大脳半球内占拠性病変における痙性とF波の意義

PHYSIOLOGICAL VALUE OF F-WAVE IN THE DIAGNOSIS OF INTRACEREBRAL MASS LESIONS AS REGARDS THE SPASTICITY

　抄録　目的：大脳半球内占拠性病変患者のF波を検討し，痙性麻痺の診断および病変の局在によるαmoto—neuronへの影響を調べた。方法：対象は正常例として成人10名，腱反射の亢進および左右差を示さない脳腫瘍患者10名である。手根部で正中神経幹上を経皮的にsupramaximal刺激を加え，導出電極は拇指球上に置いた。F波を20個記録し，その振幅，立ち上り潜時を計測した。また64回の刺激に対するF波の出現頻度を検討した。結果：F波の振幅，立ち上り潜時の平均および最短潜時の左右差には正常例との間に有意差はみられなかった。しかしF波の出現頻度に関しては，出現率の高い方を100とした対側の出現率は正常ではすべて70％以上になり，疾患群では2例を除いて70％以下であった。一方腫瘍内出血のためdias—chisis状態にある例と，後頭葉腫瘍でarea 6まで障害の及ばない例では健側に高かった。CT所見から障害が大脳皮質よりも内包や大脳脚に及ぶものがF波の出現率に影響すると考えられた。結論：深部腱反射に左右差を認めない大脳半球内占拠性病変患者では早期からF波の出現頻度に差があり，痙性麻痺の早期診断に有用であり，痙性の発症と病変の局在とに示唆を与える検査法といえる。

In order to evaluate physiological significance of F-wave in the diagnosis of spasticity, 10 patients with intracranial mass lesion who did not show clinically lateralizing evidence especially in DTRs were examined and the data were compared with the results obtained from 10 other normal subjects. F-wave was recorded from thenar muscle with supramaximal stimulation to the median nerve at wrist. Latency and amplitude of F-wave failed to show any significant difference in patients compared with normal subjects both on affected sides, however, frequency of F-wave was found to be significantly higher on affected side except for 2 cases who had a mass lesion in occipital lobe in one case and the other was in the state of diaschisis due to recent hemorrhage in the parietal tumor. The site of lesion was carefully determined with CT scan and it was concluded that the F-wave could be detected quite in early stage of intracerebral mass lesion if the process had affected to internal capsule or cerebral peduncle under indirect mass effect such as cerebral edema. On the contrary, it was interest-ing to note that the mass with no affection to the premotor cortex likely showed higher fre-quency of F-wave on the ipsi-lateral side of lesion.

As the conclusion, F-wave was found to have advantage in the diagnosis of spasticity in the early stage of illness and more accurate informa-tion on spasticity could be obtained compared with T or H-wave.