STROKE OF GENIUS: Illness and Self-Discovery by Paul West (Viking: $21.95; 180 pp.) "To be born," writes Paul West, "is to be transmutable, for better or for worse, while awaiting the worst." Disease, in this context, is the "supreme art form." When he works, is able to work, he is defiant, fighting. "Each day is a pageant, an experiment, a ravishing communion with whumping, impersonal stars." West's migraine attacks began at age 10 and continued monthly for 40 years. By the time he gives us this account, he is also a diabetic, with a pacemaker, atrial fibrillation and labile blood pressure. And he is fat. Like the 25 million other Americans suffering from migraines, West is treated, with each attack, to a light show: "the petty visual fizz, the coruscating lunettes, all the way from rosy-pink silicate to the dark blue-black of the king mackerel." And if writing is fighting, here is a gorgeous round, the quiet before a vicious attack: "With sunset came an almost careless quiet as the saffron over the western range turned vermilion and the antennas, the dishes, on top began to resemble mutants semaphoring for help, silhouettes against an engulfing scarlet."