Discussion of visual hallucinations and the various conditions that can produce this phenomenon

1. Visual Hallucinations
Randy M. Rosenberg, MD FAAN FACP
Assistant Professor of Neurology
Lewis Katz School of Medicine at Temple University

2. Visual Hallucinations in Normal People
• What is this?
• NOPE!
• Concentric circles!
• Fooled by experience and
expectation

3. Perception Versus Expectation

4. Having a Hallucination Just For Fun…

5. Differential Diagnosis of Recurrent Complex
Visual Hallucinations
• Medication(s)
• Metabolic status
• Psychiatric etiology including mania, depression, substance
dependence and schizophrenia
• Neurodegenerative diseases (e.g Lewy Body Dementia, Alzheimer’s
and Parkinson’s disease)
• Release hallucinations – Charles Bonnet Syndrome
• Migraine
• Epilepsy

6. Peduncular Hallucinosis
• Complex 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

7. Nature of Peduncular Hallucinations
• Common 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.

8. Peduncular Hallucinations and the Alice in
Wonderland Syndrome
• The foremost symptom of the Alice in
Wonderland syndrome is an altered
body image and the experience of time
• The 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 size
• Among 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

9. Peduncular Hallucinations: Characteristics

10. Migraine Aura
• About 20% of migraineurs experience
migraine aura, of which 99% is visual.
• Thought to be associated with Leao's
cortical spreading depression
• Patients develop rCBF reduction
(oligemia), which does not reach
critical values (ischemia).
• Typically spread in 5–20 minutes does
not last more than 60 minutes
• If 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

11. Persistant Migraine Aura
• Persistent migraine aura without infarction (PMA) is a rare condition that is
defined as an aura that lasts longer than 1 week in absence of infarction
• Two types of PMA have been distinguished
• Persistent primary visual disturbance
• Visual snow
• Television static
• Typical aura
• Phosphenes, fortification spectra, scintillating scotoma
• Several theories on the underlying pathophysiological:
• These include abnormal energy metabolism in the brain,
• Brain magnesium levels being significantly lower than that of non-migraineurs
• Greater reactivity of N-methyl-D-aspartate receptors to glutamate
• Lowered threshold to spreading cortical depolarization
• Loss 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.

12. Visual Snow

13. Hildegard of Bingen (1098-1179)

14. Epilepsy
• About 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 migraines
• Visual 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

15. Occipital Lobe Seizures

16. Occipital Lobe Seizure: Visual Hallucinations
• Can resemble a migraine aura with 50%
having migraine-like post-ictal
headaches
• Epileptic visual hallucinations usually
occur within a few seconds, last a few
minutes and are usually colored and
circular
• Migraine visual aura develops over
minutes and typically lasts 5-50 minutes
and is often uncolored and linear
• In difficult cases, an ictal EEG may be
diagnostic

17. Posterior Cerebral Artery Ischemia
• The 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

18. Ictal Hallucinations vs Release Phenomenon

19. Charles Bonnet Syndrome
• Charles 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 loss
• 3. Absence of cognitive impairment
• First and latest hallucination are within 4 weeks of each other

20. Charles Bonnet Syndrome
• Hallucination 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

21. Charles Bonnet Syndrome: A Release
Phenomenon

22. Charles Bonnet Syndrome
• It 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 geniculate
• Damage to cone photoreceptors in the macula creates a lack of visual input
to the color areas of the visual association cortex
• Endogenous activation of color perception areas of the occipital
cortexcolorful visual hallucinations
• Usually resolves in 12-18 months

23. What A Patient Sees In Charles Bonnet

24. Charles Bonnet Syndrome: Art Work

25. Drawings By a Patient with Charles Bonnett
Syndrome

26. Lewy Body Dementia

27. Somethings to Ponder (Visually Speaking)