CASE REPORT Audiovisual Peduncular Hallucinations A Release of Cross-Modal Integration Sites? Kirsten I. Taylor, PhD, Peter Brugger, PhD, and Urs Schwarz, MD Abstract: We report the case of a patient with multiple sclerosis with congruent visual and auditory hallucinations of deceased familiar persons that lasted continuously for several days. Magnetic resonance imaging revealed an isolated, predominantly left-sided lesion in the periaqueductal segment of the mesencephalon. We propose that these hallucinations represent a bimodal variant of classic peduncular hal- lucinations, brought about by a deregulation of modulatory superior collicular activity and a release of cross-modal integrative functions of the superior temporal sulcus. Key Words: hallucinations, verbal hallucinations, auditory halluci- nations, multiple sclerosis, temporal lobe (Cog Behav Neurol 2005;18:135–136) L esions of the rostral brainstem 1,2 or its projection sites in the pulvinar or medial thalamic nuclei 3,4 may result in ‘‘peduncular hallucinations.’’ 5 These predominantly visual hallucinations occur during normal states of consciousness and typically consist of lively, colorful, and nonthreatening people or animals. They take place in the evening or dark, span both visual fields, and last for several seconds or minutes. Concomitant sleep disturbances are characteristic and attrib- uted to the involvement of the brainstem reticular formation. The pathogenesis of peduncular hallucinations is thought to reflect a release phenomenon. 5,6 A specialized brainstem neu- rotransmitter circuitry modulates retino-geniculate-cortical sig- nals via efferents to the dorsal lateral geniculate nucleus (dLGN) and lateral pulvinar. 7,8 Both cholinergic and serotonergic systems play an important role: Cholinergic inputs increase dLGN ac- tivity directly and indirectly by inhibiting GABAergic projec- tions from other parts of the thalamus; serotonergic inputs from the dorsal raphe nucleus, on the other hand, inhibit cholinergic excitation and suppress retinal input to the dLGN. Hence, lesions of the dorsal raphe nucleus or its projections may cause inappropriate excitation within the dLGN, thereby compromising the fidelity of retinogeniculate signals. These degraded visual inputs to the otherwise intact visual system may be transformed into bizarre visual perceptions, which the awake and aware patient often recognizes as hallucinations. CASE REPORT EG is a 24-year-old, left-handed female dental assistant who, during the last year, experienced a week-long episode of vertigo and diplopia and another 2-week-long period with difficulties in walking. A neuroradiologic examination revealed several demyelinating lesions in her spinal cord indicative of multiple sclerosis (MS). After developing fatigue, dizziness, and nausea, blurred and double vision, severe difficulties in speaking and walking, paresthesia in both hands, and urinary urgency, she was referred by her neurologist for further examination and confirmation of the diagnosis. Two days before admission, methylprednisolone 100 mg daily was started and maintained for 3 more days and then continuously reduced until her discharge 14 days later. She presented with a flat and labile affect and psychomotor retardation. The neurologic examination revealed a brainstem syndrome with bilateral internuclear ophthalmoplegia, dysarthria, and ataxia. Neuropsychological examinations found temporal lobe and frontosubcortical dysfunctions. A lumbar puncture revealed 10 cells/mL, normal protein contents, and intrathecal production of oligoclonal bands. The electroencephalogram was normal. Two hyperintense and contrast-enhanced magnetic resonance imaging (MRI) signal alterations in the splenium (small) and the periaque- ductal segment of the mesencephalon were suggestive of active demyelinating lesions (Fig. 1); the retino-geniculate-cortical tracts and primary and secondary visual areas were unremarkable. Visual fields as examined by Goldmann perimetry and visually evoked potentials were normal. Subsequently, the diagnosis of MS was confirmed. EG’s Hallucinations EG reported two episodes of synchronized visual and auditory hallucinations: initially for 5 consecutive days, during which time her atactic symptoms appeared, and 2 weeks later for 1 day, during which she experienced an adverse reaction to her steroid medication. Hallucinations in other sensory modalities were denied. The contents of the hallucinatory experiences were identical in both episodes: Her grandfather and her cat, both of whom were deceased at the time, as well as a familiar male person who had committed suicide only days before the onset of her symptoms, appeared out of the upper left side of extrapersonal space. All looked and moved in both visual fields as they had in real life; the male figures even ate and slept when EG did. Her grandfather and acquaintance verbally pleaded with her to join them in heaven. EG rejected their continuous requests aloud, upon which they became angry. Although she was initially frightened by the visual and auditory experiences, she realized that they were not Received for publication May 18, 2004; revised November 23, 2004; accepted December 16, 2004. Department of Neurology, University Hospital Zu ¨rich, Zu ¨rich, Switzerland. This study was supported by a grant from the Roche Research and Hartmann Mu ¨ller Foundations. Dr. Taylor’s current address is Centre for Speech and Language, Universityof Cambridge, Cambridge, UK, and Memory Clinic-NPZ, University Hospital, Basel, Switzerland. Reprints: Dr. Urs Schwarz, Department of Neurology, University Hospital Zu ¨ rich, Frauenklinikstrasse 26, CH-8091 Zu ¨ rich, Switzerland (e-mail: us@neurol.unizh.ch). Copyright Ó 2005 by Lippincott Williams & Wilkins Cog Behav Neurol  Volume 18, Number 2, June 2005 135 JOBNAME: nube 18#2 2005 PAGE: 1 OUTPUT: Wednesday June 8 17:13:44 2005 lww/nube/91636/04-18