1.2.3.1.3 Familial hemiplegic migraine type 3 (FHM3)

A woman came for review the day after her third such attack. She describes a prickling, electric sensation, distinctly a positive feeling rather than any numbness, spreading from her right fingertips up towards her shoulder and jaw. This built up steadily over roughly sixteen minutes rather than appearing suddenly. Toward the end of that period her right hand became noticeably weak and she struggled to fasten a button, and at the same time her speech grew slurred and she had to slow right down to be understood. Her older cousin experienced a run of very similar attacks in her twenties, also with matching one-sided weakness, and was seen by a specialist who concluded that her presentation satisfied the full set of inherited features described for this family. There is no history of significant past illness. Genetic testing has now confirmed a disease-causing SCN1A gene alteration in her own sample, the same laboratory having confirmed a disease-causing SCN1A gene alteration in her own sample.