Reducing Ataxia in Essential Tremor Patients

Essential tremor (ET) is a common movement disorder that causes involuntary shaking of the hands, head, or other body parts. It usually affects older adults and can run in families. The tremors can be mild or severe, making it difficult to perform everyday tasks like writing or eating. Though the exact cause is unknown, it's believed to involve abnormal brain activity. Essential tremor isn't life-threatening but can impact a person's quality of life. Treatments may include medications, physical therapy, and lifestyle changes. Consulting a healthcare professional for an accurate diagnosis and appropriate management is essential.

Deep brain stimulation (DBS) is a promising treatment for ET. Researchers have been exploring ways to optimize the therapy's effectiveness while minimizing potential side effects. One such approach is using symmetric biphasic pulses, which have been shown to widen the therapeutic window compared to traditional cathodic pulses.

Clinical Trial

A clinical trial investigated the impact of 3 hours of biphasic stimulation on tremors, ataxia, and dysarthria in ET patients who received DBS treatment. A randomized, double-blind, cross-over design was utilized to compare the effects of standard cathodic pulses with anode-first symmetric biphasic pulses. Throughout 3 hours, all other stimulation parameters remained constant, allowing for a fair comparison between the two pulse shapes.

The study involved twelve ET patients, and hourly assessments were conducted during stimulation. The researchers used the Fahn-Tolosa-Marin Tremor Rating Scale to evaluate tremor control, the International Cooperative Ataxia Rating Scale to measure ataxia, and acoustic and perceptual measures to assess speech quality.

Results

Pulse shapes provided equivalent tremor control during the 3-hour stimulation period. However, the use of symmetric biphasic pulses was found to elicit significantly less ataxia compared to conventional cathodic pulses. Ataxia refers to a lack of coordination and balance, and reducing this side effect is crucial to improving patient comfort and safety during DBS treatment.

Additionally, the study found that the rate of speech articulation, known as diadochokinesis, was better for patients receiving biphasic pulses. Although other dysarthria (speech impairment) measures did not show significant differences between the pulse shapes, the improved speech articulation indicates a potential benefit of using symmetric biphasic pulses for ET patients undergoing DBS treatment.

Conclusion

This research highlights the advantages of symmetric biphasic pulses in DBS for essential tremor. Compared to cathodic pulses, biphasic stimulation was associated with reduced ataxia and potentially improved speech articulation after 3 hours of treatment. These findings contribute to the ongoing efforts to optimize deep brain stimulation therapy for essential tremor and enhance the overall quality of life for affected individuals.
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