Complex Visual and Auditory Hallucinations Following Neurosurgical Injury: A Case Series and Systematic Review.

Hallucinations - perceptions without external stimuli - are complex neuropsychiatric phenomena that remain poorly understood in neurosurgical contexts.  We present two cases of multimodal visual and auditory hallucinations following neurosurgical interventions: a 34-year-old woman with occipital venous stasis following torcular tumor resection and sinus thrombosis, and a 53-year-old man with parieto-occipital edema from a traumatic contusion. Both cases featured vivid, meaningful perceptions without epileptiform activity on electroencephalogram (EEG), suggesting network-level dysfunction rather than focal pathology. A systematic review of 16 prior non-epileptic cases revealed that visual hallucinations predominated, typically associated with parieto-occipital involvement, while auditory hallucinations were less common and linked to temporal or insular lesions. Notably, concurrent visual and auditory hallucinations, as observed here, have not been previously reported post-neurosurgery. Treatment targeting underlying causes (anticoagulation for venous thrombosis and edema reduction) led to complete symptom resolution within weeks to months, highlighting the importance of etiology-specific management. These findings demonstrate that hallucinations in neurosurgical patients may result from transient disturbances to association cortices and white matter tracts, with a favorable prognosis when secondary to reversible conditions. The study underscores the need for increased clinical awareness, systematic evaluation to exclude seizures, and tailored therapeutic approaches for this underrecognized complication.