Myoclonic seizures occur frequently. These are mainly of the head (causing nodding), eyeballs (which roll upwards), upper extremities (causing the arms to fling up and out) and diaphragm (resulting in vocalization). Rarely the lower limbs are affected, causing falls. They can be singular or occur in a series and may vary in severity. They may occur in all states (alert, drowsiness, slow sleep and on wakening). They may be induced by photic stimulation, sudden noise or touch (seen in a third of patients).