title: Eye and hand motor interactions with the Symbol Digit Modalities Test in early multiple sclerosis.
abstract: OBJECTIVE
  Eye and hand motor dysfunction may be present early in the disease course of relapsing-remitting multiple sclerosis (RRMS), and can affect the results on visual and written cognitive tests. We aimed to test for differences in saccadic initiation time (SI time) between RRMS patients and healthy controls, and whether SI time and hand motor speed interacted with the written version of the Symbol Digit Modalities Test (wSDMT).
  
  
  METHODS
  Patients with RRMS (N = 44, age 35.1 ± 7.3 years), time since diagnosis < 3 years and matched controls (N = 41, age 33.2 ± 6.8 years) were examined with ophthalmological, neurological and neuropsychological tests, as well as structural MRI (white matter lesion load (WMLL) and brainstem lesions), visual evoked potentials (VEP) and eye-tracker examinations of saccades.
  
  
  RESULTS
  SI time was longer in RRMS than controls (p < 0.05). SI time was not related to the Paced Auditory Serial Addition Test (PASAT), WMLL or to the presence of brainstem lesions. 9 hole peg test (9HP) correlated significantly with WMLL (r = 0.58, p < 0.01). Both SI time and 9HP correlated negatively with the results of wSDMT (r = -0.32, p < 0.05, r = -0.47, p < 0.01), but none correlated with the results of PASAT.
  
  
  CONCLUSIONS
  RRMS patients have an increased SI time compared to controls. Cognitive tests results, exemplified by the wSDMT, may be confounded by eye and hand motor function.
authors.affiliation: Department of Neurology, Oslo University Hospital, Postal Box 4950 Nydalen, 0424 Oslo, Norway; Department of Clinical Medicine, University of Oslo, Postal Box 1171 Blindern, 0318 Oslo, Norway. Electronic address: g.o.nygaard@medisin.uio.no.
authors.forename: Gro O
authors.initials: GO
authors.lastname: Nygaard
authors.affiliation: Department of Clinical Medicine, University of Oslo, Postal Box 1171 Blindern, 0318 Oslo, Norway; Department of Ophthalmology, Oslo University Hospital, Postal Box 4950 Nydalen, 0424 Oslo, Norway. Electronic address: s.a.d.r.benavent@medisin.uio.no.
authors.forename: Sigrid A
authors.initials: SA
authors.lastname: de Rodez Benavent
authors.affiliation: Department of Neurology, Oslo University Hospital, Postal Box 4950 Nydalen, 0424 Oslo, Norway; Department of Clinical Medicine, University of Oslo, Postal Box 1171 Blindern, 0318 Oslo, Norway. Electronic address: h.f.harbo@medisin.uio.no.
authors.forename: Hanne F
authors.initials: HF
authors.lastname: Harbo
authors.affiliation: Department of Psychology, University of Oslo, Postal Box 1094 Blindern, 0317 Oslo, Norway. Electronic address: b.laeng@medisin.uio.no.
authors.forename: Bruno
authors.initials: B
authors.lastname: Laeng
authors.affiliation: Department of Clinical Medicine, University of Oslo, Postal Box 1171 Blindern, 0318 Oslo, Norway; Department of Radiology, Oslo University Hospital, Postal Box 4950 Nydalen, 0424 Oslo, Norway. Electronic address: piotr.sowa@medisin.uio.no.
authors.forename: Piotr
authors.initials: P
authors.lastname: Sowa
authors.affiliation: Department of Neurobiology, Karolinska Institute, SE-171 77 Stockholm, Sweden. Electronic address: soheil.damangir@ki.se.
authors.forename: Soheil
authors.initials: S
authors.lastname: Damangir
authors.affiliation: Department of Neurology, Oslo University Hospital, Postal Box 4950 Nydalen, 0424 Oslo, Norway; Department of Neuroscience, Norwegian University of Science and Technology, 7489 Trondheim, Norway. Electronic address: kristian.b.nilsen@ntnu.no.
authors.forename: Kristian
authors.initials: K
authors.lastname: Bernhard Nilsen
authors.affiliation: Department of Neurology, Oslo University Hospital, Postal Box 4950 Nydalen, 0424 Oslo, Norway. Electronic address: lareth@ous-hf.no.
authors.forename: Lars
authors.initials: L
authors.lastname: Etholm
authors.affiliation: Department of Clinical Medicine, University of Oslo, Postal Box 1171 Blindern, 0318 Oslo, Norway. Electronic address: siren.tonnesen@medisin.uio.no.
authors.forename: Siren
authors.initials: S
authors.lastname: Tønnesen
authors.affiliation: Department of Neurology, Oslo University Hospital, Postal Box 4950 Nydalen, 0424 Oslo, Norway; Department of Clinical Medicine, University of Oslo, Postal Box 1171 Blindern, 0318 Oslo, Norway. Electronic address: emilia.kerty@medisin.uio.no.
authors.forename: Emilia
authors.initials: E
authors.lastname: Kerty
authors.affiliation: Department of Clinical Medicine, University of Oslo, Postal Box 1171 Blindern, 0318 Oslo, Norway; Department of Ophthalmology, Oslo University Hospital, Postal Box 4950 Nydalen, 0424 Oslo, Norway. Electronic address: liv.drolsum@medisin.uio.no.
authors.forename: Liv
authors.initials: L
authors.lastname: Drolsum
authors.affiliation: Department of Psychology, University of Oslo, Postal Box 1094 Blindern, 0317 Oslo, Norway. Electronic address: n.i.landro@psykologi.uio.no.
authors.forename: Nils
authors.initials: N
authors.lastname: Inge Landrø
authors.affiliation: Department of Neurology, Oslo University Hospital, Postal Box 4950 Nydalen, 0424 Oslo, Norway. Electronic address: uxelgu@ous-hf.no.
authors.forename: Elisabeth G
authors.initials: EG
authors.lastname: Celius
mesh_terms: D000328:Adult; D004185:Disability Evaluation; D005074:Evoked Potentials, Visual; D005260:Female; D006225:Hand / Q000503:physiopathology*; D006801:Humans; D016014:Linear Models; D008297:Male; D009048:Motor Skills / Q000502:physiology; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000175:diagnosis* / Q000503:physiopathology* / Q000523:psychology; D015999:Multivariate Analysis; D009460:Neurologic Examination; D009483:Neuropsychological Tests; D012438:Saccades / Q000502:physiology; D012720:Severity of Illness Index; D013997:Time Factors
keywords: Cognition; Eye; Hand function; Multiple sclerosis; Multiple sclerosis functional composite; Saccades; Symbol Digit Modalities Test; Symptom assessment