434 - Phantom Vision: A Probable Case of Charles Bonnet Syndrome in a Patient with Central Cord Syndrome

Case Diagnosis: Charles Bonnet syndrome in a patient with central cord syndrome

Case Description: A 61-year-old male with a history of retinal degeneration, glaucoma, chronic hydrocephalus, and HIV was admitted to acute rehabilitation for central cord syndrome secondary to a fall. He complained of new-onset visual hallucinations described as intermittent, purely visual “phantoms, figurines, faces, and different textures such as brickwork.” He denied auditory or somatosensory components and his insight was intact. They appeared as “ghosts” overlayed upon his surroundings and never interacted with him. He did not see them with eyes closed. A psychiatry consultation endorsed an organic neurologic cause and ruled out psychiatric illness. A neurology consultation suggested hyponatremia or delirium as possible cause, as the patient had an episode of drowsiness at the time (likely from uptitration of neuropathic pain medication). However, the patient had intact cognition, no delusions, and was fully oriented even when drowsy. He continued to see the hallucinations upon return to his baseline mental status.

Discussions: Charles Bonnet syndrome refers to visual “release hallucinations” caused by the brain’s adaptation to visual field or visual acuity loss of any cause, especially in the setting of retinal disease and glaucoma. The most accepted hypothesis is that the deafferentation of visual sensory fibers leads to disinhibition and firing of the visual cortex. The diagnosis is made when characteristic visual hallucinations occur in a patient with known ocular disease, in the absence of psychosis, delirium, or other causes.

Conclusions: Charles Bonnet syndrome should be considered in the work-up of visual hallucinations, which can significantly impact quality of life. Some surveys have demonstrated a prevalence of 39% and 20% in patients with macular disease and glaucoma, respectively. Patients may be reluctant to disclose their symptoms due to fear of psychiatric illness.