title: Myotonia-like symptoms in a patient with spinal and bulbar muscular atrophy.
abstract: We describe the case of a 33-year-old man with a 4-year history of worsening muscle stiffness and weakness in his right hand. He showed elevated serum creatine kinase levels at the onset of muscle stiffness that was characterized by delayed muscle relaxation after voluntary contraction. This symptom often occurred during cold exposure, and was partially attenuated by sodium channel blockade. Electrodiagnostic findings in repetitive nerve stimulation, short-exercise, and cooling tests were normal. Electromyography showed chronic denervation potentials in his cranial, cervical, thoracic, and lumbosacral myotomes without myotonic discharge. He exhibited facial and tongue fasciculations, hypernasality, gynecomastia, neurogenic changes in muscle biopsy, and increased serum testosterone levels. Spinal and bulbar muscular atrophy (SBMA) was diagnosed on the basis of the CAG trinucleotide expansion in the gene coding androgen receptor. A myotonia-like symptom without myotonic discharge may present as an early neurological sign of SBMA, which possibly reflects a sodium channel dysfunction in skeletal muscles.
authors.affiliation: Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Araki
authors.affiliation: Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Nakanishi
authors.affiliation: Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Nakamura
authors.affiliation: Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Atsuta
authors.affiliation: Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Yamada
authors.affiliation: Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Hijikata
authors.affiliation: Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hashizume
authors.affiliation: Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Suzuki
authors.affiliation: Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.
authors.forename: Masahisa
authors.initials: M
authors.lastname: Katsuno
authors.affiliation: Department of Neurology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan. Electronic address: sobueg@med.nagoya-u.ac.jp.
authors.forename: Gen
authors.initials: G
authors.lastname: Sobue
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology; D009134:Muscular Atrophy, Spinal / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology / Q000503:physiopathology*; D009222:Myotonia / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology / Q000503:physiopathology*
keywords: Androgen receptor; Motor neuron; Myotonia; Spinal and bulbar muscular atrophy