Objective:

We aim to propose diagnostic criteria for peduncular hallucinosis through a systematic review

Background:

Peduncular Hallucinosis (PH), is defined as a rare clinical syndrome characterized by vivid and colorful visual hallucinations of both humans and animals, which are recognized as not real, accompanied by manifestations such as ophthalmoparesis, hemiparesis, gait ataxia, among others. However, there are discrepancies in the correct diagnostic criteria.

Design/Methods:

We conducted a systematic review across seven databases and screened reports describing PH until August 2025. Based on a narrative synthesis, we proposed diagnostic criteria.

Results:

We found 105 reported cases across 94 publications. More than half were females (53.4%) with a median age of 60 years old (Range: 8 to 85). The most common identified etiologies were ischemic stroke (54; 51.4%), brain tumor (21; 20.0%), hemorrhagic stroke (9; 8.6%), and demyelinating disease (7; 6.7%). We found the following frequent characteristics in patients with a diagnosis of PH: Complex (100; 95.2%), vivid and colorful (67, 63.8%) visual hallucinations with content of people (78; 74.3%), objects (36, 34.3%), and/or animals (56; 53.3%). Hallucinations were present during wakefulness (54; 51.5%) and with insight predominance (62, 59.0%). Most of the cases had an identified intraparenchymal lesion in the thalamus (27; 25.4%), midbrain (39; 37.1%), and/or pons (39; 37.1%), and with partial or total improvement (79; 75.2%).

Conclusions:

Peduncular Hallucinosis represents a distinctive clinico-anatomical syndrome. Our synthesis supports the following proposed diagnostic criteria: 1) Complex and vivid complex visual hallucinations with objectivable content; 2) Preserved insight and wakefulness predominance; 3) Neuroimaging evidence of a lesion involving the midbrain-pontine-thalamic network; 4) Partial or total improvement; and 5) Exclusion of psychiatric or metabolic causes.