anatomic characteristics of 44 patients with cervical myelopathy. This study was conducted to clarify the patterns of spinal cord expansion after decompression, their relationship to clinical recovery, and the capacity of the compressed spinal cord for restoration. No previous studies have clearly assessed the relationship between morphological changes of the spinal cord and clinical improvement after posterior decompression in patients with cervical myelopathy using computerized tomography myelography and intraoperative spinal sonography. Forty-four patients with cervical myelopathy underwent posterior decompression. The diagnosis was cervical spondylosis in 26 patients and ossification of the posterior longitudinal ligament in 18 patients. The cross-sectional area, sagittal diameter, and frontal diameter of the spinal cord at the level of maximum compression were determined by computerized tomography myelography (performed before and 1 month after decompression) and by intraoperative spinal sonography. Expansion of the spinal cord was defined as immediate or gradual. Of the 44 patients, 20 demonstrated gradual expansion, and their clinical recovery rate was 68.4%. In contrast, the clinical recovery rate of patients without gradual expansion was only 32.6%. Good clinical recovery was significantly related to gradual expansion. The patients were divided into four groups (A-D) based on the clinical recovery rate and compression ratio. Group A (severe compression and poor clinical recovery) showed a significantly smaller cross-sectional area of the spinal cord than Group D (severe compression, but good clinical recovery). Preservation of the cross-sectional area of the spinal cord, even when it is severely compressed and deformed, is an important factor in a good surgical outcome.