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J "Ross Fiziol Zh Im I M Sechenova". 2004, V 90, #8, p.2, pp 444-445.
Hyperventilation-induced changes in stutterers' speech and EEG.
Nabieva T.N.
Brain Institute of Russian Academy of Medical Sciences. 105064, per. Obukha 5, Moscow, Russia.
In clinical electroencephalography, hyperventilation is the most frequently used method for activation and provocation. Speech and electrophysiological activity of 12 stuttering children (age 4-14) were tested after the standard hyperventilation test. By a routine EEG examination we revealed (in background before the hyperventilation) signs of paroxysmal activity (sharp waves of alpha and theta range) in 10 participants from 12 stuttering children. In these 10 cases, hyperventilation has led to a relative increase in the power density of delta and theta bands, to an occurrence/increase in number of sharp waves, the "peak-wave" and "sharp wave-slow wave" complexes. It is known that hyperventilation causes temporary decrease of blood PCO2 and reduction in cerebral blood flow due to vasoconstriction. As a result, the tone of arterial vessels of the brain and arterial blood flow reduces, venous outflow and arterial pressure increases, and oxygen consumption grows. Hyperventilation-induced hypocapnia considerably raises neuronal excitability and leads to spontaneous and/or asynchronous firing of cortical neurons, which in turn reduces stimulus-locked synaptic events (Huttunen J, Exp Brain Res. 125, 1999), or leads to temporary delay of neural afferent transmission (Gavriysky VS, Doctor Oftalmol. 77, 1991). Taking into account the fact that in the same 10 participants" hyperventilation had provoked temporary strengthening of muscle spasms and impairment of stuttering, it is possible to assume that increase of neuronal excitability and delay of neural afferent transmission are the key parts of the stuttering central mechanisms.
Key words: stuttering, hyperventilation, EEG, stuttering pathogenesis.
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