Progressive Cervical Myelopathy in a 57-year-old
The patient is a 57-year-old male with progressive cervical myelopathy. He has been ambulating with a walker during the last four weeks. He is medically stable and otherwise healthy.
The examination revealed left arm weakness; deltoid 3/5, biceps 4-/5. His lower extremities are hyper-reflexic with positive Babinski reflexes.
Anterior posterior and laterals cervical radiographs (Figs. 1A, 1B) and flexion (Fig. 1C) and extension (Fig. 1D) views.
Figure 1A. Anterior posterior x-ray
Figure 1B. Lateral x-ray
Figure 1C. Flexion
Figure 1D. Extension
Sagittal MRI views (Figs. 2A-2C)
Sagittal reconstructions (Figs. 3A, 3B)
Axial CT scans (Figs. 4A, 4B)
Figure 4A. C4
Figure 4B. C5
Cervical myelopathy with cervical kyphosis
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Figure 5. 30-pounds traction
C3 and C4 corpectomy, with anterior cervical discectomy and fusion at C5-C6, C6-C7, and C7-T1. Posterior C3-C6 laminectomy and fusion from C2 to T2.
Lateral postoperative x-rays (Figs. 7A, 7B)
The patient is much improved at one-year postoperative. He ambulates independently, with significant improvement in deltoid power (4/5 strength), and has no signs of myelopathy.
Dr. Albert presents a complex case demonstrating the combination of rapidly progressive cervical spondylotic myelopathy (CSM) with sagittal plane imbalance. Cervical spondylotic myelopathy, resulting from narrowing of the cervical spinal canal by a combination of acquired degenerative changes and longstanding congenital abnormalities, is the most common type of spinal cord dysfunction seen in patients over 55 years of age, the most common cause of adult acquired spastic paraparesis and one of the more difficult diagnostic and treatment challenges facing a practicing spinal surgeon today.
The pathogenesis of cervical spondylotic myelopathy is thought to be a combination of both static compression of the spinal cord and intermittent dynamic impingement resulting from motion. Static factors include congenital spinal canal stenosis (defined as antero-posterior canal diameter of <12 mm); disc protrusions, disc-osteophyte complexes, ossification or thickening of the posterior longitudinal ligament (PLL), degenerative arthropathy of the uncovertebral or facet joints, and buckling or hypertrophy of the ligamentum flavum.
Dynamic impingement results from the normal pulsatile nature of the spinal cord in close proximity to stenotic regions of the spine. Similarly, flexion and extension under a physiologic load within the normal limits of cervical range of motion may cause the spinal cord to be draped over anterior osteophytes or indented by ligamentum flavum buckling inward from the posterior aspect of the canal. Essentially, a progressive traumatic injury to the cord may result from repetitive compression against a stenotic area.
Finally, it has also been hypothesized that CSM may arise from a vascular or ischemic event. It is well documented that the lower cervical region, from C5-C7, has both a very high incidence of spondylotic disease and a relatively sparse blood supply. Pathologic findings which support a vascular theory are the presence of myelomalacia, central cord necrosis and the appearance of an ischemic penumbra.
The onset of cervical spondylotic myelopathy is generally insidious, characterized by long-standing dysfunction with episodic, occasionally dramatic worsening. Frequently, symptoms have been present for years with a patient only agreeing to seek medical attention once a significant or life-changing deterioration occurs. The onset is typically in the 5th or 6th decade of life, presenting in a variety of ways. A common sign is a notable alteration in gait or the appearance of spasticity. Upper extremity numbness and loss of dexterity or clumsiness are often manifestations of the frequently observed loss of fine motor control.
Concerning Symptoms and Signs
- Pain in the neck, scapular region or shoulder.
- Numbness or paresthesias in the upper or lower extremities.
- Difficulty with ambulation ("spastic gait," coordination).
- Loss of proprioception or vibration sense in lower extremities (dorsal columns).
- Distal motor weakness in the extremities, loss of fine motor skills.
- Lower extremity findings of hyper-reflexia, spasticity, clonus, positive Babinski, and bowel and bladder dysfunction.
- Upper extremity hyporeflexia (lower cervical lesion) or hyper-reflexia (upper cervical lesion with a positive Hoffman sign) and intrinsic muscular atrophy.
The differential diagnosis of cervical spondylotic myelopathy is quite broad. It is important to rule out multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS), which are common to this age group. Cervical spondylotic myelopathy has no effect upon the cranial nerves, so facial sensation, vision and swallowing, as well as the jaw jerk reflex, may be completely normal. Additionally, amyotrophic lateral sclerosis (ALS) is known to be a pure motor neuron disease, which should leave sensation relatively unaffected. Cervical spondylotic myelopathy may have motor findings similar to those of amyotrophic lateral sclerosis, in addition to sensory findings such as numbness or paresthesia in the upper extremities.
Other disorders which should be considered in the differential diagnosis include cerebrovascular occlusive disease, spinal cord tumors, syringomyelia, subacute combined degeneration, peripheral neuropathy and normal pressure hydrocephalus (NPH), which is often accompanied by both gait and bladder abnormalities.
Cervical spondylotic myelopathy patients treated with a nonoperative approach (anti-inflammatory medications, collar immobilization and physical therapy) show continual progressive neurologic deterioration in a step-wise fashion. CSM is a surgical disease meaning that the goal of surgery for CSM is to halt the progression of the neurologic deterioration. Realizing that the room available for the cord is diminished and the room available for shock-absorbing cerebrospinal fluid is similarly decreased, these patients are at risk of spinal cord injury even from a relatively trivial traumatic injury. Multiple studies have demonstrated the benefit of early surgical intervention and the positive predictive value of short symptom duration, younger age at symptom onset, presence of a focally stenotic area and presence of a unilateral motor deficit.
Both dorsal and ventral surgical approaches may be appropriate for cervical spondylotic myelopathy. I believe that two factors are paramount in determining the surgical approach: vector of cord compression and sagittal balance. If the vector of compression is anterior, perhaps discectomy or corpectomy with interbody fusion is appropriate. If there is a kyphotic deformity in the setting of circumferential compression, perhaps a combined anterior-posterior approach is indicated. I have had the unfortunate experience of revising dozens of posterior cervical decompressions from referring physicians once post-laminectomy kyphosis has developed. Obviously, choice of hardware, interbody device, use of biologics, etcetera is beyond the scope of this article.
Take Home Points
- Cervical spondylotic myelopathy is a surgical disease.
- The vector of compression (anterior, posterior, or circumferential) should determine the primary approach to the cervical spine, since the primary goal is to relieve cord compression.
- The sagittal balance of the cervical spine is the second factor used to determine approach. In patients with normal lordosis, the anterior or posterior approach is reasonable. In kyphosis, either an anterior or combined anterior-posterior approach is recommended to avoid the risk of progressive kyphotic deformity associated with cervical decompression alone.