title: Patterns of motor signs in spinocerebellar ataxia type 3 at the start of follow-up in a reference unit.
abstract: BACKGROUND
  Spinocerebellar ataxia type 3 (SCA3) is a neurodegenerative disorder that affects the cerebellar system and other subcortical regions of the brain. As for other cerebellar diseases, the severity of this type of ataxia can be assessed with the Scale for Assessment and Rating of Ataxia (SARA) which gives a total score that reflects functional impairment out of 8 cerebellar function tests. SCA3 patients score profile is heterogeneous on at the start of follow up. This study investigates possible patterns in those profiles and analyses the impact of other usually concurrent signs of impairment of extracerebellar motor systems in that profile variability by means of multivariate statistical approaches.
  
  
  METHODS
  Seventeen patients with SCA3 underwent systematic anamnesis, neurological and SARA assessment, visual evaluation of (123)I-Ioflupane (DaTSCAN) single-photon emission computed tomography (SPECT) imaging and electrophysiological studies (nerve conduction and electromyography). Patterns in the profiles of SARA item scores were investigated by hierarchical clustering after multivariate correspondence analysis. A network analysis was used to represent relationships between SARA item scores, clinical, genetic and neurological examination parameters as well as abnormalities of DaTSCAN SPECT imaging and electrophysiological studies.
  
  
  RESULTS
  The most frequently altered SARA items in all patients are gait and stance, and three profiles of SCA3 patients can be distinguished depending mainly on their degree of impairment in those two items. Other SARA items like the score on heel-shin slide contribute less to the classification. Network analysis shows that SARA item scores configure a single domain that is independent of the size of the mutated expanded allele and age of onset, which are, in turn closely and inversely correlated. The severity of cerebellar dysfunction is correlated with longer disease duration, altered visual evaluation of DaTSCAN SPECT imaging and decreased patellar reflexes. Neither the presence of pyramidal or extrapyramidal signs nor the intensity of polyneuropathy is correlated with the SARA items scores.
  
  
  CONCLUSIONS
  Pattern recognition approaches are useful tools to describe clinical phenotypes of ataxias and to identify particular configurations of cerebellar signs.
authors.affiliation: Department of Anatomy, Histology and Neuroscience, School of Medicine, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo 4, 28029 Madrid, Spain ; Trastornos del Desarrollo y Maduración Neurológica (TRADESMA), IdiPaz-UAM, Madrid, Spain ; Department of Neurology, Hospital Universitario La Paz, Madrid, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: Pulido-Valdeolivas
authors.affiliation: Department of Anatomy, Histology and Neuroscience, School of Medicine, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo 4, 28029 Madrid, Spain ; Trastornos del Desarrollo y Maduración Neurológica (TRADESMA), IdiPaz-UAM, Madrid, Spain ; Department of Pediatrics, Hospital Universitario Infanta Sofía, San Sebastián de los Reyes, Madrid, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Gómez-Andrés
authors.affiliation: Department of Neurology, Complejo Asistencial de Ávila, Ávila, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: Sanz-Gallego
authors.affiliation: Department of Anatomy, Histology and Neuroscience, School of Medicine, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo 4, 28029 Madrid, Spain ; Trastornos del Desarrollo y Maduración Neurológica (TRADESMA), IdiPaz-UAM, Madrid, Spain.
authors.forename: Estrella
authors.initials: E
authors.lastname: Rausell
authors.affiliation: Department of Anatomy, Histology and Neuroscience, School of Medicine, Universidad Autónoma de Madrid, C/ Arzobispo Morcillo 4, 28029 Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Arpa
keywords: Ataxia; Machado-Joseph disease; Multivariate analysis; Network analysis; SARA scale; SPECT