Common cause of low back and leg pain; usually at L4-L5 or L5-S1 levels. Dermatomal sensory loss, reduction or loss of deep tendon reflexes, or myotomal pattern of weakness more informative than pain pattern for localization. Usually unilateral; can be bilateral with large central disk herniations compressing multiple nerve roots and causing cauda equina syndrome (Chap. 188. Spinal Cord Diseases).

Indications for lumbar disk surgery:

• Progressive motor weakness on examination or progressive nerve root injury is demonstrated on EMG.
• Cauda equina syndrome or spinal cord compression is usually indicated by abnormal bowel or bladder function.
• Incapacitating nerve root pain despite conservative treatment for at least 6-8 weeks: Trials indicate surgery leads to more rapid pain relief but no difference at 1-2 years compared with nonsurgical treatment.