Functional stereotactic surgery for treatment of cervical dystonia: review of the experience from the lesional era

Background: Functional stereotactic neurosurgery has been rediscovered as a powerful tool to treat various manifestations of medically refractory dystonia. The purpose of this study was to provide the first systematic review of previous experience with thalamic and basal ganglia surgery in the treatment of cervical dystonia (CD).

Methods: A comprehensive review of the literature published between 1950 and 1990 was performed. In addition, data from an unpublished doctoral thesis on 162 patients with CD operated on by Mundinger between 1972 and 1986 were analyzed.

Results: Overall, there is published documentation of experience with more than 300 patients with CD who underwent functional stereotactic surgery between the late 1950s and the early 1980s. In general, amelioration of CD was achieved in about 50-70% of patients in most studies. Bilateral surgery generally provided better outcomes than unilateral surgery. Postoperative benefit was reported to become evident only after a delay in several studies. Some reports demonstrated sustained benefit after follow-up of more than 5 years. Bilateral procedures, in particular bilateral thalamotomies, were clearly associated with a higher rate of postoperative side effects, such as dysarthria, dysphagia and ataxia, ranging from 20 to 70%. In the first decade after its introduction, thalamotomy was the preferred procedure. Later, the subthalamic area was targeted more frequently in order to affect pallidal outflow. Experience with targeting the pallidum proper was limited. Functional stereotactic surgery for CD was abandoned in the late 1970s for several reasons, including the general decline in movement disorder surgery at that time, the introduction of selective peripheral denervation and the widespread and beneficial use of botulinum toxin soon thereafter.

Conclusions: Functional stereotactic surgery for treatment of CD has a rich history. There are several lessons to be learned from review of earlier experience. Contemporary techniques have led to a significant improvement in the benefit to risk ratio, in particular regarding bilateral surgery.