Cervical spondylotic myelopathy is the most common spinal cord disorder in people over the age of 55. Myelopathy (my·e·lop·a·thy) is deterioration of the spinal cord. Myelopathy caused by spinal arthritis and degenerative disks (spondylosis) is called cervical spondylotic myelopathy. Myelopathy is essentially a slow and insidious spinal cord injury.
Of all the spinal conditions that I treat, myelopathy is the most likely to be previously misdiagnosed. Cervical and lumbar radiculopathy (radiating arm or leg pain from a pinched nerve) and lumbar stenosis with neurogenic claudication (pain in the low back and buttocks from a narrow spinal canal) are often accurately diagnosed and have been treated with appropriate nonoperative interventions prior to being referred to a spine surgeon. Patients with cervical myelopathy, on the other hand, often present with vague complaints and have not been accurately diagnosed. Some “vague” complaints include:
- “trouble walking”
- “my legs feel weak”
- “my legs feel numb”
- “electric shocks” in the back
- “I drop things”
- “my hands feel stiff or like I’m wearing gloves”
- Diffuse back pain
Many patients will not complain of neck pain at all. Frequently, patients will be diagnosed with:
- Lumbar stenosis
- Peripheral neuropathy
- Arthritis of the hands
They may have a low back imaging study with mild stenosis, hand radiographs with mild arthritis, or a nerve conduction study with mild peripheral neuropathy. In these patients, some or all of their complaints may be caused by deterioration of the spinal cord, myelopathy, secondary to cervical stenosis (narrowing of the spinal canal in the neck.)
Gait and balance complaints are common and may be mild initially. Family members may prompt the visit for increasing frequency of falls. Some patients will use a cane or a walker. Neck pain is usually present, but not always. Problems with fine motor skills such as buttoning buttons, handling coins, and handwriting is a common complaint. Global numbness or paresthesia (tingling) in the arms may be noted. Hip and thigh weakness may result in trouble rising from a chair.
Gait examination is sensitive for detecting advanced myelopathy. Look for:
- A wide-based gait or difficulty performing a hell-to-toe tightrope gait
- Neck range of motion may be limited
- An electric shock-like sensation down the center of the back following flexion of the neck (Lhermitte’s sign) may indicate spinal cord compression
- Weakness or sensory changes may be found, but are often nonspecific
- Decreased vibratory sensation may indicate posterior-columns dysfunction
- Atrophy of the hand or shoulder musculature may be seen
- Hyperreflexia in both the upper and lower extremities is often present (foraminal stenosis or peripheral neuropathy may result in absent reflexes)
- The inverted radial reflex (finger flexion instead of a brachioradialis reflex)
- Positive Babinski and Hoffman reflexes
Romberg test (loss of balance while standing with eyes closed and arms outstretched) can be abnormal in myelopathy.
Upright radiographs with flexion and extension views may reveal:
- Congenital stenosis
- Increased kyphosis
Magnetic Resonance Imaging (MRI) is the most useful test to evaluate patients with suspected cervical myelopathy. MRI can reveal the source and severity of stenosis. It can also show myelomalacia (shrinkage of the spinal cord due to injury) and spinal cord edema (increased water content due to bruising).
Immobilization with a cervical collar may be tried, but it is usually not beneficial except in cases of instability. In cases of moderate and severe myelopathy with documented progression, an operation is indicated to decompress the spinal cord. This may be done from the front by removing disks and part of the vertebral body, from the back by removing the lamina, or both. The choice of approach depends on the number of stenotic levels and which direction the spinal column curved. Isolated laminectomy is rarely performed due to risk of instability, and it is accompanied by fusion with rods, screws, and bone graft.
A newer treatment, laminoplasty, enlarges the spinal canal without fusion, with less risk of instability. Laminoplasty is becoming the treatment of choice for many patients with cervical spondylotic myelopathy. Laminoplasty is not right for everyone, however. If the spine curves forward too much (kyphosis), then a posterior decompression may not work because the spinal cord continues to drape of spondylotic disks anteriorly. Patients with instability or significant neck pain would probably best benefit form a fusion.