Surgical Treatments for Movement Disorders

Published on 03/03/2015 by admin

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Last modified 03/03/2015

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43 Surgical Treatments for Movement Disorders

Jeffrey E. Arle

Surgical therapies for certain movement disorders are important treatment modalities, particularly in medically refractory cases where the patient has become significantly disabled. Early on, thousands of surgically induced brain lesions were performed between 1950 and 1970 after a serendipitous surgical “mistake” led to loss of a classic Parkinson disease (PD) tremor in one patient. Very rapidly an initial enthusiasm developed for this therapeutic modality. However, the introduction of levodopa in 1966 led to a significant cessation in the development of more sophisticated surgical treatment for PD. Subsequently our understanding of the physiology of movement disorders and our ability to better assess baseline and outcome data in these patients have markedly improved since the initial historical period. Concomitantly, it became clear that medical management would not provide long-term resolution of the classic PD in many patients. Today PD primarily includes mostly the idiopathic subset in contrast to the combined idiopathic as well as the postencephalitic variants present when surgical therapeutic methodologies were in their infancy. Currently there are several operations performed for the rather few neurologic disorders that are treated effectively by surgery (Table 43-1). These include very specific intentional destructive lesions targeting specific basal ganglia sites as well as deep brain stimulation (DBS) within the basal ganglia and thalamus.

Table 43-1 Summary of Current Best Procedures for Movement Disorders*

Disorder Procedures
Essential (familial) tremor Vim Thalamic DBS or
Thalamotomy (unilateral)
Parkinson disease DBS either to the STN or
Gpi or
Pallidotomy (unilateral)
Dystonia Gpi DBS

* DBS, deep brain stimulation; Gpi, globus pallidus pars interna; STN, subthalamic nucleus; Vim, ventralis intermedius.

Patient Selection

Patients who are candidates for DBS are typically refractory to standard medical therapy that included multiple trials with varying dosages and combinations of pharmacotherapy. Once a diagnosis of PD is confirmed, expeditious medication trials are encouraged, in order that years of potential benefit from subsequent surgery are not lost if the patient eventually becomes a medication failure. Ideally the surgeon prefers to consider patients whose clinical severity has not progressed toward end stages where surgical intervention becomes less appropriate. However, in most centers, DBS and lesion placement for PD are performed as late as age 80 years. This is predicated on the patient still evidencing good results to preoperative neuropsychological testing that demonstrates no more than minimal signs of dementia. Similar criteria are applied when contemplating DBS treatment for tremor per se.

Dystonia, in contrast, typically involves children as young as ages 6–8 years. Although adequate genetic testing is helpful for diagnosis, many dystonia patients are DYT-1 negative. The presence or absence of genetic confirmation does not determine which child will benefit from DBS.

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