Mental disturbances after thalamolysis

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Abstract
Two middle-aged men had surgery for the purpose of controlling Parkinsonian tremor and rigidity affecting mainly the right side. The balloon-and-cannula technique was used in producing a left thalamolysis. The operation resulted in a severe, protracted psychic disturbance, characterized by confusion, amnesia, confabulation, euphoria, restlessness and incontinence. Both also developed dysphasia. One patient committed suicide nine months after the surgery and a detailed anatomical and histological examination was carried out on his brain. Microscopic examination showed the extent of the surgical lesion, generalized shrinkage of the left thalamus and loss of pigment in the substancia nigra and locus pigmentosus pontis on both sides. Microscopically it was demonstrated that most of the damage was in the lateral and ventrolateral nuclei of the thalamus and a portion of the internal capsule just behind the genu. A band of Wallerian degeneration appeared in the medial third of the crus. The portion containing the cortico-spinal tract was intact and along with this no signs of degeneration appeared in the pyramid. The cause of the mental disturbance is related to the lack of control over the size and spread of the lesions produced by the technique. It is suggested that this method is not suitable for use in the dominant hemisphere.