Cervical Spondylotic Myelopathy

Cervical spondylotic myelopathy (CSM) is spinal cord dysfunction caused by age-related degenerative narrowing of the cervical spinal canal. As discs, ligaments, and bony structures degenerate, the cord is chronically compressed, producing a slowly progressive myelopathy. It is the most common cause of non-traumatic spinal cord dysfunction in adults and is the prototypical degenerative form of cord compression.

Definition

Cervical spondylotic myelopathy is a myelopathy resulting from degenerative (spondylotic) narrowing of the cervical spinal canal that chronically compresses the spinal cord and impairs its function.

Scope

The topic covers how cervical spondylosis compresses the cord, the mechanisms by which chronic compression injures neural tissue, the characteristic clinical picture of myelopathy, and the rationale for considering surgical decompression. CSM is increasingly described under the broader umbrella term degenerative cervical myelopathy. The entry is a reference orientation and does not provide diagnostic thresholds or treatment recommendations.

Core questions

• How does degenerative spondylosis produce mechanical and ischaemic injury to the cervical cord?
• What clinical signs distinguish myelopathy from radiculopathy?
• How is CSM situated within the broader concept of degenerative cervical myelopathy?
• What is the evidence base for surgical decompression versus conservative management?

Key concepts

• Static and dynamic compression
• Spondylosis and canal stenosis
• Upper motor neuron signs
• Chronic ischaemia and demyelination
• Degenerative cervical myelopathy umbrella
• T2 cord signal change on MRI
• mJOA functional grading

Mechanisms

Degeneration of the cervical discs, facet joints, ligamentum flavum, and vertebral bodies narrows the spinal canal, compressing the cord both statically and dynamically during neck movement. Chronic compression injures the cord through direct mechanical deformation and through ischaemia from compromised microcirculation, leading to demyelination, neuronal loss, and gliosis (Karadimas, 2013). The natural history is variable but often slowly progressive, and the burden and duration of compression influence the degree of irreversible damage (Wilson, 2017). Because these changes accumulate over years, presentation is typically insidious (Bakhsheshian, 2017).

Clinical relevance

CSM is a leading reason adults develop progressive gait, hand, and balance dysfunction from cord compression, and understanding its mechanism underpins critical appraisal of the surgical literature. This entry describes the disorder for reference; it is not a basis for individual diagnosis, grading, or treatment selection, which rest with treating clinicians.

Epidemiology

CSM is the most common cause of non-traumatic spinal cord dysfunction in adults and its prevalence rises with age as degenerative change accumulates; it is increasingly conceptualised within the wider spectrum of degenerative cervical myelopathy, which also includes ossification of the posterior longitudinal ligament and other degenerative contributors (Tetreault, 2015; Bakhsheshian, 2017).

History

Recognition of cervical spondylosis as a cause of progressive myelopathy was consolidated in the mid-twentieth century, and the advent of magnetic resonance imaging allowed direct visualisation of cord compression and intramedullary signal change. More recent work has reframed CSM within the broader degenerative cervical myelopathy spectrum and has synthesised its natural history and management in formal reviews (Tetreault, 2015; Wilson, 2017).

Debates

How should mild or non-progressive CSM be managed?

The threshold for surgical decompression versus structured observation in milder disease remains an area of active discussion, balancing the risk of progression against operative risk; contemporary reviews summarise the evolving evidence rather than offering a single rule.

Key figures

• Michael Fehlings
• Spyridon Karadimas
• Lindsay Tetreault
• Jefferson Wilson

Seminal works

• karadimas-2013
• tetreault-2015
• wilson-2017

Frequently asked questions

How does cervical spondylotic myelopathy differ from cervical radiculopathy?

Radiculopathy reflects compression of a nerve root and tends to cause dermatomal arm pain and weakness, whereas myelopathy reflects compression of the spinal cord itself and produces long-tract signs such as gait disturbance, hand clumsiness, and hyperreflexia.

Why is CSM often described as 'degenerative cervical myelopathy'?

The broader term groups spondylotic compression with related degenerative causes such as ossified ligaments under a single spectrum, reflecting that these processes share a common mechanism of chronic degenerative cord compression.