Deep Brain Stimulation for Parkinson’s Disease Relieves Symptoms | Observed benefits for patients with and without disease mutations

Subthalamic deep brain stimulation (DBS) significantly improves motor and non-motor symptoms in people with early-stage Parkinson’s disease, a new study has found.

In fact, data showed that people with this early form of the neurodegenerative disease saw an improvement or decrease in motor symptoms of more than 50% on a Parkinson’s disease rating scale.

“Consistent with this, patients experienced a significant reduction in additional motor and non-motor neuropsychiatric symptoms,” the researchers wrote.

According to the team, the findings appear to hold in patients with and without disease-associated mutations.

The findings were reported in “Deep brain stimulation in early Parkinson’s disease», a study published in the journal Frontiers in Neurology.

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Use of DBS for Early Parkinson’s Disease

Deep brain stimulation for Parkinson’s disease – a surgical procedure commonly known as DBS – involves implanting electrodes that deliver electrical stimulation to specific areas of the brain and help improve brain function.

Subthalamic DBS, or DBS applied to the subthalamic nucleus of the brain, has been used to treat motor symptoms in people with more advanced Parkinson’s disease and those who respond poorly to other therapies. It has been shown to relieve symptoms such as dyskinesia or involuntary movements, tremors, stiffness and walking problems.

Studies have shown that DBS can also be a useful treatment for patients with early-stage Parkinson’s disease – who are usually diagnosed before the age of 50. These younger patients are usually at a different stage of life, where parenthood and employment are part of their responsibilities; as such, they face unique psychological and social challenges.

Genetic factors appear to be involved in the development of motor symptoms and are known to influence an individual’s response to DBS and levodopa – a precursor to dopamine, which is lacking in people with Parkinson’s disease.

Now, a team of researchers in Germany has studied how genetic factors may affect how patients with early-stage Parkinson’s disease respond to SCP.

“Specific genetic mutations appear to exert an individually different impact on disease progression, but also on the effects of DBS,” the researchers wrote, noting that “at least 5-10% of so-called early-onset cases [Parkinson’s disease] (EOPD) patients are believed to carry genetic mutations.

The team assessed the effect of DBS in 46 people with early-stage Parkinson’s disease, with and without disease-causing mutations, over a 12-month period. Of the patients analyzed, 15% had genetic mutations associated with Parkinson’s disease.

Several parameters were assessed and compared before and after DBS, including scores for motor and non-motor symptoms, as well as for quality of life.

Motor symptoms were assessed by the levodopa challenge test, in which patients receive a single dose of levodopa. This test is usually done to determine if patients may benefit from DBS by assessing their responsiveness to levodopa.

During the test, doctors assess whether the patient’s motor symptoms improve with the single dose, by assessing what is known as the “med-ON state” versus the drug-free period (med-OFF state). .

The analysis here revealed a 52.4% improvement in mean motor scores during the med-OFF state 12 months after DBS surgery, compared to before the procedure.

Patients also experienced a significant reduction in levodopa equivalent daily dose (LEDD) – by nearly 59% – 12 months after DBS implantation. This means they needed less levodopa treatment after the procedure.

Non-motor symptoms, including impulsivity and quality of life, were also assessed.

Neuropsychiatric assessment of impulsive control disorder revealed a 6.6-point decrease after DBS, using the Questionnaire for Impulsive-Compulsive Disorder in Parkinson’s Disease-Rating Scale (QUIP-RS).

In addition, a 30% reduction in the Total Parkinson’s Disease Questionnaire 39 (PDQ39) score, used to assess quality of life, was also observed. In the PDQ39, lower scores indicate better quality of life.

Together, these lower scores indicated marked improvements in impulsivity and quality of life after DBS.

The results also showed that there were significantly fewer patients who presented with motor and/or neuropsychiatric symptoms 12 months after surgery (14 patients), compared to what was observed before DBS (41 patients).

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Fewer symptoms, better quality of life after DBS

Before the intervention, 11 patients worked full-time and four part-time; the remaining 31 patients were not working (25 being retired). After DBS, at the end of the 12-month follow-up period, 15 patients were working, nine full-time and six part-time.

Regarding the mutations, seven patients in the group analyzed had mutations known to cause Parkinson’s disease. The results showed no significant difference in motor symptoms after DBS between patients with and without disease-associated mutations.

In terms of safety, serious side effects associated with DBS included postoperative confusion (three patients), wound healing problems (one patient), and intracranial (brain) bleeding around an electrode (one patient).

Overall, the team concluded that “the results of the present study demonstrate that EOPD [early-onset Parkinson’s disease] patients with and without a known genetic history benefit from STN-DBS [subthalamic deep brain stimulation] with a significant improvement in motor and non-motor symptoms.

“In addition, patients experienced significant improvements of 30% in [quality of life] measured by PDQ-39,” the researchers added.

Nevertheless, the team acknowledged that “a better understanding of the genetic background and associated clinical characteristics could impact decision-making in DBS and eventual individual outcome.”

In fact, the team has started a patient registry. Its goal, they noted, is “to gain insights into patient progression and long-term outcomes that could enable clinicians to improve counseling of EOPD patients.”

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