Update on deep brain stimulation at Mayo Clinic

Secured stimulation electrode attached to pulse generator

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Final lead placement in motor cortex stimulation for neuropathic pain

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Final lead placement in motor cortex stimulation for neuropathic pain

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Point to remember

• The goal of deep brain stimulation and motor cortex stimulation is to restore function or relieve pain by stimulating neural activity through surgically implanted electrodes.

Developed in the 1980s, deep brain stimulation (DBS) was principally used to treat movement disorders associated with essential tremor (ET) and Parkinson's disease (PD). Today, its applications include other types of movement disorders and certain nonmotor syndromes and conditions.

Successful DBS depends on careful patient selection, precise neural targeting, and extensive, individualized programming. It is generally reserved for symptoms that are unresponsive to other therapies.

For 14 years, neurologists, neurosurgeons, and members of the multidisciplinary DBS teams across Mayo Clinic's 3 sites have gained experience, conducted research, and explored new clinical applications. Overall, they agree that for certain disorders in carefully selected patients, DBS and motor cortex stimulation (MCS) can markedly improve patient lives. The following update summarizes their findings and experience during the past several years.

Treatment of primary disorders

Essential tremor
DBS for ET continues to have positive results, and other types of tremor are being addressed. Recently, Mayo physicians have reported success in using DBS to treat both orthostatic tremor, a variant of ET that affects the lower limbs on standing and spreads up the trunk, and rubral tremor, a rare tremor associated with the red nucleus.

Parkinson's disease
In the right patients, DBS continues to be effective in improving motor function and in reducing dyskinesias and symptom fluctuations related to on-off medication effects. The main indication is the patient's need for increased frequency and levels of medication. Previously reserved for patients under the age of 70 years, DBS is now offered by Mayo Clinic physicians to selected older PD patients, some in their 80s.

Dystonia
Patients with focal and generalized dystonia represent a large percentage of patients treated with DBS at Mayo Clinic. Good results have been reported using DBS for early-onset primary dystonia or early-onset torsion dystonia. Most patients with other forms of dystonia are helped, although the response may not be dramatic. To improve outcomes, the Mayo Clinic DBS team is considering transcortical magnetic stimulation for some dystonias.

Possible future applications

Epilepsy
Mayo Clinic has completed a study of neurostimulation for focal epilepsy. Although the results are not yet in, several study participants whose seizures were intractable have become seizure-free.

Motor cortex stimulation to treat centrally mediated facial pain

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Centrally mediated neuropathic pain
Treatment of centrally mediated pain is experimental. The results at Mayo for trigeminal autonomic cephalgia, including cluster headaches, have been mixed. The use of preoperative positron emission tomography scans to determine if hypothalamic sites should be stimulated unilaterally or bilaterally in a given patient is under consideration. Mayo physicians note that intractable face pain in the distribution of the trigeminal nerve may respond to MCS.

Psychiatric disorders
Mayo researchers have performed DBS in patients with Tourette syndrome, considered both a movement and a psychiatric disorder. They are exploring DBS for other types of tics and are in the early stages of investigating neurostimulation for depression and obsessive-compulsive disorder.

Potential secondary symptom benefits

Restless legs syndrome
Although DBS has not been used as a primary treatment for restless legs syndrome, Mayo researchers note that there is often a post-DBS reduction in restless legs associated with PD, a finding they confirmed in a retrospective study. Early study results and other case studies suggest DBS may be a promising option for primary treatment of restless legs syndrome.

Spasmodic dysphonia
In 2008, Mayo researchers presented the first report on improved vocal control in a patient with spasmodic dysphonia—a primary focal dystonia of the vocal muscles during speech. Noting that there are now a growing number of reports of DBS for spasmodic dysphonia outside the United States, Mayo Clinic may explore this application in the future.