Transcranial magnetic resonance-guided focused ultrasound for Parkinson's disease

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Transcranial Magnetic Resonance-Guided Focused Ultrasound (tcMRgFUS) is a non-invasive therapeutic modality that has shown promise in treating symptoms of Parkinson's disease (PD), particularly tremors and dyskinesias. This approach uses focused ultrasound waves to thermally ablate specific brain regions under the guidance of real-time magnetic resonance imaging (MRI).

• Ultrasound Waves: High-frequency ultrasound waves are focused on a target in the brain, leading to localized heating and ablation of the target tissue without the need for open surgery.
• MRI Guidance: MRI provides real-time imaging to precisely locate the target region and monitor tissue temperature during the procedure to ensure safety and efficacy.
• Target Areas:
  • Ventral intermediate nucleus (VIM) of the thalamus for tremor-dominant PD.
  • Globus pallidus internus (GPi) or subthalamic nucleus (STN) for motor symptoms and dyskinesias.

see Pallidal Transcranial magnetic resonance-guided focused ultrasound for Parkinson's disease

• Tremor-predominant Parkinson's disease.
• Medically refractory dyskinesias.
• Patients who are not candidates for invasive surgical options like deep brain stimulation (DBS).

• Non-Invasive: Unlike DBS, tcMRgFUS does not require incision or implantation of hardware.
• Immediate Effect: Symptom relief can often be observed immediately after the procedure.
• No Hardware Maintenance: Eliminates the need for battery replacements and maintenance associated with DBS devices.

• Symptom Specificity: Most effective for tremor and less so for other motor symptoms like bradykinesia or rigidity.
• Unilateral Treatment: Typically performed on one side of the brain to reduce the risk of side effects.
• Irreversibility: The effects are permanent, which means any unintended adverse effects cannot be undone.

• Headache and dizziness.
• Gait disturbances or balance issues.
• Sensory disturbances (e.g., numbness, tingling).
• Rare but severe complications like brain edema or hemorrhage.

Studies have demonstrated significant tremor reduction and improvements in quality of life following tcMRgFUS in patients with Parkinson's disease. However, long-term efficacy and broader application for other PD symptoms are still under investigation.

• Expanding the applicability to bilateral treatment.
• Refining targeting for more comprehensive symptom control.
• Exploring combinatory therapies with pharmacological treatments or DBS.

Bilateral lesions of the basal ganglia using thermocoagulation or radiation for improving tremor, bradykinesia, and rigidity in people with Parkinson's disease (PD) have been performed starting several decades ago, especially when levodopa and deep brain stimulation (DBS) surgery were not available. However, because of unclear additional benefits compared to unilateral lesions, particularly the evidence of increased adverse events occurrence, bilateral lesions were abandoned at the end of the 20th century. Therefore, bilateral DBS has become the standard procedure for treating PD. Magnetic resonance imaging-guided focused ultrasound (MRgFUS) is an emerging incision-less technique used to produce therapeutic brain ablation. The positive experiences of unilateral MRgFUS ablation for PD, along with the preliminary favorable outcomes of bilateral thalamic MRgFUS for essential tremor, raise the possibility of eventually reintroducing bilateral lesioning in managing PD motor features. This possibility has so far only been tested in a few small studies. Rodriguez-Oroz et al. review the evidence of bilateral lesioning of the basal ganglia for Parkinson's disease treatment and elaborate on current gaps, controversies, and perspectives of the different available neurosurgical procedures specifically of MRgFUS ablation ¹⁾.

The review underscores that current evidence is insufficient to justify a widespread reintroduction of bilateral lesions, even with advanced techniques like MRgFUS. This work serves as a call to action for the scientific and medical communities to rigorously evaluate this approach through well-designed studies.

The article is a timely contribution to the field and raises critical questions about how innovation should be balanced with patient safety and established treatment paradigms. It will undoubtedly serve as a reference point for future discussions on this topic.

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Magnetic resonance guided focused ultrasound thalamotomy for essential tremor