1.2.3.1.4 Familial hemiplegic migraine, other loci

This 22-year-old university student has now had five episodes of a visual disturbance affecting only his left eye. He describes shimmering, zigzag lines appearing gradually over some five to eight minutes in that eye alone, spreading outward until roughly half of the visual field on that side goes blank for a few minutes before clearing; the shimmering and the blank patch have never happened in the same eye at the same time as anything on the right. Each episode then merges into a further phase in which his left arm and hand become distinctly weak, sometimes dropping items he is holding. The visual and limb symptoms are always followed by a throbbing headache on the same side, lasting several hours. His maternal uncle has a well-recognised history of arm and leg weakness during his own attacks, formally documented by a neurologist some years ago. Genetic screening for CACNA1A, ATP1A2 and SCN1A, requested in view of the family history, came back unremarkable with no pathogenic change identified.