[Neurootological examinations in neurosurgical patients (author's transl)].

The examinations of gaze and optokinetic nystagmus were porformed at bed side before and after craniotomy. Gaze nystagmus were observed regularly in 120 cases who got the intracranial surgical procedures in Nagoya university hospital. Postoperative nystagmus which were not seen before operation appeared in 16 cases of 91 patients with supratentorial lesions and 24 cases of 27 patients with infratentorial lesions. These postoperative nystagmus continued for from 3 days to 21 days. The state of the direction of spontaneous horizontal nystagmus and directional preponderance were examined on 23 cases who were diagnosed as having unilateral lesion. In the cases with supratentorial lesion, the nystagmus appeared to be dominant toward the affected side, while in patients with infratentorial lesion, it had a tendency to be dominant toward the intact side. The mechanism of spontaneous and gaze nystagmus was discussed. The investigation could not conform whether nystagmus in supratentorial lesion was caused due to disturbance of the cerebral cortex or secondary disturbance of the brain stem. The postoperative nystagmus in the infratentorial lesion was possibly caused by the potoperative edema, operative injury, circulatory disturbance, and anoxia. Examinations of the optokinetic nystagmus had been done with hand-made drum at bed side for several weeks until the patients were stabilized. In most of 52 cases, horizontal optokinetic nystagmus were decreased in their frequency after craniotomy and gradually increased again. The similar observations were done in both supra- and infratentorial lesions. The optokinetic directional preponderance was examined on 30 cases diagnosed as having unilateral lesion. Eight supratentorial cases showed the decrease of intact side nystagmus and 2 infratentorial cases showed the decrease of affected side. The change of postoperative transient gaze nystagmus and horizontal optokinetic nystagmus were thought to be the functional alteration of the cerebral hemisphere and the brain stem. The examinations of gaze nystagmus and optokinetic nystagmus were harmless, simple and could be repeated at bed side easily, so these examinations were reliable for the expectation of the postoperative status of the brain stem as well as cerebral hemisphere and the necessity of neurosurgical examination.