Delusion of oral parasitosis and thalamic pain syndrome.

BACKGROUND Delusional parasitosis is an uncommon psychiatric condition in which patients have the immutable conviction that small, living organisms, such as worms, insects, or larvae infest their skin or other organs. OBJECTIVE/METHOD The authors describe a case of an unusual association of delusional parasitosis and thalamic pain syndrome after left-posterior thalamic hemorrhage. The patient initially suffered from dysesthesia and burning pain typical of thalamic pain syndrome and subsequently developed delusional oral parasitosis ("worms" infesting her mouth). RESULTS Sulpiride 100 mg/day administered in addition to amitriptyline gradually improved her delusions within 3 months. DISCUSSION The authors speculate that this specific type of delusion can be elicited by the disruption of the somatosensory pathway and that the subsequent cortical sensory deafferentiation and reorganization arising from this disruption may contribute to the development of delusional parasitosis.