[Delayed finger opening caused by a midbrain lesion].
We report a 25 year-old woman with delayed finger opening caused by a midbrain lesion. Magnetic resonance imaging revealed an abnormal intensity area in the left midbrain in the vascular territory corresponding to the mesencephalic inferomedian branch and central posteromedian branch of posterior cerebral artery. Clinically, she suffered from Weber's syndrome, and in the course of recovery, she developed marked delayed finger opening. Her weakness was slight, this delayed finger opening was observed only after maximal grip, and she required about ten seconds to open her right fingers. She could open and grip her fingers easily and quickly in moderate contraction. In the electromyogram, the action potentials of flexor digitorum profundus muscle did not disappear promptly upon instruction to open her fingers, and they lasted for approximately six seconds with gradual decrease. On the other hand, the action potentials of extensor digitorum muscle were reciprocally inhibited and increased gradually after the decrease of the flexor muscle potentials. The abnormally continuing discharges in the flexor muscles were thought to be the cause of her delayed finger opening. The phenomenon of delayed finger opening caused by cervical root lesions, peripheral nerve lesions, or a brain stem (pons-medulla oblongata) lesion have been reported. But, the phenomenon caused by a midbrain lesion, like our case, has not been reported. The present case was different from the previously reported cases with this phenomenon showing simultaneous discharges from both agonistic and antagonistic muscles.
Saito
Y
Y
Department of Neurology, Tokyo Medical and Dental University, Japan.
Wada
Y
Y
Nakayama
T
T
Furukawa
T
T
Tsukagoshi
H
H
D000328:Adult; D001927:Brain Diseases / Q000150:complications / Q000175:diagnosis; D004576:Electromyography; D005260:Female; D005385:Fingers; D006801:Humans; D008279:Magnetic Resonance Imaging; D008636:Mesencephalon; D009069:Movement Disorders / Q000175:diagnosis / Q000209:etiology*