The treatment of posttraumatic tremor by stereotactic surgery

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Abstract
The authors report the long-term results of stereotactic surgery for severe posttraumatic appendicular tremor in 35 patients. The tremors developed after severe head trauma in 33 patients (94%) and after mild to moderate head trauma in two (6%). In all but one, the tremor was most evident during activity. The amplitude of the kinetic tremor was greater than 5 cm in 33 patients (94%) and greater than 12 cm in 19 patients (54%). All were severely incapacitated in their daily living activities due to the tremors. The 35 patients underwent 42 stereotactic operations; five patients were reoperated on the same side and two were treated with a bilateral staged procedure. The contralateral zona incerta was the stereotactic target in 12 patients and was targeted in combination with the base of the ventrolateral (oroventral) thalamus in 23 patients. Long-term postoperative follow-up review was obtained in 32 patients (mean follow-up period 10.5 years). Persistent improvement of tremor was noted in 88%. The tremor was absent or markedly reduced in 65%. Functional disability was assessed and quantified with a modified form of an established rating scale for patients with tremor; it was reduced from a mean value of 57% of maximum disability to 37% over the long term (p < 0.001). Follow-up lesion assessment was obtained in 18 patients by multiplanar magnetic resonance imaging and at autopsy in one patient whose death was unrelated to surgery. As in previous studies, the frequency of persistent side effects was relatively high (38%). These consisted mainly of aggravation of preoperative symptoms. The results are compared to those of a total of 55 patients reported from 1960 to 1992. The occurrence of dystonia and dystonic postures is discussed. Stereotactic surgery is a powerful tool to alleviate posttraumatic tremor and to improve functional disability. However, as there is considerable risk of persistent morbidity in patients after severe head trauma, the operation should be restricted to selected cases with disabling tremor.
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