薬効ピーク時に移動能力, ADLが向上する一方で, 一時的な起声困難が出現する若年性パーキンソン病患者を経験した.本症例の起声困難はドラッグコントロールにより改善しており, 薬物 (L-DOPA) に起因するすくみ現象による声帯の内転障害と考えられた.同一個体内で歩行と発声という異なる運動間ですくみ現象が時間的解離をもって出現した原因について考察した.結果, 同一個体内においても四肢・体幹と喉頭ですくみ現象の発現機序に相違がある可能性, あるいは薬物の治療閾値がおのおのの筋において異なる可能性を考えた.また, 本症例の起声困難には“kinesie paradoxale”を伴っており, 声帯のすくみ現象には発声を他の目標行動に変換して誘発する方法が有用であった.
A 62-year-old man with juvenile Parkinson's disease was reported. When L-Dopa was working the patient felt difficulty in voicing although he could walk smoothly. Meanwhile, when L-Dopa was not working his difficulty in voicing disappeared but he was unable to walk. This discrepancy between voicing and walking is disussed.
Laryngofiberscopic examination showed the following intriguing findings. When L-Dopa was working the patient's vocal cords assumed the hyperabduction position. Also, during an attempts at phonation, the vocal cords developed a tendency to adduct but were unable to. This movement seemed to correspond to a“freezing”phenomenon in walking. The adduction tendency of the vocal cords ameliorated temporazily by voluntarily making a cough instead of voicing. Such a phenomenon appeared as a freezing of vocal cord movement with kinesie paradoxale.
Two hypotheses were raised to explain this “see-saw” phenomenon between voicing and walking. First, the mechanism of the freezing phenomenon might differ for voicing and walking. Second, the threshold for the effectiveness of L-Dopa might differ for the intrinsic laryngeal muscles controlling voicing and for the limb and truncal muscles controlling walking. The task of hawking which we attempted was very useful in speech therapy on PD patients who exhibited the freezing phenomenon of the vocal cords with kinesie paradoxale.