Micro Discectomy

Since the initial description of a herniated intervertebral disc as the cause of sciatica (pain radiating down the back of the leg) in 1934, the operation to relieve this pain has undergone considerable refinement. Compression of a nerve root in the low back causes pain in the leg, back pain, and sometimes dysfunction of the nerve. Usually pain begins in the low back then radiates into the leg with tingling numbness and weakness in the leg. The cause is herniation or bulging of softened intervertebral disk material into the spinal canal compressing the overlying nerve root. In older individuals, an over-growth of bone (osteophytes) may compress the nerve. Diagnosis is dependent upon the history of pain, physical examination of the patient, and anatomical changes seen with CT/MR imaging of the spine:

  • Pain in the back and extremity, usually back of the leg
  • Pain and limitation of raising leg with patient lying on his back
  • Loss of sensation in the leg
  • Weakness in specific muscle groups in the leg
  • Loss of reflexes at the knee and ankle
  • CT/MR images showing compression of a nerve root by disc material or osteophyte

Fortunately the vast majority of individuals spontaneously recover from their first episode of sciatica. Bed rest for a day or two may be helpful. The most important medicine is time. After three months, perhaps 90% of sufferers will recover. Operation is indicated in those who continue to have pain and/or significant weakness and numbness.

The aim of operation is decompression of the nerve root. Under general anesthesia a 1 inch incision is made in the low back overlying the nerve root. Using the operative microscope a small crescent of bone is removed from the spine, exposing the nerve root and herniated disc material (laminotomy). The disc material compressing the nerve root is removed and the underlying central disc space is curetted free of retained, degenerated disc nucleus (discectomy). Decompressing the nerve root relieves the sciatic pain in the leg and back pain as well. Buried, absorbable sutures are used for closure. The procedure takes less than one hour. Most individuals can return home the same day as surgery and return to normal or light limited activities within a day or two. Athletic activities can be resumed in one month. There is virtually no blood loss and no support corset is prescribed. More than 90% of patients experience total or near total pain relief, usually within a day or two of operation.

Case History:

Herniated lumbar disc with sciatica, pain and numbness

Patient is a 30-year-old housewife and mother who had experienced recurring episodes of low back pain for the past ten years. This pain was progressively more severe for the past two years. A month before admission to the hospital, she awoke with excruciating low back pain and pain with numbness down the back of her right leg. She complained of weakness in the leg and the weakness progressed although the pain had improved.

Examination demonstrated pain when the right leg was passively elevated. There was weakness in the muscles which flexed up the foot at the ankle, numbness to pin prick over the top of the foot. The reflexes at the knee and ankle were normal.

A MRI image demonstrated a very large herniated disc fragment compressing the right L5 nerve root. A microlumbar discectomy was performed because of the failure of conservative treatment and the presence of severe pain and weakness. She left the hospital the same day and enjoyed immediate, near complete relief of sciatic pain. The weakness is greatly improved, but the numbness persists.


The L5 nerve root is usually the root compressed by a fragment of disc material which prolapses from the disc space between the 4th and 5th lumbar vertebrae. The nerve root controls the muscles of elevation of the foot at the ankle, elevation of the big toe, sensation on the top of the foot. The L5 nerve root does not control the knee or ankle reflex. Irritated L5 and S1 nerve roots cause pain with raising the straighten leg. By examination, the surgeon could determine which nerve root was involved as confirmed by spinal imaging. The failure of sciatic to respond to medical treatment is an indication for operation. The presence of weakness makes the operation more urgent. Marked weakness of one or both legs, especially when there is loss of bowel and bladder control is an emergency and requires prompt surgery.