The toxin of the anaerobic bacterium CLOSTRIDIUM BOTULINUM is now routinely used to treat focal DYSTONIAS in adults. These include blepharospasm (see EYE, DISORDERS OF), SPASMODIC TORTICOLLIS, muscular spasms of the face, squint and some types of tremor. Injected close to where the nerve enters the affected muscles, the toxin blocks nerve transmissions for up to four months, so relieving symptoms. The toxin can be used in cerebral palsy and for writers’ cramp. It is also widely used in providing temporary improvement of wrinkles between the eyebrows. Although very effective, there are many possible unwanted effects of the toxin, especially if too high a dose is used or the injection is misplaced. Two types are available (A & B) and there are different reasons for using one or other preparation.