title: Differential infraslow (<0.1 Hz) cortical activations in the affected and unaffected hemispheres from patients with subacute stroke demonstrated by noninvasive DC-magnetoencephalography.
abstract: OBJECTIVE
  Sustained mass depolarization of neurons, termed cortical spreading depolarization, is one electrophysiological correlate of the ischemic injury of neurons. Cortical spreading depolarizations spread in the gray matter at a rate of approximately 3 mm/min and are associated with large infraslow extracellular potential changes (<0.05 Hz). Moreover, smaller infraslow potential changes accompany functional activation and might help to assess neuronal repair after stroke. The objective of the present pilot study was to investigate whether it is feasible to apply noninvasive near-DC-magnetoencephalography to detect and monitor infraslow field changes in patients with acute stroke.
  
  
  METHODS
  A simple motor condition was used to induce physiological cortical infraslow field changes. Five patients in a subacute state after ischemic stroke performed self-paced simple finger movements (30-second periods of finger movements, always separated by 30-second periods of rest, for a total of 15 minutes). Near-DC-magnetoencephalography signals were recorded over the contralateral primary motor cortex for the affected and unaffected hemisphere, respectively.
  
  
  RESULTS
  In all patients, the time courses of the contralateral cortical field amplitudes in the infraslow frequency range followed closely the motor task cycles revealing statistically significant differences between finger movement and rest periods. In 4 of 5 patients, infraslow field amplitudes were significantly stronger over the unaffected hemisphere compared with the affected hemisphere.
  
  
  CONCLUSIONS
  This study demonstrates that cortical infraslow activity can be recorded noninvasively in patients in the subacute state after ischemic stroke. It is suggested that near-DC-magnetoencephalography is a promising tool to also detect cortical spreading depolarization noninvasively.
authors.affiliation: Department of Neurology, Campus Benjamin Franklin, Charite-Universitaetsmedizin Berlin, Berlin, Germany. stefanie.leistner@charite.de
authors.forename: Stefanie
authors.initials: S
authors.lastname: Leistner
authors.forename: Tilmann
authors.initials: T
authors.lastname: Sander
authors.forename: Michaela
authors.initials: M
authors.lastname: Wachs
authors.forename: Martin
authors.initials: M
authors.lastname: Burghoff
authors.forename: Gabriel
authors.initials: G
authors.lastname: Curio
authors.forename: Lutz
authors.initials: L
authors.lastname: Trahms
authors.forename: Bruno-Marcel
authors.initials: BM
authors.lastname: Mackert
mesh_terms: D000368:Aged; D002545:Brain Ischemia / Q000150:complications; D002540:Cerebral Cortex / Q000098:blood supply / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D013181:Cortical Spreading Depression / Q000502:physiology; D003627:Data Interpretation, Statistical; D004576:Electromyography; D005260:Female; D005385:Fingers / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology; D009068:Movement / Q000502:physiology; D020521:Stroke / Q000209:etiology / Q000503:physiopathology*