Sciatica is caused by irritation or compression (pinching) of the sciatic nerve or the lumbar spinal nerve roots that merge to form the sciatic nerve. Sciatica typically manifests as pain radiating from the buttock down the back of the thigh into the calf and/or foot. The word “sciatica” derives from the Latin word “ischiadicus”, which means pain in the buttocks/hip region. Sciatica is often associated with numbness and tingling in addition to the pain symptoms. Occasionally, patients may also have some associated weakness. Sciatica is often a form of radiculopathy (please see Radicular Syndrome for more details).
Most commonly, sciatica is due to a ruptured/herniated disc in the lumbar spine (lower back). Other causes of nerve compression include bone spurs in the spine, overgrown spinal ligaments, synovial cysts of the spine, tumors of the spinal nerves, or entrapment of the sciatic nerve itself. Rarely, sciatica can be caused by a direct trauma to the sciatic nerve in the leg or buttock.
MRI or Myelogram of the spine are usually the main forms of imaging utilized to diagnose causes of sciatica. The studies will usually identify compressive etiologies of the spine, such as a disc herniation or compression by bone spur/ligament. Other testing may include electromyelogram (EMG) to identify damage to the sciatic nerve or one of the originating lumbar spinal nerves. Physical finding history by the physician alone can usually make the diagnosis of sciatica, but the structural cause usually requires further investigation or testing.
MRI or CT Myelogram of the spine are usually the main forms of imaging applied to diagnose causes of sciatica. These studies will usually identify compressive etiologies in the spine, such as a disc herniation or lumbar spondylosis. Other testing might include electromyelogram (EMG) to identify damage to the sciatic nerve or one of its originating lumbar spine nerves. Physical findings and history taking by the physician alone can usually make the diagnosis of sciatica, but the structural cause usually requires further testing.
Sciatica often responds favorably to a combination of rest, oral medication (analgesics, anti-inflammatory medication, muscle relaxants), physical therapy, chiropractic, or acupuncture treatment. Sciatic pain from a disc herniation often gets better if one is willing to wait, as the disc herniation desiccates and is reabsorbed. Improvement in sciatica from disc herniation often spontaneously occurs within 6 to 8 weeks without surgery. During this time epidural spinal injections can help mitigate pain symptoms. Unlike sciatica originating from a disc herniation, sciatica from thickened ligaments or bone overgrowth (aka lumbar spondylosis, spinal stenosis) is less likely to improve spontaneously. In these cases, it is reasonable to attempt physical therapy, medication, or epidural steroid injections. Surgery, however, is more likely to be indicated if the spinal stenosis is severe.
Success rate for relieving sciatica due to compressed nerves is very good, in the 80 to 95% range. With resolution of sciatica, it may be realistic to return to previous activities.
Sciatica often resolves with non-surgical treatment but when surgery is required, success rates are high. Complication risks are rare but include persistent pain, infection, nerve damage, and spinal fluid leak.