What do you use to treat cramping in Kennedy's disease?   

Trial of low dose testosterone 40mg orally daily as needed is worth to consider to combat symptoms since there is not specific cure. It seems working for paramyotonia congenita symptoms having similar symptoms of muscle cramps, pain and in many cases subjective weakness over years. 

Same remedies that we use for cramps in other motor neuron diseases or neurogenic disorders. I still endorse oral magnesium 600-800 Mg daily which anecdotally works in occasional patients, even though AAN does not recommend it. Mexiletine at 150 Mg tid can also work well for cramps in MND. May also ...