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Degenerative Cervical Myelopathy (DCM) falls under a broad umbrella of conditions affecting the spinal cord. Within this umbrella lies a subset of myelopathy caused by bulging or herniated discs, vertebral deformities, osteophytes, facet joint arthropathies, hypermobility, instability, and spondylolisthesis.
On the other side of this umbrella are ligamentous pathologies like OPLL (Ossified Posterior Longitudinal Ligament) and OLF (Ossified Ligamentum Flavum). Along with these, several occupational, behavioural, inherited, congenital, systemic, and sports-related factors also play a crucial role in the development of degenerative cervical myelopathy.
Earlier, this condition was simply referred to as cervical myelopathy, but over time the terminology has evolved to the broader and more accurate term Degenerative Cervical Myelopathy (DCM).
Video Link: Cervical Myelopathy Explained by Dr. Jitesh Manghwani | Conceptual Orthopedics
Compressive Myelopathy: Understanding the Causes
Compression leading to myelopathy can occur due to multiple mechanisms, and it is not always extradural. The compression may even be intradural or intramedullary. Interestingly, there are cases of non-compressive myelopathy, where the patient shows clinical signs of myelopathy without any visible compressive element on imaging.
Extradural Causes
- Cervical spondylosis
- Disc prolapse
- Trauma
- Tumour or metastasis (important to remember—can mimic myelopathy)
- Multiple myeloma
- CV junction anomalies
- Thoracic spine issues
- Epidural abscess
- Epidural hematoma
Infections, abscesses, and hematomas can also compress the spinal cord and present as compressive myelopathy.
Intradural–Extramedullary Causes
- Intradural tumors
- Neurofibromatosis
- Meningiomas
- Lipomas
- Sarcomas
- Metastasis
- Arachnoiditis
- Sarcoidosis
- Cervical meningitis
- AVMs (arteriovenous malformations)
- Leukemic infiltration
- Arachnoid cysts
Intramedullary (Intradural) Causes
- Syrinx
- Tumors such as ependymoma, astrocytoma, hemangioblastoma
These intramedullary pathologies can also give rise to myelopathy.
Tandem Stenosis
Tandem stenosis refers to simultaneous stenosis in both the cervical and lumbar spine. Surprisingly, up to 20% of patients with stenosis in one area have concurrent stenosis elsewhere.
For example:
- Patients with lumbar canal stenosis may also have cervical compression.
- Patients with cervical myelopathy may also have lumbar canal stenosis.
Natural History of DCM
Degenerative cervical myelopathy is slowly progressive and rarely improves with non-operative treatment.
A classic pattern seen is step-like deterioration, where the patient worsens, then stabilises, then worsens again. A trivial neck injury or jerk can cause sudden deterioration.
Prognosis
Early recognition and treatment—before cord edema or myelomalacia develops—is critical for achieving good outcomes.
Static and Dynamic Insults: How Compression Happens
The etiology of compression can involve:
Static insults
- Herniated disc
- Osteophytes
- Enlarged ligaments
- Hypertrophied facet joints
Dynamic insults
- Instability
- Excessive spinal range of motion
Both static and dynamic factors disrupt the microvasculature, causing endothelial damage, inflammation, and ultimately apoptosis of neurons and oligodendroglial cells.
This leads to:
- Neuronal loss in grey matter
- Demyelination in white matter
These microscopic injuries explain the clinical progression of cervical myelopathy. Importantly, neural cells do not regenerate, which makes early management essential.
Radiological Understanding: Key Compression Patterns
A commonly referenced image demonstrates:
- OPLL with hypertrophied and ossified PLL causing anterior compression
- Retrolisthesis of C6, producing posterior compression
- Soft disc herniation at C4–5
- Posterior osteophytes compressing the cord (unlike harmless anterior osteophytes)
- Hourglass deformity due to long-term compression and vertebral height loss
- Ligamentum flavum hypertrophy or ossification, causing posterior compression
- Long-standing compression leading to cavitation within the spinal cord
Both anterior and posterior compressive elements contribute to myelopathy.
Classification Systems for Cervical Myelopathy
1. Nurick’s Classification
This system focuses on employment status and gait abnormalities.
- Grade 0 – Root symptoms only
- Grade 1 – Spinal cord signs, normal gait
- Grade 2 – Gait difficulty, fully employed
- Grade 3 – Gait difficulty prevents employment, ambulates unassisted
- Grade 4 – Requires assistance to walk
- Grade 5 – Wheelchair-bound or bedridden
Nurick grading is frequently asked in exams and helps in clinical documentation.
2. Ranawat Classification (Historical Importance)
- Class I – Pain, no deficit
- Class II – Subjective weakness, hyperreflexia, positive Hoffmann’s signs
- Class IIIA – Objective weakness, long-tract signs, ambulatory
- Class IIIB – Objective weakness, long-tract signs, non-ambulatory
Conclusion:
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