Differentiation of epileptic seizures from dissociative attacks remains challenging without the benefit of video EEG (VEEG), according to a Brisbane study.
The study, presented at the 2019 American Academy of Neurology Annual Meeting in May, comprised a case review of all patients seen at the Mater Advanced Epilepsy Unit between 2015 and 2018.
Two cohorts of patients had a diagnostic reclassification following VEEG review of their cases including 16 patients initially diagnosed with dissociative attacks and subsequently re-diagnosed with epilepsy.
The meeting was told semiology commonly consisted of non-naturalistic, complex motor or hypermotor movements. The most common networks implicated in an incorrect diagnosis were pre-frontal especially the insulo-cingulate network and the mesial parietal networks.
A second cohort of 46 patients were initially diagnosed with epilepsy and then re-classified as dissociative attacks following VEEG.
The semiology varied widely from somatosensory descriptions to hypotonia to generalised convulsions.
Dr Fiona Chan, an advanced trainee in neurology, told the limbic the differentiating element was that dissociative attacks were not associated with an ictal discharge on EEG.
“Hence, the gold standard for a dissociative attack diagnosis is the absence of ictal changes on VEEG during an attack. Differentiating events based on prior descriptions alone can be very difficult and reasons behind an incorrect initial diagnosis can be related to patients not accessing centres with VEEG capabilities and epileptologist assessment, which can be limited in certain regions.”