Deep brain stimulation

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Definition

In deep brain stimulation (DBS), electrodes are implanted within the brain to deliver a continuous low electric current to the target area. The current is passed to the electrodes through a wire running under the scalp and skin to a battery-powered pulse generator implanted in the chest wall.

Purpose

DBS is used to treat Parkinson's disease (PD) and essential tremor (ET). It has also been used to treat dystonia, chronic pain, and several other conditions

The movement disorders of PD and ET are due to loss of regulation in complex circuits within the brain that control movement. While the cause of the two diseases differ, in both cases, certain parts of the brain become overactive. Surgical treatment can include destruction of part of the overactive portion, thus rebalancing the regulation within the circuit. It was discovered that the same effect could be obtained by electrically stimulating the same areas, which is presumed to shut down the cells without killing them.

DBS may be appropriate for patients with PD or ET whose symptoms are not adequately controlled by medications. In PD, this may occur after five to ten years of successful treatment. Continued disease progression leads to decreased effectiveness of the main treatment for PD, levodopa. Increasing doses are needed to control symptoms, and over time, this leads to development of unwanted movements, or dyskinesias. Successful DBS allows a reduction in levodopa, diminishing dyskinesias.

For PD, deep brain stimulation is performed on either the globus pallidus internus (GPi) or the subthalamic nucleus (STN). Treatment of essential tremor usually targets the thalamus. Each of these brain regions has two halves, which control movement on the opposite side of the body: right controls left, and left controls right. Unilateral (onesided) DBS may be used if the symptoms are much more severe on one side. Bilateral DBS is used to treat symptoms on both sides.

Precautions

DBS is major brain surgery. Bleeding is a risk, and patients with bleeding disorders or who are taking blood thinning agents may require special management. DBS leaves metal electrodes implanted in the head, and patients are advised not to undergo diathermy (tissue heating) due to the risk of severe complications or death. Diathermy is used to treat chronic pain and other conditions. Special cautions are required for patients undergoing MRI after implantation.

Description

In DBS, a long thin electrode is planted deep within the brain, through a hole in the top of the skull. To make sure the electrode is planted in the proper location, a rigid "stereotactic frame" is attached to the patient's head before surgery. This device provides a three-dimensional coordinate system, used to locate the target tissue and to track the placing of the electrodes.

A single "burr hole" is made in the top of the skull for a unilateral procedure. Two holes are made for a bilateral procedure. This requires a topical anesthetic. General anesthesia is not used, for two reasons. First, the brain does not feel any pain. Second, the patient must be awake and responsive in order to respond to the neurosurgical team as they monitor the placement of the electrode. The target structures are close to several nerve tracts that carry information throughout the brain. Abnormalities in vision, speech, or other cognitive areas may indicate that the electrode is too close to one of these regions, and thus needs repositioning.

Other procedures may be used to ensure precise placement of the electrode, including electrical recording and injection of a contrast dye into the spinal fluid. The electrical recording can cause some minor odd sensations, but is harmless.

The electrode is connected by a wire to an implanted pulse generator. This wire is placed under the scalp and skin. A small incision is made in the area of the collarbone, and the pulse generator is placed there. This portion of the procedure is performed under general anesthesia.

Preparation

A variety of medical tests are needed before the day of surgery to properly locate the target (GPi, thalamus, or STN), and fit the frame. These may include CT scans, MRI, and injection of dyes into the spinal fluid or ventricles of the brain. The frame is attached to the head on the day of surgery, which may be somewhat painful, although the pain is lessened by local anesthetic. A mild sedative is given to ease anxiety.

Aftercare

Implantation of the electrodes, wire, and pulse generator is a lengthy procedure, and the patient will require a short hospital stay afterward to recovery from the surgery. Following this, the patient will meet several times with the neurologist to adjust the stimulator settings, in order to get maximum symptomatic improvement. The batteries in the pulse generator must be replaced every three to five years. This is done with a small incision as an outpatient procedure.

The patient's medications are adjusted after surgery. Most PD patients will need less levodopa after surgery, especially those who receive DBS of the STN.

Risks

Risks from DBS include the surgical risks or hemorrhage and infection, as well as the risks of general anesthesia. Patients who are cognitively impaired may become more so after surgery. Electrodes can be placed too close to other brain regions, which can lead to visual defects, speech problems, and other complications. If these occur, they may be partially reduced by adjusting the stimulation settings. DBS leaves significant hardware in place under the skin, which can malfunction or break, requiring removal or replacement.

Normal results

Deep brain stimulation improves the movement symptoms of PD by 25–75%, depending on how carefully the electrodes are placed in the optimal target area, and how effectively the settings can be adjusted. These improvements are seen most while off levodopa; DBS does little to improve the best response to levodopa treatment. DBS does allow a reduction in levodopa dose, which usually reduces dyskinesias by 50% or more. This is especially true for DBS of the STN; DBS of the GPi may lead to a smaller reduction. Levodopa dose will likely be reduced, leading to a significant reduction in dyskinesias.

DBS in essential tremor may reduce tremor in the side opposite the electrode by up to 80%.

Resources

BOOKS

Jahanshahi, M., and C. D. Marsden. Parkinson's Disease: A Self-Help Guide. New York: Demos Medical Press, 2000.

WEBSITES

National Parkinson's Disease Foundation. (December 4, 2003). www.npf.org.

WE MOVE. (December 4, 2003). www.wemove.org.

ORGANIZATIONS

International Essential Tremor Foundation. P.O. Box 14005, Lenexa, Kansas 66285-4005. 913-341-3880 or 888-387-3667; Fax: 913-341-1296. staff@essentialtremor.org. http://www.essentialtremor.org/.

Richard Robinson

Definition

Deep brain stimulation (DBS) delivers a constant low electrical stimulation to a small region of the brain, through implanted electrodes connected to an implanted battery. It is used to partially restore normal movements in Parkinson's disease, essential tremor, and dystonia.

Purpose

Parkinson's disease is due to degeneration of a group of cells called the substantia nigra. These cells interact with other brain regions to help control movement. The normal signals from the substantia nigra inhibit these other regions, and so when it degenerates, these regions become overactive. The electrical signals from the DBS electrodes mimic the inhibitory function of the substantia nigra, helping to restore more normal movements.

The substantia nigra normally releases the chemical dopamine, which exerts its inhibitory action on the globus pallidus interna (GPi) and the subthalamic nucleus (STN). For Parkinson's disease, deep brain stimulation is performed on these two centers. The target for DBS in dystonia is the GPi as well. Treatment of essential tremor usually targets the thalamus.

Each of these brain regions has two halves, which control movement on the opposite side of the body: right controls left, and left controls right. Unilateral DBS may be used if the symptoms are much more severe on one side. Bilateral DBS is used to treat symptoms on both sides.

Demographics

Parkinson's disease affects approximately one million Americans. The peak incidence is approximately age 62, but young-onset PD can occur as early as age 40. Because young-onset patients live with their disease for so many more years, they are more likely to become candidates for surgery than older-onset patients. In addition, younger patients tend to do better and have fewer adverse effects of surgery. Approximately 5% of older PD patients receive one form or another of PD surgery. Many more develop the symptoms for which surgery may be effective, but either develop them at an advanced age, making surgery inadvisable, or decide the risks of surgery are not worth the potential benefit, or do not choose surgery for some other reason.

Essential tremor is more common than Parkinson's disease, but rarely becomes severe enough to require surgery. Dystonia is a very rare condition, and the number of patients who have received DBS as of 2003 is under 100.

Description

Deep brain stimulation relies on implanting a long thin electrode deep into the brain, through a hole in the top of the skull. In order to precisely locate the target area and to ensure the probe is precisely placed in the target, a "stereotactic frame" is used. This device is a rigid frame attached to the patient's head, providing an immobile three-dimensional coordinate system, which can be used to precisely track the location of the GPi or STN and the movement of the electrode.

For unilateral DBS, a single "burr hole" is made in the top of the skull. Bilateral DBS requires two holes. A strong topical anesthetic is used to numb the skin while this hole is drilled. Since there are no pain receptors in the brain, there is no need for deeper anesthetic. In addition, the patient must remain awake in order to report any sensory changes during the surgery. The electrode is placed very close to several important brain structures. Sensory changes during electrode placement may indicate the electrode is too close to one or more of these regions.

Once the burr hole is made, the surgeon inserts the electrode. Small electric currents from the electrode are used to more precisely locate the target. This is harmless, but may cause twitching, light flashes, or other sensations. A contrast dye may also be injected into the spinal fluid, which allows the surgeon to visualize the brain's structure using one or more imaging techniques. The patient will be asked to make various movements to assist in determining the location of the electrode.

The electrode is connected by a wire to an implanted pulse generator. This wire is placed under the scalp and skin. A small incision is made in the area of the collarbone, and the pulse generator is placed there. This portion of the procedure is performed under general anesthesia.

Diagnosis/Preparation

DBS for Parkinson's disease is considered as an option in a patient who is still responsive to levodopa (used to treat symptoms) but has developed motor complications. These include the rapid loss of benefit from a single dose (wearing off), unpredictable fluctuations in benefit (on-off), and uncontrolled abnormal movements (dyskinesias). Essential tremor patients who are candidates for surgery are those whose tremor is unsatisfactorily controlled by medications and whose tremor significantly impairs activities of daily living. Similar criteria apply for dystonia patients.

The patient who is a candidate for DBS discusses all the surgical options with his neurologist before deciding on deep brain stimulation. A full understanding of the risks and potential benefits must be understood before consenting to the surgery.

The patient will undergo a variety of medical tests, and one or more types of neuroimaging procedures, including MRI, CT scanning, angiography (imaging the brain's blood vessels) and ventriculography (imaging the brain's ventricles). On the day of the surgery, the stereotactic frame is fixed to the patient's head. A local anesthetic is used at the four sites where the frame's pins contact the head; there may nonetheless be some initial discomfort. A final MRI is done with the frame in place, to set the coordinates of the targeted area of the brain in relation to the frame.

The patient will receive a mild sedative to ease the anxiety of the procedure. Once the electrodes are positioned, the patient receives general anesthetic to implant the pulse generator.

Aftercare

The procedure is lengthy, and the patient will require a short hospital stay afterward to recover from the surgery. Following the procedure itself, the patient meets several times with the neurologist to adjust the stimulation. The pulse generator is programmable, and can be fine-tuned to the patient's particular needs. This can provide a higher degree of symptom relief than lesioning surgeries, but requires repeated visits to the neurologist. Pulse generator batteries must be replaced every three to five years. This is done with a small incision as an outpatient procedure. Since the generator is in the chest area, no additional brain surgery is required.

The patient's medications are adjusted after surgery, with a reduction in levodopa likely in most patients who receive DBS of the subthalamic nucleus.

Risks

Deep brain stimulation entails several risks. There are acute surgical risks, including hemorrhage and infection, and the risks of general anesthesia. The electrodes can be placed too close to other brain regions, which can lead to visual defects, speech problems, and other complications. These may be partially avoided by adjusting the stimulation settings after the procedure. Because a device is left implanted under the skin, there is the risk of breakage or malfunction, which requires surgical removal.

A patient with implanted electrodes must not receive diathermy therapy. Diathermy is the passage of radiowaves through the tissue to heat it, and is used as a physical therapy for muscle pain and other applications. Diathermy poses a risk of death in a patient with DBS electrodes.

Patients who are cognitively impaired may become more so after surgery, and cognitive impairment usually prevents a patient from undergoing surgery.

Normal Results

Deep brain stimulation improves the movement disorder symptoms of Parkinson's disease by 25–75%, depending on the care of the placement and the ability to find the optimum settings. These improvements are seen most while off levodopa; DBS does little to improve the best response to levodopa treatment. Levodopa dose will likely be reduced, leading to a significant reduction in dyskinesias.

Morbidity and Mortality Rates

The rate of complications depends highly on the skill and experience of the surgical team performing the procedure. Rates from one of the most experienced teams, in a study of over 200 patients, were as follows.

Post-operative complications:

• asymptomatic intracranial bleed (10% of procedures)
• symptomatic intracranial bleed (2%)
• seizures (3%)
• headache (25%)
• infection (6%)

Device-related complications:

• lead replacements (9%)
• lead repositionings (8%)
• extension wire replacements (6%)
• implantable pulse generator replacements (17%), approximately half of which were due to malfunction

The risk of death is less than 1%.

Alternatives

Patients who are candidates for deep brain stimulation have usually been judged to require surgery for effective treatment of their symptoms. Other surgical alternatives for Parkinson's disease include pallidotomy and thalamotomy, which destroy brain tissue to achieve the same effect as the stimulation. Pallidotomy is rarely performed for Parkinson's disease, unless tremor is the only debilitating symptom. It is common in essential tremor. DBS for dystonia is the only really promising neurosurgical treatment for this condition. Some peripheral surgeries may be appropriate for selected patients.

Resources

Books

Jahanshahi, M., and C. D. Marsden. Parkinson's Disease: ASelf-Help Guide. New York: Demos Medical Press, 2000.

Organizations

National Parkinson's Disease Foundation. Bob Hope Parkinson Research Center, 1501 N.W. 9th Avenue, Bob Hope Road, Miami, FL 33136-1494. (305) 547-6666. (800) 327-4545. Fax: (305) 243-4403. http://www.parkinson.org.

WE MOVE, Worldwide Education and Awareness for Movement Disorders. 204 West 84th Street, New York, NY 10024. (800) 437-MOV2, Fax: (212) 875-8389. http://www.wemove.org.

— Richard Robinson

In neurotechnology, deep brain stimulation (DBS) is a surgical treatment involving the implantation of a medical device called a brain pacemaker, which sends electrical impulses to specific parts of the brain. DBS in select brain regions has provided remarkable therapeutic benefits for otherwise treatment-resistant movement and affective disorders such as chronic pain, Parkinson’s disease, tremor and dystonia.^[1] Despite the long history of DBS,^[2] its underlying principles and mechanisms are still not clear. DBS directly changes brain activity in a controlled manner, its effects are reversible (unlike those of lesioning techniques) and is one of only a few neurosurgical methods that allows blinded studies.

The Food and Drug Administration (FDA) approved DBS as a treatment for essential tremor in 1997, for Parkinson's disease in 2002,^[3] and dystonia in 2003.^[4] DBS is also routinely used to treat chronic pain and has been used to treat various affective disorders, including major depression. While DBS has proven helpful for some patients, there is potential for serious complications and side effects.

Contents 1 Components and placement 2 Biochemistry 3 Applications 3.1 Parkinson's disease 3.2 Major depression 3.3 Tourette syndrome 3.4 Other clinical applications 4 Potential complications and side effects 5 See also 6 Notes 7 References 8 External links

Components and placement

The deep brain stimulation system consists of three components: the implanted pulse generator (IPG), the lead, and the extension. The IPG is a battery-powered neurostimulator encased in a titanium housing, which sends electrical pulses to the brain to interfere with neural activity at the target site. The lead is a coiled wire insulated in polyurethane with four platinum iridium electrodes and is placed in one of three areas of the brain. The lead is connected to the IPG by the extension, an insulated wire that runs from the head, down the side of the neck, behind the ear to the IPG, which is placed subcutaneously below the clavicle or in some cases, the abdomen.^[5] The IPG can be calibrated by a neurologist, nurse or trained technician to optimize symptom suppression and control side effects.^[6]

DBS leads are placed in the brain according to the type of symptoms to be addressed. For non-Parkinsonian essential tremor the lead is placed in the ventrointermedial nucleus (VIM) of the thalamus. For dystonia and symptoms associated with Parkinson's disease (rigidity, bradykinesia/akinesia and tremor), the lead may be placed in either the globus pallidus or subthalamic nucleus.^[7]

All three components are surgically implanted inside the body. Under local anesthesia, a hole about 14 mm in diameter is drilled in the skull and the electrode is inserted, with feedback from the patient for optimal placement. The installation of the IPG and lead occurs under general anesthesia.^[8] The right side of the brain is stimulated to address symptoms on the left side of the body and vice versa.

Biochemistry

It has been shown in thalamic slices from mice^[9] that DBS causes nearby astrocytes to release adenosine triphosphate (ATP), a precursor to adenosine (through a catabolic process). In turn, adenosine A1 receptor activation depresses excitatory transmission in the thalamus, thus causing an inhibitory effect that mimicks ablation or "lesioning".

Applications

Parkinson's disease

Insertion of electrode during surgery

Parkinson's disease (also known as paralysis agitans) is a neurodegenerative disease whose primary symptoms are tremor, rigidity, bradykinesia and postural instability.^[10] DBS does not cure Parkinson's, but it can help manage some of its symptoms and subsequently improve the patient’s quality of life.^[11] At present, the procedure is used only for patients whose symptoms cannot be adequately controlled with medications, or whose medications have severe side effects.^[5] Its direct effect on the physiology of brain cells and neurotransmitters is currently debated, but by sending high frequency electrical impulses into specific areas of the brain it can mitigate symptoms^[12] and/or directly diminish the side effects induced by Parkinsonian medications,^[13] allowing a decrease in medications, or making a medication regimen more tolerable.

There are a few sites in the brain that can be targeted to achieve differing results, so each patient must be assessed individually, and a site will be chosen based on their needs. Traditionally, the two most common sites are the subthalamic nucleus (STN) and the globus pallidus interna (GPi), but other sites, such as the caudal zona incerta and the pallidofugal fibers medial to the STN, are being evaluated and showing promise.^[14]

Research is being conducted as of 2007 to predict the onset of tremors before they occur by monitoring activity in the subthalamic nucleus. The goal is to provide stimulating pulses only when they are needed, to stop any tremors occurring before they start.^[15]

DBS is approved in the United States by the Food and Drug Administration for the treatment of Parkinson's.^[3] DBS carries the risks of major surgery, with a complication rate related to the experience of the surgical team.

Major depression

There is insufficient evidence to support DBS as a therapeutic modality for depression, however, the procedure may be an effective treatment modality in the future.^[16] Researchers reported in 2005 that electrical stimulation of a small area of the frontal cortex brought about a "striking and sustained remission" in four out of six patients suffering from major depression. Their symptoms had previously been resistant to medication, psychotherapy and electroconvulsive therapy.^[17]

Using brain imaging, the researchers had noticed that activity in the subgenual cingulate region (SCR or Brodmann area 25)—the lowest part of a band of tissue that runs along the midline of the brain—seemed to correlate with symptoms of sadness and depression. They implanted electrodes into six patients while they were locally anesthetised, but alert. While the current was switched on, four of the patients reported feeling a black cloud lifting, and became more alert and interested in their environments. The changes reversed when the current was switched off.^[17]

The effects of continuous SCR stimulation have produced sustained remission from depression in the four patients for six months. When reporting the results, the team did caution that the trial was so small that the findings must be considered only provisional.^[17]

Another hypothetically interesting site for DBS in depression is the nucleus accumbens,^[18] as that region appears to be associated with pleasure and reward mechanisms. A 2007 study reported that experimental use of deep brain stimulation of the nucleus accumbens showed promising results, with patients suffering from profound depression reporting relief from their symptoms.^[19]

Tourette syndrome

Deep brain stimulation has been used experimentally in treating a few patients with severe Tourette syndrome. Despite widely publicized early successes, DBS remains a highly experimental procedure for the treatment of Tourette's, and more study is needed to determine whether long-term benefits outweigh the risk.^[20] The procedure is well tolerated, but complications include "short battery life, abrupt symptom worsening upon cessation of stimulation, hypomanic or manic conversion, and the significant time and effort involved in optimizing stimulation parameters".^[21] As of 2006, there were five published reports of DBS in patients with TS; all experienced reduction in tics and the disappearance of obsessive-compulsive behaviors. "Only patients with severe, debilitating, and treatment-refractory illness should be considered; while those with severe personality disorders and substance abuse problems should be excluded."^[21] There may be serious short- and long-term risks associated with DBS in persons with head and neck tics. The procedure is invasive and expensive, and requires long-term expert care. Benefits for severe Tourette's are not conclusive, considering less robust effects of this surgery seen in the Netherlands. Tourette's is more common in pediatric populations, tending to remit in adulthood, so this would not generally be a recommended procedure for use on children. Because diagnosis of Tourette's is made based on a history of symptoms rather than analysis of neurological activity, it may not always be clear how to apply DBS for a particular patient. Due to concern over the use of DBS in the treatment of Tourette syndrome, the Tourette Syndrome Association convened a group of experts to develop recommendations guiding the use and potential clinical trials of DBS for TS.^[22]

Other clinical applications

In August 2007, Nature reported that scientists in the US had stimulated a 38-year-old man who had been in a minimally conscious state for six years using DBS.^[23] The patient initially had increased arousal and sustained eye-opening, as well as rapid bilateral head-turning to voice. After further stimulation, the previously non-verbal patient became capable of naming objects and using objects with his hands—for example, bringing a cup to his mouth. Moreover, he could swallow food and take meals by mouth, meaning he was no longer dependent on a gastrostomy tube.^[24]

This result follows research carried out over 40 years, which has analyzed the effects of deep brain stimulation in the thalamus (and elsewhere) in patients with post-traumatic coma.^[25][26][27] While this research has shown some potential, deep brain stimulation is not yet a reliable cure for patients in post-traumatic coma.

DBS has been used in the treatment of obsessive-compulsive disorder^[28] and phantom limb pain.^[29] Although the clinical efficacy is not questioned, the mechanisms by which DBS works are still debated.^[30] Long-term clinical observation has shown that the mechanism is not due to a progressive lesion, given that interruption of stimulation reverses its effects.^[30] Results of DBS in dystonia patients, where positive effects often appear gradually over a period of weeks to months, indicate a role of functional reorganization in at least some cases.^[31] The procedure is being tested for effectiveness in patients with severe epilepsy.^[32]

DBS has been tried for patients with Lesch-Nyhan syndrome in Japan, Switzerland and France.^{[citation needed]}

Potential complications and side effects

While DBS is helpful for some patients, there is also the potential for neuropsychiatric side effects. Reports in the literature describe the possibility of apathy, hallucinations, compulsive gambling, hypersexuality, cognitive dysfunction, and depression. However, these may be temporary and related to correct placement and calibration of the stimulator and so are potentially reversible.^[33] A recent trial of 99 Parkinson's patients who had undergone DBS suggested a decline in executive functions relative to patients who had not undergone DBS, accompanied by problems with word generation, attention and learning. About 9% of patients had "psychiatric events", which ranged in severity from a relapse in voyeurism to a suicide attempt. Most patients in this trial reported an improvement in their quality of life following DBS, and there was an improvement in their physical functioning.^[34]

Because the brain can shift slightly during surgery, there is the possibility that the electrodes can become displaced or dislodged. This may cause more profound complications such as personality changes, but electrode misplacement is relatively easy to identify using CT or MRI. There may also be complications of surgery, such as bleeding within the brain.

After surgery, swelling of the brain tissue, mild disorientation and sleepiness are normal. After 2–4 weeks, there is a follow-up to remove sutures, turn on the neurostimulator and program it.

See also

• Neurosurgery
• Stereotactic surgery
• Psychosurgery
• Neuroprosthetics
• Brain implant
• Vagus nerve stimulation

Notes

1. ^ Kringelbach ML, Jenkinson N, Owen SLF, Aziz TZ (2007). "Translational principles of deep brain stimulation". Nature Reviews Neuroscience. 8:623–635. PMID 17637800.
2. ^ Gildenberg PL (2005). "Evolution of neuromodulation". Stereotact Funct Neurosurg, 83(2–3), 71–79. PMID 16006778.
3. ^ ^{a b} U.S. Department of Health and Human Services.FDA approves implanted brain stimulator to control tremors. Retrieved October 18, 2006.
4. ^ 'Brain pacemaker' treats dystonia. KNBC TV, April 22, 2003. Retrieved October 18, 2006.
5. ^ ^{a b} National Institute of Neurological Disorders and Stroke. Deep brain stimulation for Parkinson's Disease information page. Retrieved 23 November 2006.
6. ^ Volkmann J, Herzog J, Kopper F, Deuschl G. "Introduction to the programming of deep brain stimulators". Mov Disord. 2002 17, S181–187. PMID 11948775.
7. ^ Deep brain stimulation. Surgery Encyclopedia. Retrieved January 25, 2007.
8. ^ Deep Brain Stimulation, Department of Neurological Surgery, University of Pittsburgh. Retrieved 13 May 2008.
9. ^ Bekar L, Libionka W, Tian G, et al. (2008). "Adenosine is crucial for deep brain stimulation–mediated attenuation of tremor". Nature Medicine 14 (1): 75–80. doi:10.1038/nm1693. 
10. ^ Ropper (2005), p. 916
11. ^ Kleiner-Fisman G, Herzog J, Fisman DN, et al. "Subthalamic nucleus deep brain stimulation: summary and meta-analysis of outcomes." Mov Disord. 2006 Jun;21 Suppl 14:S290–304 PMID 16892449
12. ^ Moro E, Lang AE. "Criteria for deep-brain stimulation in Parkinson's disease: review and analysis". Expert Review of Neurotherapeutics. 2006 Nov;6(11):1695–705. PMID 17144783
13. ^ Apetauerova D, Ryan RK, Ro SI, Arle J, et al. "End of day dyskinesia in advanced Parkinson's disease can be eliminated by bilateral subthalamic nucleus or globus pallidus deep brain stimulation". Movement Disorders. 2006 Aug;21(8):1277–9. PMID 16637040
14. ^ Plaha P, Ben-Shlomo Y, Patel NK, Gill SS. "Stimulation of the caudal zona incerta is superior to stimulation of the subthalamic nucleus in improving contralateral parkinsonism". Brain (2006). 129, 1732–1747 PMID 16720681
15. ^ The blade runner generation. The Sunday Times, July 22, 2007. Retrieved on 2008-03-20.
16. ^ Curr Opin Psychiatry. 2009 May;22(3):306–11
17. ^ ^{a b c} Mayberg HS, Lozano AM, Voon V, McNeely HE, Seminowicz D, Hamani C, Schwalb JM, Kennedy SH (March 3, 2005). "Deep brain stimulation for treatment-resistant depression". Neuron. 45(5):651–60. PMID 15748841.
18. ^ Schlaepfer TE, Lieb K. "Deep brain stimulation for treatment of refractory depression". Lancet. 2005 Oct 22-28;366(9495):1420–2. PMID 16243078.
19. ^ Schlaepfer TE, Cohen MX, Frick C, Kosel M, Brodesser D, Axmacher N, Joe AY, Kreft M, Lenartz D, Sturm V. "Deep Brain Stimulation to Reward Circuitry Alleviates Anhedonia in Refractory Major Depression". Neuropsychopharmacology. 2007 Apr 11. PMID 17429407.
20. ^ Tourette Syndrome Association. Statement: Deep Brain Stimulation and Tourette Syndrome. Retrieved November 22, 2005.
21. ^ ^{a b} Malone DA Jr, Pandya MM (2006). "Behavioral neurosurgery". Adv Neurol. 99:241–7. PMID 16536372
22. ^ Mink JW, Walkup J, Frey KA, et al. (November 2006). "Patient selection and assessment recommendations for deep brain stimulation in Tourette syndrome". Mov Disord. 21(11):1831–8. PMID 16991144
23. ^ Implant boosts activity in injured brain. Nature news (1 August 2007). Retrieved on 2007-08-01
24. ^ Schiff N. D. et al. "Behavioural improvements with thalamic stimulation after severe traumatic brain injury". Nature. 448, 600–3. (2007) PMID 17671503
25. ^ Tsubokawa T, Yamamoto T, Katayama Y, Hirayama T, Maejima S, Moriya T. "Deep-brain stimulation in a persistent vegetative state: follow-up results and criteria for selection of candidates". Brain Inj. 1990 Oct-Dec;4(4):315–27. PMID 2252964
26. ^ Sturm V, Kühner A, Schmitt HP, Assmus H, Stock G. "Chronic electrical stimulation of the thalamic unspecific activating system in a patient with coma due to midbrain and upper brain stem infarction". Acta Neurochir (Wien). 1979;47(3–4):235–44. PMID 314229
27. ^ Hassler R, Dalle Ore G, Dieckmann G, Bricolo A, Dolce G. "Behavioural and EEG arousal induced by stimulation of unspecific projection systems in a patient with post-traumatic apallic syndrome". Electroencephalogr. Clin. Neurophysiol. 27, 306–310 (1969). PMID 4185661
28. ^ Nuttin B, Cosyns P, Demeulemeester H, Gybels J, Meyerson B (1999). "Electrical stimulation in anterior limbs of internal capsules in patients with obsessive-compulsive disorder". Lancet. 1999 Oct 30;354(9189):1526 PMID 10551504
29. ^ Kringelbach, Morten L. et al. (2007). "Deep brain stimulation for chronic pain investigated with magnetoencephalography". Neuroreport, 18(3), pp. 223–228.
30. ^ ^{a b} Benabid AL, Wallace B, Mitrofanis J, Xia R, Piallat B, Chabardes S, Berger F. (2005). "A putative generalized model of the effects and mechanism of action of high frequency electrical stimulation of the central nervous system". Acta Neurol Belg. 2005 Sep;105(3):149–57. PMID 16255153
31. ^ Krauss JK (2002). "Deep brain stimulation for dystonia in adults. Overview and developments". Stereotactic and Functional Neurosurgery 78 (3–4): 168–182. doi:10.1159/000068963. PMID 12652041. 
32. ^ Velasco F, Velasco M, Velasco AL, Jimenez F, Marquez I, Rise M (1995). "Electrical stimulation of the centromedian thalamic nucleus in control of seizures: long-term studies". Epilepsia 36: 63–71. PMID 8001511
33. ^ Burn D, Troster A (2004). "Neuropsychiatric Complications of Medical and Surgical Therapies for Parkinson's Disease". Journal of Geriatric Psychiatry and Neurology 17 (3): 172–180. doi:10.1177/0891988704267466. PMID 15312281. 
34. ^ Smeding H, Speelman J, Koning-Haanstra M, et al. (2006). "Neuropsychological effects of bilateral STN stimulation in Parkinson disease: A controlled study". Neurology 66 (12): 1830–1836. doi:10.1212/01.wnl.0000234881.77830.66. PMID 16801645. 

References

• Appleby BS, Duggan PS, Regenberg A, Rabins PV (2007). "Psychiatric and neuropsychiatric adverse events associated with deep brain stimulation: A meta-analysis of ten years' experience". Movement Disorders 22:1722–1728 PMID 17721929
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External links

• Deep brain stimulation for movement disorders

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