title: Changes of neural activity correlate with the severity of cortical ischemia in patients with unilateral major cerebral artery occlusion.
abstract: OBJECTIVE
  In major cerebral arterial steno-occlusive diseases, there can be remarkably decreased hemodynamic reserve without marked neurological impairments. In such settings, it is not known whether the neural activity is well maintained or disturbed according to the severity of cerebral ischemia. The present study was therefore undertaken to examine the neural activity under mild cerebral ischemia resulting from major cerebral arterial occlusion.
  
  
  METHODS
  Seven patients with minor neurological impairment as well as either unilateral internal carotid artery or middle cerebral artery occlusion were studied. The severity of the cortical ischemia was assessed by measuring regional cerebral blood flow (rCBF) with positron emission tomography. The change in neural activity in the ischemic brain was then evaluated by means of somatosensory evoked magnetic field with magnetoencephalography.
  
  
  RESULTS
  The rCBF in the primary sensory area and the strength of the initial component of somatosensory evoked magnetic field (N20 m) were significantly reduced (P<0.01) and the second component (P30 m) was significantly augmented (P<0.05) in the lesioned cerebral hemisphere as compared with the nonlesioned hemisphere. The asymmetry indexes for N20 m were positively correlated (r=0.78) and those for P30 m were inversely correlated (r=-0.92) with asymmetry indexes for rCBF.
  
  
  CONCLUSIONS
  In patients with either unilateral internal carotid artery or middle cerebral artery occlusion and minor neural impairments, there was a reduction of afferent signal and an augmentation of the secondary response of the neurons in the primary sensory area. This showed correlation with the severity of cortical ischemia.
authors.affiliation: Department of Biofunctional Research, National Institute for Longevity Sciences, Ohbu, Japan. ibundou@nils.go.jp
authors.forename: Masahiko
authors.initials: M
authors.lastname: Bundo
authors.forename: Suguru
authors.initials: S
authors.lastname: Inao
authors.forename: Akinori
authors.initials: A
authors.lastname: Nakamura
authors.forename: Takashi
authors.initials: T
authors.lastname: Kato
authors.forename: Kengo
authors.initials: K
authors.lastname: Ito
authors.forename: Masanori
authors.initials: M
authors.lastname: Tadokoro
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Kabeya
authors.forename: Toru
authors.initials: T
authors.lastname: Sugimoto
authors.forename: Yasukazu
authors.initials: Y
authors.lastname: Kajita
authors.forename: Jun
authors.initials: J
authors.lastname: Yoshida
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000098:blood supply / Q000000981:diagnostic imaging; D002545:Brain Ischemia / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002560:Cerebrovascular Circulation; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow; D014055:Tomography, Emission-Computed / Q000379:methods