title: Peripheral nerve abnormalities in pediatric patients with spinal muscular atrophy.
abstract: We examined the specific nerve conduction deficits distinguishing spinal muscular atrophy (SMA) subtypes I and II. Five SMA I patients (age, 0.2-1.1 years) and 10 SMA II patients (age, 1.0-2.8 years) were examined. Patients were compared to age-matched controls for motor and sensory conduction velocity (MCV and SCV) changes, compound muscle and sensory nerve action potential amplitudes (CMAP and SNAP), and F-wave occurrence (FO). Slower MCVs were found in three of five SMA I patients; all five exhibited markedly decreased CMAP amplitudes. Tibial nerve CMAP amplitudes significantly reduced in SMA II patients (p<0.01). Slower SCVs and decreased SNAP amplitudes were observed in three of five SMA I patients but not in SMA II patients. Although FOs were reduced in both extremities of SMA I patients, the reduction was prominent in the tibial nerve of SMA II patients (p=0.031). Loss of motor units may be widespread in the early stage of SMA I, while specific to the legs in young SMA II patients. SMA I showed sensory nerve degeneration, especially of large myelinated fibers. SMA II showed no sensory nerve abnormalities.
authors.affiliation: Department of Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yonekawa
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Komaki
authors.forename: Yuko
authors.initials: Y
authors.lastname: Saito
authors.forename: Kenji
authors.initials: K
authors.lastname: Sugai
authors.forename: Masayuki
authors.initials: M
authors.lastname: Sasaki
mesh_terms: D000200:Action Potentials / Q000502:physiology; D001369:Axons / Q000502:physiology; D002675:Child, Preschool; D003627:Data Interpretation, Statistical; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D007223:Infant; D007866:Leg / Q000294:innervation; D008297:Male; D008475:Median Nerve / Q000503:physiopathology; D009046:Motor Neurons / Q000502:physiology; D009431:Neural Conduction / Q000502:physiology; D051616:Neuronal Apoptosis-Inhibitory Protein / Q000235:genetics; D010525:Peripheral Nerves / Q000503:physiopathology*; D012189:Retrospective Studies; D011984:Sensory Receptor Cells / Q000502:physiology; D014897:Spinal Muscular Atrophies of Childhood / Q000503:physiopathology*; D013497:Sural Nerve / Q000503:physiopathology; D055533:Survival of Motor Neuron 1 Protein / Q000235:genetics; D013979:Tibial Nerve / Q000503:physiopathology; D014459:Ulnar Nerve / Q000503:physiopathology
chemical_list: D051616:Neuronal Apoptosis-Inhibitory Protein; C526471:SMN1 protein, human; D055533:Survival of Motor Neuron 1 Protein