Intrathecal Baclofen In Brain Injured Patients

Spasticity is an increase in tone which results from hyperactivity of the muscle stretch reflexes. Although spasticity may have some beneficial effects such as maintaining muscle mass, decreasing edema and the risk for deep vein thrombosis, and assisting in transfers, spasticity can also be a source of extreme discomfort in patients with brain injury who have intact sensation. It may also lead to contracture formation, skin breakdown, and impaired sleep and sexual functioning. For many years, patients with spasticity secondary to brain injury were treated in the same manner as those with spasticity secondary to spinal cord injury; however, these medications often have side effects such as drowsiness, confusion, memory and attention problems.

Baclofen is an analog of gamma-aminobutyric acid (GABA), which binds to receptors in the central nervous system and suppresses release of excitatory neurotransmitters. It has been the drug of choice in spinal forms of spasticity, but because of its cognitive side effects, it was not generally used for cerebral spasticity. There are now options for baclofen to be administered through an intraspinal catheter into the subarachnoid space of the spinal canal (intrathecal baclofen pump), which concentrates the medication in the cerebrospinal fluid at much higher levels than those attainable by the oral route, and minimizes the central side effects. In a recent study of brain injury patients with spastic hypertonia, there were significant reductions in both upper and lower extremity tone and spasm without significant cognitive side effects at the end of one year using continuous intrathecal baclofen. Potential complications include technical difficulties with the baclofen pump, seizures secondary to abrupt withdrawal, and bladder problems. There is also a question of tolerance. Potential candidates must be screened for failure to other forms of oral antispasmodics, and screening trials with bolus injections of intrathecal baclofen are recommended.

Additional information may be found in:

Meythaler, M.D., JD, Guin-Renfroe, MSN, RN, CRNP, Grabb, MD, Hadley, MD. Long Term Continuously Infused Intrathecal Baclofen for Spastic Dystonic Hypertonia in Traumatic Brain Injury: 1-Year Experience. Archives PMR: 1999 (80): pp. 13-19.

Abstract by Lisa Palen Hu, MD