Universitätsklinik
für Neurochirurgie Innsbruck

Lumbar Spinal Stenosis

Lumbar spinal stenosis describes narrowing of the spinal canal in the lower back. It is most common in elderly patients. Radiological studies have shown that approximately 20% of all patients older than 60 years showed signs of degenerative spinal narrowing of the lower back on their imaging. Typical symptoms include pain or cramping in the legs that worsen with standing or walking (“pseudoclaudication”) and usually ease when bending forward or sitting. Most patients also experience lower back pain and sensory disturbances. In rare cases, additional muscle weakness of the legs or feet may occur. The treatment of choice in patients without any neurological deficits consists of conservative treatment including a sufficient pain medication regimen combined with physical therapy. If conservative measures fail to restore the symptoms, a microsurgical decompression of the spinal narrowing may be considered.

Causes

Degeneration is the major cause of spinal stenosis. Ageing or degenerative discs lose their firmness and elasticity, leading to segment instability. The disc protrudes into the spinal canal, causes canal narrowing and affects nerves. In an attempt to stabilize the segment, the body reacts by enlargement of facet joints and thickening of ligaments, which in return cause further narrowing of the spinal canal.

Depending on the extend of the narrowing, the lumbar spinal stenosis can be classified as “relative” or “absolute”. Lumbar segments of the spinal canal with a diameter of 10-14mm are considered as relatively stenotic, while a segment narrower than 10mm constitutes an absolute stenosis. A stenosis can either affect the whole spinal canal circumferentially or only the smaller nerve root canals to its both sides (“lateral recess stenosis”). This is most commonly seen in the segments L3/4 and L4/5. Also, tumors, fractures and infections may cause stenosis of the spine.

Diagnosis

History taking plays a crucial role in the diagnosis of spinal stenosis. Additional information is gained through a physical examination. Flexion-extension X-rays help detecting signs of instability but do not suffice for the identification of the structural causes of a spinal stenosis. An MRI scan is the best method to illustrate the structural causes of the patient’s symptoms and to aid further treatment decisions.

Treatment

For patients who suffer from pain with numbness or tingling but do not have any neurological deficits (palsy or bladder/bowel dysfunction), the treatment of choice consists of a sufficient pain medication regimen combined with physical therapy. In most cases, these measures help to relief the symptoms. If the pain does not resolve within 6-8 weeks of conservative management, an image-guided injection of cortison and local anesthetics can be helpful. The effect of an injection may diminish after some time. In cases, where the injection led to sufficient but only temporary pain relief, it might be senseful to repeat the injection.

Considering that spinal stenosis is mostly found in elderly patients, microsurgical decompression should be considered at an early stage in order to preserve the patient’s mobility and self-sufficiency. Also, most elderly patients have comorbidities that restrict the choice of medical treatment.

The surgical procedure consists of the removal of excessive bony and tissue material that cause the spinal or lateral recess stenosis. The surgical decompression is the only permanent solution.