title: Direct comparison of cortical excitability to transcranial magnetic stimulation in obstructive sleep apnea syndrome and restless legs syndrome.
abstract: OBJECTIVE
  Changes to transcranial magnetic stimulation (TMS) have been reported in obstructive sleep apnea syndrome (OSAS) and restless legs syndrome (RLS), although no direct comparison study is available. The aim of this new investigation is to assess and compare cortical excitability of OSAS and RLS patients using the same methodology and under the same experimental conditions.
  
  
  METHODS
  Fourteen patients with OSAS and 12 with RLS were compared to 14 age-matched controls. All patients were untreated and had a severe degree of disease. Resting motor threshold (rMT), cortical silent period (CSP) and motor evoked potentials MEPs, as well as intracortical inhibition (ICI) and facilitation at interstimulus interval (ISI) of 3 and 10 ms, respectively, were explored from the right first dorsal interosseous muscle, during wakefulness.
  
  
  RESULTS
  rMT was higher in OSAS than in RLS and controls. CSP was shorter in RLS only when compared to apneic patients, whereas it was similar between OSAS and controls. OSAS subjects exhibited slightly prolonged central motor conductivity, whereas MEP amplitude was smaller in both patient groups. The ICI ratio at ISI of 3 ms was decreased in RLS patients only.
  
  
  CONCLUSIONS
  Distinct changes of responses at TMS were found, probably connected with the different neurophysiological substrates underlying OSAS and RLS and could not be interpreted as a mere reflection of the effects of sleep architecture alteration. TMS can be considered an additional tool for the understanding of clinical and pathophysiological aspects of sleep disorders, and possibly for the evaluation of the effect of therapy.
authors.affiliation: Department of Neurology I.C., Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Via Conte Ruggero, 73 - 94018 Troina (EN), Italy. Electronic address: glanza@oasi.en.it.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lanza
authors.affiliation: Department of Neurology I.C., Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Via Conte Ruggero, 73 - 94018 Troina (EN), Italy.
authors.forename: Bartolo
authors.initials: B
authors.lastname: Lanuzza
authors.affiliation: Department of Neurology I.C., Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Via Conte Ruggero, 73 - 94018 Troina (EN), Italy.
authors.forename: Debora
authors.initials: D
authors.lastname: Aricò
authors.affiliation: Department of Chemistry, University of Catania, Viale Andrea Doria, 6 - 95125 Catania, Italy.
authors.forename: Mariagiovanna
authors.initials: M
authors.lastname: Cantone
authors.affiliation: Department of Neurology I.C., Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Via Conte Ruggero, 73 - 94018 Troina (EN), Italy.
authors.forename: Filomena Irene Ilaria
authors.initials: FI
authors.lastname: Cosentino
authors.affiliation: Department of Chemistry, University of Catania, Viale Andrea Doria, 6 - 95125 Catania, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Pennisi
authors.affiliation: Department "G.F. Ingrassia", Section of Neurosciences, University of Catania. Via Santa Sofia, 78 - 95123 Catania, Italy.
authors.forename: Rita
authors.initials: R
authors.lastname: Bella
authors.affiliation: Department "G.F. Ingrassia", Section of Neurosciences, University of Catania. Via Santa Sofia, 78 - 95123 Catania, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Pennisi
authors.affiliation: Department of Neurology I.C., Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Via Conte Ruggero, 73 - 94018 Troina (EN), Italy.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Ferri
mesh_terms: D000368:Aged; D001143:Arousal / Q000502:physiology*; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D012148:Restless Legs Syndrome / Q000503:physiopathology* / Q000628:therapy; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology* / Q000628:therapy; D050781:Transcranial Magnetic Stimulation
keywords: Central motor conductivity; Cortical excitability; Disinhibition; Obstructive sleep apnea; Restless legs syndrome; Transcranial magnetic stimulation