Concurrent Delusions of Ocular Parasitosis and Complex Visual Hallucinations from Charles Bonnet Syndrome Treated Successfully with Aripiprazole in an Elderly Male: A Case Report.

Introduction Delusional parasitosis (DP) has been described as among the most challenging diagnosis to manage in dermatology and psychiatry literature. Patients with this perplexing and enigmatic condition present potentially to a wide range of specialties including primary or emergency care, dermatology, infectious diseases, neurology, and psychiatry. DP is probably underdiagnosed from patients' underreporting of symptoms of being infested with parasites, resulting from the associated social stigma. In addition, specialists who most often encounter these patients often possess low familiarity and comfort level in the diagnosis and therapy of this disorder. To our knowledge, we present only the fifth case of delusional parasitosis that was associated with complex visual hallucinations. Both concurrent conditions were treated successfully with aripiprazole. Interestingly, in all of these prior cases including ours, the patients were elderly (age range, 74-95 years). Delusions of ocular parasitosis has been described in fewer than 11 cases. When delusions occur concurrently with hallucinations, the differential diagnosis becomes even more challenging and may include schizophrenia, drug-induced psychosis, Lewy body dementia, and Charles Bonnet syndrome. Our patient's delusions of ocular parasitosis led to ocular damage and severe visual impairment because of his constant need to extract the parasites from his eyes. We speculate that the subsequent complex visual hallucinations that developed can best be understood as Charles Bonnet syndrome. Case presentation A 78-year-old healthy African American male complained of pests and bugs approximately 2 cm in size that infested the skin of his entire body. He also described the life cycle of these parasites, which jumped onto his eyelids and conjunctiva. He developed functional vision blindness from his unwillingness to open his eyelids as a result of his attempts to block the parasites. He was evaluated by dermatology, infectious diseases, ophthalmology, and psychiatry. All specialists agreed with the diagnosis of DP, and recommended antipsychotic therapy. They consistently dismissed the patient's symptoms as anything more than psychiatric, so the patient did not follow-up for further assessments or other therapies. Even months after the diagnosis of DP, he developed complex visual hallucinations. He described new visions in vivid detail: inanimate objects (buildings, jackhammers, torches, planes), animals (bears, doves, sharks), shapes (triangles, rectangles, omega, and mason signs). The objects interacted on high-definition landscapes such as oceans. He refused further psychiatric assessment because he felt strongly that the symptoms were infectious in nature and not psychiatric. However, a therapeutic relationship with his geriatrician was established through empathic communications, goal setting, and shared decision making. He even agreed to start treatment with aripiprazole 2 mg because the shared goal was symptom management of the concurrent delusional parasitosis and complex visual hallucinations. The slow titration of aripiprazole to 6 mg led to a 75% reduction in the delusions and hallucinations. He initially declined higher dosages of the aripiprazole because of sedation and personal wariness of medications in general. However, a therapeutic relationship was nurtured based on respect, careful listening, and provision of options. Eventually, he agreed to a higher dosage of aripiprazole and thus titrate antipsychotic therapy that he rejected when prescribed by the dermatology and psychiatry specialists. We attempted to approximate the 15-mg dosage that led to remission of symptoms in previous case reports.