[Lateral coordinate of the thalamic Vim neurons in the cases with dilated third ventricle]

Precise radiographical measurement of the third ventricle in the first and essential procedure in stereotaxic surgery in order to determine the target point. This is done while referring to an available standard brain atlas such as Schaltenbrand & Bailey. However there have been no criteria established for determining the deviation of the coordinates of the thalamic nuclei, especially in their lateral coordinates when the third ventricle is highly dilated. Therefore, in 109 cases encountered recently (81 parkinsonism, 11 essential tremor, 10 cerebral palsy, 3 thalamic pain, 1 Benedikt's syndrome, 1 torticollis, 1 oral dyskinesia, 1 striato-nigral degeneration), we studied the correlation between the width of the third ventricle and the lateral coordinate of the thalamic point where kinesthetic neurons or tremor-synchronously discharging neurons were detected. These neurons were especially related to the arm. According to the width of the third ventricle, we classified the cases into three types: 18 cases with large ventricles (more than 10 mm), 37 cases with medium-sized ventricles (4-10 mm) and 16 cases with small ventricles (less than 4 mm). By plotting the lateral coordinate of the thalamic point where kinesthetic neuron of the upper extremity was recorded in reference to the radiogram of anteroposterior view, we found that the lateral coordinates of large ventricular cases generally tended to show more lateral displacement than cases where the ventricles were narrower. Their mean lateral coordinate was 16.9 mm from midline in contrast ot 14.0 mm in cases with small ventricular width. There was a linear correlation between the width of the third ventricle and the lateral coordinate of the kinesthetic neuron of the Vim nucleus.(ABSTRACT TRUNCATED AT 250 WORDS)