BASICS

DESCRIPTION

• Visual hallucinations are visual sensory perceptions without external stimulation associated with ophthalmologic, neurologic, metabolic, toxic, and psychiatric diseases.

• Charles Bonnet syndrome (CBS) is vivid, detailed, but nonthreatening hallucinations in visually deprived but cognitively unimpaired patients (1).

EPIDEMIOLOGY

Incidence

The incidence of the Charles Bonnet syndrome varies among different population groups. Common in patients with dementia or confusional states secondary to metabolic insults.

Prevalence

The prevalence of visual hallucinations in a range of ophthalmological populations, is around 10%, varying between 0.4% and 63%, significantly associated with an age over 64 years and a visual acuity in the best eye of 0.3 or less (2,3).

RISK FACTORS

Dementia, psychiatric disorders, drugs, alcohol, social isolation, visual loss, female sex, and old age.

PATHOPHYSIOLOGY

• Visual loss due to certain conditions produces a state of sensory deprivation that releases the visual cortex from regulation by external stimuli, resulting in visual hallucinations (cortical release phenomenon-deafferentation).

• Ictal hallucinations are caused by spontaneous or iatrogenic stimulation of the occipital or temporal cortex.

• Hallucinogenic agents have effects on serotonergic and limbic system structures.

• Migraine aura is caused by cortical spreading depression, which is a wave of electro-physiological hyperactivity followed by a wave of inhibition, usually in the visual cortex.

ETIOLOGY

• Ophthalmologic diseases (Visual loss due to enucleation, cataract, glaucoma, optic nerve, or retinal disease)

• Neurologic disorders (Epilepsy, migraine, narcolepsy, brainstem disorders, hemispheric lesions, Alzheimer, Parkinson, and Lewy body disease)

• Toxic and metabolic conditions (encephalopathies, drugs, alcohol, and withdrawal syndromes)

• Psychosis

COMMONLY ASSOCIATED CONDITIONS

• Hallucinogenic agents

• Visual deprivation

• Psychosis

• Delirium, delirium tremens

• Dementia (Alzheimer disease, vascular dementia, Dementia with Lewy bodies (DLB), Creutzfeldt–Jakob disease)

DIAGNOSIS

HISTORY

• Detailed description of seeing things

• Any clues to the cause anywhere in the body

• Neurologic or ophthalmologic symptoms

• Smoking, alcohol, illicit drugs

• Most patients are reluctant to admit hallucinations due to fear of being labeled with a psychiatric disease. Therefore, directed questioning of susceptible patients is essential.

PHYSICAL EXAM

• Visual acuity

• Visual fields

• Full neurologic examination

DIAGNOSTIC TESTS & INTERPRETATION

Lab

• Drug levels if patient is on medications

• Electroencephalography (EEG) for seizure disorders and encephalopathy

Imaging

MRI if brainstem or hemispheric lesion is suspected.

DIFFERENTIAL DIAGNOSIS

• Delusions are abnormal beliefs that are endorsed by patients as real.

• Confabulations are fabricated facts or events and occur primarily in patients with memory disturbances.

• Visual illusions are abnormal visual perceptions of a viewed object (metamorphopsia, cerebral diplopia, polyopia, and palinopsia).

• Hallucinations are the visual sensation that does not correspond to a real object.

– Simple (flashes, sparkles, haloes, lights, shapes, patterns, phosphenes)

– Complex (flowers, animals, people)

• Release hallucinations represent images formed from memory traces which would ordinarily be blocked by incoming sensory data.

• Charles Bonnet syndrome (CBS) is characterized by complex formed and recurrent visual hallucinations in psychologically normal people, and is often associated with eye pathology.

• Ictal hallucinations are brief, stereotyped visual experiences. Ictal hallucinations tend to be unformed when associated with occipital lesions and formed when associated with temporal lobe lesions.

• Peduncular hallucinosis is colorful, vivid images associated with midbrain, pontine, and thalamic lesions due to damage to the ascending reticular activating system.

• Migraine aura is a disturbance of vision consisting unformed black and white flashes, multicolored lights, dazzling zigzag lines (scintillating scotoma); and fortifications (teichopsia).

• “Alice in Wonderland” syndrome is a rare form of migraine aura. The most distinctive symptom is metamorphopsia, a distortion of body image and perspective.

• Hypnagogic hallucinations are dreamlike hallucinations associated with narcolepsy that occur as a person is falling to sleep.

• Schizophrenia sufferers experience auditory, visual, tactile, olfactory, and taste hallucinations. Auditory hallucinations are more common.

• Hallucinations are primarily visual in delirium which can be caused by drugs or metabolic diseases.

Pediatric Considerations

• Children may have hallucinations associated with substance abuse, psychosis, night terrors, decongestant medications, and seizures. Vivid recall of visual images with hallucinatory character can occur in some children.

• “Alice in Wonderland” syndrome can occur at any age, but is more commonly experienced by children.

Geriatric Considerations

• Elderly people, especially who are suffering with dementia might see people, animals, complicated scenes, and other bizarre scenarios.

• Hallucinations associated with:

– 25% of Parkinson’s disease

– 25% of Alzheimer disease

– 57% of patients with a variety of causes of visual loss (Charles Bonnet Syndrome)

– Hallucinations and agitation are especially troublesome in dementia with Lewy bodies (DLB). Clinical characteristics include progressive dementia, persistent visual hallucinations, extrapyramidal syndrome, and severe sensitivity to neuroleptics.

TREATMENT

Current evidence of treatment comes from case reports. No controlled clinical trials have been reported. The treatment is dependent on the underlying cause.

MEDICATION

First Line

• Antipsychotics

– Drug selection should be individualized to the patient’s previous history of antipsychotic use, current medical conditions, potential drug interactions, and side effects of the medication.

• In dementia with Lewy bodies, if symptoms are mild, no medical treatment may be necessary.

– Therapeutic strategies include prescription of L-dopa and cholinesterase inhibitors such as rivastigmine, and avoidance of anticholinergic medications and neuroleptics.

– Atypical neuroleptics are recommended such as clozapine, quetiapine, or aripiprazole when cholinesterase inhibitors are ineffective (4)

– Caution is also required when prescribing memantine to patients with possible DLB.

• Antiepileptics in seizure disorders

Second Line

Selective serotonin reuptake inhibitors and tricyclic antidepressants (3).

ADDITIONAL TREATMENT

General Measures

Visual improvement and reassurance are the mainstays of treatment.

Issues for Referral

Ophthalmology, Psychiatry, Neurology consultations for related problems

SURGERY/OTHER PROCEDURES

Not indicated except tumors causing ictal hallucinations

IN-PATIENT CONSIDERATIONS

Initial Stabilization

Make sure that the metabolic status is normalized.

Admission Criteria

Metabolic disorders, delirium, agitation.

IV Fluids

Given as supplement and to correct the metabolic status.

Nursing

Careful monitoring for agitation and self-destruction.

Discharge Criteria

When the metabolic status is normalized

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

Reassurance and regulation of medications

Patient Monitoring

Metabolic side effects should be closely monitored in this population.

DIET

No specific diet, thiamine in alcohol withdrawal

PATIENT EDUCATION

Reassurance

PROGNOSIS

• Depends on the cause and complications

• Most patients are relieved by reassurance and medications but resolution of symptoms over time does not always occur.

COMPLICATIONS

Hallucinations may be persistent despite the treatment

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