Rationale

Patients may have unexplained weakness in their muscles from a variety of diseases. Some are treatable and some are not. EMG is used to help confirm this general diagnosis, which is called myopathy. However, a specific diagnosis is required before treatment. When a medical history, clinical exam, and laboratory tests do provide the specific diagnosis, then a muscle biopsy is often requested. The results help guide further treatment. It must be kept in mind that even when a small sample of your muscle is sent to the laboratory, there is still a chance that the diagnosis is not certain, or that your illness is not treatable.

Surgical Procedure

The procedure takes about thirty minutes and is performed in day surgery under sterile conditions. It can either be performed with only a local injection of lidocaine, or with some intravenous sedation. About half of patients request sedation in addition to lidocaine. The incision is about 1.5 inches long, so that a 2cm by 0.5cm piece of muscle can be removed (about the diameter of a pencil). This size is required for an adequate diagnostic yield. The skin is then closed with two layers of sutures that absorb by themselves. Almost any muscle can be biopsied, but the most common are the quadriceps, deltoid, and gracilis. The risk of the procedure is about a 1% chance of infection. Since the muscle sample is so small, no additional muscle weakness should occur.

Quadriceps biopsy under local anesthesia in day surgery

Day of Surgery

If sedation is requested, then you must not eat or drink after midnight the day before the procedure. You may take your normal medication with a sip of water the morning of surgery. Furthermore, for sedation you need to have some laboratory tests performed beforehand in pre-admission testing. No aspirin or Motrin should be taken the week before or after the surgery. You arrive in day surgery an hour before the procedure where you meet the surgeon. After the procedure you are observed in the recovery room for about an hour. You may go home with a family or friend taking you home.

Recovery

Overall this is not a painful procedure. It is normal to have some bruising near the wound and for the muscle to feel sore for about a week or so. The occlusive dressing is removed after 3 days, revealing some stickers underneath. These stickers are left in place until you see your surgeon about one week later for a wound check. You may shower immediately after surgery with either the occlusive dressing or the stickers exposed. For the first week after surgery, you may work, but should avoid strenuous activity with the affected muscle. Although rare, signs of infection include discharge, redness, and progressively worsening pain. If these occur, you should notify the surgeon.

Results

The laboratory results take about 1-2 weeks to be completed by the pathologist. These results are faxed to your referring physician for analysis. In general, you should follow-up with him or her in regard to an explanation and further treatment.

Further Reading

National Institute of Neurological Disorders and Stroke
Myopathy Information Page