THE TREATMENT OF POSTTRAUMATIC TREMOR BY STEREOTAXIC SURGERY - SYMPTOMATIC AND FUNCTIONAL OUTCOME IN A SERIES OF 35 PATIENTS

The authors report the long-term results of stereotactic surgery for s evere posttraumatic appendicular tremor in 35 patients. The tremors de veloped after severe head trauma in 33 patients (94%) and after mild t o moderate head trauma in two (6%). in all but one, the tremor was mos t evident during activity. The amplitude of the kinetic tremor was gre ater than 5 cm in 33 patients (94%) and greater than 12 cm in 19 patie nts (54%). Ail were severely incapacitated in their daily living activ ities due to the tremors. The 35 patients underwent 42 stereotactic op erations; five patients were reoperated on the same side and two were treated with a bilateral staged procedure. The contralateral zona ince rta was the stereotactic target in 12 patients and was targeted in com bination with the base of the ventrolateral (oroventral) thalamus in 2 3 patients. Long-term postoperative follow-up review was obtained in 3 2 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 modif ied form of an established rating scale for patients with tremor; it w as 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 st udies, the frequency of persistent side effects was relatively high (3 8%). These consisted mainly of aggravation of preoperative symptoms. T he results are compared to those of a total of 55 patients reported fr om 1960 to 1992. The occurrence of dystonia and dystonic postures is d iscussed. Stereotactic surgery is a powerful tool to alleviate posttra umatic 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.