From selective thalamotomy with microrecording to gamma thalamotomy for movement disorders

A theoretical and practical process from microrecording-guided thalamotomy to gamma knife thalamotomy was briefly reviewed. Based on our own experiences of selective thalamotomy with microrecording, we are trying to apply gamma knife to the treatment of movement disorders. An important technical problem is how to determine the exact thalamic target. At first we refer to the posterior commissure and coordinate of the standard atlas for approximately determining the lateral part of the ventral intermediate nucleus. Then the point is further corrected by anatomical landmark (45% of the thalamic length) to compensate the individual difference. A final lesion is made by gamma knife using a 4-mm collimator, 130 Gy in 1 shot. The average delay of clinical improvement is about 6 months after irradiation. Thus far the results are satisfactory, being 80-85% successful without any noticeable complications. Only 3 days of hospitalization with minimal invasion could be a big advantage for the patient. Further technical progress may improve the clinical results in the future.