Epilepsy can cause auditory verbal hallucinations, says study
According to a new study, epilepsy patients with damage to the left temporal cortex are at risk of experiencing complex, auditory verbal hallucinations (AVHs) – suggesting there is a neurological, as well as psychiatric, origin of these phenomena.
While AVHs are well documented in people with psychiatric conditions, reports from neurological patients are rare and have not been extensively studied.
Now, though, researchers from the Swiss Federal Institute of Technology in Lausanne and University Hospital Geneva have suggested epilepsy patients with prevalent language deficits, as well as damage to posterior and basal language areas in the left temporal cortex, sometimes hallucinate voices.
The study, which is published in this month’s edition of the journal Epilepsy Behaviour, comprised an examination of more than 350 people with epilepsy.
Nine of these subjects – all of whom had drug-resistant forms of the neurological condition – were found to experience AVHs, underlining the rarity of the phenomenon. They were studied by means of a semistructured interview, neuropsychological tests and multimodal imaging. The scientists used a combination of functional and structural neuroimaging data, and surface and intracranial EEG, to locate the damaged brain tissue from which their epilepsies originated.
They found the occurrence of AVHs in epilepsy patients was associated with the neurodevelopmental problems outlined above.
Subjects’ AVHs also followed common patterns – they heard single voices at a time, speaking in their native languages and of the same gender as the patient. The hallucinations also had consistent spatial features – most subjects reported they heard voices that seemed to come from external space, contralateral to the parts of their brain tissue that were damaged.
“We argue that the consistent location of AVHs in the contralesional external space, the prominence of associated language deficits and the prevalence of lesions to the posterior temporal language areas characterise AVHs of neurological origin, distinguishing them from those of psychiatric origin,” the report’s authors commented.
Posted by Bob Jones