Abstracts

Rationale: Distinguishing nocturnal epilepsy from other paroxysmal events during sleep poses special challenges in an Epilepsy Monitoring Unit (EMU). Here we describe our experiences in the diagnosis of primary sleep disorders mimicking epilepsy.Methods: We reviewed all admissions from our EMU database from 7/1/11-7/1/12 for all patients diagnosed with primary sleep disorders. Cases were verified by group consensus of three neurologists trained in both epilepsy and sleep medicine.Results: Of 222 patient admissions, we found 4 cases (1.8%) of primary sleep disorders; one case of REM Behavior Disorder (RBD), one case of confusional arousals and two cases of sleep rhythmic movement disorder (SRMD). Three of these patients were admitted to the EMU with a high index of suspicion for epilepsy, while one (diagnosed with RBD) was not. By history, all patients had new onset events in adulthood.Conclusions: Paroxysmal events during sleep pose a major diagnostic challenge for the clinician, both in the clinic and in the EMU. Parasomnias, sleep related movement disorders, normal physiologic sleep movements, nocturnal frontal lobe epilepsy, and psychogenic seizures are part of the differential. In our unit, these disorders were infrequent but important, representing 1.8% of voluntary admissions over a one year period. While RBD is a well known epilepsy mimic, confusional arousals and SRMD are less well described, especially in adults. SRMD is described as repetitive stereotyped and rhythmic motor behaviors occurring during drowsiness. Onset is typically in infancy, with the vast majority of patients outgrowing the phenomena by age 5, persistence past this age is traditionally described as seen in children with developmental delay. Onset in adulthood and occurrence in those without cognitive delay is reported infrequently. Similarly, confusional arousals are typically viewed as a parasomnia of childhood, typically arising from slow wave sleep. As our patients had onset of symptoms after the age of 18, these diagnoses were unexpected. Advantages of utilizing the EMU for diagnosis include the ability to discontinue AEDs, to capture typical events over several nights of monitoring, high quality video, as well as screening EEG for epileptiform abnormalities. In all of these cases, making the proper diagnosis and distinguishing the above conditions from epilepsy allowed patients to come off unnecessary antiepileptic drugs. The conditions we describe while uncommon in the EMU are important for epileptologists to consider in their differential diagnosis in order to provide proper treatment for these challenging patients.