85 percent of adults over the age of 60 experience cervical spondylosis. (1)
Cervical spondylosis as the name suggests most commonly affects the cervical region and in turn, the functions performed by the cervical spine are also affected. It is commonly associated with the presentation of more symptoms of the upper body involving the arms, trunk, and neck region. But it is not always as cervical spondylosis can also affect lower body involving legs, thighs, torso, etc. (2)
When the changes occurring in the cervical spine becomes accumulated over a large period then there is cervical disc herniation and compression of the whole of the spinal cord. It denotes a chronic change but can also occur as an acute episode after there is some precipitating cause encountered such as heavy weight lifting, sudden fall from a height, snapping of the neck, etc. (2)
Does Cervical Spondylosis Affect The Legs & Cause Leg Weakness?
The herniation of the disc causes the collapse of the space available around the spinal cord and it is known as cervical stenosis. The spinal cord gets compressed entirely leading to disruption of the function of the spinal cord. It affects the whole of the body including legs and the symptoms may range from simple leg weakness to complete leg paralysis. Leg weakness or paralysis can also occur in transverse lesion syndrome and brown Sequard syndrome (2).
To understand the mechanism of involvement of leg in cervical spondylosis, it is very much important to look into the arrangement of tracts of the spinal cord. The sensory tracts so-called spinothalamic tract which takes the sensation of pain and temperature from the body to the brain are arranged at the cervical level in a manner in which sacral fibers are located at the outermost part and cervical fibers are located at the innermost part of the tract.
When there is cervical spondylosis in its initial phase then it starts by affecting the innermost part which leads to disruption of the function of cervical fibers and the upper body gets symptoms of loss of sensation. The outermost fibers of the sacral region are intact and legs are not experiencing any symptoms. But when there is complete stenosis of spinal space, outermost fibers are also affected and the patient presents with loss of sensations in the lower body.
Similar is the case with the corticospinal tract which is responsible for transmitting the motor impulse from the brain to the muscles. The arrangement of the corticospinal tract at the cervical level is similar to that of the spinothalamic tract but are located anteriorly. It causes the symptoms of weakness of the muscles of the upper body in its initial presentation and later on it can involve the lower body as well then there is the symptom of leg weakness and leg paralysis (3).
Bladder/bowel involvement can also be seen at such a later stage off the condition leading to incontinence of urine and feces. Posterior column fibers have an opposite arrangement to that of sensory and motor tract arrangement but are located posteriorly in the spinal cord and get involved at the last. So, its involvement in the upper and lower body can present at the same time.
It is very much possible that the patient of cervical spondylosis can present with the symptoms of leg weakness and leg paralysis. It can be unilateral or bilateral depending upon the extent of involvement of the spinal cord. But it usually is seen either in the acute episode when there is a sudden collapse of the cervical vertebrae under some injury mechanism or it occurs in the later stages of a chronic case of cervical spondylosis. It can also lead to the involvement of the autonomic system which controls the sphincters like that of bladder or bowel presenting with the complaint of incontinence. The good part about the cervical spondylosis is that it has a very slow progression and can be kept in control with adequate measures.