Botulinum toxin, commonly known by its Allergan-registered trade name of Botox, has been used by the medical profession for decades for the relaxation of spasticity in skeletal muscles. This was common in the limbs of children with cerebral palsy. It was subsequently recognised to have other medical applications, by far the commonest now being the non-surgical cosmetic relaxation of wrinkles.

Facial

Mr Woollard has a sub-specialist interest in facial palsy. In many instances this results in asymmetry of the face that does not require a full re-anmination reconstruction. In many cases the symmetry of the face can be improved through a reduction in the mimetic power of the muscles in the non-paralysed side. Most often this is the muscle on the forehead, or of the lower lip. the effect of the Botox is to reduced the difference between the two sides and provide more stable facial position both at rest and during movement.

The weakening of the muscles of the face is also used cosmetically. By carefully weakening some of the muscles of the face it is possible to smooth out some of the fine wrinkles (rhytids) that arise in the overlying skin due to their movement. This works best for fine wrinkles, once they have come engrained and deep this alone is not sufficient to eliminate them. Most frequently it is the muscles of the forehead, central brow and around the eyes (“crow’s feet”) that can be treated in this way.

Botulinum works by permanently blocking the nerve receptors on the muscle. It takes approximately 3 months for the muscle to generate new receptors, which is why the action of Botox is temporary. Treatments need to be repeated every 3 months for the action to continue to be effective. The botulinum takes 3-5 days to take effect, and is completely eliminated but the body. There is no ‘build-up’ over time. If you are unhappy with the result there is no antidote, but the effects will resolve over time. One of the most significant potential complications is where the botulinum affects the muscle that allows you to open the eye (orbicularis oculi). This can happen when the botulinum diffuses from the location of the injection towards the eye, resulting in an undesired weakness and droopiness. It is possible to prescribe eyedrops that act on the muscle of the eye to assist in eye opening until the effect of the botulinum has resolved.

Hyperhidrosis

Botulinum has a similar effect on the receptors that control sweating in the skin. Subcutaneous injections can therefore be used to treat excessive sweating (hyperhidrosis) in the axillae or groins. As with the muscle receptors, the toxin blocks the receptors and the treatment lasts until new receptors can be manufactured by the skin. This also takes approximately three months and therefore the treatment needs to be repeated at this interval to maintain the effect.

Sweating can be very debilitating for amputees as it loosens the interface between the stump and a traditional socket. This results in twisting of the stump within the socket and reduces confidence in the prosthesis or even falls. It can also contribute to folliculitis and localised infections of the glands in the skin. Botulinum can be used to treat this in the same way as hyperhidrosis, often in conjunction with hair removal techniques.