Abstract Details

Title The Neuroanatomy of Peduncular Hallucinosis: A Case Series and Lesion Overlap Analysis

Topic Behavioral Neurology

Presentation(s) S18 - (-)

Poster/Presentation
Number 004

Objective

Background PH refers to predominately visual hallucinations that occur in the setting of a midbrain or thalamic lesion. In the 90 years that have passed since Lhermitte's initial description, the phenomenology of this disorder has been delineated in over one hundred published cases. The precise anatomy of PH, however, remains relatively understudied. The ascending reticular activating system (ARAS) nuclei are commonly implicated, but a large-scale anatomical analysis to better localize the critical neuroanatomical substrate is lacking.

Design/Methods We synthesized a lesion overlap map to identify the structures most commonly lesioned in cases of PH. This mapping is derived from a local case series of PH in addition to inclusion of all previously published cases of PH that include an anatomical figure demonstrating a focal intrinsic lesion to the brainstem or diencephalon, excluding those with significant cortical involvement or extrinsic compressive lesions (N=20).

Results The regions of highest lesion overlap in cases of PH include the rostral midline mesencephalic tegmentum, a region densely packed with ARAS nuclei and ascending reticulo-thalamic fibers, and the thalamic intralaminar complex, including the mediodorsal and centromedian-parafascicular nuclei.

Conclusions By demonstrating the neural structures most commonly involved in PH we may better understand this mechanistic basis of phenomenon. In addition these findings may lend insight into the neurobiology of other types of hallucinations and, more generally, how the ARAS modulates the content of consciousness in humans.

Authors/Disclosures
Aaron D. Boes, MD (University of Iowa Hospitals and Clinics) PRESENTER	No disclosure on file
Sashank Prasad, MD (University of Pennsylvania Perelman School of Medicine)	Dr. Prasad has received personal compensation in the range of $50,000-$99,999 for serving as a Consultant for Medicolegal firms. Dr. Prasad has received publishing royalties from a publication relating to health care.
Verne S. Caviness, Jr., MD (Massachusetts General Hospital)	No disclosure on file
Michael W. Devereaux, MD, FAAN (Univ Hospitals of Cleveland)	Dr. Devereaux has received personal compensation for serving as an employee of DigiTrace part of Sleepmed. Dr. Devereaux has received personal compensation in the range of $5,000-$9,999 for serving as an Expert Witness for Kevin Trangle and Associates.

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