Gulliver's world: Persistent lilliputian hallucinations as manifestation of Charles Bonnet syndrome in a case of cataract and normal pressure hydrocephalus.

Charles Bonnet Syndrome (CBS) typically occurs in elderly people with peripheral vision impairment, or interruptions in the connections from eyes to visual cortex. The heterogeneity of presentations and causal mechanisms warrants clinical caution. In this report, we describe a case of CBS developing in the form of Lilliputian Hallucinations in an elderly gentleman, on the background of cataract and normal pressure hydrocephalus, the complexities arising out of such aetiogenesis, and its management. We emphasize upon the fact that CBS might develop through two concurrent mechanisms in a given individual. Treating one of these would mean persistent symptoms, and failing to recognize these would lead to continued morbidity.

INTRODUCTION

Charles Bonnet Syndrome (CBS) involves visual hallucinations (VH) and typically occurs in elderly people with peripheral vision impairment[1] or interruptions in the connections from the eyes to the visual cortex.[23] Due to its atypical and varied presentations, CBS has a high propensity for misdiagnosis and treatment misadventures.[4] In this report, we describe a case of CBS secondary to cataract and normal pressure hydrocephalus (NPH) and discuss the challenges we faced while managing the patient, along with its heuristic explanations.

CASE REPORT

A 78-year old retired male – with comorbid diabetes and hypothyroidism – was referred to us from ophthalmology for VH of 1-year duration. He had a history of severe depressive episode 2 years back and had not taken any psychotropic medicines or psychoactive substances for more than 1 year. He also had bilateral cataract, which had led to deterioration in his visual acuity over the last few years. He presented to his ophthalmologist 1 year ago, reporting VH. The ophthalmologist suspected CBS, and he was successfully operated for his cataract; however, the VH persisted.

A careful symptom analysis revealed ongoing VH, where he reported seeing 2–3 men, a foot-high, sitting on the table, or wandering around him through most of the day. He also saw various objects – as photo frames and clocks, suitably minimized – moving, and tiny birds flying inside the room. He did not report feeling distressed by the VH, he was rather amused and liked “their company.” Only when he started acting out on them – asking his family members to be careful about the “tiny people” – they were brought to light. The objects would present in vivid on bright, sunny days but would exist without any associated sound effects. According to the patient, the images were vivid and would come from external spaces. He had a depressed affect. There were nil other abnormalities noted on his mental state examination. A rating on mini-mental status examination revealed a score of 28/30.

He also had a mild gait difficulty and reported occasional urinary incontinence. Neurological examination revealed a positive Romberg sign and tandem gait difficulty. All other blood parameters, except for mildly elevated serum triglyceride and low-density lipoproteins levels, were normal. We performed a magnetic resonance imaging of the brain, which revealed age-related cortical atrophy, lacunar infarct in basal ganglia and paraventricular region, disproportionately dilated ventricles, and flow void at cerebral aqueduct – the features suggestive of NPH [Figure 1].

Figure 1

Magnetic resonance imaging of the brain showing dilated ventricles disproportionate to cerebral atrophy and flow void in fourth ventricle region

We made a diagnosis of moderate depressive episode with isolated CBS, and the patient was treated with tablets Escitalopram 10 mg mane and Quetiapine 50 mg nocte, and neurology consultation was sought. The latter treated NPH conservatively. Within 1 month, his symptoms improved, and he was maintaining well at 3-month follow-up.

DISCUSSION

CBS was first described by Charles Bonnet in 1769, and the term was coined by George de Morsier in 1938.[5] Its prevalence is around 0.4% in both Asian and non-Asian population.[6] In the absence of official diagnostic criteria, Gold and Rabins' definition of CBS is most commonly used in making a diagnosis [Table 1].[7] Mechanistically, there are few well-recognized explanations for CBS, as the irritative theory[8] (visual association cortices sending excitatory discharges, like on migraine or seizure), the release phenomenon theory[9] (stimulus deprivation of the visual system suppresses the inhibitory discharges to the visual cortex) and the deafferentation or sensory deprivation theory[10] (loss of visual input into the brain leads to change in excitability of visual association cortex). In this case, the patient had a stress-induced depressive episode in the past, followed closely by significant deterioration in vision and associated CBS. The initial expectation by his ophthalmologist that deterioration in his cataract might explain the onset of CBS (in accordance with the release phenomenon theory) did not prove correct, possibly due to a comorbid NPH (which explains CBS by deafferentation theory). Subsequent treatment of the NPH, along with improvement in his mood, led to lasting remission.

Table 1

Diagnostic criteria for Charles Bonnet syndrome (Teunisse et al., 1996)

Although in CBS the hallucination should disappear with the improvement of visual acuity, there are accounts of using drugs in many patients. Anecdotally, VH has been reported to improve with olanzapine,[11] risperidone, ondansetron, mirtazapine,[12] and antiepileptics.[1] Considering the profile of our patient, i.e., diabetic, having minimal vascular risk factors, and high propensity for extrapyramidal symptoms (due to NPH), we chose Quetiapine. We found good response with comparatively lower dose.

CONCLUSION

We, therefore, propose that CBS might develop through two concurrent mechanisms in a given individual. Treating one of these would mean persistent symptoms, and failing to recognize these would lead to continued morbidity. CBS is usually considered in all elderly patients presenting with VH; however, we should remain open to more sinister causes and should endeavor to rule them out.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

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Conflicts of interest

There are no conflicts of interest.