Isolated nostril myoclonus: A novel ictal presentation in structural generalised epilepsy

Perioral myoclonus (POM) is a rare seizure manifestation which may present in either idiopathic or structural epilepsies. There has been little description of the rarer ictal manifestations in POM in generalised epilepsy. It is important during Electroencephalography (EEG) testing to carefully monitor clinical change during inter-ictal bursts, as this condition, demonstrated in this case, can exhibit extremely subtle seizure semiology which can allude typical clinical examination.

Presented is a four-year-old boy with a complex medical history, referred following episodes up to six times per day consisting of perioral myoclonus at a rate of ∼3p/s alongside behavioural arrest lasting up to thirty seconds. Electroencephalography (EEG) recording captured nine seizures within a twenty-five-minute period, where only one seizure was of his stereotyped semiology. Additional seizures commonly adopted a novel semiology of isolated nostril ("flaring") myoclonus, on some occasions with concomitant head bobbing. Surface EMG and high resolution zoomed video revealed time-locked myoclonus to the generalised spike and wave discharges seen in on EEG.

The findings demonstrate a novel epileptic seizure manifestation of nostril myoclonus, in which detailed electroencephalographic and video correlation was essential to minimise risk of underestimating seizure frequency in this rare and complex epilepsy disorder.