運動障害性（麻痺性）構音障害におけるoral diadochokinetic testとしての「声のon-off検査」について

SIGNIFICANCE OF "ON-OFF PHONATION TEST" TO DETECT ORAL DIADOCHOKINESIA IN DYSARTHRIC PATIENTS

　抄録　／a／の硬い声たてを反復させる「声のon-off検査」を，単音節／pa／の反復課題とともに小脳失調性構音障害と痙性麻痺性構音障害の各6名ならびにパーキンソン症候群の3名，正常者6名に行なった。オシロスコープを用いて音声波形を作り有声・無声区間，ピーク値を計測しその特徴を分析した。これにより次の結果を得た。音節長はパーキンソン群を除いては正常群に比べ有意に延長していた。音節長とピーク値における変動の各疾患ごとの特性をとらえるには，測定値の標準偏差ないしは変動係数のみでは不充分であることが示唆された。一方，／a／の反復において痙性群で有声区間が，小脳群では無声区間が延長していた。本課題における声帯の運動パターンから，痙性群では喉頭の内転筋群の過緊張が誘発されて有声区間が延長するのに対し，小脳群では発声筋群の筋緊張低下が無声区間の延長に反映されたものであると考察した。これにより，「声のon-off検査」は発声筋群の動態を知るひとつの手掛りとなるものであることが示唆された。

Oral diadochokinetic abilities in 6 patients with ataxic dysarthria (ATAXICs), 6 with spastic dysarthria (SPASTICs), 3 with parkinsonism (PARKINs), and 6 normal subjects (NORMALs) were investigated using repetition of monosyl-lable /pa/ and "on-off phonation test" in which they had been requested to repeat interrupted vowel /a/ as fast as possible. Oscillographic as well as photographic records of the speech acous-tic signal were obtained to analyse interval for a syllable, which consisted of voiced and unvoiced intervals, and peak-value of voiced interval.

The results were as follows ;

1) ATAXICs and SPASTICs showed prolonged interval for a syllable, yet that of PARKINs was within normal range, when tested either in /a/ or in /pa/.

2) Standard deviaton and coeficient of variation for intervals of syllable and those of peak-values in voiced interval could not distinguish their characteristics among ATAXICs, SPASTICs, and PARKINs.

3) In "on-off phonation test", ATAXICs showed prolonged unvoiced intervals, while SPASTICs did prolonged voiced intervals. Results suggested that hypotonic laryngeal muscles in ATAXICs might result in prolongation of unvoiced interval, but that prolonged voiced interval related to biased hypertonus of laryngeal adductor.

It is concluded that "on-off phonation test" could, with reasonable sensitivity, reflect the phonatory dynamics of laryngeal muscles in dysarthric pa-tients.