Regional cerebral blood flow changes in a patient with delusional parasitosis before and after successful treatment with risperidone: a case report

Prog Neuropsychopharmacol Biol Psychiatry. 2006 Jun;30(4):737-40. doi: 10.1016/j.pnpbp.2005.11.029. Epub 2006 Jan 23.


The pathophysiology and appropriate pharmacological interventions for delusional parasitosis (DP) remain unknown. Here, we present a case of DP following brain infarction of the right temporoparietal region. Pharmacotherapy with risperidone resulted in a dramatic therapeutic response over a short period. In a sequential N-isopropyl-p-[(123)I]-iodoamphetamine single photon emission computed tomography ([(123)I]-IMP SPECT) study, post-treatment SPECT images revealed a marked increase of rCBF in the large areas including the bilateral frontal and left temporoparietal regions, the right parietal operculum and the bilateral basal ganglia, in contrast to pre-treatment SPECT images showing a global decrease of rCBF. Our clinical outcome suggests the efficacy and safety of risperidone for treatment of DP and that both dopaminergic and serotonergic dysfunction may play a role in DP. Our sequential SPECT findings suggest that psychiatric improvement of DP is associated with increased rCBF.

Publication types

  • Case Reports

MeSH terms

  • Aged, 80 and over
  • Antipsychotic Agents / therapeutic use*
  • Cerebrovascular Circulation / drug effects*
  • Humans
  • Magnetic Resonance Imaging / methods
  • Male
  • Parasitic Diseases / psychology*
  • Regional Blood Flow / drug effects
  • Risperidone / therapeutic use*
  • Schizophrenia, Paranoid / drug therapy*
  • Schizophrenia, Paranoid / pathology
  • Schizophrenia, Paranoid / physiopathology
  • Tomography, Emission-Computed, Single-Photon / methods


  • Antipsychotic Agents
  • Risperidone