Differentiation of dissociative attacks (DA) from epileptic seizures has long been a cause of diagnostic difficulty.  Specific features such as rapid limb movements and blinking have been reported as being a reliable marker to distinguish between these. However, increasing knowledge of seizure semiology and underlying functional anatomical networks, has shown that these features alone are not diagnostic. 

All admissions to the Mater Advanced Epilepsy Unit (Brisbane, Australia) from June 2015 - 2018 were reviewed.  Cases were included if a diagnostic re-classification was made after video electroencephalographic evaluation (VEEG).  Semiological features were recorded and classified according to neuroanatomical networks.

We report two cohorts: 1) 16 patients diagnosed with DA who were subsequently re-diagnosed with epilepsy after VEEG.  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.  2)  46 patients diagnosed with epilepsy who were re-diagnosed as DA consequent to VEEG. The semiology varied widely from somatosensory descriptions to hypotonia to generalized convulsions. 42 patients were either on antiepileptic drugs (AEDs) or had trialled an AED in the past, this ranged from one to 5 simultaneous agents. All 46 patients consequently had the diagnosis of epilepsy revoked and AEDs tapered. 

The regions implicated in the misdiagnosed epilepsies often produce bizarre semiology and subtle EEG change due to their mesial location, so anatomo-electro-clinical correlation is essential. This study also highlights the complexity surrounding an epilepsy diagnosis often resulting in inappropriate commencement of AEDs and profound psychosocial, occupational and economical consequences for patients.