Causes / typical injury mechanism: Cervical myelopathy (CM) is a common neurologic disorder that arises from compression of the cervical spinal cord, usually related to cervical spine degeneration with age. CM may be painful and can be associated with symmetric numbness and clumsiness in both upper extremities and gait disturbance. The most common cause of CM is stenosis of the spinal canal due to decreased disk height, osteophytes, thickening of longitudinal ligaments, and degenerative spondylolisthesis.

Classic history and presentation: Patients typically present with a gradual decline in fine motor activities and gait stability. This decline is often accompanied by progressive pain in the neck and shoulder(s). Pain and numbness can radiate down the upper extremities if spinal roots are involved. In advanced cases, patients can present with incontinence and symptoms in their lower extremities, which can progress to tetraplegia. Examination will show a wide-based, ataxic gait, positive Hoffman sign and Babinski sign with hyperactive reflexes, and clonus.

Prevalence: CM is one of the most common causes of spinal cord dysfunction. More than 70% of people over the age of 65 years show radiologic evidence of cervical degeneration, although this may be underestimated due to asymptomatic patients. About 25% of patients with cervical degeneration will develop myelopathic symptoms from spinal cord compression. This condition is more common in older patients and is mostly diagnosed after the age of 50 years.

Risk factors: Risk factors for CM include conditions that promote degeneration of the cervical spine, such as rheumatoid arthritis and cervical spine trauma. See cervical radiculopathy for more details.

Changes in the curvature of the cervical spine, including hyperlordosis, scoliosis, or kyphosis, can also predispose an individual to cervical myelopathy. CM has a higher frequency in patients with congenital disorders such as Down syndrome, Klippel-Feil syndrome, or congenital cervical spinal stenosis. Multiple genetic polymorphisms have been linked to increased susceptibility to CM.

Pathophysiology: CM arises from both static and dynamic factors that compress the spinal cord, lead to ischemia and inflammation, and ultimately trigger neuronal degeneration and demyelination.

• Static factors include congenital abnormalities or anatomic changes that reduce the cross-sectional area of the spinal canal. Aging is a frequent cause of static factors, as it leads to spondylosis, disk herniation, ligament hypertrophy, and osteophyte formation.
• Dynamic factors include physiologic or pathologic movements that compress the spinal cord, such as instability, increased range of motion (ROM), and trauma.

Grade/classification system: CM is classified as mild, moderate, or severe based on the patient's symptoms and symptom progression. The most common grading method is the modified Japanese Orthopedic Association scale, which is an 18-point scale based on motor function of all limbs, upper limb sensation, and sphincter function. A low score correlates with poor function.