Spasticity is a common side effect of spinal cord injury (SCI). It is caused by a velocity-dependent increase in the tonic stretch reflexes and exaggerated tendon jerks. While spasticity can interfere with walking and other daily activities, there are many ways to manage it. One option is chemodenervation. This involves injecting botulinum toxin into muscles to temporarily paralyze them. Botox is better known for its cosmetic use, but it is also used to treat other movement disorders. Injections are done by a neurologist, who is specially trained in movement disorders. They are usually quick and easy, but may take up to 20 minutes if several muscles need to be injected. The doctor will numb the area before injecting. Most people don’t need anesthesia.
A small number of studies with low levels of evidence have been performed examining the effectiveness of chemodenervation with BoNT, phenol or alcohol in managing limb spasticity in SCI. While this is an important area for future research, it is essential that outcomes be clearly defined and that the impact on function is considered.
Oral antispasticity medications can be effective in some patients, but many experience side effects such as sedation, confusion, hallucinations, general weakness or hypotension. Surgical denervation of the bladder with rhizotomy or catheter insertion reduces detrusor dysenergia, but can compromise reflexive urination and vaginal lubrication. Bladder chemodenervation using neurotoxins such as onabotulinumtoxin A is a less invasive treatment that can be applied to individuals with a wide range of etiologies and can be targeted at specific muscle groups.