The characteristic symptom of lumbar spinal stenosis (LSS) is neurogenic claudication (spinal claudication). When walking, the patient experiences pain (which usually starts in the back and radiates to the legs), numbness or weakness.
If the symptoms are tolerable and the patient's functional capacity is intact, the first-line management option is conservative treatment (including e.g. analgesia and physiotherapy).
Consider surgery, if needed, after 3-6 months of conservative treatment.
Indications for surgery include
unbearable or clearly interfering pain not relieved with conservative treatment
gradually shortening walking distance
progressing neurological deficit - LSS may be behind paraparesis
cauda equina syndrome (a rare situation: LSS usually progresses slowly).
Definition and epidemiology
Lumbar spinal stenosis denotes a stricture (stenosis) in the lumbar spine region, which may be either
a central stenosis (compression of the cauda equina in the spinal canal) or
a lateral stenosis (nerve root compression in the root canal or intervertebral foramen).
Degenerative changes are the most common cause of stenosis (ostephyte formation or ligament hypertrophy). Disc protrusion or prolapse may also be present.
Division into central and lateral forms is a radiological differentiation; mixed form LSS is the most common type.
Prevalence and incidence increase with age.
LSS is the most common reason for spinal surgery in patients aged over 65 years.
MRI and CT scans are carried out more than before, and consequently an increasing number of patients are diagnosed with LSS.
Symptoms and history
The most common symptom is neurogenic (spinal) claudication; when walking, the patient experiences pain (which usually starts in the back and radiates to the legs), numbness or weakness. The pain is usually relieved by sitting or leaning forward and worsened by extension.
Pain which is caused by chronic compression of a nerve root (”chronic sciatica”) is more persistent or manifests itself as numbness and paraesthesia; the symptoms may be localised to the affected dermatome or be more widespread.
The symptoms of LSS may be unilateral or bilateral. The intensity of pain often shows variation both from day to day and over the long term.
Patients may describe the symptoms in very different ways, and it is important to ask carefully about the location and nature of symptoms experienced during walking, exercise or at rest.
What distance can the patient walk on level ground without stopping? Does he/she stop due to claudication or for another reason?
Leaning forward for a prolonged period, exercise and even sitting may worsen the symptoms of LSS, particularly back pain. As is the case with all degenerative low back problems, reduced exercise tolerance of the back should be identified by taking a careful history, particularly when the symptoms threaten the patient's work capacity, since a physical examination of a patient with LSS may produce only a few findings.
Remember cauda equina symptoms and other critical "red flag" symptoms Low Back Pain.
Clinical findings
Patients with LSS-induced neurogenic claudication may be relatively asymptomatic when examined at rest, and findings of neurological examination may be completely normal. The importance of the history is thus emphasized.
If LSS is characterised with chronic nerve root compression, the patient may have pain when moving his/her back, and the SLR (straight leg raising) and Lasègue tests may be positive.
In the SLR test, the examiner raises the patient's straightened leg upwards by supporting it at the underside of the ankle so that the ankle remains free. In the Lasègue test the examiner has a hold on the patient's foot and keeps the ankle dorsiflexed in straight angle (90°) while raising the leg. In both tests, the examiner's other hand lies on the anterior surface of the patient's thigh to keep the knee straight.
Extension test: the patient is asked to fully extend his/her back whilst standing with the knees straight. The posture is held for 30-60 seconds. Low back pain/numbness provoked by the posture supports the diagnosis of LSS. The specificity of the test is not known.
Approximately half of the patients with LSS have sensory or reflex defects.
The pulses of the dorsal pedis artery and the posterior tibial artery should be palpated. A significant vascular occlusion may be excluded if the pulses are present, which will strengthen the suspicion of back problems as the cause of claudication.
Consider performing digital rectal examination (cauda equina compression; carcinoma of the prostate as the cause of back pain).
Diagnosis
The diagnosis of LSS is based on the history and clinical findings which must be supported by radiological abnormalities; decisions regarding radiological studies (MRI/CT) should be reserved for specialist physicians.
Plain radiograph of the back does not provide adequate information for LSS diagnosis and is not a necessary examination to be performed before an MRI is carried out.
Diagnostic criteria:
one or both of the following symptoms: neurogenic claudication or symptoms suggestive of chronic nerve root compression AND
Back pain; differential diagnosis as for normal back pain Low Back Pain. Lower limb symptoms; differential diagnosis should take into account the possibility of local aetiology and other factors.
Pain usually in the calf and relieved by resting (flexing forward does not relieve pain); bicycling triggers claudication. Often abnormalities in pulse palpation.
Disc prolapse in the lumbar spine
Often a symptom that has appeared fairly rapidly in a younger patient. A positive nerve stretch test (Lasègue, femoral stretch test) is suggestive of a prolapse but does not exclude LSS.
Muscle trigger points at the lumbar spine/buttock/lower limb areas may cause local pain. Occasionally they will only cause non-specific reflex abnormalities (absent).
The trigger point may be anaesthetised as a diagnostic and therapeutic test.
Treatment
The outcome of patients with LSS is moderately good without surgery, and conservative treatment should therefore always be tried at first. ”Watchful waiting” may be sufficient for some patients.
Decompressive surgery and, if needed, fusion is more effective in symptomatic patients if 3 to 6 months of conservative treatment has failed.
The better results (pain, functional ability) achieved with surgical treatment in symptomatic LSS patients may last for up to 4 years. The benefit is reduced during 8 to 10 years of follow-up.
Conservative treatment
Indications for conservative treatment
The patient is able to tolerate the symptoms and daily functional capacity is adequate.
The patient does not want to be operated; assessment of surgery-related risks takes place usually within specialized care.
Encouragement to normal daily activities; appropriate aerobic exercise (e.g. "Nordic walking" with special walking poles similar to ski poles)
Reduction of significant overweight and cessation of smoking
At work: positions that alleviate pain, ergonomics, recovery pauses, rotation of work tasks
A lumbar corset may increase walking distance by over 30% and alleviate symptoms during strain.
Physiotherapy
Physiotherapy may reduce the need for surgical treatment within one-year follow-up, but it does not seem to improve functional capacity nor to reduce symptoms or use of medications.
Individually tailored easing of the pain and tightness of the myofascial tissues in the lower back and gluteal and thigh area, muscle activation exercises, self-care training programme
Front thigh tightness or poor condition of muscles in the abdominal, gluteal and posterior thigh areas may cause the pelvis to tilt forward (anterior pelvic tilt), which results in hyperlordosis (saddle back), extension of the lumbosacral spine and worsening of symptoms. Try to notice front thigh tightness (flexion of knee/extension of thigh, i.e. femoral stretching, while patient is lying in prone position/face down) and anterior tilt/saddle back and refer the patient for physiotherapy.
Also ultrasound and TNS therapies have been used as treatments.
Acupuncture
Treating L5 nerve root symptom with acupuncture for a period of 4 weeks yielded in one study a better result than exercise or drug therapy.
Analgesic medication
Analgesics (paracetamol, NSAIDs, mild opioids if necessary); dosage according to the intensity and appearance of symptoms, taking into account other medication and diseases
Vitamin B12, prostaglandins and gabapentin may increase walking distance.
Pregabalin alleviates symptoms in lower extremities and, when combined with a NSAID, may reduce need for surgical treatment.
Long-term use of opioids may be considered in refractory pain (whilst monitoring the response) after the diagnosis is verified if, for example, the patient will not benefit from surgery.
Strong opioids for long-term use should be initiated in specialist care (a physiatrist, a surgeon, a doctor at a pain clinic).
The treatment should be monitored according to local protocols.
Epidural anaesthetic blocks may provide short-term relief of pain and improvement of functional ability, but they have been associated with a risk of worse prognosis (pain, functional ability) in 4-year follow-up.
Surgical treatment
Surgical treatment for LSS has been shown to be effective and cost-effective in 4-year follow-up as compared to conservative treatment, and surgical treatment should be considered after 3 to 6 months of conservative treatment that has failed. Results of surgery become poorer if the preoperative symptoms that require surgery last for more than one year.
Preoperative use of analgesic drugs for more than 12 months is predictive of worse functional result in LSS patients who undergo surgery. Delaying the operation is hence not recommended, if the symptoms are severe and clinical-radiological indication exists.
Cauda equina syndrome and paraparesis require urgent surgical assessment. The development of degenerative LSS is usually slow.
Surgery is considered on the basis of radiologically confirmed stenosis compatible with the patient history and/or clinical findings.
Indications for surgery in LSS are considered to be
clearly disturbing or intolerable pain or significant functional impairment that are not relieved with conservative management
gradually shortening continuous walking distance (< 200-300 m).
The walking distance should, however, be set in proportion to other symptoms, diseases and the age of the patient. In a younger patient, a milder symptom may be relatively more impairing, and surgical treatment may occasionally be used even if the patient were able to walk over a kilometre.
About two out of three patients treated surgically are reported to have good to excellent outcomes. Cessation of smoking improves recovery from surgery. Attention should be pain on treatment of depressive symptoms both pre- and postoperatively because they are predictive of worse recovery. In LSS, preoperative factors predicting a better postoperative outcome include
pronounced constriction of the spinal canal
better walking ability and general health as assessed by the patient.
Factors predicting a worse postoperative outcome include
preoperative lumbar scoliosis
cardiovascular diseases
overweight (decreases satisfaction with the operation)
concomitant disease affecting walking ability (e.g. in concomitant hip osteoarthritis one should evaluate as to what extent the symptoms are caused by LSS and whether the patient will benefit from back operation).
A history of previous back operation as well as age over 75 years predict lower satisfaction with the operation, but the functional result in these patients is comparable to others.
It is not possible, however, to conclude from the predictive factors who warrants surgery.
Active postoperative rehabilitation on an outpatient basis may improve the functional treatment results, as well as pain in the back and lower extremities.
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