L.W. Organ

What Happened to VIM Thalamotomy for Parkinson's Disease?

A prospective review of 75 of 190 parkinsonian patients undergoing unilateral thalamotomy was displayed with a computer graphics technique examining three equal consecutive groups from the pre-, early, and late L-dopa eras. Histograms for average function and scattergrams of individual patients performance preoperatively and up to 2 years postoperatively were prepared. No ipsilateral effects or consistent iatrogenic deterioration of any function were identified. 2 years after surgery, 82% had no tremor in the contralateral fingers or hand and 7% had almost no tremor; contralateral tremor elsewhere was infrequent. Rigidity and manual dexterity improved less strikingly, the latter only reflecting abolition of tremor; locomotion, speech, facial movement and handwriting did not improve. There was no mortality, but 8% had persistent significant complications. VIM thalamotomy remains the treatment of choice for severe drug-resistant parkinsonian tremor.

Third Ventricular Width and the Thalamocapsular Border

65 patients were selected to assess variations in third ventricular width. The patients suffered from various extrapyramidal movement disorders, and all had undergone stereotactic VL thalamotomies. Third ventricular width was correlated with age, sex, diagnosis and intercommissural distance. Based upon the analysis of somatosensory response mappings, a medial displacement of the thalamocapsular border was demonstrated for patients with narrow third ventricles.

Computerized Graphic Display of Physiological Data Collected during Human Stereotactic Surgery

An on-line computerized graphic display has been developed for use during stereotactic operations. This depicts in the form of figurine charts and alph-numeric symbols, appropriately oriented on saggital brain diagrams, the results of serial threshold stimulation of the brain. The display facilitates choice of target sites and the data can be stored in a tape library from which search-and-plot programs can be activated for any type or combination of types of response.

Sensory Organization of the Human Thalamus

A computerized program has been developed for on-line display and tape-library storage of stimulation-mapping data collected during stereotactic procedures. Using computer-generated displays of pooled clinical physiological data it has been possible to map through the upper midbrain and thalamus the lemniscal, spinoquintothalamic, auditory, vestibular, visual, extrapyramidal, and motor pathways, as well as the location of the pia. Each system is recognizable by a stereotyped, artificial, somatotopically organized stimulation-induced response that is devoid of modality information and independent of the site and parameters of stimulation.

CASS: computer-assisted stereotaxic surgery

An interactive computer graphics system has been developed for online use with a two-stage stereotaxic technique in man. The computer plots sagittal sections approximating the region of the brain being stimulated on a display screen located in the operating room. When responses are elicited by electrical stimulation, they are graphically illustrated on the template, accurately positioned at the brain site being stimulated. If such evoked responses do not fit the template, they can be replotted on a modified template in a manner prescribed by the neurosurgeon. Such a system allows optimal localization of subcortical lesion sites.