Peduncular hallucinosis

Diagnostic Approach to the Patient with Altered Mental Status

Acute encephalopathy is a common presenting symptom in the emergency room and complicates many hospital and intensive care unit admissions. The evaluation of patients with encephalopathy poses several challenges: limited history and examination due to the patient's mental status, broad differential diagnosis of systemic and neurologic etiologies, low yield of neurodiagnostic testing due to the high base rate of systemic causes, and the importance of identifying less common neurologic causes of encephalopathy that can be life-threatening if not identified and treated. This article discusses the differential diagnosis of acute encephalopathy, presents an approach to the history and examination in a patient with encephalopathy, reviews the literature on the yield of neurodiagnostic testing in this population, and provides a diagnostic framework for the evaluation of patients with altered mental status.

Prevalence of Neuroradiological Abnormalities in First-Episode Psychosis: A Systematic Review and Meta-analysis

Importance

Individuals presenting with first-episode psychosis (FEP) may have a secondary ("organic") etiology to their symptoms that can be identified using neuroimaging. Because failure to detect such cases at an early stage can have serious clinical consequences, it has been suggested that brain magnetic resonance imaging (MRI) should be mandatory for all patients presenting with FEP. However, this remains a controversial issue, partly because the prevalence of clinically relevant MRI abnormalities in this group is unclear.

Objective

To derive a meta-analytic estimate of the prevalence of clinically relevant neuroradiological abnormalities in FEP.

Data Sources

Electronic databases Ovid, MEDLINE, PubMed, Embase, PsychINFO, and Global Health were searched up to July 2021. References and citations of included articles and review articles were also searched.

Study Selection

Magnetic resonance imaging studies of patients with FEP were included if they reported the frequency of intracranial radiological abnormalities.

Data Extraction and Synthesis

Independent extraction was undertaken by 3 researchers and a random-effects meta-analysis of pooled proportions was calculated. Moderators were tested using subgroup and meta-regression analyses. Heterogeneity was evaluated using the I2 index. The robustness of results was evaluated using sensitivity analyses. Publication bias was assessed using funnel plots and Egger tests.

Main Outcomes and Measures

Proportion of patients with a clinically relevant radiological abnormality (defined as a change in clinical management or diagnosis); number of patients needed to scan to detect 1 such abnormality (number needed to assess [NNA]).

Results

Twelve independent studies (13 samples) comprising 1613 patients with FEP were included. Of these patients, 26.4% (95% CI, 16.3%-37.9%; NNA of 4) had an intracranial radiological abnormality, and 5.9% (95% CI, 3.2%-9.0%) had a clinically relevant abnormality, yielding an NNA of 18. There were high degrees of heterogeneity among the studies for these outcomes, 95% to 73%, respectively. The most common type of clinically relevant finding was white matter abnormalities, with a prevalence of 0.9% (95% CI, 0%-2.8%), followed by cysts, with a prevalence of 0.5% (95% CI, 0%-1.4%).

Conclusions and Relevance

This systematic review and meta-analysis found that 5.9% of patients presenting with a first episode of psychosis had a clinically relevant finding on MRI. Because the consequences of not detecting these abnormalities can be serious, these findings support the use of MRI as part of the initial clinical assessment of all patients with FEP.

Understanding visual hallucinations: a new synthesis

Despite decades of research, we do not definitively know how people sometimes see things that are not there. Eight models of complex visual hallucinations have been published since 2000, including Deafferentation, Reality Monitoring, Perception and Attention Deficit, Activation, Input, and Modulation, Hodological, Attentional Networks, Active inference, and Thalamocortical Dysrhythmia Default Mode Network Decoupling. Each was derived from different understandings of brain organisation. To reduce this variability, representatives from each research group agreed an integrated Visual Hallucination Framework that is consistent with current theories of veridical and hallucinatory vision. The Framework delineates cognitive systems relevant to hallucinations. It allows a systematic, consistent, investigation of relationships between the phenomenology of visual hallucinations and changes in underpinning cognitive structures. The episodic nature of hallucinations highlights separate factors associated with the onset, persistence, and end of specific hallucinations suggesting a complex relationship between state and trait markers of hallucination risk. In addition to a harmonised interpretation of existing evidence, the Framework highlights new avenues of research, and potentially, new approaches to treating distressing hallucinations.

Complex Hallucinations in Hospitalized Rehabilitation Patients With COVID-19

Objectives

To explore the characteristics of hallucinations in hospitalized rehabilitation patients with COVID-19.

Design

Retrospective review using medical records of patients with COVID-19 and admitted to the acute inpatient rehabilitation unit (ARU).

Setting

A public hospital in southern California, specializing in rehabilitation medicine. Participants: Patients with COVID-19 and hallucinations who were consecutively admitted from January 1st to April 30th, 2021.

Interventions

Not applicable.

Main Outcome Measures

Types and themes of hallucinations.

Results

Eight of the 37 patients (21.6%) admitted to the ARU with COVID-19 exhibited hallucinations. All were Hispanic and 7 of them were men; their average age was 56.5 (range: 38-71). Seven patients had COVID-19 pneumonia and 1 developed respiratory distress secondary to Guillain-Barre Syndrome. One patient had posterior reversible encephalopathy syndrome. The average length of stay in the intensive care unit (ICU) was 31.3 days (range: 8-48). Most of the hallucinations occurred during their ICU stay and 2 continued to their ARU stay. All recalled details of hallucinations with 7 exhibiting visual hallucinations, consistent with peduncular hallucinosis with or without auditory and/or tactile components. One patient experienced tactile hallucinations. The themes of hallucinations identified to reflect the contents of the hallucinations were patients' comfort-seeking, fearfulness, and seeing deceased family members. All patients had impaired cognition at the ARU admission but improved at discharge. Four patients had depressed mood/anxiety and 1 had depressed mood alone but without a history of psychiatric illness. ICU delirium was documented in 5 patients. The negative experience of hallucinations seemed to affect their participation of the ARU stay.

Conclusions

More than 20% of patients with COVID-19 who were transferred to attend inpatient rehabilitation exhibited hallucinations. It remains uncertain if these hallucinations were related to the SARS-CoV-2 infection. Multidisciplinary rehabilitation team should be aware to support patients with COVID-19 who experience hallucinations.

Clarithromycin-Induced Visual Hallucinations

An independent 90-year-old woman presented to hospital with vivid and dynamic visual hallucinations following initiation of clarithromycin therapy. She had a background of previous cataract removal with good visual resolution and no significant deficits in visual acuity. Notably, she had been taking sertraline and quinine concurrently. Her symptoms fully resolved 72 hours following cessation of clarithromycin therapy. Visual hallucinations associated with clarithromycin could be explained by recent research demonstrating clarithromycin increases neuronal excitability by inhibiting gamma-aminobutyric acid-ergic signalling. Case reports of similar nature are rare, and we believe this report adds to a currently growing body of literature of visual hallucinations as a side effect of clarithromycin.

Peduncular Hallucinosis 7 Months After Pontine Hemorrhage With Hypertrophic Olivary Degeneration: A Case Report

Peduncular hallucinosis is a rare type of hallucination, wherein patients see colorful and vivid images. It usually appears after damage to the midbrain, pons, or thalamus. We report the case of a 56-year-old man with peduncular hallucinosis after conservative care for spontaneous pontine hemorrhage, 7 months prior to presentation. He was treated with atypical antipsychotics, which resolved the symptoms. We suggest that it is important to consider peduncular hallucinosis in patients after injuries in subcortical areas and the brainstem. Additionally, we found changes in the hypertrophic olivary degeneration using magnetic resonance imaging, and we suggest the possibility of their correlation with peduncular hallucinosis.

A Case for Thalamic Mechanisms of Schizophrenia: Perspective From Modeling 22q11.2 Deletion Syndrome

Schizophrenia is a severe, chronic psychiatric disorder that devastates the lives of millions of people worldwide. The disease is characterized by a constellation of symptoms, ranging from cognitive deficits, to social withdrawal, to hallucinations. Despite decades of research, our understanding of the neurobiology of the disease, specifically the neural circuits underlying schizophrenia symptoms, is still in the early stages. Consequently, the development of therapies continues to be stagnant, and overall prognosis is poor. The main obstacle to improving the treatment of schizophrenia is its multicausal, polygenic etiology, which is difficult to model. Clinical observations and the emergence of preclinical models of rare but well-defined genomic lesions that confer substantial risk of schizophrenia (e.g., 22q11.2 microdeletion) have highlighted the role of the thalamus in the disease. Here we review the literature on the molecular, cellular, and circuitry findings in schizophrenia and discuss the leading theories in the field, which point to abnormalities within the thalamus as potential pathogenic mechanisms of schizophrenia. We posit that synaptic dysfunction and oscillatory abnormalities in neural circuits involving projections from and within the thalamus, with a focus on the thalamocortical circuits, may underlie the psychotic (and possibly other) symptoms of schizophrenia.

Imagine that: cholinesterase inhibitor treatment of complex visual hallucinations of unknown aetiology

Introduction: Our objective is to highlight the value of the neurophenomenological classification of complex visual hallucinations (VHs). This approach enabled the authors to successfully treat VHs of uncertain aetiology with cholinesterase inhibitors because the content of the hallucinations suggested dysfunction in cholinergic modulated networks.Methods: We utilise the single case report to describe the nature and content of chronic VHs experienced by a 49-year-old woman following a prolonged admission to ITU. Despite extensive investigation, no clear cause was identified for these hallucinations and the patient did not respond to rationalisation of medications or trials of antipsychotics. We therefore adopted the neurophenomenological approach to classifying and treating her VHs.Results: After several years of distressing visual hallucinations, a course of Rivastigmine was trialed despite no evidence suggestive of a Parkinsonian syndrome. Nevertheless, the patient reported a dose-effect response with significant reduction in the frequency and intensity of her hallucinations, almost to complete resolution.Conclusions: At present there is limited evidence about the medical management of visual hallucinations. This case report suggests that cholinesterase inhibitors may be of benefit, even in the absence of clear parkinsonsian features, if the form and content of the VHs suggest dysfunction in cholinergic modulated attentional networks.

[Visual hallucinations in Parkinson's disease]

Visual hallucinations have a negative effect on the course of Parkinson's disease (PD), being a source of stress for the patients themselves and caregivers. The article discusses the basic theories and pathogenetic mechanisms of the development of visual hallucinations in PD consisting of the following components: impairment of the visual information received from the retina with subsequent disruption of its processing in the central parts of the visual system; lack of suppression of internally generated images through the ponto-geniculo-occipital system; the invasion of REM sleep patterns in wakefulness; decreased ability of the brain stem structures to implement appropriate information filtering as well as excessive drug-induced activation of the mesolimbic system. Particular attention is paid to visual impairment and changes in the transmission of information along the retino-hypothalamic tract. In this connection, dysfunction in the «retina - hypothalamus» system can also be considered as one of the factors that determines the time and rhythm of occurrence or exacerbation of visual hallucinations in PD. Attracting attention to this aspect opens new therapeutic possibilities where the circadian system can be positioned as a target of additional exposure in the treatment of visual hallucinations in PD.

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.

The man behind the bed: a case of peduncular hallucinosis treated with quetiapine and melatonin

An 81-year-old female presented with a right pontine infarct and later developed recurrent vivid hallucinations. After a workup for delirium and hallucinosis was unrevealing, a diagnosis of peduncular hallucinosis (PH) was proposed. Treatment with quetiapine and, later, adjunctive nightly melatonin resulted in return to cognitive baseline. An array of etiologies can be responsible for visual hallucinations, including PH. Herein, we review several disorders of hallucinosis and their diagnostic workup. Additionally, we explore the pathophysiology of PH and its association with the pontine-geniculate-occipital (PGO) pathway and propose why correction of the sleep-wake cycle may benefit patients with PH.

New-Onset Psychosis Associated With a Lesion Localized in the Rostral Tectum: Insights Into Pathway-Specific Connectivity Disrupted in Psychosis

OBJECTIVE

To investigate pathway-specific connectivity disrupted in psychosis.

METHODS

We carried out a case study of a middle-aged patient who presented with new-onset psychosis associated with a space-occupying lesion localized in the right superior colliculus/periaqueductal gray. The study sought to investigate potential connectivity deficits related to the lesion by the use of diffusion tensor imaging and resting-state functional magnetic resonance imaging. To this aim, we generated a functional connectivity map of the patient's brain, centered on the lesion area, and compared this map with the corresponding map of 10 sex- and age-matched control individuals identified from the Max Planck Institute-Leipzig Mind-Brain-Body database.

RESULTS

Our analysis revealed a discrete area in the right rostral tectum, in the immediate vicinity of the lesion, whose activity is inversely correlated with the activity of left amygdala, whereas left amygdala is functionally associated with select areas of the temporal, parietal, and occipital lobes. Based on a comparative analysis of the patient with 10 control individuals, the lesion has impacted on the connectivity of rostral tectum (superior colliculus/periaqueductal gray) with left amygdala as well as on the connectivity of left amygdala with subcortical and cortical areas.

CONCLUSIONS

The superior colliculus/periaqueductal gray might play important roles in the initiation and perpetuation of psychosis, at least partially through dysregulation of left amygdala activity.

Visual hallucinations, thalamocortical physiology and Lewy body disease: A review

One of the core diagnostic criteria for Dementia with Lewy Bodies (DLB) is the presence of visual hallucinations. The presence of hallucinations, along with fluctuations in the level of arousal and sleep disturbance, point to potential pathological mechanisms at the level of the thalamus. However, the potential role of thalamic dysfunction in DLB, particularly as it relates to the presence of formed visual hallucinations is not known. Here, we review the literature on the pathophysiology of DLB with respect to modern theories of thalamocortical function and attempt to derive an understanding of how such hallucinations arise. Based on the available literature, we propose that combined thalamic-thalamic reticular nucleus and thalamocortical pathology may explain the phenomenology of visual hallucinations in DLB. In particular, diminished α7 cholinergic activity in the thalamic reticular nucleus may critically disinhibit thalamocortical activity. Further, concentrated pathological changes within the posterior regions of the thalamus may explain the predilection for the hallucinations to be visual in nature.

Jacques Jean Lhermitte and Lhermitte’s sign

Jacques Jean Lhermitte, a forefather of modern clinical neurology, was a French neurologist conducting the majority of his research between 1908 and 1957. Although less well known than his contemporaries at the time, Lhermitte eventually was famously recognized for his eponymously named “Lhermitte’s sign.” Lhermitte’s contributions to the field of neurology spanned that of monographic clinical descriptions of syndromes to exquisitely detailed descriptions of neuropathology, finally delving into the realm of modern neuropsychiatry in his later years. Lhermitte laid the groundwork for the burgeoning field of neurology, developing the reputation of a renaissance physician by both his contemporaries and current neurologists. Here, we take an extensive look into the life and career of Lhermitte and the legacies that he left behind.

Peduncular hallucinosis associated with a pontine cavernoma

Peduncluar hallucinosis is a rare neurological disorder characterized by visual hallucinations, often described to be vivid and dream-like. While the exact pathophysiology has yet to be elucidated, most cases to date have suggested an etiology stemming from lesions to the thalamus or midbrain. Here presented is a case of a 54-year-old female with peduncular hallucinosis secondary to a pontine cavernoma hemorrhage in the setting of essential hypertension. The patient’s vivid visual and auditory hallucinations aligned temporally with the lesion’s discovery and resolved after pharmaceutical treatment. This case represents a rare form of peduncular hallucinosis secondary to a pontine cavernoma hemorrhage leading to vasospasm in the arteries feeding the brain-stem.

Peduncular Hallucinosis and Autonomic Dysfunction in Anti-Aquaporin-4 Antibody Syndrome

Neuromyelitis optica is a rare, severe inflammatory demyelinating disease of the central nervous system, previously described as affecting only the optic nerve and spinal cord. Since the discovery of a highly specific autoantibody, anti-aquaporin-4, lesions are now recognized outside these regions. We report a man with severe, debilitating symptoms resulting from a symptomatic lesion within the diencephalon, manifesting with abnormal circadian rhythms, autonomic dysfunction, behavioral disturbance, and complex visual hallucinations. The patient reported seeing nonexistent small people and animals, streaks of color across people's faces, movement of objects and facial features, water cascading down walls, bright spots, and writing appearing as hieroglyphics. His centrally driven sick sinus syndrome required insertion of a permanent cardiac pacemaker. We have been able to suppress his disease activity with methotrexate for 30 months. We review the literature on patients with positive anti-aquaporin-4 serology and dysregulation of hypothalamic function, to provide evidence that the clinical manifestations can include complex visual phenomena.

Peduncular psychosis

Psychotic symptoms are rarely documented in association with cortex-sparing central nervous system (CNS) lesions limited to the midbrain. We present the case of a 15-year-old boy with hereditary and environmental risk factors for psychiatric illness, as well as a history of midbrain pilocytic astrocytoma treated with chemotherapy and focused radiation, who presented with non-epileptic seizures, hyper-religiosity and frank psychosis. The space-occupying midbrain lesion has been radiographically stable while the patient has decompensated psychiatrically. Differential aetiology for the patient's psychiatric decompensation is discussed, including psychosis secondary to a lesion of the midbrain. Literature linking midbrain lesions to psychotic features, such as in peduncular hallucinosis, is briefly reviewed. This case suggests that a midbrain lesion in a susceptible patient may contribute to psychosis.

Auditory hallucinations in cognitive neurology

INTRODUCTION

Different types and localisations of neurological lesions can produce tinnitus and verbal or musical hallucinations (VMH).

METHOD

These symptoms were screened for in 1,000 outpatients at a cognitive neurology clinic, and epidemiological and neuroimaging data were recorded.

RESULTS

Tinnitus was present in 6.9% of the total and VMH in 0.9%. The paracusia group was predominantly female but the difference was not statistically significant. Patients with tinnitus were younger and those with VMH were older than the rest of the sample (mean ages). Hearing loss was more prevalent in the paracusia group (difference was significant in VMH subgroup). There were no intergroup differences in the prevalence of psychotic and obsessive-compulsive disorders, or of leukoaraiosis. Treatment with acetylsalicylic acid was more frequent in the VMH group, whereas other non-opioid analgesics and benzodiazepines were more commonly prescribed to patients with tinnitus. The suspected cause of VMH was dementia with Lewy bodies (n=2, one with vascular disease), Alzheimer disease (n=2, one with vascular disease), isolated cerebrovascular disease (n=3), traumatic brain injury (n=1), and surgical brainstem lesion (n=1). All VMH cases displayed an underlying factor that might prompt this symptom, eg, hearing loss (n=6), a predisposing drug (n=9), and polypharmacy (n=9).

CONCLUSIONS

Treatment with benzodiazepines and non-opioid analgesics was more frequent in the tinnitus group, whereas the VMH group showed a higher prevalence of hearing loss and treatment with acetylsalicylic acid. The causes of VMH were dementia with Lewy bodies, Alzheimer disease, and focal lesions in the mesencephalon, pons, left temporal lobe, or left claustrum.

Altered functional connectivity in lesional peduncular hallucinosis with REM sleep behavior disorder

Brainstem lesions causing peduncular hallucinosis (PH) produce vivid visual hallucinations occasionally accompanied by sleep disorders. Overlapping brainstem regions modulate visual pathways and REM sleep functions via gating of thalamocortical networks. A 66-year-old man with paroxysmal atrial fibrillation developed abrupt-onset complex visual hallucinations with preserved insight and violent dream enactment behavior. Brain MRI showed restricted diffusion in the left rostrodorsal pons suggestive of an acute ischemic stroke. REM sleep behavior disorder (RBD) was diagnosed on polysomnography. We investigated the integrity of ponto-geniculate-occipital circuits with seed-based resting-state functional connectivity MRI (rs-fcMRI) in this patient compared to 46 controls. Rs-fcMRI revealed significantly reduced functional connectivity between the lesion and lateral geniculate nuclei (LGN), and between LGN and visual association cortex compared to controls. Conversely, functional connectivity between brainstem and visual association cortex, and between visual association cortex and prefrontal cortex (PFC) was significantly increased in the patient. Focal damage to the rostrodorsal pons is sufficient to cause RBD and PH in humans, suggesting an overlapping mechanism in both syndromes. This lesion produced a pattern of altered functional connectivity consistent with disrupted visual cortex connectivity via de-afferentation of thalamocortical pathways.

Network localization of neurological symptoms from focal brain lesions

A traditional and widely used approach for linking neurological symptoms to specific brain regions involves identifying overlap in lesion location across patients with similar symptoms, termed lesion mapping. This approach is powerful and broadly applicable, but has limitations when symptoms do not localize to a single region or stem from dysfunction in regions connected to the lesion site rather than the site itself. A newer approach sensitive to such network effects involves functional neuroimaging of patients, but this requires specialized brain scans beyond routine clinical data, making it less versatile and difficult to apply when symptoms are rare or transient. In this article we show that the traditional approach to lesion mapping can be expanded to incorporate network effects into symptom localization without the need for specialized neuroimaging of patients. Our approach involves three steps: (i) transferring the three-dimensional volume of a brain lesion onto a reference brain; (ii) assessing the intrinsic functional connectivity of the lesion volume with the rest of the brain using normative connectome data; and (iii) overlapping lesion-associated networks to identify regions common to a clinical syndrome. We first tested our approach in peduncular hallucinosis, a syndrome of visual hallucinations following subcortical lesions long hypothesized to be due to network effects on extrastriate visual cortex. While the lesions themselves were heterogeneously distributed with little overlap in lesion location, 22 of 23 lesions were negatively correlated with extrastriate visual cortex. This network overlap was specific compared to other subcortical lesions (P < 10(-5)) and relative to other cortical regions (P < 0.01). Next, we tested for generalizability of our technique by applying it to three additional lesion syndromes: central post-stroke pain, auditory hallucinosis, and subcortical aphasia. In each syndrome, heterogeneous lesions that themselves had little overlap showed significant network overlap in cortical areas previously implicated in symptom expression (P < 10(-4)). These results suggest that (i) heterogeneous lesions producing similar symptoms share functional connectivity to specific brain regions involved in symptom expression; and (ii) publically available human connectome data can be used to incorporate these network effects into traditional lesion mapping approaches. Because the current technique requires no specialized imaging of patients it may prove a versatile and broadly applicable approach for localizing neurological symptoms in the setting of brain lesions.

Locus coeruleus syndrome as a complication of tectal surgery

We describe a case of a 48-year-old woman who underwent a resection of a tectal pilocytic astrocytoma complicated by a sequence of fluctuating consciousness, psychosis with complex hallucinations and lasting sleeping disturbances in which she vividly acts out her dreams. Based on the clinical and anatomical evidence of this case, we propose the term locus coeruleus syndrome to describe this association of iatrogenic symptoms. Along with those of the locus coeruleus, lesions of the dorsal raphe nucleus, ventral tegmentum, substantia nigra pars compacta, the superior colliculus and other peduncular lesions (such as peduncular hallucinosis) are involved in the regulation of sleep-wake/arousal, behaviour, sleeping disorders and rapid eye movement atonia. However, iatrogenic lesion of the locus coeruleus could explain the complications on all levels in our patient.

Auditory hallucinations associated with migraine: Case series and literature review

Objective

The objective of this review is to describe auditory hallucinations (paracusias) associated with migraine attacks to yield insights into their clinical significance and pathogenesis.

Background

Isolated observations have documented rare associations of migraine with auditory hallucinations. Unlike visual, somatosensory, language, motor, and brainstem symptoms, paracusias with acute headache attacks are not a recognized aura symptom by the International Headache Society, and no systematic review has addressed this association.

Methods

We retrospectively studied patients experiencing paracusias associated with migraine at our center and in the literature.

Results

We encountered 12 patients (our center = 5, literature = 7), 58% were female, and 75% had typical migraine aura. Hallucinations most commonly featured voices (58%), 75% experienced them during headache, and the duration was most often <1 hour (67%). No patients described visual aura evolving to paracusias. Most patients (50%) had either a current or previous psychiatric disorder, most commonly depression (67%). The course of headache and paracusias were universally congruent, including improvement with headache prophylaxis (58%).

Conclusion

Paracusias uncommonly co-occur with migraine and usually feature human voices. Their timing and high prevalence in patients with depression may suggest that paracusias are not necessarily a form of migraine aura, though could be a migraine trait symptom. Alternative mechanisms include perfusion changes in primary auditory cortex, serotonin-related ictal perceptual changes, or a release phenomenon in the setting of phonophobia with avoidance of a noisy environment.

Acute Psychosis Associated with Subcortical Stroke: Comparison between Basal Ganglia and Mid-Brain Lesions

Acute onset of psychosis in an older or elderly individual without history of previous psychiatric disorders should prompt a thorough workup for neurologic causes of psychiatric symptoms. This report compares and contrasts clinical features of new onset of psychotic symptoms between two patients, one with an acute basal ganglia hemorrhagic stroke and another with an acute mid-brain ischemic stroke. Delusions and hallucinations due to basal ganglia lesions are theorized to develop as a result of frontal lobe dysfunction causing impairment of reality checking pathways in the brain, while visual hallucinations due to mid-brain lesions are theorized to develop due to dysregulation of inhibitory control of the ponto-geniculate-occipital system. Psychotic symptoms occurring due to stroke demonstrate varied clinical characteristics that depend on the location of the stroke within the brain. Treatment with antipsychotic medications may provide symptomatic relief.

Preclinical polymodal hallucinations for 13 years before dementia with Lewy bodies

Objective. We describe a case of dementia with Lewy bodies (DLB) that presented long-lasting preclinical complex polymodal hallucinations. Background. Few studies have deeply investigated the characteristics of hallucinations in DLB, especially in the preclinical phase. Moreover, the clinical phenotype of mild cognitive impairment-(MCI-) DLB is poorly understood. Methods. The patient was followed for 4 years and a selective phenomenological and cognitive study was performed at the predementia stage. Results. The phenomenological study showed the presence of hypnagogic and hypnopompic hallucinations that allowed us to make a differential diagnosis between DLB and Charles Bonnet syndrome (CBS). The neuropsychological evaluation showed a multiple domain without amnesia MCI subtype with prefrontal dysexecutive, visuoperceptual, and visuospatial impairments and simultanagnosia, which has not previously been reported in MCI-DLB. Conclusions. This study extends the prognostic value of hallucinations for DLB to the preclinical phases. It supports and refines the MCI-DLB concept and identifies simultanagnosia as a possible early cognitive marker. Finally, it confirms an association between hallucinations and visuoperceptual impairments at an intermediate stage of the disease course and strongly supports the hypothesis that hallucinations in the earliest stages of DLB may reflect a narcolepsy-like REM-sleep disorder.

Tricks of the mind: Visual hallucinations as disorders of attention

Visual hallucinations are common across a number of disorders but to date, a unifying pathophysiology underlying these phenomena has not been described. In this manuscript, we combine insights from neuropathological, neuropsychological and neuroimaging studies to propose a testable common neural mechanism for visual hallucinations. We propose that 'simple' visual hallucinations arise from disturbances within regions responsible for the primary processing of visual information, however with no further modulation of perceptual content by attention. In contrast, 'complex' visual hallucinations reflect dysfunction within and between the Attentional Control Networks, leading to the inappropriate interpretation of ambiguous percepts. The incorrect information perceived by hallucinators is often differentially interpreted depending on the time-course and the neuroarchitecture underlying the interpretation. Disorders with 'complex' hallucinations without retained insight are proposed to be associated with a reduction in the activity within the Dorsal Attention Network. The review concludes by showing that a variety of pathological processes can ultimately manifest in any of these three categories, depending on the precise location of the impairment.

A neurologist's approach to delirium: diagnosis and management of toxic metabolic encephalopathies

Toxic metabolic encephalopathies (TMEs) present as an acute derangement in consciousness, cognition and behavior, and can be brought about by various triggers, including endocrine and metabolic disturbances, exogenous toxins, pain and infection. Also referred to as "delirium" or "acute confusional states," TMEs are characterized by (1) an altered level of consciousness and activity, (2) global changes in cognition with inattention, (3) a fluctuating course with disturbances in the sleep-wake cycle, and (4) asterixis and myoclonus. The pathophysiology of this syndrome is poorly understood. Imbalanced neurotransmitter signaling and pathologically heightened brain inflammatory cytokine signaling have been proposed as candidate mechanisms. Focal brain lesions can also occasionally mimic TMEs. A neurological examination is required to identify the presence of focal findings, which when present, identify a new focal lesion or the recrudescence of prior ischemic, inflammatory or neoplastic insults. Diagnostic testing must include a search for metabolic and infectious derangements. Offending medications should be withdrawn. Magnetic resonance imaging, cerebrospinal fluid analysis and electroencephalography should be considered in select clinical situations. In addition to being an unpleasant experience for the patient and family, this condition is associated with extended hospital stays, increased mortality and high costs. In individuals with diminished cognitive reserve, episodes of TME lead to an accelerated decline in cognitive functioning. Starting with an illustrative case, this paper provides a neurologist's approach to the diagnosis, differential diagnosis and management of toxic metabolic encephalopathies.

Hallucinators find meaning in noises: pareidolic illusions in dementia with Lewy bodies

By definition, visual illusions and hallucinations differ in whether the perceived objects exist in reality. A recent study challenged this dichotomy, in which pareidolias, a type of complex visual illusion involving ambiguous forms being perceived as meaningful objects, are very common and phenomenologically similar to visual hallucinations in dementia with Lewy bodies (DLB). We hypothesise that a common psychological mechanism exists between pareidolias and visual hallucinations in DLB that confers meaning upon meaningless visual information. Furthermore, we believe that these two types of visual misperceptions have a common underlying neural mechanism, namely, cholinergic insufficiency. The current study investigated pareidolic illusions using meaningless visual noise stimuli (the noise pareidolia test) in 34 patients with DLB, 34 patients with Alzheimer׳s disease and 28 healthy controls. Fifteen patients with DLB were administered the noise pareidolia test twice, before and after donepezil treatment. Three major findings were discovered: (1) DLB patients saw meaningful illusory images (pareidolias) in meaningless visual stimuli, (2) the number of pareidolic responses correlated with the severity of visual hallucinations, and (3) cholinergic enhancement reduced both the number of pareidolias and the severity of visual hallucinations in patients with DLB. These findings suggest that a common underlying psychological and neural mechanism exists between pareidolias and visual hallucinations in DLB.

Visual hallucinations: charles bonnet syndrome

The following is a case of Charles Bonnet syndrome in an 86-year-old woman who presented with visual hallucinations. The differential diagnosis of visual hallucinations is broad and emergency physicians should be knowledgeable of the possible etiologies.

Peduncular hallucinosis secondary to central pontine myelinolysis

Peduncular hallucinations are generally associated with lesions in the midbrain. They have rarely been associated with central pontine myelinolysis, a condition associated with rapid alterations in serum sodium and chronic alcoholism. Described herein is the case of a 46-year-old man who developed typical peduncular hallucinations, whose imaging demonstrated central pontine myelinolysis. After alcohol cessation and neuroimaging resolution, the patient's hallucinatory phenomena abated.

Pareidolias: complex visual illusions in dementia with Lewy bodies

Patients rarely experience visual hallucinations while being observed by clinicians. Therefore, instruments to detect visual hallucinations directly from patients are needed. Pareidolias, which are complex visual illusions involving ambiguous forms that are perceived as meaningful objects, are analogous to visual hallucinations and have the potential to be a surrogate indicator of visual hallucinations. In this study, we explored the clinical utility of a newly developed instrument for evoking pareidolic illusions, the Pareidolia test, in patients with dementia with Lewy bodies—one of the most common causes of visual hallucinations in the elderly. Thirty-four patients with dementia with Lewy bodies, 34 patients with Alzheimer’s disease and 26 healthy controls were given the Pareidolia test. Patients with dementia with Lewy bodies produced a much greater number of pareidolic illusions compared with those with Alzheimer’s disease or controls. A receiver operating characteristic analysis demonstrated that the number of pareidolias differentiated dementia with Lewy bodies from Alzheimer’s disease with a sensitivity of 100% and a specificity of 88%. Full-length figures and faces of people and animals accounted for >80% of the contents of pareidolias. Pareidolias were observed in patients with dementia with Lewy bodies who had visual hallucinations as well as those who did not have visual hallucinations, suggesting that pareidolias do not reflect visual hallucinations themselves but may reflect susceptibility to visual hallucinations. A sub-analysis of patients with dementia with Lewy bodies who were or were not treated with donepzil demonstrated that the numbers of pareidolias were correlated with visuoperceptual abilities in the former and with indices of hallucinations and delusional misidentifications in the latter. Arousal and attentional deficits mediated by abnormal cholinergic mechanisms and visuoperceptual dysfunctions are likely to contribute to the development of visual hallucinations and pareidolias in dementia with Lewy bodies.

Visual symptoms in Parkinson's disease and Parkinson's disease dementia

Visual symptoms are common in PD and PD dementia and include difficulty reading, double vision, illusions, feelings of presence and passage, and complex visual hallucinations. Despite the established prognostic implications of complex visual hallucinations, the interaction between cognitive decline, visual impairment, and other visual symptoms remains poorly understood. Our aim was to characterize the spectrum of visual symptomatology in PD and examine clinical predictors for their occurrence. Sixty-four subjects with PD, 26 with PD dementia, and 32 age-matched controls were assessed for visual symptoms, cognitive impairment, and ocular pathology. Complex visual hallucinations were common in PD (17%) and PD dementia (89%). Dementia subjects reported illusions (65%) and presence (62%) more frequently than PD or control subjects, but the frequency of passage hallucinations in PD and PD dementia groups was equivalent (48% versus 69%, respectively; P = 0.102). Visual acuity and contrast sensitivity was impaired in parkinsonian subjects, with disease severity and age emerging as the key predictors. Regression analysis identified a variety of factors independently predictive of complex visual hallucinations (e.g., dementia, visual acuity, and depression), illusions (e.g., excessive daytime somnolence and disease severity), and presence (e.g., rapid eye movement sleep behavior disorder and excessive daytime somnolence). Our results demonstrate that different "hallucinatory" experiences in PD do not necessarily share common disease predictors and may, therefore, be driven by different pathophysiological mechanisms. If confirmed, such a finding will have important implications for future studies of visual symptoms and cognitive decline in PD and PD dementia.

Testing an aetiological model of visual hallucinations in Parkinson's disease

The exact pathogenesis of visual hallucinations in Parkinson's disease is not known but an integrated model has been proposed that includes impaired visual input and central visual processing, impaired brainstem regulation of sleep-wake cycle with fluctuating vigilance, intrusion of rapid eye movement dream imagery into wakefulness and emergence of internally generated imagery, cognitive dysfunction and influence of dopaminergic drugs. In a clinical study, we assessed motor and non-motor function, including sleep, mood, autonomic and global, frontal and visuoperceptive cognitive function in patients with and without visual hallucinations. A subgroup of patients underwent detailed ophthalmological assessment. In a separate pathological study, histological specimens were obtained from cases of pathologically proven Parkinson's disease and a retrospective case notes review was made for reporting of persistent formed visual hallucinations. An assessment of Lewy body and Lewy neurite pathology was carried out in five cortical regions as recommended by diagnostic criteria for dementia with Lewy Bodies and in brainstem nuclei. Ninety-four patients (mean age 67.5 ± 9.5 years) participated in the clinical study of whom 32% experienced visual hallucinations. When corrected for multiple comparisons, patients with visual hallucinations had significantly greater disease duration, treatment duration, motor severity and complications, sleep disturbances, in particular excessive daytime somnolence and rapid eye movement sleep behavioural disorder, disorders of mood, autonomic dysfunction and global, frontal and visuoperceptive cognitive dysfunction. Of the 94 patients, 50 (53%) underwent ophthalmological assessment. There were no differences in ocular pathology between the visual hallucination and non-visual hallucination groups. In a logistic regression model the four independent determinants of visual hallucinations were rapid eye movement sleep behavioural disorder (P = 0.026), autonomic function (P = 0.004), frontal cognitive function (P = 0.020) and a test of visuoperceptive function (object decision; P = 0.031). In a separate study, post-mortem analysis was performed in 91 subjects (mean age at death 75.5 ± 8.0 years) and persistent visual hallucinations were documented in 63%. Patients in the visual hallucinations group had similar disease duration but had significantly higher Lewy body densities in the middle frontal (P = 0.002) and middle temporal gyri (P = 0.033) and transentorhinal (P = 0.005) and anterior cingulate (P = 0.020) cortices but not parietal cortex (P = 0.22). Using a comprehensive assessment of the clinical, demographic and ophthalmological correlates of visual hallucinations in Parkinson's disease, the combined data support the hypothesized model of impaired visual processing, sleep-wake dysregulation and brainstem dysfunction, and cognitive, particularly frontal, impairment all independently contributing to the pathogenesis of visual hallucinations in Parkinson's disease. These clinical data are supported by the pathological study, in which higher overall cortical Lewy body counts, and in particular areas implicated in visuoperception and executive function, were associated with visual hallucinations.

The pedunculopontine nucleus is related to visual hallucinations in Parkinson's disease: preliminary results of a voxel-based morphometry study

Visual hallucinations (VH) are common in Parkinson’s disease (PD) and lead to a poor quality of life. For a long time, dopaminergic therapy was considered to be the most important risk factor for the development of VH in PD. Recently, the cholinergic system, including the pedunculopontine nucleus (PPN), has been implicated in the pathophysiology of VH. The aim of the present study was to investigate grey matter density of the PPN region and one of its projection areas, the thalamus. Thirteen non-demented PD patients with VH were compared to 16 non-demented PD patients without VH, 13 demented PD patients (PDD) with VH and 11 patients with dementia with Lewy bodies (DLB). Isotropic 3-D T1-weighted MRI images (3T) were analysed using voxel-based morphometry (VBM) with the PPN region and thalamus as ROIs. PD and PDD patients with VH showed grey matter reductions of the PPN region and the thalamus compared to PD patients without VH. VH in PD(D) patients are associated with atrophy of the PPN region and its thalamic target area, suggesting that a cholinergic deficit may be involved in the development of VH in PD(D).

Auditory hallucinations and migraine of possible brainstem origin

BACKGROUND

Concurrence of migraine and hallucinations is extremely rare and the underlying mechanism is poorly understood.

METHODS

We report a 22-year-old man with migraine associated with auditory hallucinations. Concurrent psychotic illness has been excluded.

RESULTS

Brain MR scans showed a stable, patchy FLAIR hyperintensity over the posterolateral aspect of the left cerebral peduncle, just below the level of the red nucleus. This was felt to represent an area of gliosis based on the interval stability over 19 months. There was absence of features for aggressive neoplasms, such as lesional high cellular turnover (choline/NAA ratio >1.0) or high cerebral blood volume on advanced MR imaging with MR spectroscopy and dynamic perfusion MR. EEG and brainstem auditory evoked potentials were unremarkable.

CONCLUSIONS

To our knowledge, there are no reports to date on similar auditory hallucinations in adult migraine patients, as well as with associated MRI brainstem lesions. The peduncular lesion could represent a previous migrainous infarct, and a possible analogy can be drawn from the descriptions of peduncular hallucinosis. Brainstem lesions, particularly in the midbrain and pons, have rarely been associated with this condition. It has been postulated that the damage to ascending reticular systems or thalamocortical circuitry may contribute to its pathogenesis.

Complex visual hallucinations as a presentation of temporal low-grade glioma

We report a patient with an unusual presentation of a temporal low-grade glioma with visual symptoms of formed, coloured meaningful images without coexistent psychiatric symptoms or epileptiform activity consistent with a diagnosis of visual hallucinosis. The location and extent of the lesion on the MRI differs from the lesions commonly associated with this diagnosis.

Thalamic pathology in schizophrenia

The thalamus plays a critical role in the coordination of information as it passes from region to region within the brain. A disruption of that information flow may give rise to some of the cardinal symptoms of schizophrenia. In support of this hypothesis, schizophrenia-like syndromes emerge when illnesses, such as stroke, selectively damage the thalamus while sparing the rest of the brain. Evidence from many sources has implicated thalamic dysfunction in schizophrenia. In postmortem studies, several subregions of the thalamus, including the mediodorsal nucleus and the pulvinar, have been shown to have fewer neurons in schizophrenia. Neurochemical disturbances are also seen, with changes in both the glutamate and dopamine systems; thalamic glutamate receptor expression is altered in schizophrenia, and dopamine appears to be elevated in thalamic subregions, while evidence exists of an imbalance between dopamine and other neurotransmitters. In vivo studies using magnetic resonance imaging have demonstrated smaller thalamic volumes in schizophrenia, as well as shape deformations suggesting changes in those thalamic regions that are most densely connected to the portions of the brain responsible for executive function and sensory integration. These changes seem to be correlated with clinical symptoms. The thalamus is a starting point for several parallel, overlapping networks that extend from thalamic nuclei to the cortex. Evidence is emerging that changes in the thalamic nodes of these networks are echoed by changes at other points along the chain; this suggests that schizophrenia might be a disease of disrupted thalamocortical neural networks. This model distributes the pathology throughout the network, but also concentrates attention on the thalamus as a critical structure, especially because of its role in coordinating the flow of information within and between neural networks.

New approaches to understanding hallucinations in Parkinson's disease: phenomenology and possible origins

The authors review current literature on hallucinations in Parkinson's disease (PD). Recent neuropathological studies showed that hallucinations occur in synucleinopathies and are a significant predictor of Lewy Body depositions. Therefore, hallucinations are a hallmark of PD and of dementia with Lewy Bodies. Visual hallucinations are mostly complex and kinematic; preserved or disturbed insight on the nature of hallucinations is a major prognostic factor, although eventually all hallucinators will present with reduced insight. Current theories on the origin of hallucinations point to visual dysfunction, dream overflow and cognitive impairment, yet objection can be raised on each one of the putative models of hallucinations. Understanding of the origin of hallucinations is required in order to develop treatments: all treatment evaluations were focused in general on psychosis, and only clozapine obtained positive evidence-based ratings on efficacy. However, it is likely that cholinesterase inhibitors, antipsychotics and anti-5-hydroxytryptamine(3) agents and drugs acting on sleep regulation will have different and perhaps opposite effects on different types of hallucinations, whether they are accompanied by disturbed insight, sleep disorders or other psychotic features. Further studies will try to separate phenomenology and responses to treatment and will investigate the relevance of concomitant sleep disorders and abnormality of frontoparietal networks involved in the attention process.