Cervical Myelopathy

Cervical spine myelopathy occurs due to compression of the spinal cord at the level of the cervical spine.

Some causes of cervical myelopathy include spondylosis, cervical stenosis, cervical disc herniation, a tumor, or ossification of the posterior longitudinal ligament (OPLL), which occurs more in people of Asian ancestry and at the C4-C6 level.

Cervical Myelopathy tends to be progressive and get worse in a step-like deterioration fashion, with periods of stable symptoms. It is exacerbation of symptoms followed by a long period of static or deteriorating function. For the static periods, 75% of patients will have long periods of stable neurologic function, which may be as long as multiple years. As described, for the majority of patients, the condition deteriorates between quiescent streaks, however, about 20% of patients have a slow, steady progression of symptoms. For patients with cervical myelopathy, the symptoms will not improve without surgery.

The patient will complain of neck and arm pain, which will be absent or poorly defined with vague sensory and motor changes. The patient will also have progressive gait and balance disturbance. Their gait will become a broad based ataxic gate and will be unsteady. They may also have clumsiness and weakness in the arm. Lower extremity dysfunction and spasticity will also be seen. Finally, there will be intrinsic muscle weakness with difficulty in buttoning a shirt and/or performing fine manual activities (weakness of grip strength). Poor hand fine motor function and dexterity occurs early on.

Pathologic long tract signs will be seen consisting of ankle clonus, hyperflexia, positive Hoffamn’s sign, and bilateral outgoing toes. Clonus sign is a non-voluntary sustained movement of the ankle muscles with firm, passive, continuous stretch. Hyperflexia will occur in the upper and lower extremities (triceps/quadriceps). A positive Hoffman’s sign will be seen in about 80% of patients with cervical myelopathy, and is done by flicking the nail of the middle or ring finger to produce flexion of the index finger or the thumb. The bilateral outgoing toes is a positive Babinski reflex, and is seen by running a sharp instrument along the lateral border of the foot from the calcaneus. This will produce extension of the big toe and fanning of the other toes.

The Nurick classification is often used when dealing with cervical myelopathy, and describes walking ability and gait, and ranges from normal to wheelchair bound.

When cervical myelopathy is present, and MRI will be needed. MRI is the best study for this, as it shows the compression and the changes in the spinal cord- A bright signal in T2 MRI is seen. If an MRI is unattainable, a CT myelogram is the next best option.

In patients with low back pain and gait disturbance, look at the spinal cord, specifically in the area of the cervical spine. The lumbar spine region should not be focused on. Some patients may present with lumbar stenosis, and have an MRI showing so, but they may also have a gait disturbance. If this is the case, the cervical spine should be checked! The examination may be confusing because the patient will come to the doctor with low back pain and a positive MRI for lumbar spinal stenosis. However, the patient should then be asked about neck pain and stiffness, as well as if they feel unstable when walking. Lumbar stenosis and cervical spine stenosis can coexist in about 20% of patients.

There are a few differential diagnosis, which include Amyotrophic Lateral Sclerosis (ALS), syringomyelia, spinal cord tumor, and multiple sclerosis.

Amyotrophic Lateral Sclerosis (ALS) is a motor neuron disease affecting both upper and lower extremities with no sensory changes, and will lead to progressive weakness, muscle atrophy fasciculation and spasticity, in addition to dysphagia and respiratory compromise.

In multiple sclerosis, the patient will have cranial nerve involvement, and the jaw jerk test will be positive.

Cervical myelopathy is progressive and it rarely improves with non-operative modalities. The surgery that is performed for cervical myelopathy is decompression and fusion, which should be done if the symptoms are progressive or severe. In the case of surgery, prognosis is better if the surgery is done earlier. If the patient does not have surgery, they will die earlier.

The neurological recovery after decompression is best predicted by pre-surgical posterior atlanto-dens interval exceeding 13 mm. Even with more than 10 mm space for the spinal cord, the patient will usually have improved neurological function.

Surgery is usually done anteriorly with decompression and fusion. In the case of one to two level disease, an anterior cervical decompression and fusion should be done, especially if there is a fixed cervical kyphosis to more than 10 degrees. If there is multilevel involvement of three or more dis spaces, it is easier to manage by a posterior approach, but only if there is no fixed kyphosis. A lateral x-ray will show if there is any kyphotic alignment. A multilevel posterior decompression and fusion will be done for multiple level involvement.

The posterior approach has a higher incidence of wound infection. Therefore, it should not be performed if there is cervical kyphosis. The residual kyphotic posture of the cervical spine will result in persistent spinal cord compression. For fixed kyphosis of more than 10 degrees, an anterior approach will need to be used. After laminoplasty for multilevel cervical spondylitic myelopathy, the most common adverse post-operative complication is a loss of range of motion by up to 50%. Laminoplasty should be used over laminectomy in order to prevent progressive kyphosis. A laminoplasty is achieved by widening the spinal canal through a decompression of the spine.

After surgery, the patient may get nerve root palsy, in which case the C5 nerve root is usually the most commonly involved nerve root. Fortunately, C5 nerve palsy has a good prognosis with time and patience.