Deep Brain Stimulation Found to Ease Symptoms in Parkinson’s
Benefits seen for patients with and without disease mutations
In fact, data showed that individuals with this early-onset form of the neurodegenerative disorder saw more than a 50% improvement, or lessening of motor symptoms, on one Parkinson’s rating scale.
“In line with this, patients experienced a meaningful reduction of additional motor as well as non-motor neuropsychiatric symptoms,” the researchers wrote.
According to the team, the results seem to be valid in patients with and without disease-associated mutations.
The findings were reported in “Deep brain stimulation in Early Onset Parkinson’s disease,” a study published in the journal Frontiers in Neurology.
Using DBS for early-onset Parkinson’s
Deep brain stimulation for Parkinson’s — a surgical procedure commonly known as DBS — involves implanting electrodes that deliver electrical stimulation in specific areas of the brain and help improve the brain’s functioning.
Subthalamic DBS, or DBS applied to the subthalamic nucleus in the brain, has been used to treat motor symptoms in people with more advanced Parkinson’s and those with a poor response to other therapies. It has been shown to ease such symptoms as dyskinesia, or involuntary movements, tremor, rigidity, and walking problems.
Studies have shown that DBS also can be a useful treatment for patients with early-onset Parkinson’s disease — who are typically diagnosed before age 50. These younger patients are usually at a different stage of life, where parenting and employment are part of their responsibilities; as such, they face unique psychological and social challenges.
Genetic factors seem to be involved in the development of motor symptoms and are known to influence an individual’s response to DBS and to levodopa – a precursor of dopamine, which is lacking in people with Parkinson’s.
Now, a team of researchers in Germany investigated how genetic factors may affect the way patients with early-onset Parkinson’s respond to DBS.
“Specific gene mutations seem to exert an individually different impact on disease progression, but also on DBS effects,” the researchers wrote, noting that “at least 5–10% of the so-called Early-onset [Parkinson’s disease] patients (EOPD) are estimated to carry genetic mutations.”
The team evaluated the effect of DBS in 46 people with early-onset Parkinson’s, with and without disease-causing mutations, over a 12-month period. Among the patients analyzed, 15% had Parkinson’s-associated gene mutations.
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 evaluated through the levodopa challenge test, in which patients are given a single dose of levodopa. This test typically is performed to determine if patients may benefit from DBS by evaluating their responsiveness to levodopa.
In the test, physicians evaluate whether the patient’s motor symptoms improve with the single dose, assessing the so-called “med-ON state” compared with the period without medication (med-OFF state).
The analysis here revealed an improvement by 52.4% in mean motor scores during the med-OFF state 12 months after the DBS surgery, compared with before the procedure.
Patients also experienced a significant reduction in the levodopa equivalent daily dosage (LEDD) — by nearly 59% — 12 months after DBS implantation. That means they needed less levodopa treatment after the procedure.
Non-motor symptoms, including impulsiveness and quality of life, also were assessed.
Neuropsychiatric evaluation for 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).
Furthermore, a 30% reduction in the Total Parkinson’s Disease Questionnaire 39 (PDQ39) score, used to assess quality of life, also was observed. In PDQ39, lower scores indicate a better quality of life.
Together, these lower scores indicated marked improvements in impulsiveness and quality of life after DBS.
The results also showed there were significantly fewer patients who had motor and/or neuropsychiatric symptoms 12 months after surgery (14 patients), compared with what was seen before DBS (41 patients).
Fewer symptoms, better quality of life after DBS
Before the procedure, 11 patients worked full time and four part time; the remaining 31 patients did not work (25 being retired). After DBS, at the end of the 12-month follow-up period, 15 patients were working, with nine in full-time and six in part-time jobs.
Regarding mutations, seven patients in the group analyzed had known Parkinson’s disease-causing mutations. Results showed no significant differences in motor symptoms after DBS between patients with and without disease-associated mutations.
In terms of safety, severe side effects associated with DBS included postoperative confusion (three patients), wound healing issues (one patient), and intracranial (brain) bleeding around one electrode (one patient).
Overall, the team concluded that “the present study-results demonstrate that EOPD [early-onset Parkinson’s disease] patients with and without known genetic background benefit from STN-DBS [subthalamic deep brain stimulation] with significant improvement in motor as well as non-motor symptoms.”
“Furthermore, patients experienced significant 30% improvements of [quality of life] measured by the PDQ-39,” the researchers added.
Nonetheless, the team recognized that “a better understanding of the genetic background and associated clinical features might have an impact on decision making in DBS and the eventual individual outcome.”
In fact, the team started a patient registry. Its aim, they noted, is to “to gain knowledge on patients’ progression and long-term outcome that might enable clinicians to improve the counseling of EOPD-patients.”