Delusional Infestation in Parkinson's Disease Secondary to Piribedil Escalation: An Uncommon Case Report

Abstract

Delusional infestation (DI) is characterized by delusions of being infested by small microorganisms or even inanimate objects without any medical or microbiological evidence. The pathophysiology of DI is not well understood, and there are two types of DI: the primary form, where there is no underlying cause, and the secondary form, which is related to an associated psychiatric disorder, medical condition, or substance use. DI in Parkinson's disease (PD) is rarely reported, and most published cases are due to antiparkinsonian drugs. Piribedil is a dopaminergic agonist used for the symptomatic treatment of PD either as monotherapy or as adjuvant therapy with other antiparkinsonian treatments. We report the case of an 81-year-old man followed for PD at our institution who developed DI after piribedil dose escalation. When DI is secondary to an antiparkinsonian drug, the treatment of choice is based on withdrawing the implicated drug.

Keywords: adverse event; delusional infestation; dopaminergic agonist; parkinson’s disease; piribedil.

Figure 1. Excoriation lesions on the anterior part of the right leg with repeated manipulations leading to an increase in the size of the lesions

Figure 2. The patient tried to convince us that these small white fibers are the etiology of the infestation

A: small whitish filament on his socks; B: white filament on his clothes (djellaba)