Lumbar stenosis

In lateral stenosis, the intervertebral foramina decrease in size from L1 to L5; therefore the L5 nerve root tends to be the most frequently involved.

Regarding central stenosis, Porter suggests that “Pathologically, a developmentally small canal is usually affected by multiple levels of segmental degenerative change, with venous pooling in the cauda equina between two levels of low pressure stenosis.” (4)

He also states that “the size of the lumbar vertebral canal has clinical importance. The patient with spinal stenosis has more than a spinal disadvantage.” (5). He has found through studies on the effects of Antenatal environment on the development of the spinal canal, that the L3 canal was found to be the most sensitive to the influence of the factors such as gestational age and low birth weight. (6). Alvarez (7) describes lumbar stenosis as predominantly a condition of the older age groups.

Lumbar stenosis is a condition that progresses slowly, and has few clinical signs, thus delaying diagnosis. Diagnosis relies mostly on symptomatology raising the possibility of the condition, thereby suggesting relevant investigations. “Symptoms are often chronic, frequently missed, or misdiagnosed in the medical community, and may cause severe disability or reduction in the quality of life.” (8)

The chief symptom is what is termed “neurogenic claudication” (from the Latin “claudico”, meaning “I limp”) which refers to lower limb pain, often bilateral, which comes on with walking or standing for a length of time. As the condition progresses, walking distance and standing time are progressively decreased. Symptoms are relieved by sitting down or bending forward (compare disc herniation, in which bending exacerbates the pain). Some patients will bend down or squat as if about to tie their shoe lace, to relieve pain on walking and there is the “shopping cart” sign, which is when a patient will

Lean over the back of the shopping trolley to relieve the pain on standing in a queue. Flexion of the spine reduces symptoms, whereas extension exacerbates them.

Neurogenic claudication should be distinguished from vascular intermittent claudication. The circulatory nature of the latter will present other features such as skin pallor or mottling, and impaired peripheral pulses. Significantly, resting in the standing position (unlike neurogenic claudication) relieves the pain of vascular claudication on exercise.

The pain tends to be burning, gripping or cramping in nature, and radiates from the buttocks down the leg. The patient may describe it as “vice—like”. There may also be dull aching and fatigue in the thighs and legs. Other symptoms may include tingling and numbness, as well as a degree of weakness. In severe cases, urinary incontinence can occur. Low back pain may also be a feature, but not usually a predominant one.

A study by Jonsson et al (9) concluded that: “Pain was more intense and positive straight leg raising test results were more common in younger patients, whereas reflex disturbances were more common in the elderly.”

It must be remembered that other spinal conditions may co—exist with stenosis, in particular, disc disease. This may complicate the clinical picture.

Clinical examination may not reveal abnormalities in straight leg raising or reflexes, as would be seen in disc disease. Sensory loss tends to be dermatomal (in nerve root distribution). Evaluation may include the Phalen test, which attempts to reproduce the symptoms of leg pain etc.

The patient is stood upright and the spine extended by the examiner for a minute or so, which will induce the symptoms. Then the patient is allowed to bend forward and put his hands on a table, with one leg on a stool. This should relieve the symptoms.

A further useful test is Exercise stress testing on a treadmill. (10)

Investigation of stenosis is best achieved by CT or MRI scan with axial loading, (11), which is the equivalent of the Upright flexion—extension myelography, which is also used. (12)

Bearing in mind that myelography is an invasive procedure and carries risks such as arachnoiditis (see below) the author recommends the latest MRI techniques.

For cervical spine, T2— weighted turbo spin—echo MRI is the investigation of choice. (13).

Treatment of stenosis seems to raise controversies amongst the medical profession. Many authors suggest that conservative (non—surgical) treatment is preferable, where as authors such as Alvarez (7) maintain that this has little proven benefit and that early surgery is the best method of treatment. Jonsson et al (14) suggest that the results from surgical decompression deteriorate with time, and that patients who had had symptoms for less than 4 years (and had insignificant low back pain) had the best outcomes.

A review published in 1997 concludes that: “This review of the literature shows that the least invasive surgical procedure can obtain the best results if the correct diagnosis is made and if the operation is carried out within the first years of the disease.” (15)

Another recent stud, by Javid and Hadar (16) suggests that “At 1 to 11 years the success rate was 70.8% for patients with stenosis. 66.6% for those with stenosis and herniated disc, and 63.6% for those with lateral recess stenosis.

In conclusion, long term improvement after laminectomy was maintained in two thirds of these patients”

Decompressive surgery must balance sufficient decompression with inducing spinal instability.

The principle causes of failure of surgery are inadequate decompression, recurrence of degenerative hypertrophy (overgrowth), and instability.

Arachnoiditis may also occur as a complication. (See below).

Other modes of treatment have included epidural steroid injections, but Fukusaki et al (17) in a recent paper, state that they are not effective in stenosis patients.

Other authors such as Cohen and Kostuik do not endorse their use, although some doctors (such as Rydevik) believe that they can be of use in the elderly population, for whom the risk of surgery is greater. (18)

One study in Japan (19) tried using intravenous lipoprostaglandin (Lipo—PGEI) to treat stenosis.

It produced symptomatic improvement for a limited period in the treatment of neurogenic claudication associated with stenosis.

The drug appeared to exert its effects through an increase in the circulation of blood in the nerve roots and the cauda equina.

Table of Contents

Introduction
Lumbar stenosis
NEXT: Arachnoiditis and Stenosis
References