Coexistence of Delusional Parasitosis and Complex Visual Hallucinations With Micropsia

Abstract

To the Editor: Complex visual hallucinations consist of people, deformed faces, animals, and complex scenes, which are often associated with various clinical diseases such as delirium tremens, Parkinson's disease, dementia with Lewy bodies, Charles Bonnet syndrome, and schizophrenia. 1,2 Delusional parasitosis can be defined as a delusional syndrome that primarily affects middle-aged and elderly individuals (mainly women) and consists of the belief that parasites plague the skin. 3 Of historical note, Berrios 3,4 rediscovered the term délire de zoopathie interne initially described by Dupré and Levy as a wider condition of delusion of parasitosis, which included the belief that one's body was inhabited by all types of animals. The 29 cases reported by Dupré and Levy involved rats, birds, snakes, and other animals, but no insects were mentioned. 3,4 It seems likely that animals such as rats and birds appeared smaller than usual in the delusion of parasitosis, suggesting the coexistence of micropsia. Micropsia is one of the metamorphopsias and is defined as a symptom of objects appearing smaller than usual. Micropsia has been attributed to a dysfunction of object constancy within the temporal lobe, but lesions of the lateral occipitotemporal cortex may also cause micropsia, which may relate to a deficit of object processing rather than constancy. 5 To our knowledge, there are only two case reports showing complex visual hallucinations and coexistent delusional parasitosis. 6,7 We report a third case and discuss the mechanism of coexistence from the viewpoint of micropsia.

Case report: Delusional infestation in dementia with Lewy bodies

“…Among four prior cases of delusional infestation diagnosed with DLB, two patients had visual hallucinations ( 7 – 9 ). Even in cases of suspected dementia in which a diagnosis of DLB had not been made, the coexistence of complex visual hallucinations and delusional infestation have been reported ( 15 – 17 ). The patient reported by Kanazawa and Hata was suspected of having Alzheimer’s dementia ( 15 ), and the case was reported before the publication of the first criteria for DLB ( 18 ).…”

“…Although the patient reported by Rocha et al showed cognitive impairment, the diagnosis was unclear because the patient refused detailed examinations and evaluation and was also limited by visual deficits and hypoacusis ( 16 ). Another case reported by Hirakawa et al was suspected of having DLB, and donepezil hydrochloride was prescribed ( 17 ). Delusional infestation occasionally accompanies visual hallucinations ( 13 ), possibly suggesting the presence of a certain number of cases of undiagnosed DLB among patients with dementia and delusional infestation.…”

Insights into the Medical Evaluation of Ekbom Syndrome: An Overview

“…Cases of post-stroke delusion parasitosis were reported, especially for situations of right-side lesions (right temporoparietal cortex), the thalamus, and the putamen (the putamen influences visuotactile perception; through receptive cells, it projects to the parietal cortex, primary somatosensory cortex, and premotor cortex) [127,128].…”