Is insight really necessary for diagnosis of Charles Bonnet syndrome? A case report

Charles Bonnet syndrome is a relatively common condition in elderly patients with low visual acuity and may affect up to 12% of the patients with visual impairments.¹ The syndrome is characterized by complex visual hallucinations and full or partial preservation of insight, with no other sensory hallucinations or delusions and exclusion of other mental disorders.¹ Although these are the most accepted features for diagnosis of the syndrome, controversies remain as to its diagnostic criteria.² The clinical case presented herein illustrates this diagnostic discussion.

A 70-year-old housewife with 3 years of formal education, was referred to the outpatient psychogeriatric clinic because of changes in her behavior and complex visual hallucinations in which she saw, through her window, men and women killing one another and people in the bathroom. The patient began hallucinating 8 years ago after macular degeneration with consequent severe visual impairment. She was aware that the hallucinations were not real. According to her family members, she started expressing increasing irritation about 2 years prior to presentation, but continued to carry out household chores with no significant impairment. She presented no other significant mood-related or psychiatric symptoms during the interview. However, she seemed to have experienced a major depressive episode 8 years before, between the period of macular degeneration and onset of the hallucinations. It was not until 2 years before, when she began displaying intense fear and reporting that her neighbors were “killing people” and “performing rituals” that included sex and drugs, that she was referred to a psychiatrist. Despite having no specific mood-related symptoms, she began receiving antidepressants and antipsychotics in low doses, but no improvement was observed. During this period, she lost insight into her visual hallucinations, which could appear throughout the day, and began experiencing frequent delusions. Two months before presentation, she was referred to the psychogeriatric clinic. Tests were performed for dementia syndrome screening. A computed tomography scan of the head was normal for age. Other laboratory results, including thyroid-stimulating hormone (TSH), vitamin B12, VDRL test for syphilis, and HIV test, were also normal. No significant abnormalities were observed during clinical neurological examination.

A tentative diagnostic of Charles Bonnet syndrome was made, although the most accepted criteria for the diagnosis of this syndrome require insight into the hallucinations and absence of delusions. In this syndrome, hallucinations can last from a few seconds to a whole day, and can persist for years, varying in frequency and complexity, usually with preservation of insight.³ However, in this case, the diagnosis of Charles Bonnet syndrome was hypothesized because of a temporal relationship between the onset of hallucinations and macular degeneration, with no functional impairment secondary to cognitive deficits, which is required for the diagnosis of dementia. It is worth recalling that a large proportion of these patients may develop dementia.⁴ Furthermore, other neurological diseases were ruled out. Another important disease in the differential diagnosis is schizophrenia, but the advanced age of onset ruled out this option. Psychopharmacological treatment of the Charles Bonnet syndrome with antipsychotics has low efficacy.⁵ Our patient was started on a trial of olanzapine up to 20 mg/day and showed partial remission of the psychotic symptoms.

Thus, we can conclude that the diagnosis of Charles Bonnet syndrome is complex, and, in some cases, could be considered even in the absence of critical judgment of reality, especially when the duration of disease is prolonged.

References

• ¹
  Teunisse RJ, Cruysberg JR, Hoefnagels WH, Verbeek AL, Zitman FG. Visual hallucinations in psychologically normal people: Charles Bonnet's syndrome. Lancet. 1996;347:794-7.
• ²
  Lerario A, Ciammola A, Poletti B, Girotti F, Silani V. Charles Bonnet syndrome: two case reports and review of the literature. J Neurol. 2013;260:1180-6.
• ³
  Cammaroto S, D'Aleo G, Smorto C, Bramanti P. Charles Bonnet syndrome. Funct Neurol. 2008;23:123-7.
• ⁴
  Lapid MI, Burton MC, Chang MT, Rummans TA, Cha SS, Leavitt JA, et al. Clinical phenomenology and mortality in Charles Bonnet syndrome. J Geriatr Psychiatry Neurol. 2013;26:3-9.
• ⁵
  Hughes DF. Charles Bonnet syndrome: a literature review into diagnostic criteria, treatment and implications for nursing practice. J Psychiatr Ment Health Nurs. 2013;20:169-75.

Publication Dates

• Publication in this collection
  Apr-Jun 2014

History

• Received
  15 July 2013
• Accepted
  18 Aug 2013