Psychological aspects of diencephalotomy

Abstract

The short-and long-term effects of surgery of the basal ganglia on behaviour have received relatively little attention. In previous studies emphasis has been on the more immediate post-operative changes for evaluating the effects of surgical lesions on intellectual and perceptual functions. With respect to intelligence only one aspect, intelligence quotient (I.Q.), was emphasized. The objectives in this study were to evaluate several aspects of intelligence and simple perception for relatively longer post-operative periods.METHOD PATIENTS This study was done on 25 patients (10 men and 15 women). Mean age was 54-2 years (range 40-70 years); mean educational level 13-8 years; mean duration of illness 5 4 years (range 1-10 years). The patients all showed some degree of generalized Parkinson involvement. The chief complaints ranged from moderate and unilateral to quite severe and bilateral tremor and rigidity. All patients were right-handed, i.e., left brain dominant.SURGERY Unilateral brain lesions were made under local anaesthesia. A 20-gauge barrel electrode with a 4 to 10 mm. non-insulated tip was inserted into the diencephalon through a frontal burr hole (Andy, 1959). The sites of coagulation were primarily in the posterior ventral thalamus-subthalamic region (Andy, Jurko, and Sias, 1963 514following intervals: one week pre-operatively; five days post-operatively; two months post-operatively; six to eight months post-operatively; and one and a half to two years post-operatively. All patients were tested throughout the study by the same examiner.EVALUATION OF DATA Since the Wechsler adult intelligence scale is a test which gives well-defined numerical scores continuously distributed, mean scores could be obtained and appropriately compared pre-and postoperatively with the parametric t test. However, the tests in the visual-motor performance and the simple perception groups present scoring difficulties. Tests like the Bender-Gestalt are commonly evaluated by clinical judgment and there is no widely accepted method of numerical evaluation. Observations like those made for linear deviation in the memory-for-designs test are also difficult to present in numerical scores. For tests like trail making the standardized scoring is dependent upon the patient's ability easily to execute motor movements and do require modification when used on the Parkinson patient. The spiral aftereffect has such a limited spread of scores that it is usually evaluated in terms of a cut-off score (normal vs. abnormal). In view of these difficulties the most feasible presentation of the data for the visualmotor performance and simple perception groups appeared to be reduction to categorized form. Though this type of evaluation does not permit the use of the more exacting statistical methods possible with mean scores, it avoids a deceptive aura of mathematical rigour not inherent in these types of tests. Since pre-operative performance was near optimum and in only isolated instances was there a better score post-operatively, the follow-up ...

Psychological comparison of unilateral and bilateral thalamic surgery: A preliminary report.

“…Another explanation for the lack of persistent behavioral effects of such intervention might be found in the limited size of unilateral lesions which could preclude sufficient involvement of neural systems to cause disruptions. Moreover, divergent results reported by Jurko and Andy (1964), concerning long-range psychological changes in the absence of immediate behavioral sequelae following unilateral subcortical surgery in parkinsonians, might be attributed to differences in samples, preoperative to postoperative time intervals, but, particularly, to variations in surgical procedure, such as thalamolysis through electrocoagulation, and to parameters of lesion location.…”

Behavioral Changes Correlated with Thalamotomy Site

“…IQ revealed no significant change following lesions placed in the cen ter median nucleus. Greatest decrements in IQ occurred with lesions in bordering thalamic nuclei as was found following thalamotomy for Par kinson's disease [5,8], The decrement was primarily due to impairment of one subtest, similarities.…”