Background Primary reading epilepsy (PRE), a rare reflex epilepsy, is characterised by orofacial myoclonus and jaw protrusion, and is almost exclusively reading–induced. Seizures are typically terminated by reading cessation, but can secondarily generalise. Underlying mechanisms remain incompletely understood. Unusual seizure phenotype and frequently normal inter–ictal EEG may lead to underdiagnosis and significant morbidity.

Patients and methods Four patients presented to 3 neurology centres with orofacial myoclonus/chin twitching, jaw protrusion, sense of unease, stuttering and reduced reading fluency, with occasional generalised convulsions, whilst reading, especially aloud, and if tired. Symptoms occurred with different languages. Mean age of onset was 20 years. Examination was normal in all.

Investigations Brain MRIs and routine interictal EEGs were normal. However, prolonged EEG, with specific tasks related to reading silently and aloud, and languages, elicited Spike Wave Events (SWE) associated with myoclonus and halting of speech, maximal over central regions.

In a native English speaker, reading German, especially aloud, elicited SWE, associated with epigastric discomfort, unease and jaw myoclonus, captured on video.

ERP and time–frequency analyses displayed temporal characteristics of word access, and increased gamma–band activity for varying reading materials and reading with humming.

Primary reading epilepsy was diagnosed in each case, and anti–epileptic therapy commenced (lamotrigine, carbamazepine, valproate), with improved control.

Discussion Increased awareness of PRE, which detrimentally impacts on many aspects of patients' lives, may enhance detection. The complex tasks used to elicit characteristic epileptiform features may optimise the diagnostic yield of EEG.

ERP analyses may offer insight into complex reading networks and validate cortical hyperexcitability hypotheses, and additional strategies examined, eg reading with humming, may play ancillary therapeutic roles.