Can Parkinson’s Disease Be Cured?
An Analysis of Deep Brain Stimulation…
Parkinson’s disease, a condition that can make a runner struggle to stand, a pianist falter over once familiar keys, and a family member to lose memory of their loved ones. It is a neurodegenerative disease that results in severe motor symptoms and cognitive issues that progress with age. It is a condition that has altered the lives of over 8.5 million people worldwide (Blake, 2023).
Levodopa, drug therapy, dopamine agonists as well as early detection and a healthy lifestyle all play a role in the diagnosis and treatment of Parkinson’s disease. The question is if there is a treatment method that makes a substantial difference in the quality of life of both patient and caregivers while having a high success rate and minimizing complications. A treatment method that acts as a substitute for a cure…
Deep Brain Stimulation (DBS) is an emerging technology that has changed the lives of countless patients living with neurological disorders such as Parkinson’s disease, essential tremor, epilepsy, and even psychiatric conditions (Mayo Clinic, 2023). It is a minimally invasive process that has been proven to alleviate motor-based symptoms, thereby improving patients’ quality of life.
History and Development of DBS
Deep Brain Stimulation, a technology developed in 1987 by a team treating patients with essential tremor and Parkinson’s disease at Grenoble, France, foreshadowed a promising future for the treatment of numerous neurological and psychiatric conditions. DBS originally stemmed from neurostimulation techniques which come from stereotactic surgery, a subspecialty of neurosurgery. These techniques were used to provide therapeutic relief to patients who suffered from psychiatric and neurological conditions. After the 1940s, a period of rapid growth known as the “learning in practice” (Morlacchi & Nelson, 2011) is what eventually led to the development of DBS technology (Gardner, 2013).
In 2002, DBS was granted approval by the FDA to be used to treat patients diagnosed with Parkinson’s disease. Since then, DBS therapy has been rapidly developing and has helped over 40,000 patients with either Parkinson’s disease or essential tremor.
Ideal Candidates for DBS
Not all individuals who are diagnosed with Parkinson’s disease, however, are necessarily perfect candidates for DBS surgery. Whether a patient is a potential candidate for the surgery itself would need to be decided by the referred neurologist (Johns Hopkins Medicine, n.d.).
For instance, an ideal candidate would be: a patient where their symptoms are interfering with daily activities; have an uncontrollable tremor and medications have been ineffective; respond well to medications but experience severe symptoms when the drugs wear off; and for a patient who needs higher dosage medications but is unable to do so due to side effects.
A suboptimal candidate would be one where: difficulty balancing is the major limiting symptom; there is speech difficulty; psychiatric conditions that have not been stabilized; or other conditions that increase complications during surgery (Johns Hopkins Medicine, n.d.).
Mechanisms Behind DBS
Parkinson’s disease occurs when nerve cells or neurons are impaired or die in the brain. This may occur in several regions of the brain but is typically observed in the basal ganglia, a region of the brain which controls movement (National Institute on Aging, 2022), or in the substantia nigra, near the base of the brain (National Institute of Neurological Disorders and Stroke, 2024).
Neurons of the substantia nigra communicate with neurons of the basal ganglia, producing dopamine as a neurotransmitter (signaling molecule sent between neurons across a synapse). It is the use of dopamine as a neurotransmitter that allows for the fine-tuning of an individual’s movement at the biochemical level. The death and impairment of these neurons means less dopamine is being produced, which is what leads to movement related symptoms for patients diagnosed with Parkinson’s disease (Triarhou, 2013). The cause itself for the impairment of the neurons has not been specifically identified by scientists.
Deep Brain Stimulation involves the placement of two leads with electrodes in a specific targeted region of the brain (Breit et al., 2004). These leads are connected to a stimulator which is typically surgically implanted under the skin in the chest region. Electrical impulses are then sent to the targeted regions of the brain through wires leading to altered brain function. The high frequency electrical impulses (over 100 Hz) not only excite axons or cell bodies but can lead to an ablating effect. In other words, the impulses can imitate the surgical removal of a targeted brain region (Breit et al., 2004). This can be crucial to inhibit the abnormal neural signals leading to tremors. Examples of often targeted regions of the brain include the subthalamic nucleus (STN) or the globus pallidus internus (GPi) which have led to a reduction in tremors seen in Parkinson’s disease (Breit et al., 2004).
Implementation of DBS for Patients Diagnosed with Parkinson’s Disease
Once a candidate is deemed eligible for DBS, they will undergo a first surgery where the patient is conscious in order for the surgeons to ensure that the wires have been correctly placed in the brain; patients typically return home the following day after this surgery (Walker, 2024).
A second surgery is set for approximately 2 weeks after the first one, where a battery powered stimulator is placed under the skin of the upper chest; patients are free to leave the day of the surgery. The patient is given a few weeks to recover after the initial two surgeries, after which 4–6 weeks of programming sessions are done by a movement disorder neurologist to optimize and regulate the current sent to the targeted brain region.
Although the surgical process itself may be completed within 2–3 weeks, it is believed that it can take up to 3 months before a patient experiences the most benefit due to the duration taken by programming and fine-tuning the system. Post-operative care involves the maintenance of the technology and regular checkups with the doctor to monitor symptoms of the condition and potential complications associated with surgery.
Risks and Complications
Despite the fact that DBS has helped hundreds of thousands of patients find relief from Parkinson’s disease symptoms, there have been potential side effects and complications associated with DBS…
Patients who undergo DBS have experienced side effects including cerebral edema, cerebrovascular disease, seizures, and infections (Nishiguchi et al., 2022). Cerebral edema is the swelling of tissue around the targeted brain region, this is not uncommon for patients and is a significant issue after DBS. Patients with cerebral edema not only experience headaches or seizures but a “Micro Lesion Effect.” This is when the swelling of the tissues in the targeted brain region may temporarily alter brain function in those areas. The change in brain function may also impact how Parkinson’s symptoms present themselves as well. At times, this may even result in a positive outcome where symptoms are reduced significantly. This is a short-term phenomenon and can often make it unclear for neurologists whether this immediate improvement in symptoms is a result of the effectiveness of the DBS itself or because of the micro lesion effect (Nishiguchi et al., 2022).
The invasive nature of DBS surgery can lead to other complications such as intracerebral hemorrhages, a condition where a hematoma (pooling of blood) can occur within the brain parenchyma (tissue in the brain) which can be life-threatening (Rajashekar & Liang, 2023). The insertion of intracranial electrodes can further cause skin erosion or infection (Jung et al., 2022). Currently, the mortality rate of patients with Parkinson’s disease who have undergone DBS ranges from 4.3–34%; the mortality rate and the probability of complications depends on the progression of Parkinson’s in the specific patient, age, lifestyle and a number of factors (Kim et al., 2023). However, what remains clear is that DBS surgery is still far from perfect.
Scientists do not have a clear understanding of why DBS is so effective in the first place, and with the surgery being limited to certain candidates, and complications existing, DBS is clearly not the ideal cure patients are looking for. On the other hand, it is a sign of hope that the development and accessibility of emerging technologies can change the quality of life for countless patients around the world.
There may not be a cure to Parkinson’s disease yet, but, If you know an individual who has Parkinson’s disease or has early symptoms such as slowed movement or tremors, remember, early detection of the condition can significantly alter the course of one’s life.
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