Though it has been several decades since the first clinical history of myelopathy was published, no definable natural history is available. Lees and Turner concluded clinical exacerbation added to neurologic deficits in patients with more than 10 years of myelopathy but emphasized that long periods of a neurologic stabilization occur between episodes of deterioration (Lees and Turner 1963). Nurick supported this concept and concluded that the amount of disability in cervical myelopathy was established early in the disease process and generally did not progress significantly afterwards (Nurick 1972). Epstein's clinical review of 1355 patients with cervical spondylotic myelopathy determined in a conservative treatment evaluation that 36% showed improvement, whereas 64% showed no improvement (Epstein and Epstein 1989). In the group that did not improve, 26% deteriorated neurologically with the remainders remaining stable. Sixty-seven percent of Symon and Lavender's patients displayed a linear relentless progression of neurologic deterioration rather than stabilization (Symon and Lavender 1967). A study classified patients who were “pre-symptomatic” with cervical spinal stenosis, followed them for a year, and determined that 19% had symptomatic progression; in 90% of these, an electrophysiologic data-based model was predictive (Bednarik et al 2004).
Typically, patients with myelopathy have symptoms and signs for several years before seeking medical attention. Although the progression is usually slow, the course often involves a progressive decline if the disease is left untreated. A small percentage of patients exhibit a more rapid onset of progression of symptoms and signs.
Cervical spondylotic myelopathy is an intermittently progressive disease process without significant chance of reversal when no treatment is administered. Conservative therapy rarely solves the myelopathy. Once patients have presented with the signs and symptoms of cervical spondylotic myelopathy, most have some degree of permanent disability. Little chance of symptom resolution is possible with conservative treatment; therefore, patients with moderate or severe myelopathy are candidates for surgery. The 2 most important factors for successful outcome in patients treated for cervical spondylotic myelopathy are (1) the patient's age and (2) the duration of symptoms. Young patients tend to do better than elderly patients. With respect to duration of disease, patients whose disease has been present for fewer than 6 months have a more favorable outcome than patients whose symptoms have been present for 1 year.
Chiles and colleagues examined a group of 76 individuals after anterior decompressive surgery. Interestingly, improvement occurred in the lower extremities in 47% of patients compared to a 75% improvement in the upper extremities. Approximately 2% per year developed symptomatic restenosis at adjacent levels to the original decompression (Chiles et al 1999). A prospective multicenter study with independent clinical review was performed by Sampath and colleagues to analyze the outcome of patients treated for cervical myelopathy. The study, sponsored by the Cervical Spine Research Society, indicated that surgically treated patients had a significant improvement in functional status and overall pain, with improvement also observed in neurologic symptoms (Sampath et al 2000). Several radiological studies have shown that favorable prognosis following decompressive surgery of any type may be predicted by the severity of preoperative spasticity, weakness, and atrophy coupled with critical MRI spinal cord findings; patients with normal cord appearance or presence of intramedullary high-signal change on T2WI fare better than those patients with hypointense (low signal) change on T1WI, which may indicate permanent injury (Alafifi et al 2007; Mastronardi et al 2007).