Cervical Spondylotic Myelopathy
Cervical Spondylotic Myelopathy or CSM is a condition in which the spinal cord is compressed or pinched in the neck or the cervical spine due to the aging process. The cervical spondylotic myelopathy happens due to the degeneration or wear and tear of the cervical spine due to their aging process. This can happen at one or multiple levels.
Patients with congenital stenosis of their cervical spine may be predisposed to this condition. These patients have a smaller diameter of the spinal canal since birth. The immediate effects of CSM may be precipitated by a subtle trauma overlying cervical stenosis and the aging process.
As opposed to cervical radiculopathy in which the patient has tingling, numbness or weakness of a specific nerve root presenting in the upper extremity, CSM can present with involvement of either one or to all four extremities.
The involvement can be in the form of sensory deficit and weakness with or without the involvement of gait, bowel or bladder with tingling and numbness all over the body or presenting with electric shock-like sensations going down the body. These patients may even present with inability to ambulate without aid or support. Subtle findings may be an imbalance or subclinical retention of urine.
Causes of Cervical Spondylotic Myelopathy:
CSM is essentially caused due to the aging process leading to wear and tear of the cervical spine. The presentation may be more profound or early in patients with congenital cervical stenosis. The wear and tear lead to degeneration of the disc space with protrusion of the disc towards the spinal cord.
At the same time, the degeneration will lead to thickening of the ligament of the back of the spinal cord called the ligamentum flavum which also contributes to the compression or squeezing of the spinal cord in the neck. This compression of the cord can cause a direct effect over the spinal cord as well as have an indirect effect by decreasing the blood supply to the nerves.
Presentation Signs And Symptoms of Cervical Spondylotic Myelopathy:
The patients with Cervical Spondylotic Myelopathy patients may or may not have neck pain. They may present with varied signs and symptoms involving either extremities, bowel or bladder function, or gait abnormalities. These patients may also have a loss of dexterity of their hands or an imbalance of their posture.
On examination by a physician, these patients may elicit inability to walk in a straight line, numbness in specific dermatomes, increased tone of the muscles either upper or lower extremities or spasticity, weakness of specific muscle groups specially hand grip and presentation of electric shock-like sensation or deep flexion of the neck which is also known as the Lhermitte sign.
These patients can present with specific presentations like Central cord syndrome, Brown Sequard Syndrome, Anterior Cord Syndrome, partial or complete spinal cord injury, etc.
Diagnosis of Cervical Spondylotic Myelopathy:
After a thorough history and physical examination, an initial X rays may help us know about the degenerative changes in the cervical spine as well as look for evidence of fracture, subluxation, or dislocations.
Patients will usually require advanced imaging to confirm the diagnosis as well as to know the pathology and exact level or levels involved. Magnetic Resonance Imaging (MRI) helps to look at the soft tissue, disc, ligaments, etc. and is the investigation of choice in these patients.
Computed Tomography (CT Scan) is helpful in understanding the bony anatomy of the spine and may also be needed. In patients who are not able to undergo MRI (presence of a pacemaker, aneurysmal clips, etc.) may need to undergo myelography.
Electromyography and urinary bladder studies may be helpful in milder or subtle patients to understand the severity of disease and to help decide the best course of treatment for the patient.
Treatment Options of Cervical Spondylotic Myelopathy:
The patients with mild and early presentations can be treated conservatively and followed closely for the development of any worsening of the symptoms. These patients can be followed by a spine surgeon or a neurologist. Some medications can be helpful in the symptoms. At the same time, physical therapy can also help in strengthening muscles, balance as well as keeping the neck movement at an optimum level.
The course of CSM is that of gradual worsening in most patients but there are patients who can stay stable for a long time. These patients may have sudden rapid worsening in the presence of subtle trauma or even without that.
The patients with severe CSM present with weakness, the involvement of hand dexterity, the involvement of gait, bowel, bladder, spasticity or increased tone of muscles, and usually need surgical treatment in the form of decompression of the cervical spine.
The treatment includes removing off the pressure causing compression and pinching of the spinal cord. The surgery can be performed from the front or the back of the neck. A decision to perform it from the front or back is dependent on multiple factors. Also, the surgery can be fusion or non-fusion surgery.
If the patient has good neck alignment, minimal or no neck pain, minimal or no instability then these patients can be a good candidate for non-fusion surgery like laminoplasty or Total disc replacement.
On the contrary, if the patient has more neck pain, poor neck alignment then an anterior fusion surgery or posterior fusion surgery may be needed. This fusion surgery can be done from the front or the back. If multiple levels are involved then the back surgery may be better especially in patients with proper alignment.
AP and Lateral View X-rays of Posterior Cervical Laminectomy and Fusion
Patients who need fusion surgery, need to be stabilized by the use of plates, screws, and rods. Once the compression is removed, the worsening of symptoms can be alleviated with an expectancy of recovery over a period of time. Patients usually have to go rehab especially if they are considered weak and are not able to perform the activity of daily living by themselves. These spine surgeries may be associated with complications.
Prognosis of Cervical Spondylotic Myelopathy:
The patients with mild involvement can be treated conservatively (without surgery) but need regular follow up and constant supervision under the care of a spine surgeon. These patients may have a stable period with slow and gradual worsening. Occasionally patients may do very well with conservative treatment.
Patients who do not show progressions and are treated early in the process have a fair to a good prognosis. They usually recover near to the complete functions as well as become symptom-free.
The patients who present with severe symptoms or rapid worsening have a poorer prognosis and may not be able to recover full functions and may have residual weakness, spasticity, the involvement of gait, bowel or bladder, and hand dexterity. It may take months and years to recover and rehabilitate for CSM.
Risks of Cervical Spondylotic Myelopathy Surgery:
The patients who undergo surgery for CSM have usual risks of orthopedic surgery which include infection, bleeding, failure of implants, need for repeat surgery. There is a risk of breakdown of adjacent segments with a need for extension of the fusion by another surgery.
The patients also have risks for injury to the nerves or spinal cord leading to a temporary or permanent worsening of functions, inability to recover completely, and regain full functions.
Surgery of the cervical spine also carries a risk of worsening of neurological status which may also lead to the involvement of respiratory functions needing treatment in the form of intubation and ICU support and even death.
As with any spine surgery, the patients are also at risk of blindness, stroke, cardiac events, paralysis, or death. The patient can also have secondary complications to their impaired neurological status like bedsores, lung problems like atelectasis and pneumonia, blood clots or deep vein thrombosis, pulmonary embolism, urosepsis, and even death.