Deep brain stimulation (DBS)

Overview

Deep brain stimulation (DBS) has proven to be extremely beneficial for people suffering from a variety of neurologic conditions. DBS was originally licensed in the 1990s for the treatment of movement disorders. DBS includes the insertion of electrodes near deep brain regions. These electrodes are then connected to a pulse generator that is implanted subcutaneously into the chest wall. A computer controls the pulse generator, which eventually instructs the electrodes to fire.

What is Deep brain stimulation (DBS)?

Deep brain stimulation (DBS) is a neurosurgical treatment that treats movement problems associated with Parkinson's disease (PD), essential tremor, dystonia, and other neurological illnesses with implanted electrodes and electrical stimulation.

Electrical brain manipulation has frequently been the subject of scientific study since the late nineteenth century discovery of localized activation of the motor cortex. Following the discovery of the electrical properties of the motor cortex, cortical function mapping was completed. This was followed by the discovery of deep brain regions using intraoperative stimulation in the 1950s.

Over the next decade, theories of treating neurologic diseases with continuous stimulation began to develop. Documentation of the use of persistent stimulation to treat pain, movement problems, and epilepsy was available by the 1970s. Deep brain stimulation (DBS) was eventually discovered in the 1990s by merging implantable pacemaker technology with chronically implanted deep electrodes.

Anatomy and Physiology

The deep brain stimulation (DBS) equipment comprises of electrodes implanted near to certain deep brain areas, which are subsequently linked through a subcutaneous cable to a pacemaker-like machine (pulse generator) placed on the chest wall. A computer then relays stimulation settings to the pulse generator, providing correct amplitudes, frequencies, and pulse width. DBS commonly targets the subthalamic nucleus (STN), globus pallidus interna (GPi), and ventral intermediate nucleus of the thalamus.

The specific mechanism of deep brain stimulation's therapeutic benefits is unknown; nonetheless, ideas abound. As shown by the list of probable applications, activation of deep brain areas alters a wide range of circuits involved in neuronal activity.

Therapeutic effects are dependent on the physiologic qualities of cells, the surface areas of stimulated structures, the magnitude and timing of the stimulation, and, finally, the underlying pathophysiology of various disease situations. Imaging and physiologic investigations support the theory that the ultimate result of deep brain stimulation is increased firing of the targeted neurons.

Deep brain stimulation benefits

DBS is a surgical technique that is performed in a minimally invasive manner. Most importantly, it is beneficial in the treatment of Parkinson's disease patients. DBS's key benefits are its reversibility and adaptability. DBS leads are inserted into the target(s), allowing stimulation parameters to be adjusted in response to changes in the patient's condition. If DBS causes undesired side effects, it can be turned off, modified, or deleted. If DBS is found to be clinically unsuccessful, the patient has not sustained an irreparable brain injury.

Additional benefits include the capacity to intervene at sites that cannot or should not be treated with neuroablative lesion surgery and the possibility to research human basal ganglia physiology in a unique setting.

The primary downside of DBS is its high cost. At the moment, the gadget costs around $10,000 per unit. Another downside is the increased risk of infection owing to the presence of implanted hardware, as well as the cost of maintenance (eg, repair or replacement of fractured wires or repeated office visits for stimulation adjustments). Currently, battery exhaustion mandates the replacement of the whole pulse generator, the system's most expensive component (costing around $8000), every few years.

Deep brain stimulation Indications

The United States Food and Drug Administration (FDA) has authorized deep brain stimulation (DBS) for the treatment of essential tremors, dystonia, Parkinson disease, and treatment-refractory obsessive-compulsive disorder (OCD).

DBS technology has grown in application and utilization since its early phases of discovery. The first applications of DBS were for the treatment of essential tremor (ET) and Parkinson's disease tremor (PD). DBS stimulation of the "ventral intermediate nucleus of the thalamus" leads in an average tremor reduction of more than 80%.

Stimulation of the globus pallidus internus has been shown to reduce key motor symptoms of Parkinson's disease, including but not limited to dopaminergic caused dyskinesias. By regulating the firing frequency of the malfunctioning GPi, stimulation of the GPi is thought to alleviate parkinsonian akinesia and stiffness. The stimulation of the subthalamic nucleus has been demonstrated to improve gait, tremor, and bradykinesia. The parafascicular and sensory relay nuclei of the thalamus have been shown to have analgesic effects.

The first psychiatric indication for DBS was reported in 1999. Many research concentrating on DBS for treatment-resistant mental diseases have been conducted since that first publication. DBS has recently been shown to be useful in Tourette Syndrome by stimulating the centromedian-parafascicular complex of the thalamus, as well as the GPi and the anterior limb of the internal capsule.

The use of DBS for obsessive-compulsive disorder (OCD) and treatment-refractory depression is perhaps the most notable. DBS of the subgenual cingulate white matter has been proven to enhance mood in those suffering from treatment-resistant depression, whilst DBS of the bilateral anterior limbs of the internal capsules has been reported to reduce OCD-related symptoms.

Evidence demonstrating the resolution of OCD symptoms by targeting either the ventral capsule/ventral striatum or the STN led to the FDA's approval of DBS for treatment-resistant OCD in 2009. In 2009, DBS was used for the first time to treat treatment-resistant depression (TRD). TRD therapeutic targets include the subgenual anterior cingulate cortex, ventral capsule/ventral striatum, nucleus accumbens, and medial forebrain bundle. Addiction, autism, anorexia nervosa, anxiety disorders, and schizophrenia are among the future psychiatric indications being researched.

Deep brain stimulation for Parkinson's Disease

Three types of PD patients typically benefit from DBS:

Patients with uncontrolled tremor who have failed to respond to medicines.
Patients who have symptoms that respond well to medications but experience severe motor fluctuations and dyskinesias when the medications wear off, despite medication adjustments.
Patients with movement symptoms who may benefit from greater or more frequent treatment dosages but are unable to do so due to adverse effects.

Essential Tremor

The most common movement problem is essential tremor, and DBS can be a successful therapy, especially in severe instances where the shaking can be burdensome, affecting daily functions such as dressing, grooming, eating, or drinking. Because tremor is the only symptom of essential tremor, DBS can enhance people's lives and allow them to function properly.

Dystonia

Dystonia is a rare movement illness, but its symptoms, which include aberrant postures and twisting motions, can respond to DBS when drugs fail to give significant relief. The response of a person to DBS is determined by the underlying etiology of the dystonia, which might be hereditary, drug-induced, or another condition. If the reason is unknown, the doctor will most likely order more tests as part of the DBS workup.

Psychiatric Conditions

Recent research suggests that persons suffering from depression, obsessive-compulsive disorder (OCD), or Tourette syndrome may benefit from DBS surgery. More study is needed to discover whether DBS is beneficial in the treatment of mental diseases and whether any benefits exceed the dangers and adverse effects.

Deep brain stimulation Contraindications

There are few absolute contraindications to deep brain stimulation (DBS). DBS is not recommended for patients who are unable to correctly use the neurostimulator. Patients using deep brain stimulators should avoid full-body MRIs, transcranial magnetic stimulation, and diathermy once they have been implanted.

Testing Before Deep Brain Stimulation

In the case of Parkinson's disease, the doctor must establish that the condition is levodopa-responsive and assess which symptoms are most likely to respond to DBS, which he or she must discuss with the patient.

To achieve these two goals, the movement disorders neurologist will assess the patient without his or her PD drugs, then again after taking them. Observing the effect of Parkinson's disease drugs on movement and non-motor symptoms assists the clinician and patient in identifying suitable target symptoms for DBS.

A cognitive exam can assist establish a person's capacity to engage in the operation, which entails providing input to the clinician during surgery and the neurostimulator adjustment process. This examination also informs the team of the possibility of exacerbated disorientation or cognitive issues as a result of the surgery.

Some hospitals will also do an occupational therapy review or a speech, language, and swallowing evaluation. Before the DBS operation, a psychiatrist may assess the person to see if a problem such as depression or anxiety warrants therapy.

Special Precautions After Deep Brain Stimulation

In general, people who have had DBS surgery should:

Always carry an ID card indicating that they have a DBS neurostimulator. They may also choose to wear a medical identity bracelet with this information.
People who use a neurostimulator should notify airport security screeners before passing through the scanners. Many airport detectors are safe for pacemakers, but the little quantity of metal in the neurostimulator may cause the alert to go off. Patients who are chosen for additional screening with hand-held detector devices should politely remind the screeners that the detector wand should not be held over the neurostimulator for more than a few seconds, as these devices contain magnets that may interfere with the neurostimulator's function or programming.
Certain MRI treatments may not be performed on patients who have leads or neurostimulators. Patients should always consult their doctor before undergoing any sort of MRI, while DBS can be compatible with MRI in specific instances. They should avoid areas with strong magnetic fields, such as power generators and car junkyards that employ enormous magnets.
Patients who have had DBS surgery should avoid utilizing heat to treat muscles in physical therapy.
High-voltage or radar gear, such as radio or television transmitters, electric arc welders, high-tension lines, radar stations, or smelting furnaces, should also be avoided.
If a patient is scheduled for a surgical operation, they should notify their surgeon well in advance that they have a neurostimulator. It is critical to get guidance on additional precautions before and during surgery, as equipment such as the electrocautery device used to control bleeding may interfere with the neurostimulator.
Patients should protect the neurostimulator region from injuries when engaging in physical, recreational, or sports activities. A hit to the chest near the pacemaker might disrupt its operation and necessitates a trip to the doctor.

Deep brain stimulation surgery

Once the operation begins, the surgical team will equip the patient with a specific frame that will restrain head movement during the procedure. This is referred to as a stereotactic head frame. Surgery is often conducted under general anesthesia, however, local anesthetic is sometimes an option. Surprisingly, the brain does not require an anesthetic since it lacks pain receptors. The surgeon next inserts a tiny wire lead into the sites indicated prior to surgery.

The aforementioned structures will be contacted by tiny electrodes at the wire's end. The lead is then linked to a cable that goes just beneath the skin and eventually attaches to a pulse generator within the chest wall. Throughout the treatment, the neurosurgeon and neurologist will continuously evaluate brain activity to ensure proper electrode placement.

The pulse generator is then placed slightly beneath the skin near the collarbone during the subsequent chest wall surgery. In contrast to the previous treatment, chest wall surgery necessitates general anesthesia. After then, the pulse generator is linked to a specific remote control.

The initial step of DBS for Parkinson's disease (PD), like most stereotactic movement disorder treatments, is conducted with the patient awake to allow monitoring of the neurologic condition. On the morning of the surgery, the stereotactic headframe is attached to the patient's head, and a targeting MRI is done.

To refine the intended target physiologically, a combination of microelectrode recording (MER) and macroelectrode stimulation is employed. The DBS lead is fastened to the skull with a burr hole cap once it has been inserted.

Implantation of lead

A numbing agent will be injected into your scalp, and a head frame will be used to maintain your head in the proper position for the treatment. To determine the target region in the brain for the electrode, a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan will be performed.
You will be awake during the procedure because you will be asked to move various portions of your body when the lead is put.
After injecting additional numbing medication into your scalp, the neurosurgeon will drill a tiny hole in your skull to place the lead.
As the lead is pushed through the brain tissue, recordings will be made to assist determine the exact location of the lead. During the recording, you may be requested to move your face, arm, or leg at various points.
Once the lead's precise position has been confirmed, it will be connected to an external neurostimulator. Electrical stimulation will be administered via the lead for a brief period of time to assess if symptoms improve. To ensure that the lead is in the proper position, your surgeon may purposefully induce adverse effects with electrical stimulation.
The lead will be connected once it has been placed in the right area. A wire to link the lead to an extension to the neurostimulator will be put beneath the scalp.
A plastic cap and sutures will be used to seal the hole in the skull.

Placement of the neurostimulator

This may or may not be done at the same time the electrode is placed.

You will be given general anesthetic, which will put you to sleep during the surgery.
The neurostimulator will be implanted into a "pocket" beneath the outer layers of epidermal tissue, generally immediately behind the collarbone, but also in the chest or belly.
The neurostimulator and the brain lead will be connected by an extension wire.
The neurostimulator is designed to give an electrical signal once it is implanted. The neurostimulator is normally programmed a few weeks after it is placed.

After Deep Brain Stimulation Surgery

In the Hospital

In usual, the hospital stay following DBS surgery is 24 hours, however this might vary depending on how fast the patient heals and is ready to go home. The doctor will pay a visit to confirm that the patient is ready to go and will offer instructions for home care.

At Home

It is critical to keep the incisions clean and dry at home. While the surgical site heals, the doctor will instruct the patient on how to bathe. If sutures are used, they will be removed during a subsequent appointment visit. If adhesive strips are present, they should be kept dry and will usually peel off within a few days.

The patient will be given a magnet that may be used to switch on or off the neurostimulator under doctor-prescribed settings.

Deep Brain Stimulation Complications

The side effect profile of deep brain stimulation is also ambiguous. Whereas surgical issues associated with deep brain stimulation, such as bleeding, surgical hardware revision, and infection, are more obvious and objective, the evaluation of psychological and neurologic symptoms of adverse effects varies from patient to patient. The source of this ambiguity is multifaceted. For starters, patients may simply fail to report their symptoms to their particular physicians.

In consequence, the physician may not ask the right questions to clarify persisting unpleasant side effects. Even if side effects are recorded, it is possible that they will not be noted if they do not satisfy an arbitrary degree of severity. Furthermore, it might be difficult to distinguish between pre-existing symptoms and comorbidities and the initiating adverse effects of DBS. Furthermore, certain adverse effects tend to appear gradually and with delay.

Axillary symptoms in Parkinson's disease are one example of this slow start. Finally, as research progresses and behavioral derivatives of neurocircuitry are identified, what was originally welcomed as therapeutic results from DBS therapy may now be seen as red signals. For example, although the spontaneous emergence of initiative in STN-stimulated Parkinson's disease patients was originally acclaimed as improvement, it is now, regrettably, seen as a pathological sign of impaired impulse control.

However, current scientific research shows that deep brain stimulation is generally safe and has a limited, if not insignificant, adverse effect profile. Despite this, the following adverse effects have been reported: modest gait or speech difficulties, emotional liability, exacerbated depression, seizure, trouble concentrating, disorientation, and headache.

What is the Prognosis?

Although most patients must continue to take medication following DBS, many people see a significant improvement in their PD symptoms and are able to lower their prescriptions significantly. The quantity of decrease varies depending on the individual.

Medication dose reduction reduces the risk of side effects such as dyskinesia (involuntary movements of the arms, legs and head). Per side performed, there is a one to three percent danger of infection, stroke, cranial hemorrhage, or other problems linked with anesthesia. It is advisable to consult with your neurologist and neurosurgeon about any potential hazards.

Conclusion

Deep brain stimulation has the potential for widespread use, and has been hailed as providing "a new life for patients with Parkinson's disease." The FDA has already approved DBS for essential tremor, dystonia, and treatment-refractory obsessive-compulsive disorder. Ongoing research is looking into prospective off-label use in addiction, autism, anorexia nervosa, anxiety disorders, and schizophrenia.

Deep brain stimulation (DBS) requires integrative, collaborative communication and care to be successful. An experienced surgeon (with knowledge in functional neurosurgery), a movement disorder neurologist, a psychiatrist, a neuropsychologist, and a neuropsychologist should be part of an interprofessional DBS team. The nurse is crucial in ensuring that the patient gets the most out of the surgical intervention. To get the best results for the patient, all healthcare staff must be engaged and in sync.