Surgery is reserved for patients with severe dystonia with significant impairment in quality of life. Usually, this means that patients have an inadequate response to aggressive treatment with botulinum toxin injections and oral medications. Surgery may also be used in patients who initially responded well, but who have subsequently developed resistance to both botulinum toxin Type A and Type B. Most commonly, surgery is especially helpful in patients who have marked anterocollis (neck flexion) or retrocollis (neck extension) since it may be difficult to adequately improve patients with severe anterocollis without causing substantial trouble swallowing. It may be difficult to adequately improve patients with severe retrocollis since this may result in excessive weakness of the neck extensor muscles. Cervical dystonia may also occur as part of more widespread segmental and generalized dystonia, in which case botulinum toxin injections may not be able to be applied throughout the entire affected areas.
Local surgery which involves cueng specific overactive nerves and muscles causing the abnormal movements is referred to as selective denervation. This surgery is usually applied in patients who have predominantly abnormal neck turning, also known as torticollis, or neck tilting, also called laterocollis. It is usually used in patients who initially had a good response to botulinum toxin injections but subsequently developed resistance. Since the efficacy of this surgery is similar to that seen with botulinum toxin injections. It is usually not very effective for patients with predominantly retrocollis, where the head is pulling back, or anterocollis where the head is pulling forward. Since nerves and muscles are cut, the effect is permanent.
Typical complications include tingling and burning in the areas of the skin where the nerves have been cut, trouble swallowing, or excessive weakness of the neck. Many of these adverse effects gradually resolve aYer surgery over a period of weeks or months.
Deep brain stimulation refers to I am planning electrodes in specific areas of the brain and hooking up the electrode to a pacemaker-‐like device, which is usually implanted just below the collar bone. The idea behind this surgery is to jam the abnormal brain signals responsible for generating the dystonia. The electrodes are usually placed in the globus pallidus or less commonly the subthalamic nucleus. In patients with cervical dystonia, surgery is usually performed bilaterally with electrodes placed on both sides of the brain. After surgery, the electrical parameters of stimulation need to be set which is a process which is typically done gradually over several weeks and begins soon after surgery.
The benefit usually occurs gradually over hours to weeks. Up to 90% of patients who undergo this surgery see significant improvement with average improvement of about 50%. Deep brain stimulation is usually performed in patients who have dystonia involving not only the neck but also other areas of the body or in patients who have severe complex dystonia with retrocollis, anterocollis, or complex jerking movements.
Deep brain stimulation is appropriate for patients who have an inadequate response to aggressive treatment with oral medications and botulinum toxin injections, those who have complex or difficult-‐to-‐treat cervical dystonia with retrocollis, anterocollis, or complex jerking, or those with more widespread dystonia. Deep brain stimulation may adversely affect cognitive abilities and as a result, patients should have intact memory and thinking abilities prior to surgery in order to minimize the risk of significantly adversely affecting cognition.
On average deep brain stimulation improves symptoms about 50%. The abnormal head position and tremulous movements may be improved, pain is typically markedly improved, and use of other medications may be reduced. Some patients who continue to respond to botulinum toxin injections prior to surgery may continue to receive injections but with an altered dose and pattern in order to maximize the benefit of the combined approach to treatment with both deep brain stimulation plus injection therapy. As a result of these improvements, patients may lead a more normal life and may have improvement in mood and anxiety.
The most severe complication seen from deep brain stimulation is hemorrhage in the brain during the surgical procedure. This risk is approximately 1 to 2% for each side of the brain operated. The result is similar to that seen with stroke and may result in trouble with language, vision, paralysis, or rarely even death. The implanted hardware may break or may become infected in up to 5 to 10% of patients at sometime during their lifetime. Most of these hardware complications or infections typically occur in the first two or three months aYer surgery, but rarely may occur months or years later. During the course of programming the stimulation parameters, numbness and tingling may occur in the body due to current spread to close-‐by fibers conveying sensory information in the brain. Similarly, slurred speech may occur due to occurring spread to the motor fibers to the face or throat.
Oral medications are usually used only in patients with more severe cervical dystonia who do not have an adequate response to treatment with botulinum toxin injections alone. Only a small minority, perhaps 20 or 25% of patients, demonstrate significant improvement with use of oral medications.