Pediatric Movement Disorders - Diagnostic Methods

Biopsy of Muscle, Skin, Nerve, or Brain

In some cases, it is not possible to determine the diagnosis by looking only at blood, urine, cerebrospinal fluid, and other studies. Therefore, it may be necessary to microscopically examine the involved tissue; special stains are used that are able to look for particular abnormalities. If this is needed, then a biopsy may be suggested.

Skin biopsy is a rapid procedure during which a small circular knife is used to extract a 2 to 3 millimeter piece of skin. The resulting hole heals rapidly. This entire procedure may be performed with local anesthesia and is usually done in the doctor's office. Muscle or nerve biopsy is performed in the operating room. This is a simple procedure and the child can usually go home the same day. The incision leaves a small scar over the area where the muscle or nerve is removed.

For nerve biopsy, a relatively unimportant nerve is chosen to minimize the effect for the procedure. For muscle biopsy, only a small piece of tissue is taken so there is no effect on strength. For certain tests, the muscle must be immediately analyzed or flash-frozen for transport to a specialized laboratory. Brain biopsy is used only in the most severe cases and is performed in the operating room by a neurosurgeon. The skull must be opened and several days are usually required for recovery.