Visual Hallucinations

Visual HallucinationsRandy M. Rosenberg, MD FAAN FACPAssistant Professor of NeurologyLewis Katz School of Medicine at Temple University

Visual Hallucinations in Normal People

What is this?NOPE!Concentric circles!Fooled by experience and expectation

Perception Versus Expectation

Having a Hallucination Just For Fun

Differential Diagnosis of Recurrent Complex Visual HallucinationsMedication(s)Metabolic statusPsychiatric etiology including mania, depression, substance dependence and schizophreniaNeurodegenerative diseases (e.g Lewy Body Dementia, Alzheimers and Parkinsons disease)Release hallucinations Charles Bonnet SyndromeMigraineEpilepsy

Peduncular HallucinosisComplex visual hallucinations occur as a result of lesions in the midbrain and/or thalamus. The term peduncular does not only imply cerebral peduncles but includes the midbrain and surrounding area.

Peduncular hallucinosis has been associated vascular and infectious pontine, midbrain, and thalamic lesions, local subarachnoid hemorrhage, compression by local and distal tumors, basilar vascular hypoplasia, basilar migraine, and after surgical and angiographic interventions

Nature of Peduncular HallucinationsCommon hallucinations experienced by these individuals include people, animals, landscapes, grotesque and deformed faces, repeated patterns, and Lilliputian hallucinations.

Typically occurs a few days after the infarct

Each hallucination episode will last for a few minutes to several hours and can be accompanied by tactile or auditory hallucinations differentiating it from Charles Bonnet Syndrome.

Peduncular Hallucinations and the Alice in Wonderland SyndromeThe foremost symptom of the Alice in Wonderland syndrome is an altered body image and the experience of timeThe person observes sizes of parts of the body wrongly. More often than not, the head and hands seem disproportionate, The person perceives growth of various parts rather than a reduction in their sizeAmong adults, people who have migraine, epilepsy, or head trauma are the most likely to report Alice in Wonderland syndrome

(A) Alice experiences partial macrosomatognosia, and (B) Alice experiences total body microsomatognosia

Peduncular Hallucinations: Characteristics

Migraine AuraAbout 20% of migraineurs experience migraine aura, of which 99% is visual.Thought to be associated with Leao's cortical spreading depressionPatients develop rCBF reduction (oligemia), which does not reach critical values (ischemia).Typically spread in 520 minutes does not last more than 60 minutesIf these symptoms last longer, between 60 minutes and 1 week, they are called prolonged aura. Persistent migraine aura without infarction (PMA) is a condition in which auras last longer than 1 week, in absence of radiological evidence of infarction

Persistant Migraine AuraPersistent migraine aura without infarction (PMA) is a rare condition that is defined as an aura that lasts longer than 1 week in absence of infarctionTwo types of PMA have been distinguished Persistent primary visual disturbance Visual snowTelevision staticTypical auraPhosphenes, fortification spectra, scintillating scotomaSeveral theories on the underlying pathophysiological:These include abnormal energy metabolism in the brain,Brain magnesium levels being significantly lower than that of non-migraineursGreater reactivity of N-methyl-D-aspartate receptors to glutamateLowered threshold to spreading cortical depolarizationLoss of inhibitory GABA-ergic interneurons; they may combine to cause sustained visual aura Sustained hyperexcitability of the visual cortex without significant dynamic modulation.Lamotrigine may be the most effective treatment.

Visual Snow

Hildegard of Bingen (1098-1179)

EpilepsyAbout 5% of patients with epilepsy have occipital lobe foci with visual manifestations.Since occipital seizures are frequently accompanied by a postictal headache, they may be difficult to distinguish from migrainesVisual hallucinations caused by seizures have often been described as simple, brief, and consistent for each patient.They usually consist of small, brightly colored spots or shapes that flash.Content of the hallucination may be distorted in size or it may suddenly change shape Moving from a lateral field toward the center of the field of vision

Occipital Lobe Seizures

Occipital Lobe Seizure: Visual Hallucinations

Can resemble a migraine aura with 50% having migraine-like post-ictal headachesEpileptic visual hallucinations usually occur within a few seconds, last a few minutes and are usually colored and circularMigraine visual aura develops over minutes and typically lasts 5-50 minutes and is often uncolored and linearIn difficult cases, an ictal EEG may be diagnostic

Posterior Cerebral Artery IschemiaThe most frequent finding in patients with PCA territory infarction is a hemianopia. At times, the central or medial part of the field is spared, so-called macular sparing.When the full PCA territory is involved, visual neglect can accompany the hemianopia. Patients are aware of the visual defect when infarcts are restricted to the striate cortex and do not extend into the adjacent parietal cortex. Release phenomenon

Ictal Hallucinations vs Release Phenomenon

Charles Bonnet SyndromeCharles Bonnet described a case of complex hallucinations due to visual loss association with cataracts in his cognitively intact grandfather in 1760.

Characterized by the triad:1. Complex visual hallucinations (CVH)2. Ocular pathology or visual pathway disease causing visual loss3. Absence of cognitive impairmentFirst and latest hallucination are within 4 weeks of each other

Charles Bonnet SyndromeHallucination characteristics: Simple flashing lights (40-80% especially at beginning) May evolve into people or animals (50-80%), patterns (55%) including brick like structures and swirling orbital structures, faces (40%), often distorted or cartoon. Gargoyle type images are common, and cause distress.Often patients experience hallucinations of children playing at the bottom of the bed, or trees and plants appearing in the room.CBS hallucinations are colorful, vivid, clearer and more detailed than normal vision. They have no personal meaning or association unlike VH associated with psychoses.The patient knows that the hallucinations are not real

Charles Bonnet Syndrome: A Release Phenomenon

Charles Bonnet SyndromeIt is important to understand that visual acuity loss is not a requirement for Charles Bonnet Syndrome visual hallucinations to occur.Age related macular degeneration damages the cones==lack for color input through the lateral geniculateDamage to cone photoreceptors in the macula creates a lack of visual input to the color areas of the visual association cortexEndogenous activation of color perception areas of the occipital cortexcolorful visual hallucinationsUsually resolves in 12-18 months

What A Patient Sees In Charles Bonnet

Charles Bonnet Syndrome: Art Work

Drawings By a Patient with Charles Bonnett Syndrome

Lewy Body Dementia

Somethings to Ponder (Visually Speaking)