title: Pattern of Peripheral Nerve Involvement in Spinocerebellar Ataxia Type 2: a Neurophysiological Assessment.
abstract: Peripheral neuropathy is frequent in spinocerebellar ataxia type 2 (SCA2), but the pattern and characteristics of nerve involvement are still an unsettled issue. This study aimed to evaluate the prevalence, extent, and distribution of nerve involvement in SCA2 patients through neurophysiological studies. Thirty-one SCA2 patients and 20 control subjects were enrolled in this study. All subjects were prospectively evaluated through electromyography, including nerve conduction, needle electromyography in proximal and distal muscles of the upper and lower limbs, and sural radial amplitude ratio (SRAR). We aimed to differentiate distal axonopathy from diffuse nerve commitment, characterizing neuronopathy. Nerve involvement was observed in 83.6 % (26 individuals) of SCA2 patients. Among these, 19 had diffuse sensory abnormalities on nerve conduction predominantly on the upper limbs, with diffuse chronic denervation on needle electromyography and elevated SRAR values. Four individuals had only diffuse sensory involvement, and 2 had only motor involvement on needle evaluation and normal nerve conduction. These were interpreted as neuronopathy due to the diffuse distribution of the involvement. One individual had distal sensory axonopathy, with lower limb predominance. In this study, we found neuronopathy as the main pattern of nerve involvement in SCA2 patients and that motor involvement is a frequent feature. This information brings new insights into the understanding of the pathophysiology of nerve involvement in SCA2 and sets some key points about the phenotype, which is relevant to guide the genetic/molecular diagnosis.
authors.affiliation: Department of Neurology, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Marcio Luiz Escorcio
authors.initials: ML
authors.lastname: Bezerra
authors.affiliation: Department of Neurology, Universidade Federal de São Paulo, São Paulo, SP, Brazil. jlpedroso.neuro@gmail.com.
authors.forename: José Luiz
authors.initials: JL
authors.lastname: Pedroso
authors.affiliation: Department of Neurology, Universidade Federal de São Paulo, São Paulo, SP, Brazil.|Center of Health Sciences, Universidade Estadual do Ceará, Fortaleza, Brazil.
authors.forename: Pedro
authors.initials: P
authors.lastname: Braga-Neto
authors.affiliation: Department of Neurology, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Agessandro
authors.initials: A
authors.lastname: Abrahao
authors.affiliation: Department of Neurology, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Marcus Vinicius Cristino
authors.initials: MV
authors.lastname: de Albuquerque
authors.affiliation: Department of Neurophysiology, Fundação Beneficente, Hospital de Cirurgia, Aracaju, SE, Brazil.|Department of Neurosurgery, Fundação Beneficente, Hospital de Cirurgia, Aracaju, SE, Brazil.
authors.forename: Franklin Roberto Pereira
authors.initials: FR
authors.lastname: Borges
authors.affiliation: Department of Biochemistry and Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Maria Luiza
authors.initials: ML
authors.lastname: Saraiva-Pereira
authors.affiliation: Department of Internal Medicine and Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Laura Bannach
authors.initials: LB
authors.lastname: Jardim
authors.affiliation: Department of Neurology, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Nadia Iandoli
authors.initials: NI
authors.lastname: de Oliveira Braga
authors.affiliation: Department of Neurology, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Gilberto Mastrocola
authors.initials: GM
authors.lastname: Manzano
authors.affiliation: Department of Neurology, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Orlando G P
authors.initials: OG
authors.lastname: Barsottini
mesh_terms: D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000503:physiopathology; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology; D009431:Neural Conduction; D009482:Neurophysiology; D010525:Peripheral Nerves / Q000503:physiopathology*; D010641:Phenotype; D011446:Prospective Studies; D012678:Sensation Disorders / Q000209:etiology / Q000503:physiopathology; D020754:Spinocerebellar Ataxias / Q000150:complications / Q000503:physiopathology*; D034941:Upper Extremity / Q000503:physiopathology
keywords: Neuronopathy; Peripheral neuropathy; SCA2; Spinocerebellar ataxia type 2; Spinocerebellar ataxias