Misdiagnosing the vegetative state after severe brain injury: the influence of medication.

Patients who suffer severe brain damage may be left unaware of self and of the environment and in a permanent vegetative state (PVS). The difficulties in correctly ascertaining unawareness after brain injury have been emphasized by a number of authors. It is well recognized that toxic-metabolic and drug-induced cerebral depression occurs acutely after brain injury. However, less attention has been drawn to the effects of medication months after brain injury and the way in which medication may confound assessment of awareness and, thus, the reliable assessment of long-term prognosis. This paper describes two patients who sustained a severe and well-documented structural brain injury, one hypoxic and one traumatic. Both were unaware when first seen at 3 months post-injury, but both have made useful functional recovery. The paper discusses their progress and how the early prescription of large doses of anti-epileptic drugs, sedatives and anti-spastic agents in these circumstances may result in an initial misdiagnosis of the vegetative state.