OBJECT:A variety of factors may affect the neurological improvement in patients with cervical compression myelopathy (CCM) after surgery. The aim of this study was to report and discuss the prognostic factors in a group of patients with insufficient decompression of the spinal canal. METHODS:A prospective follow up and analysis of 20 consecutive patients with CCM treated between 2000 and 2002 was performed. All patients were surgically treated via an anterior approach, either by anterior cervical discectomy and fusion with instrumentation or by cervical corpectomy and fusion with instrumentation. The surgical results were examined using the modified Japanese Orthopaedic Asssociation disability scale, with reference to the findings of magnetic resonance imaging, computed tomography, and radiography. Seventeen patients (85%) experienced a 50% or more recovery rate as calculated using the Hirabayashi formula during the follow-up period (mean 32.5 months), despite a persistently narrow spinal canal and permanent or increased intramedullary high-intensity signal after surgery. CONCLUSIONS:Results of the study showed that patients with CCM benefited from anterior cervical discectomy and fusion with instrumentation or cervical corpectomy and fusion with instrumentation procedures despite insufficient decompression of the spinal canal. Fusion of the affected level(s) might be the reason for the acquired high recovery rates. The authors also conclude that the neurological improvement is not correlated with the reversal of or decrease in the intramedullary high-intensity signal change after surgery.