Spinal stenosis overview

# Classification
Spinal stenosis may be classified according to where on the spine the condition occurs, into three groups: Cervical spinal stenosis, thoracic spinal stenosis and lumbar spinal stenosis. Spinal stenosis occurs most often in the lower back and in the neck.

# Pathophysiology
Spinal stenosis is the narrowing of the vertebral canal tube. This narrowing produces neurovascular compression that may lead to pain and other neurology manifestations of spinal stenosis. Radiographic changes associated with stenosis are very common with aging. Although symptoms may arise from narrowing of the spinal canal, not all patients with narrowing develop symptoms. The spinal cord extends from the foramen magnum down to the level of the first and second lumbar vertebrae. At L2 level spinal cord transforms into spinal roots and forms a cone-shaped structure called conus medullaris. The cord is protected by the vertebral column, which is mobile and allows for movement of the spine. It is enclosed by the dura mater and the vessels supplying it. The cord floats in the cerebrospinal fluid which acts as a buffer to movement and early degrees of compression. The cord substance contains a gray area centrally and is surrounded by white matter communication tracts, both ascending and descending. The spinal stenosis may result from any condition that narrows the spinal canal and compresses nerve roots. The most common cause of spinal stenosis is degenerative joint disease. The spinal cord and nerve roots depend on a constant blood supply to perform axonal signaling. Conditions that interfere, either directly or indirectly, with the blood supply will cause malfunction of the transmission pathway. It initiates a cascade of events in the gray matter and white matter and results in hypoperfusion. The following results in autonomic dysfunction leading to neurogenic shock ( triad of hypotension, bradycardia and peripheral vasodilation) and eventually hemorrhagic necrosis. The extent of necrosis depends on the severity of the compression, and blood flow. The tissue responses by gliosis, demyelination, and axonal loss. This results in injury to the white matter (myelinated tracts) and the gray matter (cell bodies) in the cord with loss of sensory reflexes (pinprick, joint position sense, vibration, hot/cold, pressure) and motor function.

# Causes
The most common cause of spinal stenosis is degenerative joint disease. Other common causes of spinal stenosis include: Spinal disc herniation, thickness of the Ligamentum Flavum, trauma, tumor (primary or secondary), scoliosis, vertebral compression fractures, epidural abscess, epidural hematoma and ligamentum flavum cyst.

# Differentiating spinal stenosis from Other Diseases
Spinal stenosis must be differentiated from other diseases that cause lower extremity pain and back pain , such as: Intervertebral disk herniation, metastatic disease of the spine, vertebral osteomyelitis or discitis, degenerative disk disease, compression fracture, spondylolysis, spondylolisthesis, Mechanical low back pain, Rheumatoid arthritis and primary spinal, intradural, or intramedullary tumor. The relieving of the pain by spinal flexion (e.g sitting, cycling) is specific for spinal stenosis and is the key point for differentiation of spinal stenosis from other common causes of lower extremity pain and back pain. The pain of spinal stenosis is usually associated with activity and walking, as lumbar extension during activity worsens the narrowing of the spinal canal.

# Epidemiology and Demographics
The incidence of lumbar stenosis in the general population is between 1700 and 8000 per 100,000 and it increases from the fifth decade of life. The prevalence of spinal stenosis in the US community based sample is approximately 4710 per 100,000 and 26200 per 100,000 for relative and absolute stenosis in the 6069 year-old age group. Patients of all age groups may develop spinal stenosis. The incidence of spinal stenosis increases with age. There is no racial predilection to spinal stenosi.

# Risk Factors
Common risk factors in the development of spinal stenosis include cumulative trauma, osteoporosis, obesity, loss of muscle tone, congenital defects, Paget's disease, achondroplasia and cigarette smoking.

# Screening
There is insufficient evidence to recommend routine screening for spinal stenosis.

# Natural History, Complications, and Prognosis
The symptoms of spinal stenosis usually develop in the old age, and start with symptoms such as pain and cramping in neck, back and legs. Common complications of spinal stenosis include: Numbness of limbs, Paralysis of limbs, Weakness of limbs, Obesity due lack of activity, Bladder or bowel incontinence,Depression, and other psychological problems. Prognosis in patients with spinal stenosis who initially treated with medical or physical therapy is variable. Among treated patients without surgery in one study, about 50% remain unchanged, 25% improve, and 25% worsen (mean follow-up was 49 months, range 10 to 103 months). Outcome in patients treated surgically is not significantly better rather than nonsurgically treated patients.

# Diagnosis

## Diagnostic Study of Choice
MRI is preferred diagnostic imaging for spinal stenosis. Findings include:The narrowing of the spinal canal, bulging or herniated discs, pinched, inflamed or compressed nerves in the spinal cord, extradural spinal hematoma, abscess or tumor, disk rupture, spinal cord hemorrhage, contusion or edema.

## History and Symptoms
A positive history of trauma, osteoporosis, obesity, congenital defects, Paget's disease, achondroplasia and cigarette smoking is suggestive of spinal stenosis. Most patients with spinal stenosis present with lower extremity pain relieved spinal flexion (e.g sitting, cycling). The pain of spinal stenosis is usually associated with activity and walking, as lumbar extension during activity worsens the narrowing of the spinal canal. Other common symptoms of spinal stenosis include: Numbness or tingling in a hand, arm, foot or leg, weakness in a foot or leg, back pain, weakness in a hand, arm, foot or leg, problems with walking and balance and in severe cases, bowel or bladder dysfunction.

## Physical Examination
Patients with spinal stenosis usually appear normal. Patients with spinal stenosis usually have a normal vital signs.Physical examination of patients with spinal stenosis may be remarkable for: Neck pain and tenderness, Lower back pain and tenderness, Scrotal and perianal claudication, Hyperreflexia, positive Romberg test, decrease in upper extremity sensation, weak knee and ankle reflexes, leg muscle weakness bilaterally, positive straight leg raise test, abnormal gait, bilateral calf muscle atrophy, weak knee and ankle reflexes and muscle atrophy.

## Laboratory Findings
There are no diagnostic laboratory findings associated with spinal stenosis.

## Electrocardiogram
There are no  electrocardiogram findings associated with spinal stenosis.

## X-ray
An x-ray may be helpful in the diagnosis of spinal stenosis. Findings on an x-ray suggestive of spinal stenosis include: Narrowed spinal canal, short pedicles of vertebraes, spondylophytes, osteoarthritis of spinal canal.

## Echocardiography and Ultrasound
There are no echocardiography findings associated with spinal stenosis. Ultrasound may be helpful to demonstrate spinal canal narrowing but ultrasound is not widely used for diagnosis of spinal stenosis.

## CT scan
Cervical and lumbar CT scans of spinal column may be helpful in the diagnosis of spinal stenosis. Findings on CT scan suggestive of spinal stenosis include: Facets hypertrophy, Osteophytes, Hypertrophy of ligamentum flavum, Narrowed spinal canal, Compression of the neural elements, Hypertrophic bones, Disc herniation, Metastases and Infections.

## MRI
MRI is preferred diagnostic imaging for spinal stenosis. Findings include:The narrowing of the spinal canal, bulging or herniated discs, pinched, inflamed or compressed nerves in the spinal cord, extradural spinal hematoma, abscess or tumor, disk rupture, spinal cord hemorrhage, contusion or edema.

# Treatment

## Medical Therapy
Pharmacologic medical therapy is recommended among patients with spinal stenosis. Pharmacologic medical therapy is the first step in treatment of patients with spinal stenosis. Pharmacologic medical therapies for spinal stenosis include Non-steroidal anti-inflammatory drugs, muscle relaxants, opioid analgesics and injectable calcitonin. The use of epidural steroid injections is controversial and evidence of their efficacy is contradictory. Physical therapy is recommended for all patients with spinal stenosis. No conclusions could be drawn from the review regarding which physical therapy treatment is superior for spinal stenosis.

## Surgery
If the pain is persistent and does not respond to these measures, surgery is considered to relieve the pressure on the nerves or spinal cord. Surgery is performed on the neck or lower back, depending on the site of the nerve compression. Regarding indications for laminectomy, a complicated, nonrandomized analysis of a randomized controlled trial of laminectomy\, in patients with:neurogenic claudication or radicular leg pain with associated neurologic signs, spinal stenosis shown on cross-sectional imaging, and degenerative spondylolisthesis shown on lateral radiographs obtained with the patient in a standing position. The patients had had persistent symptoms for at least 12 weeks and had been confirmed as surgical candidates by their physicians. Patients with adjacent levels of stenosis were eligible; patients with spondylolysis and isthmic spondylolisthesis were not."found that patients: treated surgically showed substantially greater improvement in pain and function during a period of 2 years than patients treated nonsurgically.