Cervical Myelopathy

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Definition/Description

Cervical myelopathy is the result of spinal cord compression in the cervical spine. Any space occupying lesion within the cervical spine with the potential to compress the spinal cord can result in this degenerative disease of the spinal cord. Cervical compression in myelopathy is predominantly due to pressure on the anterior spinal cord with ischaemia and to deformation of the cord by anterior herniated discs, spondylitic spurs or an ossified posterior longitudinal ligament. Human histological studies revealed degeneration of the anterior horns, cavity formation, and demyelination in the severely compressed spinal cord. The spontaneous course of myelopathy is characterized either by long periods of stable disability followed by episodes of deterioration or a linear progressive course. The presentation of a cervical myelopathy varies in accordance to the severity of the spinal cord compression, and it's location.

Clinically Relevant Anatomy

There are seven cervical vertebrae and eight cervical nerve roots.  The spinal cord is the extension of the central nervous system outside the cranium. It is encased by the vertebral column and begins at the foramen magnum.  The spinal cord is an extremely vital part of the central nervous system, and even a small injury to it can lead to severe disability. 
A complex system of ligaments serves to stabilize and protect the cervical spine. For example, the ligamentum flavum that extends from the anterior surface of the cephalic vertebra to the posterior surface of the caudal vertebra and connects to the ventral aspect of the facet joint capsules. A ligament that is also often involved in this condition is the posterior longitudinal ligament. It is situated within the vertebral canal, and extends along the posterior surfaces of the bodies of the vertebræ, from the body of the axis, where it is continuous with the membrana tectoria, to the sacrum.

Cervical Vertebra

Ligamentum Flavum

Chronic cervical degeneration is the most common cause of progressive spinal cord and nerve root compression. Spondylotic changes can result in stenosis of the spinal canal, lateral recess, and foramina.  Spinal canal stenosis can lead to myelopathy, whereas the latter two can lead to radiculopathy.

Cervical spine myelopathy resulting from sagittal narrowing of the spinal canal and compression of the spinal cord is present in 90% of individuals by the seventh decade of life

Although the exact prevalence is unknown cervical, spine myelopathy is recognized as the most common form of spinal cord dysfunction in individuals over the age of 55

Epidemiology /Etiology

Cervical spondylotic myelopathy is the most common disorder of the spinal cord in persons older than 55 years of age.  Radiologic spondylotic changes increase with patient age; 90% of asymptomatic persons older than 70 years have some form of degenerative change in the cervical spine. Both sexes are affected equally. Cervical spondylosis usually starts earlier in men (50 years) than in women (60 years). It causes hospitalization at a rate of 4.04 per 100,000 person-years.  

The causes of cervical myelopathy can be divided into different categories:
• Static factors: A narrowing of the spinal canal size can result from disc degeneration, spondylosis, stenosis, osteophyte formation at the level of facet joints, segmental ossification of the posterior longitudinal ligament and yellow ligament hypertrophy, calcification or ossification. Patients with a congenitally narrow spinal canal (<13mm) have a higher risk for the development of symptomatic cervical myelopathy.  
• Dynamic factors: due to mechanical abnormalities of the cervical spine or instability.
• Vascular and cellular factors: Spinal cord ischemia affects oligodendrocytes, which results in demyelination exhibiting features of chronic degenerative disorders. Also glutamatergic toxicity, cell injury and apoptosis may occur. 

Mechanism of Injury / Pathological Process

The onset is insidious and gradual, which is related to degenerative changes in the cervical spine anatomy. Osteophytic overgrowth, thickening of the ligamentum flavum (dorsally) and of the posterior longitudinal ligament can compress the spinal cord.  The intervertebral discs dry out resulting in loss of disc height, which increases compression of the vertebral end plates and osteophytic spurs develop at the margins of the end plates.  The degenerative changes encroach on the spinal cord and cause compression.

According to Cook et al cord compression may occur from:

1. osteophytes secondary to degeneration of intervertebral joints
2. stiffening of connective tissues, such as the ligamentum flavum at the dorsal aspect of the spinal canal, which can impinge on the cord by "buckling" when the spine is extended
3. degeneration of the intervertebral discs together with subsequent bony changes
4. other connective tissue changes

The cord compression is thought to be a combination of static compression and intermittent dynamic compression from cervical motion (flexion/extension).

Clinical Presentation

Cervical spondylotic myelopathy can cause a variety of signs and symptoms. Symptoms are divided into two groups: long-tract and segmental symptoms. Onset is insidious, typically in persons aged 50-60 years.

Early symptoms of this condition are ‘numb, clumsy, painful hands’ and disturbance of fine motor skills. Weakness and numbness occur in a non-specific/non-dermatomal pattern. As spinal cord degeneration progresses, lower motor neuron findings in the upper extremities, such as loss of strength, atrophy of the interosseous muscles and difficulty in fine finger movements, may present. Additional clinical findings may include: neck pain and stiffness (decreased ROM, especially extension), shoulder and scapular pain, paresthesia in one or both arms or hands, signs of radiculopathy, Babinski and Hoffman's sign, ataxia and dexterity loss.    Typical neurological signs of long-tract involvement are exaggerated tendon reflexes (knee and ankle), presence of pathological reflexes (e.g. clonus, Babinski and Hoffman's sign), spastic quadriplegia, sensory loss and bladder-bowel disturbance.
Once the disorder is diagnosed, complete remission to normality never occurs and spontaneous temporary remission is uncommon. In 75% of the patients, episodic worsening with neurological deterioration occurs, 20% have slow steady progression and 5% experience rapid onset and progression.

File:Cervical Osteophytes.jpg Osteophytes with Cord Compression

Cervical Spondylosis

Common Symptoms

• Distal weakness
• Decreased ROM in the cervical spine, especially extension.
• Clumsy or weak hands
• Pain in shoulder or arms
• Unsteady or clumsy gait
• Increased reflexes in the lower extremities and in the upper extremities below the level of the lesion.
• Numbness and parasthesia in one or both hands
• Radiculopathic signs

Differential Diagnosis

• Adhesive Capsulitis
• Brown-Sequard Syndrome
• Carpal Tunnel Syndrome
• Central Cord Syndrome
• Cervical Disc Disease
• Cervical Myofascial Pain
• Cervical Sprain and Strain
• Chronic Pain Syndrome
• Diabetic Neuropathy
• Multiple Sclerosis
• Myofascial Pain
• Neoplastic Brachial Plexopathy
• Osteoporosis and Spinal Cord Injury
• Radiation-Induced Brachial Plexopathy
• Rheumatoid Arthritis
• Traumatic Brachial Plexopathy
• Tumors

Examination

The diagnosis of CSM is primarily based on the clinical signs found on physical examination and is supported by imaging findings of cervical spondylosis with cord compression.  According to Cook et al Selected combinations of the following clinical findings are effective in ruling out and ruling in cervical spine myelopathy. Combinations of three of five or four of five of these tests enable post-test probability of the condition to 94–99%:

1. gait deviation
2. +Hoffmann’s test
3. inverted supinator sign
4. +Babinski test
5. age 45 years or older

Other clinical examination tests often used for myelopathy include  :
• Spurling’s test http://www.physio-pedia.com/Spurling's_Test
• Distraction test
• Positive clonus/Babinski/Hoffman's
• Hyper-reflexia biceps
• Hyper-reflexia quadriceps
• Hyper-reflexia achilles
• Pain constancy
• L’hermitte’s sign
• Romberg test http://www.physio-pedia.com/Romberg_Test
However, although these tests exhibit moderate to substantial reliability among skilled clinicians, they demonstrate low sensitivity and are not appropriate for ruling out myelopathy. One method used to improve the diagnostic accuracy of clinical testing is combining tests into clusters. These often overcome the inherent weakness of stand alone tests. 

However, although these tests exhibit moderate to substantial reliability among skilled clinicians, they demonstrate low sensitivity and are not appropriate for ruling out myelopathy.

Diagnostic Procedures

A detailed and thorough neurologic examination is the current standard to diagnose the presence of cervical myelopathy. A magnetic resonance image (MRI) is considered the best imaging method for confirming the presence of cervical stenosis, cord compression, or myelomalacia, elements germane to cervical spine myelopathy. An MRI is most useful because the tool expresses the amount of compression placed on the spinal cord, and demonstrates relatively high levels of sensitivity and specificity.   Anterior-posterior width reduction, cross-sectional evidence of cord compression, obliteration of the subarachnoid space and signal intensity changes to the cord found on MR imaging are considered the most appropriate parameters for confirmation of a spinal cord compression myelopathy.  Moore than half of patients with cervical spine myelopathy show intramedullary high signal intensity on T2-weighted imaging, mainly in the spinal gray matter.  MRI of the cervical spine can not only identify spinal canal stenosis, but can also rule out spinal cord tumors.

Imaging

 Plain radiographs alone are of little use as an initial diagnostic procedure. MRI of the cervical spine can identify spinal canal stenosis, as well as rule out spinal cord tumors.  Radiographic cervical spinal cord compression and hyperintense T2 intraparenchymal signal abnormalities (MRI) correlate well with the presence of myelopathic findings on physical examination.

Outcome Measures

• Neck disability index http://www.physio-pedia.com/Neck_Disability_Index
• Neck pain and disability scale http://www.physio-pedia.com/Neck_Pain_and_Disability_Scale
• Nurick-score 
• Japanese-orthopaedic-association-score (JOA-Score)   
• Cooper-myelopathy-scale (CMS) 
• European-myelopathy-score (EMS) 

Management / Interventions

Patients with cervical myelopathy that are treated with a conservative approach (anti-inflammatory medications, collar immobilization and physical therapy) may have some short term benefit in relief of painful symptoms.  Because the condition is degenerative and progressive, slow and continued progressive neurologic deterioration will occur.  

There is no consensus about the treatment of mild and moderate forms of cervical myelopathy(The Japanese Orthopaedic Association developed a scoring system for cervical myelopathy). Surgical treatment has no better results than conservative treatment over 2 years of follow-up. Motor training programmes may improve arm and hand functioning at function and/or activity level in cervical spinal cord injured patients. Surgery is needed in severe forms of progressive cervical myelopathy.

Physiotherapy has an important role before and after the surgery. In the pre-operative phase the physiotherapist will inform about the patients history and about the activity of daily living. The physiotherapist will inform the patient about the treatment and the expectations after the surgery. There are different tests to have an objective view on the abilities of the patient: distance of walking, Neck Pain and Disability Scale, Neck Disability Index and lung function.

Exercises to improve the mobility and the proprioception will be given to the patient. The patient starts unencumbered stabilisation exercises and then evolves to more active mobilisation exercises. During the day the patient is stimulated and helped to do daily life activities. The second day the intensity of the exercises increases and then evolve to standing and walking exercises. After a normal rehabilitation progress the patient can go home after nine day. At home the physiotherapy continues with active exercises. The physiotherapist has to make sure that the patient can continue his activity of daily living (ADL) and increases the intensity of it every day. After a normal rehabilitation there are no limitations to the adl-activities of the patient. Also important in the rehabilitation is to improve the posture. Physiotherapy is important before the surgery to inform the patient and for the physiotherapist to get to know the patient and to set up a rehabilitation program. The main goal is to make the patient able to participate in society again without permanent restrictions due to the surgery.

Resources

Dr. Pablo Pazmino, MD on Cervical Myelopathy

Mayo Clinic information on Spinal Stenosis

Wikipedia on Spinal Stenosis

In this video, Dr. Jeffrey Wang, a professor in the Department of Orthopaedic Surgery of UCLA, reviews Spinal Stenosis

Case Studies

57 Year-old male diagnosed with Cervical Myelopathy

Cervical Spondylotic Myelopathy in a Patient Presenting With Low Back Pain

Clinical Bottom Line

Cervical myelopathy is the result of spinal cord compression in the cervical spine and is the most common disorder of the spinal cord in persons older than 55 years of age. Cervical compression in myelopathy is predominantly due to pressure on the anterior spinal cord with ischaemia and to deformation of the cord by anterior herniated discs, spondylitic spurs or an ossified posterior longitudinal ligament. Early symptoms of this condition are ‘numb, clumsy, painful hands’ and disturbance of fine motor skill. The diagnosis of CSM is primarily based on the clinical signs found on physical examination and is supported by imaging findings of cervical spondylosis with cord compression. Once the disorder is diagnosed, complete remission to normality never occurs, and spontaneous remission to normal normality is uncommon. Exercises and techniques that may help relieve symptoms of cervical myelopathy include: cervical traction, manual therapy techniques, proprioceptive neuromuscular facilitation, cervical stabilization exercises and dynamic upper and lower limb exercises.

Recent Related Research (from Pubmed)

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References

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