["Jaw drop" as an atypical manifestation of Kennedy's disease].

Kennedy's disease, or spinal and bulbar muscular atrophy (SBMA), is an inherited X-linked degenerative disorder characterised by slowly progressive proximal limb weakness, bulbar weakness, fasciculations, signs of androgen insensitivity and characteristic EMG findings. The disease is caused by a trinucleotide (CAG) repeat in the androgen receptor gene. We describe a patient with atypical symptoms who was initially misdiagnosed after presenting with weakness of mm. masseter and mm. temporales that caused his jaw to hang open. The initial diagnosis was suspicion of myasthenia gravis or ALS. Genetic testing later confirmed the diagnosis of Kennedy's disease.