Fatty infiltration of the cervical multifidus musculature and their clinical correlates in spondylotic myelopathy

Cervical spondylotic myelopathy (CSM) is among the most common spinal cord disorders of the elderly. Muscle fat infiltration (MFI), a potential pathological sign of muscle adiposity, may contribute to or be associated with pain/disability/impairments in patients with CSM. We examined the relationship between MFI and CSM's clinical manifestations by enrolling nine CSM patients and five aged-matched controls to undergo MRI imaging of the cervical spine with MFI. A blinded investigator calculated MFI for each of the bilateral multifidii muscles from C3 to C7 on the MRI images. Nurick scores, Neck Disability Index, and modified Japanese Orthopedic Association scores were collected for all patients. CSM patients and controls were equivalent with respect to age, height, weight, gender, race, smoking status, and employment status. MFI was higher in patients with CSM than in controls (31.7% v. 24.6%, respectively, p = 0.0178). Higher MFI was associated with increased disability on the Nurick scale (p = 0.0371). MJOA scores correlated linearly with MFI (R = 0.542, p = 0.0453), but not NDI (p = 0.3125). Increased MFI of the multifidus muscles is associated with cervical myelopathy and a clinically significant decline in sensorimotor function as measured by mJOA and Nurick scores. Spinal injury in CSM may lead to secondary muscle loss and muscle fat infiltration.