Spondylosis – Degenerative changes in the spine are commonest cause of diseases of spinal cord and nerve roots after the age of 50 years. Majority of elders have asymptomatic picture and diagnosis rests often on radiological studies.
Degenerative changes in the spine predominantly in cervical and lumbar regions are associated with osteophyte formation, degeneration of intervertebral discs with protrusion of nucleus pulposus and their subsequent effects on nerve roots and the cord.
The acute protrusion of nucleus pulposus is in direct contrast to chronic protrusion of the annulus fibrosus of one or more intervertebral discs. All these degenerative changes are grouped under the general term of spondylosis.
The appearances of cervical spondylosis can be seen radio-logically in 75 percent of the population aged 50 and above and in 95 per cent of those over the age of 70. In considerable number there are associated signs of neurological dysfunction ranging from pain in the distribution of nerve roots to compressive myelopathy.
Aetiology and pathogenesis
The intervertebral disc consists of gelatinous nucleus pulposus, the annular fibrosis and the upper and lower cartilaginous plates and these play important role in maintaining correct static and dynamic function of the spine.
The stresses on the spine are mainly static in the lumber region and dynamic in the cervical region. Pressure on the disks and movements of the spine tend to expand the annulus fibrosis laterally.
The occurrence of disc prolapse and degeneration in the lumbar and cervical regions is as a result of mechanical injury like lifting and carrying of loads as well as by sudden uncoordinated movements of the spine.
The nucleus pulposus and annulus fibrosus also play part in the functioning of the intervertibral discs. As a result of regressive changes, these loose their elasticity due to aging which in turn depends on body’s constitution, the amount of daily stress and the person’s habits.
The intervertebral discs are subject not only to mechanical effects but also to changes in its histochemical stmctures which impair its resistance to mechanical injury.
Disc degeneration results in narrowing of intervertebral spaces with thinning and protrusion of the nucleus pulposus and bulging of annulus fibrosus. There are associated changes in the adjacent vertebral margins which are responsible for neurological deficit.
Disc protrusion signifies not only nuclear extension but also ligamentous and annular thickening with secondary osteophyte formations on the dorsal aspect of the vertebral bodies.
Root compression is secondary to osteophyte extension of the bar laterally associated with articulatory hypertrophic changes. Further there may be root sleeve fibrosis which includes thickening of the dura and arachnoid in the vicinity of root ostia with production of a constriction ring.
Partial sublaxation of the vertebra may cause impinging of nerve roots by osteophytes during movements of the spine.
Owing to tethering of the cord by the ligamenta denticulata and of spinal roots by narrowed intervertebral foramina, cumulative trauma to cord may be produced resulting in non-compressive myelopathy.
This is due to interference in the blood flow in the anterior spinal artery and its branches caused by compression possibly intermittent in a spinal canal that is narrowed beyond a certain minimum.
Causes of cervical spondylosis
2. Repeated trauma of spine
3. Narrowing of inter-vertebral spaces
4. Osteophytes on the posterior aspect of vertebral bodies
5. Subluxation of vertebrae
6. Hypertrophy of dorsal spinal ligament
7. Congenital spinal canal stenosis
Spondylosis may be present without any symptoms but a sudden hyperextension or acute flexion of the cervical spine may cause contusion of the cervical cord with sudden paraplegia.
The main complaint is pain in the neck and shoulder region with or without radiation in the distribution of nerve roots. This is variable and is usually exaceberated by mechanical stress on the spine.
The range of movements of the spine are not markedly restricted though rotation and lateral movement of the head produces pain. Coughing and sneezing may worsen the pain.
Objective findings may not be there. Pressure on nerve roots is associated with radicular pain in their distribution. Most often it is in the distribution of C5, C6. Motor weakness and wasting of the muscles depends on the root compressed. Sensations are involved in the form of tingling sensation, radiation and areas of hyperaesthesia.
Headache is often present. It is dull, nagging type starting in the back of the neck and spreading upto the occipital region. Compression of cervical cord produces a slowly progressive spastic paraparesis. Motor weakness of varying degrees is present.
In upper limbs, the small muscles of the hand with or without involvement of adjacent fore arm is affected while in the lower limbs weakness predominates in gluteal, quadriceps and calf muscles. The reflexes are asymmetrical and increased in lower limbs Babinski sign is usually present while reflexes in upper limb are either diminished or exaggerated.
Sensory loss may be present and there may be dermatological level. Vibratory sensation is usually diminished in the lower limbs. Sphincter involvement in the form of urinary retention and incontinence may be present. Involvement of vertebral foramina produces pictures of vertebro basilar artery insufficiency (Wrtigo, tinnitus, intermittent blurring of vision).
Clinical signs of cervical spondylosis
1. Root pains in the distribution of CS, C6, C7.
2. Restricted movements of spine
3. Compressive myelopathy
(a) Slow, progressive para paresis, asymmetrical
(b) Wasting of muscles
(c) Sensory loss
(d) Deep reflexes (Diminished / exaggerated)
(e) Urinary urgency / incontinence
It is based on
(a) Symptoms in the muscles and tendons of the cervical spine, shoulder girdle and arms.
(b) Parasthesia in feet and hands
(c) Signs of progressive myelopathy
(d) Wasting of muscles especially small muscles of hands and of lower limbs.
Further radiological examination of the spine is helpful. Plain X-ray of the spine shows narrowing of intervertebral discs, loss of natural curvature of spine and reduction of saggital diameter of the canal and osteophytes arising at the anterior and posterior borders of vertebral bodies.
Oblique radio-graphs show narrowing of inter-vertebral foramina, prolongation of inter-vertebral articular processes and bony spurs which may bridge the inter-vertebral spaces. In elderly patients disk degeneration with bony changes is frequently complicated by diffuse osteoporosis of the spine.
For demonstration of compressive myelopathy contrast myelogram is necessary. CT Scan and MRI scan are better options. The total and while differential cell counts as well as erythrocyte sedimentation rate, semm calcium and phsopoms, alkaline and acid phosphatase are normal.
CSF is usually normal but it may sometimes show slightly elevated proteins. Electro myography may be helpful in demonstrating radicular lesions.
Cervical spondylosis may have to be differentiated from other diseases producing myelopathy (Amyotrophic lateral sclerosis, multiple sclerosis, sub-acute combined degeneration of the cord and spinal tumours.
Basically it is conservative and consists of Rest, immobilization and diathermy supplemented by NSAIDs. Physiotherapy has important role to play and cervical traction, static and dynamic exercises of neck are beneficial.
In addition short wave diathermy and ultrasonic irradiation are also employed. Patients where pain is marked in neck region, cervical collar is advised to reduce movements of neck.
Where there are advanced symptoms and features of compression (as demonstrated by myelography & CT scan) as well as intractable root pains surgical intervention is advised in the form of laminectomy (removal of offending bar). For severe root pains, foraminotomy is beneficial.
Prognosis in a case of cervical spondylosis shall depend on the extent and duration of the disease as well as age of the patient.