Abstracts

Rationale: Frontal lobe epilepsy (FLE) is the second most common type of focal epilepsy, accounting for 20–30% of focal epilepsy patients(1). Frontal lobe seizures are known for their perplexing characteristics, making their diagnosis and differentiation from psychogenic non epileptic seizures (PNES) challenging.

Methods: We present a case of a 33-year-old woman, with FLE diagnosed at age 14 now presenting with new types of events over 6 months. Her initial seizures had 3 main semiologies: 1) hour-long nausea and dizziness, followed by atonia with preserved awareness. 2) Depersonalization followed by right finger extension and right arm clonic jerking, neck extension, eyes rolling up and circular rightward walking, sometimes progressing to GTCS. 3) Confusion, nausea, anxiety and depersonalization lasting seconds. EEGs were abnormal for left frontal or frontotemporal epileptiform discharges. Over the last 6 months, in the setting of 2 miscarriages, she described events preceding with a feeling to “let some energy out” followed by jumping, unilateral or bilateral leg or hand banging on a surface with intact awareness lasting up to 15 seconds, with post-event fatigue. Event frequency varied from every few days to multiple per day, worse with sleep deprivation. She was admitted for video EEG monitoring to characterize these events. Three typical events were captured as described in the table. Ictal EEG prior to each event began with a single L >R frontal slow wave followed by a single left frontal epileptiform discharge and then 2-3 seconds of diffuse attenuation prior to obscuration by movement artifact. She was then diagnosed with evolving FLE, requiring further anti-epileptic drug(AED) management.

Results: Frontal lobe seizures are often misdiagnosed as PNES due to several factors. The ictal EEG findings may not be picked on surface EEG in the mesial and inferior frontal cortex and can sometimes be obscured by movement artifacts especially in hypermotor episodes. Brief duration and prominent vocalisation are also features of frontal lobe seizures(2). In our case, recent stress with miscarriages, episodes only while staying awake and non-stereotypical movements leaned us towards PNES, although with video EEG monitoring findings, the diagnosis of evolving FLE was confirmed.

References:
1. Manford, M., Hart, Y. M., Sander, J. W., & Shorvon, S. D. (1992). National General Practice Study of Epilepsy (NGPSE): Partial seizure patterns in a general population. Neurology, 42(10), 1911-1917.
2. International League Against Epilepsy. (n.d.). Frontal lobe epilepsy: Overview. EpilepsyDiagnosis.org.

Conclusions: This case highlights the challenge of differentiating FLE and PNES, especially in a patient with multiple seizure semiologies. Timely and definitive diagnosis with video-EEG monitoring not only helps with the appropriate AED management but also avoids patient’s stigma with psychogenic seizures and prevents unnecessary referrals to psychiatry for presumed PNES.

Funding: none