The association between multiple sclerosis and spondylosis: When and why

Objectives: To evaluate risk factors for the development of cervical spine spondylosis (CSS) in patients with multiple sclerosis (MS) and to propose a pathogenetic mechanism. Methods: Forty-two consecutive patients aged 23-66 years with MS and 42 age and sex matched controls were evaluated retrospectively; Clinical disability was evaluated with the expanded disability status scale (EDSS) and spasticity with the Asworth score. Total brain lesion volume (BLV), total grey matter (GM) volume and deep GM volume were assessed. In the cervical spine CSS indices (disk dehydration, disk protrusion, abnormal posture and osteophytosis) and the spinal cord lesion load (SLL) was evaluated. The association of CSS indices with the presence of MS, the clinical scales and the brain and spinal cord imaging measurements were assessed. Results: Presence of MS was positively associated with abnormal posture (P= 0.002), disk dehydration at C6-C7 (P = 0.049) and posterior disk protrusion at C5-C6 (P = 0.033) and C6-C7 (P= 0.001). All patients had spasticity. Patients with abnormal posture were younger (37.5 +/- 11.1 years) than those with normal (45.4 +/- 8.6 years), P = 0.024. Age (P= 0.008), EDSS (P = 0.045) and BLV (P= 0.084) were significant independent predictors of abnormal posture. Younger age combined with worse EDSS and increased BLV predicted abnormal posture. Conclusions: Patients with MS present more frequently spondylosis which is associated with younger age, more severe disability and extensive lesions in the brain. Spasticity induced by the brain lesions and abnormal expression of extracellular matrix proteins in the brain and the intervertebral disk constitute a possible pathogenetic mechanism.