This is a spinal condition where an intervertebral disc herniates posteriorly and puts pressure on one or more nerve roots. When the disc compresses a nerve root, it causes radiculopathy – a combination of pain, sensory change, and weakness – affecting an area of the leg supplied by that particular nerve.
The disc is the shock absorbing component of the spine, sitting between the two bony vertebral bodies. It is flat and round, and made up of a tough outer ring called the annulus fibrosis, and a jelly like inner component called the nucleus pulposus. When the outer ring is worn or acutely injured, the inner nucleus can “herniate” through and cause the symptoms described. Risk factors for this include:
There are indications for immediate or early surgical treatment, particularly if a large disc prolapse causes compression of all lumbar and sacral nerve roots below the level (cauda equina syndrome) leading to a combination of bowel/bladder incontinence, bilateral leg numbness/weakness, and bilateral leg pain. If there is less severe compromise of the spinal canal, but the patient has weakness and difficulty mobilising, early surgery may also be recommended.
MRI scan is the gold standard for diagnosis of disc prolapse, as it allows for accurate identification of the disc as well as the nerve roots that may be affected. Imaging is required prior to injection or operation, to confirm the diagnosis and ensure that correct levels are being treated.
In some patients MRI scanning is not possible. CT scan is then used for diagnosis, and if this is not considered diagnostic then an injection may need to be placed to increase the accuracy – CT myelogram.
For most patients, non-surgical treatment will lead to resolution of symptoms within 3-4 months. Treatment includes initial rest, physical therapy, analgesia (particularly non-steroidal anti-inflammatory medications), and corticosteroid injections into the affected area.
If surgical treatment is required due to severe symptoms, or failure of non-surgical treatment, there are a number of treatment options that will depend on the location of the disc prolapse, as well as the stability of the spine and length of time the disc prolapse has been present for. Surgical treatment options include microdiscectomy, laminectomy, far lateral discectomy and lumbar decompression + fusion.