Cervical Myelopathy

, by  Christophe Nuti, François Vassal, Jacques Brunon , popularity : 10%
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DIAGNOSIS

**I- CLINICAL FEATURES

The clinical features result from the direct compression of the nerve roots and/or the spinal cord, alteration in the arterial flow, venous congestion and inflammation. Certain genetic elements can influence the resistance of the neural structures (33).

***1. Mode of onset

The affection is two times more common in males than in females and begins between the ages of 50 and 60 years (25). Before 50 years, it is more often a discogenic canal stenosis from a “soft” central disc. Neurological impairment is often preceded for several months or years by mechanical cervical pain (50 to 80% of cases) which is poorly systematized, episodes of torticollis or even true cervico-brachial neuralgia . 
This often occurs in a context of repetitive microtraumas, occupational or sports related spinal "overload" and more rarely cervical spine injury without obvious radiological lesion, labelled "cervical sprain", which can only be discerned through dynamic images. However, it is possible that such a trauma causes discs and/or ligamentous injuries leading to degenerative lesions (14). The more common scenario is that of mundane mechanical pain from cervical spondylosis.

Gait disturbances are usually early in the form fatigability, tendency to the fall, reduction in the walking distance that can correspond to a true intermittent neurological claudication and sometimes episodes of flinching movements of the lower limbs. Gait disturbances may also be related with difficulties of coordination (ataxia sensory), disorders of balance, a poor perception of the ground, or even pain or paresthesia that occur for increasingly shorter distances.

In practice these disorders are fairly easy to differentiate from gait apraxia (astasia abasia) observed in adults chronic hydrocephalus, and from intermittent claudication due to lumbar canal stenosis while bearing in mind that these pathologies frequent in this age group may be associated.

Upper limbs affection can be another mode of presentation of the disease. Most frequently presents with pain or paresthesia more or less systematized in a radicular territory accompanied by a subjective sensation of clumsiness or functional disability making it increasingly difficult to achieve the delicate(fine) movements. Amyotrophy may be the presenting symptom.

Acute decompensation of a latent form during a relatively minor cervical trauma is a common mode of revelation: the clinical picture is that of a central cord contussion (Schneider’s syndrome) with incomplete tetraplegia where the motor impairment is disproportionately greater in upper compared to lower extremities and maximally brachial diplegia (72).

***2. Neurological examination findings

Neurological signs vary from one patient to another and occur in different proportions in the upper limbs, lower limbs and to a lesser degree the sphincters (63).

2a- Upper limbs affection

Because of their pathophysiologic mechanism there is still no good correlation between the topography of segmental neurological signs and the site of the anatomical lesions.
Subjective sensory manifestations (Symptoms) are almost always present as paresthesia or mechanical pain triggered by straining or neck movements, or as nocturnal neuropathic pain. The symptoms are unilateral or bilateral and often asymmetrical without an accurate radicular pattern. More rarely, it presents by a typical picture of cervico-brachial neuralgia that can be revealed during history taking a few years earlier.

Radicular pain of mechanical origin, secondary to degenerative changes, can be provoked during the clinical examination by eliciting Spurling’s sign (radicular pain reproduced when the examiner exerts down­ward pressure on vertex with the neck in extension while tilting head towards symptomatic side) and the abduction relief sign (reduction or disappearance of the radicular pain when the patient abducts the arm by putting his hand on his head) (21).

Objective sensory manifestations (Signs) can be demonstrated by the examination of the painful region. They lack an accurate radicular topography and are often in the form of hypoesthesia of all sensory modalities. The disturbances may be prominent on the lemniscal pathway explaining the clumsiness to achieve fine movements: holding pencil, sewing, manipulating small objects .

A segmental motor affection may be due to a lesion of the nerve root or of the anterior horn cell; the latter sometimes simulate starting amyotrophic lateral sclerosis. The affection is usually distal in the hand muscles accompanied by muscle atrophy and rarely fibrillations localized in the upper limbs.

The abolition of one or more reflexes is frequently observed but their exaggeration can be found in the high cord affection. Clinical examination may reveal a Hoffmann’s sign in upper limbs in cases of involvement the pyramid tract.

The functional impairment felt by the patient stems from both an affection of the sensation and diminished motor power.

2b-Lower limbs Affection

It is responsible for abnormal gait, impaired balance, functional impotence and tendencies to the fall.

Pyramidal involvement is rarely responsible for a significant motor deficit. There is often spastic paraparesis with hypertonia of the extensors, an exaggeration of deep tendon reflexes and a bilateral positive Babinski sign. The affection can be discrete at the beginning and objectified only after fatigue and after classical facilitation maneuver. It can be masked when associated with lumbar canal stenosis or peripheral neuropathy.
Involvement of the posterior column is responsible for subjective manifestations such as paresthesia, numbness and pain sometimes spontaneous or provoked by neck flexion (Lhermitte’s sign). Posterior column lesion is objectivated by the decrease in vibration sensation, impairment of arthrokinesthesia and sometimes presence of Romberg’s sign.

Involvement of the spinothalamic tact is rarer and late and results in a thermal hypoesthesia and hypalgesia.

The gait disturbance presented by the patient are more related to hypertonia and sensory ataxia than to the motor deficit.

2c-Sphincter dysfunction

Present in 30-40% of the cases and are often underestimated. They are in the form of dysuria, urinary frequency and sometimes stress incontinence. They are not always related to their cause (suggestive of prostatism or age-related incontinence in women) and should be systematically investigated by measuring the post-void residual via an ultrasound of the bladder.

***3. Clinical forms

The condition is in fact very polymorphic; depending on the topography of symptoms, their severity and evolution. It is therefore possible to individualize several clinical forms:

3a-Ataxic-Spastic Form  : It is the most frequent form predominantly manifesting by gait disturbances and dysequilibrium with sub-clinically affection of the upper limbs. All lesions causing cord affection can be evoked faced with this form notably “slow” cord compression in which there is no sensory level and the sensory manifestations are discrete, and multiple sclerosis (in which the signs are not diffused).

3b-Amyotrophic form predominantly affecting the upper limbs can at the beginning simulate amyotrophic lateral sclerosis but the course is much more rapid and disabling.

3c-Spastic paraparetic forms-with minimal sensory lesion,

3d-Brown Sequard-like forms-occur when there is predominantly unilateral cord lesion.

3e- Forms evolving by successive spurts are suggestive of late onset multiple sclerosis.

Nurick’s classification established in 1972 (61) evaluates in a simple and reproducible manner the functional disability of patients, monitoring of their progress and evaluates the results of treatment, but is relatively imprecise (Table 1).

The classification of the Japanese Orthopaedic Association (JOA) (38) which is imposed on most English speaking authors after modification (6) is the sum of functional scores. The maximum score is 17 for patients without any neurological disease (Table 2).

***4-Evolution

There is no spontaneous improvement. The course is unpredictable with progressive neurological deterioration occurring most often (33). However, long periods of dormancy can be observed (53). In about 75% of the cases, the evolution occurs in a discontinuous mode by successive bouts over several years. In 20% of the cases the evolution is more or less rapidly progressive and in 5% of the cases, there is a sudden decompensation often caused by cervical trauma of varying severity. This decompensation is rare in patients below 75 years with moderate cervical myelopathy (JOA score> 12) (53).

In the case of degenerative cervical stenosis without myelopathy, the presence of electromyographic abnormalities or clinical radiculopathy predicts progression to symptomatic cervical myelopathy (53).

The end stage is represented by a complete inability to ambulate and / or severe functional impairment of the upper limb producing severe disability.