Microelectrode-guided thalamotomy for Parkinson's disease

OBJECTIVE: To describe the outcomes in our first 40 microelectrode-guided t halamotomies for parkinsonian tremor. METHODS: Twenty-four left-sided and 16 right-sided thalamotomies were perfo rmed between October 1984 and January 1996; the mean follow-up period was 3 5.8 months (range, 1-152 mo). The results were evaluated retrospectively an d semiquantitatively by a disinterested observer (MNL) and correlated with the quality of the microelectrode recording and the number and size of radi ofrequency lesions made. The first 20 and second 20 procedures were evaluat ed separately. RESULTS: At the last follow-up, the Unified Parkinson's Disease Rating Scal e showed no or virtually no tremor in the upper limb in 75% of patients or in the lower limb in 73% of patients. No significant persistent complicatio ns were found. These results were achieved at the expense of having to repe at the procedure on 11 sides (in 5 because of technical problems and in 6 f or no obvious reason). Total or nearly total abolition of tremor occurred a fter the first procedure in 40% of the first 20 operations and in 65% of th e second 20. Eight of the first 20 procedures and 2 of the second 20 failed for technical reasons. Lesions were made larger in the second 20 procedure s than in the first 20. With the use of an electrode with a 1.1 x 3-mm bare tip for 60 seconds, it seems that lesions had to be created at 60 degrees C or more to produce a successful result. CONCLUSION: Thalamotomy with microelectrode recording is an effective proce dure with which to treat tremor in patients with Parkinson's disease and ma y involve fewer complications than conventional techniques. The procedure a ppears to involve a learning curve.