555 - Complex Visual and Haptic Hallucinations in an Elderly Patient… A diagnostic challenge

Background:Hallucinations are common in elderly. Understanding the diverse aetiologies and behavioural reactions to hallucinations is vital to provide the best level of care.Case report:An 85-year-old man, with several cerebrovascular risk factors (dyslipidaemia, atrial fibrillation, previous ischemic-stroke), developed cognitive impairment after an acute confusional state (two years before), characterized mainly by short-term memory deficit and executive dysfunction. In the meantime, he started recurrent periods of multimodal hallucinations, with predominant sundowning pattern, along several months, comprising complex visual hallucinations, with which he interacted, sometimes combined with haptic hallucinations, describing a plastic sensation in his hands, and manifesting carphologia and psychomotor agitation. Insight into the hallucinatory nature of the phenomenon recovered after a few hours. The neurologic examination revealed partial left oculomotor nerve palsy (left exotropia and diplopia on the right conjugate eye movement), postural instability, slight truncal bradykinesia, and symmetrical rigidity. The neuroimaging studies confirmed small vessel disease with leukoaraiosis and lacunar infarcts in the lentiform nuclei. No lesions were observed within the visual pathway nor the midbrain.Discussion:This case leads to an interesting discussion regarding the differential diagnosis of combined hallucinations in elderly.The presence of the oculomotor nerve palsy selectively affecting somatic fibers, raised the suspicious of peduncular hallucinosis, in the framework of vascular disorder. Combination of visual and tactile may occur in peduncular hallucinosis. However, the neuroimaging studies did not reveal ischemic lesions in the midbrain. Therefore, the most plausible aetiology for hallucinations is a demential syndrome, namely a vascular dementia, considering the findings on neuroimaging. Additionally, a Lewy-body disease (LBD) cannot be ruled out by virtue of the clinical picture of recurrent well-formed visual hallucinations, symptom fluctuation and slight parkinsonism, or even a Lewy-body variant of Alzheimer disease, considering the presence of amnestic symptoms. Tactile hallucinations have been described in alfa-synucleinopathies. Contrarily to Parkinson disease, when the LBD patients touch their visual hallucinations, the perceived objects often do not disappear and may experience specific texture and thermic sensations.Future research would benefit from a more detailed investigation of the profile of similarities and differences in hallucinations across clinical disorders to facilitate differential diagnosis.

Complex auditory impairment with peduncular hallucinosis due to pontine haemorrhage – a case report

Peduncular hallucinosis is a rare syndrome that develops with upper brainstem and diencephalon lesions. Patients complain of vivid hallucinations that usually occur in hypnagogic states but maintain critical appraisal. Pathological disruption of the reticular activating systems partially explains this clinical phenomenon. We report the case of a 47-year-old man presenting with peduncular hallucinosis associated with central auditory disturbance consisting of bilateral hypoacusis and left-sided paradoxical hyperacusis, secondary to a pontine haemorrhage.

Intracerebral Hemorrhage, Visual Hallucination and COVID-19: What Is the Connection? A Case-Related Review of the Literature on Peduncular Hallucinosis Following Intracerebral Hemorrhage

Previous publications have discussed the occurrence of intracerebral hemorrhages, hallucinations and psychosis in COVID-19 patients. In this article, we have reviewed the literature on the subject while depicting the case of a 63-year-old female patient who suffered from an intracerebral hemorrhage in the right basal ganglia and thalamus two weeks after a COVID-19 diagnosis and who developed a visual hallucinosis shortly after. We concluded that, while there may be a correlation between COVID-19 and hallucinations according to current literature, more research is yet needed to clarify. In our case, we rather interpreted the hallucinations in the context of a peduncular hallucinosis related to the intracerebral hemorrhage. We compared our patient’s lesion localization to other 15 reported cases of peduncular hallucinations following intracerebral hemorrhages reported on Pubmed. In summary, the lesions were localized in the pons in 52.9% of the cases, 17.7% were in the thalamus and/or the basal ganglia, 17.7% in the mesencephalon and respectively 5.8% in the temporal and occipital lobe. The distribution pattern we found is consistent with the previously proposed mechanism behind peduncular hallucinations.

Visual hallucinations

Visual hallucinations have intrigued neurologists and physicians for generations due to patients’ vivid and fascinating descriptions. They are most commonly associated with Parkinson’s disease and dementia with Lewy bodies, but also occur in people with visual loss, where they are known as Charles Bonnet syndrome. More rarely, they can develop in other neurological conditions, such as thalamic or midbrain lesions, when they are known as peduncular hallucinosis. This review considers the mechanisms underlying visual hallucinations across diagnoses, including visual loss, network dysfunction across the brain and changes in neurotransmitters. We propose a framework to explain why visual hallucinations occur most commonly in Parkinson’s disease and dementia with Lewy bodies, and discuss treatment approaches to visual hallucinations in these conditions.

Peduncular hallucinosis after a thalamic stroke

Peduncular hallucinosis is a rare form of hallucinations consisting of vivid and nonthreatening colourful visual hallucinations. It was first described by French neurologist Jean Lhermitte in 1922. It sometimes includes distorted images of animals and people. Peduncular hallucinosis has been described after vascular and infective lesions of the mesencephalon and thalamus.We present a case of peduncular hallucinosis after a right thalamic infarction. This is a case of a 75-year-old Caucasian man with a previous medical history of hypertension and hyperlipidaemia who presented as a transfer from an outside hospital with transient left facial palsy, upper and lower extremity weakness. His symptoms resolved on arrival. CTA head and neck revealed focal filling defect in the basilar artery and a right posterior cerebral artery (PCA) occlusion at its origin. MRI brain without contrast revealed a right thalamic infarct. The patient had vivid hallucinations including his wife sleeping on his hospital bed, seeing his favourite book on the table while he had left it at home, seeing his dogs and a TV show on his room television while it was off. He was easily redirectable, and the hallucinations resolved over 2 days without pharmacological intervention. In cases of thalamic, midbrain or peduncular infarctions, physicians should be cognizant of the possibility of peduncular hallucinosis and inquire about hallucinations. New onset hallucinations in a patient with no prior psychiatric history presenting with concerns for stroke should prompt physicians to strongly consider peduncular hallucinosis.