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Discectomy - The Procedure

Introduction

This will explain the discectomy procedure. It will tell you WHY it is done, HOW it is done, and WHAT happens afterwards.

Indications

A discectomy is done when you have a disc prolapse or herniation that is causing sciatica. There are a number of conditions that need to be satisfied in order for your condition to be suitable for surgery

Emergency surgery

Very rarely the surgery is done for urgent reasons.

Cauda equina syndrome

This is where a very large disc prolapse severely compresses the nerves and leads to weakness and numbness or tingling in both legs together with loss of the use of the bladder, causing urinary retention. It also may affect bowel and sexual function. The disc prolapse must be removed urgently (within 48 hours) to minimize permanent damage.

Progressive neurological deficit

This is where leg weakness that may have been present at the onset of symptoms is getting progressively worse with time. Removal of the disc prolapse may stop the weakness worsening.

Non-emergency surgery

The most common reason for surgery is that your sciatic has not settled down by itself. You must usually meet all of the following criteria in order for surgery to be considered.

Duration of pain

Your pain must have been present for at least six weeks. Very occasionally if your pain is excruciating, surgery may be done a little earlier. Of course if your pain is tolerable, you may wait longer than six weeks before deciding to proceed with surgery.

Location of pain

Your pain must be mostly in the leg rather than in the back.

Type of pain

Your pain must be in an area that corresponds with one particular nerve supply. This usually means it must extend below the knee.

Signs of nerve tension

You must have signs on examination that the nerve is being stretched across the disc prolapse. This is usually demonstrated with the straight leg raising test.

Signs of nerve compression

You must have signs on examination that the nerve is being compressed by the disc prolapse. This is usually demonstrated by testing the power, sensation and reflexes in your leg.

Confirmatory imaging

The suspected nerve compression must be confirmed by identifying a disc prolapse on CT scan or MRI.

The Options

Discectomy is a very common operation and there are a number of ways of performing the procedure

Open

Standard discectomy ("laminectomy")

This is the operation that has been performed for many years for disc prolapse. It involves a larger incision and removal of more bone than the procedure described below. It allows excellent access to and visualization of the nerves and discs.

Mini-discectomy

This is the procedure described below. It is becoming the standard procedure for disc prolapse. It involves making a smaller incision and removing less bone. It is possible with modern headlights and retractors to allow the surgeon to see what is needed through a smaller hole.

Micro-discectomy

This involves using a microscope that provides better light and vision. Advantages are a slightly smaller incision and disadvantages are a more lengthy procedure with a somewhat increased risk of incomplete nerve decompression and maybe of infection.

Percutaneous

This means "through the skin" (without an incision). There are two current techniques available. Both are specialised techniques needing extensive training and equipment, and not widely done. In expert hands they may be useful techniques in a limited number of cases.

Automated percutaneous lumbar discectomy (APLD)

This is done without a general anaesthetic. A needle is passed into the disc through the skin and along this track, a probe is inserted which mechanically removes some of the central disc material. It does not directly visualize or decompress the nerve.

Endoscopic discectomy

A telescope similar to that used for laparoscopy or arthroscopy is passed into the spinal canal or disc and the disc prolapse is removed with specialized instruments.

The procedure using the mini-discectomy technique

You will be prepared for surgery by the nursing staff in hospital. You will be taken from the ward to the operating theatre on a trolley.

The anaesthetic

The anaesthetist will give you a general anaesthetic. A small needle will be placed in the back of your hand or in your forearm. This will be connected to a drip. You will be asked to breathe on an oxygen mask and the drugs to make you fall asleep will be injected through the drip. You will be asleep and not be aware of anything further until the operation is completed. Antibiotics are given to you at this stage.

The surgery

You will be placed on the operating table lying with your back up (i.e., face down) in a kneeling position. This gives the best access to the lumbar spine. A needle will be placed in your back and an x-ray will be taken with an image intensifier (fluoroscopy). This will help identify the correct level at which to make the incision. Your back will be prepped (cleaned with antiseptic solution) and draped (covered with sterile sheets). The incision will then be made. It is usually 2 to 4 cm long. The muscles covering the spine will then be detached and retracted to expose the space between the laminae of the vertebrae. There is a tough fibrous tissue called the ligamentum flavum between the laminae and this along with some surrounding bone will be removed. This allows access to the dura, or delicate tube containing the spinal fluid and nerves. The compressed nerve is identified and retracted out of the way. This exposes the disc. The soft prolapse may be covered with annulus fibrosis (outer disc material), may have passed through this, or even be floating free. The prolapse is identified and removed. Sometimes an incision into the annulus needs to be made. Instruments are then passed into the disc and any other loose fragments are removed. The whole disc is not removed - all of the annulus and some or most of the inner gel (nucleus pulposis) remains. The hole in the annulus is not closed as it is not possible to repair it. It repairs by itself with time. Any bleeding is stopped and long-acting local anaesthetic (Marcain) is applied to the nerve and surrounding tissues. This provides pain relief for up to 12 hours. The wound is closed with deep long-lasting dissolving stitches and more rapidly dissolving stitches are used to close the skin. These are just under the skin and do not have to be removed. A dressing is applied and you are transferred back to the trolley.

The recovery

The anaesthetist will reverse the anaesthetic. You will wake up in the recovery room. The nurses there will check your observations and the movement in your feet. Once you are sufficiently awake, you will be transferred back to the ward. Once in the ward, your progress will follow the clinical pathway.