Spinal stenosis

Spinal stenosis is a narrowing of the spinal canal that causes compression of the spinal roots (sometimes the spinal cord) before they exit the intervertebral foramen, position-dependent back pain, and symptoms of nerve root compression.

Spinal stenosis can be congenital or acquired. It can be in the cervical and lumbar spine. Acquired lumbar spinal stenosis is a common cause of sciatica in middle-aged patients. It is most often caused by degenerative processes such as osteoarthritis, disc pathology, facet arthropathy, ligament thickening and deformity, spondylolisthesis with compression of the cauda equina. Other causes may include Paget's disease, rheumatoid arthritis, and ankylosing spondylitis. All of these precipitating factors tend to worsen with age.

Symptoms of Spinal Stenosis

Typically, spinal stenosis presents clinically with pain and weakness in the legs while walking. This neuropathic pain is called "pseudo-intermittent claudication" or neurogenic intermittent claudication. Patients with spinal stenosis may also experience paresis, sensory disturbances, and decreased reflexes.

Patients suffering from spinal stenosis complain of calf and leg pain and weakness when walking, standing, lying on the back, pain in the buttock, thigh, or calf when walking, running, climbing stairs, or even standing. The pain is not relieved by standing quietly. These symptoms disappear if patients kyphosis in the lumbar region or adopt a sitting position. Walking uphill is less painful than walking downhill because the back is slightly bent. Often, patients with spinal stenosis adopt a crouch-like posture with the trunk bent forward, knees slightly bent when walking to reduce the symptoms of pseudo-intermittent claudication. Spinal extension may induce symptoms. Patients also complain of pain, numbness, tingling, paresthesia in the innervation zone of the affected root or roots. Weakness and loss of coordination in the affected limb may be noted. A positive flexion test is often observed in case of spinal canal stenosis. Along with pain radiating to the trapezoid and interscapular regions, muscle spasms and back pain are observed. Physical examination reveals decreased sensitivity, weakness, and changes in reflexes.

Sometimes patients with spinal stenosis develop compression of the lumbar roots and cauda equina, leading to lumbar myelopathy and cauda equina syndrome. This manifests itself as varying degrees of weakness in the lower extremities and symptoms of bladder and bowel dysfunction, which constitutes a neurosurgical emergency, the onset of which is often unexpected.

Survey

MRI provides the most comprehensive information about the lumbar spine and its contents and should be performed in all patients with suspected spinal stenosis. MRI is highly informative and can identify pathology that puts the patient at risk for developing lumbar myelopathy. The smallest sagittal dimension of the lumbar spinal canal is 10.5 mm. For patients who cannot undergo MRI (presence of pacemakers), CT and myelography are reasonable alternatives. If a fracture or bone pathology such as metastatic disease is suspected, radionuclide bone scanning or plain radiography is indicated.

While MRI, CT, and myelography provide useful neuroanatomical information, electromyography and nerve conduction velocity studies provide neurophysiological data on the current status of each nerve root and the lumbar plexus. Electromyography can also differentiate between plexopathy and radiculopathy and identify coexisting tunnel neuropathy that may complicate the diagnosis. If the diagnosis is in doubt, laboratory testing should be performed, including a complete blood count, ESR, antinuclear antibodies, HLA B-27 antigen, and blood biochemistry to identify other causes of pain.

Differential diagnosis

Spinal stenosis is a clinical diagnosis based on history, physical examination, radiography, and MRI. Pain syndromes that may mimic spinal stenosis include myogenic pain, lumbar bursitis, lumbar fibromyositis, inflammatory arthritis, and lesions of the lumbar spinal cord, roots, plexus, and nerves, such as diabetic femoral neuropathy.

Treatment of spinal stenosis

A multicomponent approach is most effective in treating spinal stenosis. Physical therapy, including heat therapy and deep relaxation massage, in combination with NSAIDs (eg, diclofenac, loronoxicam) and muscle relaxants (tizanidine) are reasonable initial treatments. Caudal or lumbar epilural blocks may be added if needed; local anesthetic and steroid blocks are highly effective in treating spinal stenosis. Sleep disturbances associated with depression are best treated with tricyclic antidepressants such as amitriptyline, which can be started at 12.5 mg once daily at bedtime.

Complications and diagnostic errors

Failure to diagnose spinal stenosis promptly may put the patient at risk of developing lumbar myelopathy, which, if left untreated, may progress to paraparesis or paraplegia.

Spinal stenosis is a common cause of back and lower extremity pain, and the finding of pseudo-intermittent claudication should direct the physician to this diagnosis. It should be remembered that this syndrome tends to worsen with age. The onset of lumbar myelopathy or cauda equina syndrome may be subtle, so a thorough history and physical examination are necessary to avoid missing symptoms of these complications.