Revolutions in Neuroscience: Deep Brain Stimulation

July 11, 2022 - Deep brain stimulation (DBS) — a neurosurgical approach for treatment-resistant neurological disorders — has become a revolutionary addition to the field of neuroscience and a beneficial tool for neurologists, neurosurgeons, neuropsychologists, and psychiatrists.  

What Is DBS? 

According to the American Academy of Neurological Surgeons (AANS), DBS is the surgical implantation of electrodes in the brain, which provide electrical impulses, controlling brain activity. It is also thought that DBS can adjust issues with brain chemistry.  

DBS has been approved and used in treating multiple diseases, most notably Parkinson’s Disease (PD). It is also used to treat dystonia, epilepsy, obsessive–compulsive disorder (OCD), and essential tremors. 

In addition to its current uses, the Cleveland Clinic states that DBS is also being researched for treating addiction, Alzheimer’s disease, anxiety, cluster headaches, eating disorders, schizophrenia, severe pain disorders, medication-resistant depression, and Tourette syndrome. 

Due to its invasive nature, DBS is typically used as a second line of defense when other non-invasive medication options are futile.  

Benefits and Drawbacks 

Like any medical procedure or device, DBS has both benefits and drawbacks.  

Benefits  

The primary benefit of DBS is evident in that it provides an additional option for patients who have not had success using medications. Additionally, AANS highlights multiple other benefits of DBS. First, it is a treatment method that allows for stimulation on both sides of the brain. Physicians can insert electrodes in various locations to address a patient’s condition.  

Similarly, the strength of the electrical impulses is customizable to each patient’s needs. The device is calibrated to each patient and can be adjusted based on side effects, disease progression, and other clinical signs. Unlike other medications, whose extent depends on the drug’s half-life, DBS can provide consistent stimulation without pause.  

Finally, this treatment, unlike some invasive treatments, is completely reversible. Should the patient not benefit from the procedure or have an adverse side effect, another surgery can be done to remove the brain electrodes.  

Drawbacks 

DBS risks can be associated with either the surgical aspect or the actual stimulation. These surgical risks can include brain hemorrhaging, which may lead to a stroke.  

Additionally, there is a chance of infection, headache, and worsening emotional or mental status. The Cleveland Clinic also acknowledges the potential for comas and brain swelling after receiving this procedure.  

Procedure 

The DBS treatment process is complex and involves multiple parts. 

Device  

The NIH identifies three parts of the DBS device system, including the electrode, sometimes called the lead, the extension wire, and the internal pulse generator (IPG).  

The electrode is the wire that is implanted into the brain. It is a thin and insulated wire, the only part of the system that goes under the skull and into the brain. Attached to the lead is the extension, which is another insulated wire. This wire remains under the skin but runs from the skull opening down the head, neck, and shoulders and attaches to the IPG.  

The internal pulse generator is placed near the collarbone, also under the skin. It is the device that triggers the stimulation and is sometimes referred to as the “battery pack” of the system.  

Candidacy  

Because the candidacy for DBS varies and depends on the condition it is used to treat, a consultation with multiple care team members is performed before a patient can begin the DBS process.  

The AANS identifies three patient categories that represent good candidates for DBS. Patients who seek DBS often have symptoms that severely impair their quality of life. Candidates typically have previously tried medication and either have not seen satisfactory results or have had an adverse side effect. 

Pre-Op 

There are three different portions of the DBS procedure that the Cleveland Clinic outlines. The first aspect is the pre-op stage. Before pursuing treatment, patients will discuss the procedure, risks, and benefits with their healthcare provider to determine if they qualify as a good candidate.  

Once candidacy has been discussed, the AANS outlines multiple scans and tests required prior to scheduling the first operation. These tests include blood and urine tests, MRIs and CT scans, and a general physical exam. Additional testing may be needed depending on the disorder the physicians intend to treat.  

For example, patients with PD have periodic testing of motor function. While patients with epilepsy may require an EEG, patients with OCD are typically tested using the Yale–Brown obsessive–compulsive scale (YBOCs).  

Once all these tasks have been completed and reviewed, if the patient is approved for the procedure, the physician provides them with additional instructions, including medication adjustments, skincare, and dietary adjustments.  

Operation  

The Cleveland Clinic identifies two main operational parts: lead placement and IPG placement. These portions are conducted as two separate operations, but additional surgeries can be performed if multiple portions of the brain need to be stimulated. In that case, a different lead placement occurs before IPG placement.  

During lead placement, a hole is drilled in the skull, and the lead is inserted into the portion of the brain that the physicians intend to stimulate. After recovery from this surgery, patients return for a second procedure to place the IPG. The IPG is inserted under the skin below the collarbone and connected to the extension wire, which is then attached to the lead.  

Post-Op 

After the procedure, patients will be advised by their physician on care. Patients are typically advised to avoid activities and ease themselves back into movement at the direction of a physician. Treatment for the surgical site is also given to patients upon hospital discharge.  

Weeks after both surgeries, the device is calibrated by the neurosurgeon or neurologist in charge of the case. Subsequent visits may be required before the electrical impulses are adjusted to treat each patient.  

Patients may also need to return for an additional surgical procedure every few years to replace the batteries.  

Uses for DBS  

As previously noted, DBS is approved for treating PD, dystonia, epilepsy, OCD, and essential tremors. However, Parkinson’s disease treatment is the most common use for DBS.  

PD symptoms may include bradykinesia, tremors, and difficulty walking. These symptoms can severely worsen the quality of life. According to a 2013 publication in SAGE, DBS was first approved by the FDA for PD treatment in 2002.  

“Within 10 years of being approved for the market within the United States, over 40,000 individuals had been treated with DBS for PD or essential tremor (Talan, 2009), and DBS had gone from being a marginal therapy to an ‘effective,’ ‘standard and accepted treatment for Parkinson’s Disease,’” stated the researchers in the publication.  

Despite its benefits in PD patients, the NIH implies that DBS works best in PD patients with some medication improvement.  

For OCD treatment, the International OCD Foundation states that stimulation in the anterior cingulate cortex is effective.  

“For individuals with dystonia, DBS may reduce the disorder’s characteristic involuntary muscle contractions that cause such symptoms as abnormal posture, repetitive movements, or twisting. DBS has been shown to reduce both the severity of symptoms caused by dystonia and the level of disability they may cause,” states the National Institute for Neurological Disorders and Stroke.  

Overall, DBS is considered a significant breakthrough in treating neurological disorders. Further research will need to be conducted before DBS use can be widened. With its benefits and drawbacks, DBS applications are decided case-by-case, with patients and care teams weighing the pros and cons.