Case Presentation: A 74-year old-female presented with visual hallucinations. These hallucinations were clear, vivid, episodic, and increasing in frequency. Starting 3 weeks prior to presentation, she saw a little boy in her room that was not there. Symptoms progressed with persistent difficulty seeing bugs, snakes, and a little girl. Her past medical history included type II diabetes mellitus complicated by diabetic retinopathy and protein c/s deficiency. Patient was also diagnosed with idiopathic intracranial hypertension (IIH) at an outside hospital.
On exam, she appeared well and in no acute distress. She was alert and oriented to person, place, time, and situation. Vital signs were normal. At time of exam patient complained of seeing “fire and snakes on trees”. She was aware that these were hallucinations. She had poor visual acuity bilaterally with scarring throughout her retina. Neurologic examination showed no focal findings. The remainder of her physical examination was normal.
Laboratory studies demonstrated elevated serum glucose of 308 mg/dL. TSH and T3 were low at 0.08 mcIU/ml and 84 ng/dL, respectively. CSF studies were unremarkable, with opening pressure of 22, and negative viral studies. CT head, MRI and MRV were unrevealing.
Based on clinical history and exam, a diagnosis of Charles Bonnet Syndrome was made. Her prior diagnosis of IIH was felt to be inaccurate and unrelated to her symptoms. She was discharged clinically stable on quetiapine, which was up-titrated with symptoms ultimately improving.
Discussion: Charles Bonnet syndrome describes visual hallucinations in patients that occur as a result of visual acuity loss. There are generally no delusions or hallucinations in other sensory modalities, patients are aware that the hallucinations are not real, and the majority of patients are elderly.
The currently accepted theory of the underlying neurophysiology suggests vision loss leading to visual sensory deafferentation, subsequent disinhibition and spontaneous firing of visual cortical lesions. Visual deficits are generally the result of macular degeneration, glaucoma, or diabetic retinopathy.
Our patient had characteristic features with her age, history of vision loss, and full insight into the fictional nature of her hallucinations. Her vision loss was likely secondary to diabetic retinopathy. While there is no universally accepted treatment, atypical antipsychotics have shown some benefit.
Conclusions: Charles Bonnet syndrome is an under reported yet common disorder in patients with visual impairment. We present a typical case of the illness that appeared to show improvement with quetiapine. Increased awareness of this syndrome will ensure effective management of patients with visual hallucinations