Psychomotor agitation following gabapentin use in brain injury

Gabapentin, an anticonvulsant structurally related to gamma-aminobutyric acid (GABA) was recently reported to be effective in pain associated with reflex sympathetic dystrophy (RSD) and in pain associated with neuropathy. Yet, to our knowledge, the use of gabapentin for neuropathic pain in the presence of cognitive impairment has not been reported. In this report, we describe two patients (one with a traumatic brain injury, one with a putative acquired brain injury) who presented to a neurorehabilitation unit complaining of pain that was diagnosed as neurologically mediated. Within one week of receiving a daily 900 mg dose of gabapentin, both patients complained of heightened anxiety and restlessness. Correspondingly, each reported a diminution of psychological symptoms within 48 hours of gabapentin cessation. These two cases suggest that gabapentin may cause agitation in cognitive impaired patients. Physicians treating brain-injured patients and prescribing gabapentin for neuropathic pain may wish to closely monitor patients for similar signs of restlessness or anxiety.