Three patients with reflex epilepsy and myoclonic jerks of the right arm and fingers precipitated by calculation using a Soroban are reported from the Department of Neuropsychiatry, Osaka University Medical School, Fukushima-ku, Osaka, Japan. The Soroban (abacus) is a Japanese traditional calculator requiring complex finger movements. Calculations are made by moving the counter beads with the fingers. The quicker the fingers move the sooner the calculation is finished. A simultaneous mental task requiring a high degree of concentration and complicated and delicate finger movements was necessary to induce the epileptic discharges consisting of a spike wave complex with left central prevalence. The reflex epilepsy in these patients resembled that induced by writing. Valproate was effective in the control of seizures and epileptic discharges. 
COMMENT:. Both mental activity under high psychological tension and complicated and delicate movements of the fingers were necessary to induce epileptic discharges and/or a clinical seizure in these patients; stimulation without these two factors had no effect. Other reflex epilepsies induced by higher mental activity include reading epilepsy, graphogenic epilepsy induced by writing, language induced epilepsy induced by reading, writing, and speaking, epilepsia arithmetices induced by calculation, decision making epilepsy induced by cards and game playing, and drawing induced seizures induced by geometric designs. Nintendo and Rubik’s cube may also cause reflex epilepsy.