Noon Report: Charles Bonnet Syndrome

With Journal Club and MM&I, there was only one case-based noon report this week but it covered a very interesting diagnosis. Below is a recap on the high yield learning points and resources from the case

The Purple Team presented the case of a patient with progressive glaucoma who presented with visual and olfactory hallucinations

Take-away Learning Points:

  • Charles Bonnet Syndrome is a rare cause of non-psychogenic, organic, and benign visual hallucinations associated with varying causes of acquired vision loss, with often with preserved neurological function

  • There are many causes of visual hallucinations that are not psychiatric. Your differential should include seizures, migraines, Parkinson's (PD), Lewy Body Dementia (LBD), CJD, and medications. Seizures can involve simple or complex hallucinations, but simple are more common. A fortification spectra or scintillating scotoma is pathognomonic for migraines. Visual hallucination typically precede Parkinsonian symptoms in LBD as opposed to PD where hallucinations occur later on in the disease after Parkinsonian symptoms are present

  • A comprehensive medical work up is important in defining the cause of visual hallucinations and should be guided by the history and physical. Medical workup may include labs (CBC, renal panel, VBG, thyroid studies, serum osm, UA, blood cultures, EtOH level, UDS, LP), imaging (CXR, CT head, MRI), as well as an EKG and EEG.

  • Visual hallucinations are likely under reported due to fear of being labeled psychotic!


  1. Franke, M, Rauschenberger, L. Challenges of diagnosing and treating Charles Bonnet Syndrome. Neurology: Clinical Practice. 2018;8(4):359-361.