Abstracts

Rationale: Rhythmic mid-temporal theta of drowsiness (RMTD) is a normal variant. This well described variant can be mistaken for a pathologic discharge due to sharply contoured rhythmic waveforms and atypical presentation. Herein, we present a patient who was misdiagnosed with epilepsy due to atypical RMTD on EEG and postural orthostatic tachycardia syndrome. 

Methods: NA

Results: A 36 years old female presented for recurrent seizures. Patient describes episodes with initial sensation of light headedness, followed by staring and loss of consciousness (LOC) at times with nonsensical speech and urinary incontinence but without associated tonic-clonic movement. She was diagnosed with neurocardiogenic syncope and postural orthostatic tachycardia syndrome (POTS) after a positive tilt table test about 2 years ago. Due to her confusion and urinary incontinence during her episodes, seizure was also suspected. She had an abnormal EEG from outside hospital showing bilateral temporal sharps waves, then she was diagnosed with temporal epilepsy about 9 months ago. Dilantin was then started; however, even with medication patient still endorsed recurrent episodes weekly.
During following EMU evaluation, video EEG demonstrated frequent episodes of rhythmic sharply contoured theta activity at 5-7 Hz in the bilateral mid-temporal regions, lasting from one second to 2 minutes, which occurred independently as well as simultaneously. The episodes of rhythmic sharply contoured theta activity were seen in awake state, but predominantly in drowsy and light sleep state. One episode of light headedness and heart palpitation was captured when patient was standing and hyperventilating. During the episode, patient had tachycardia at 140’s on EKG and bilateral temporal slowing on EEG, but there were no epileptiform discharges and no rhythmic sharply contoured theta activity. During one prolonged rhythmic sharply contoured theta activity episode, the patient was responsive; the activity resolved immediately after the patient heard the call from the EEG technician. The EMU evaluation is suggestive that the rhythmic sharply contoured theta activity in the bilateral mid temporal region is a normal variant-RMTD rather than epileptiform discharges. Dilantin was stopped after EMU evaluation, patient had no further seizures reported on subsequent follow up.

Conclusions: We demonstrated that RMTD can occur at awake and light sleep state, can be prolonged up to 2 minutes. The atypical prolonged RMTD might be misdiagnosed as epileptiform discharges or electrographic seizures in certain clinical presentation, such as POTS.

Funding: none