Botulinum toxin therapy

Botulinum toxin is produced by Clostridium botulinum, a Gram-positive anaerobic bacterium. Botulinum toxin is a neuromuscular blocking agent. It exerts its paralytic action by rapidly and strongly binding to presynaptic cholinergic nerve terminals. It is then internalized and ultimately inhibits the exocytosis of acetylcholine by decreasing the frequency of acetylcholine release. Without its nerve supply, the muscle fiber withers away. The muscle strengthens again as the nerves regenerate.

·EMG recordings

We use surface and needle electrodes to take EMG recordings in the same manner as described for MAB therapy. We choose the target muscles for injection based on the patient’s symptoms and the results of EMG recordings from the masseter, temporal, lateral pterygoid (the inferior head), medial pterygoid, digastric (the anterior belly), genioglossus, trapezius, and sternocleidomastoid muscles, etc.

·Injection

Botulinum toxin (Botox) is reconstituted with normal saline. Appropriate doses of the toxin are injected into several sites within the bulkiest portion of the target muscle during contraction using a monopolar hollow-bore EMG needle and an EMG instrument for guidance. In the first injection, we only inject a small dose of the toxin due to the large interindividual variation in its effects.

·Follow-up

The treatment first begins to have a noticeable effect a few days after the injection. The effect usually lasts a minimum of 3-4 months; however, some patients experience a lasting effect. We record the degree of jaw opening and bite force after treatment as objective assessments of the therapeutic effect. The injections should be repeated over time if the effects disappear.