[1] Kyushu Univ, Dept Clin Neurophysiol, Fukuoka 812, Japan
[2] Kyushu Univ, Dept Neurol, Fukuoka 812, Japan
[3] Kyushu Univ, Dept Neurophysiol, Fukuoka 812, Japan
[4] Kyushu Univ, Dept Neurosurg, Fukuoka 812, Japan
[5] Kyushu Rosai Hosp, Dept Neurosurg, Fukuoka, Japan