Magnetic Resonance Guided Focused Ultrasound (MRgFUS) Thalamotomy [Neurosurgery Wiki]

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====== Magnetic Resonance Guided Focused Ultrasound (MRgFUS) Thalamotomy ======

[[Magnetic Resonance Guided Focused Ultrasound]] (MRgFUS) [[Thalamotomy]] is an innovative, non-invasive surgical technique 

It combines **MRI imaging** with **high-intensity focused ultrasound (HIFU)** to precisely ablate a small region of the thalamus, specifically the **ventral intermediate nucleus (VIM)**, which is involved in the generation of tremors.

===== Procedure Overview =====
  - **Patient Preparation:**
    - The patient’s head is immobilized with a frame to ensure accurate targeting.
    - A stereotactic frame is used to improve precision.
    - Patients are awake during the procedure to provide feedback.
  - **MRI Guidance:**
    - MRI provides real-time imaging to visualize the brain and accurately locate the VIM of the thalamus.
    - MRI thermometry monitors temperature changes in the brain during the procedure.
  - **Focused Ultrasound Application:**
    - High-intensity ultrasound waves are directed to converge on the VIM of the thalamus.
    - The focused ultrasound generates heat, causing controlled thermal ablation of the targeted tissue.
  - **Verification:**
    - After initial low-power sonications, the patient’s response is assessed to ensure the correct target is being treated.
    - Adjustments are made as needed before delivering higher-intensity sonications for permanent ablation.
  - **Completion:**
    - MRI confirms the lesion's placement.
    - The patient is monitored for immediate post-procedural effects.

===== Advantages =====
  * **Non-invasive:** No incisions or craniotomy required.
  * **Precision:** MRI guidance ensures accurate targeting and minimizes collateral damage.
  * **Minimal Recovery Time:** Patients can often return to daily activities within days.
  * **Immediate Results:** Tremor reduction is often noticeable immediately after the procedure.

===== Indications =====

[[Magnetic Resonance Guided Focused Ultrasound Thalamotomy Indications]]


===== Limitations =====
  - Only treats one side of the brain (unilateral tremors).
  - Not suitable for all patients (e.g., those with extensive skull density variations that impede ultrasound transmission).
  - Potential for side effects such as **temporary numbness**, **imbalance**, or **paresthesia**.
  - Long-term effects and durability of results require more study compared to deep brain stimulation (DBS).

===== Comparison to Deep Brain Stimulation (DBS) =====
^ **Feature**                 ^ **MRgFUS Thalamotomy**    ^ **DBS**                       ^
| **Invasiveness**            | Non-invasive             | Invasive                      |
| **Adjustability**           | Fixed lesion             | Programmable stimulation      |
| **Recovery Time**           | Minimal                  | Longer recovery               |
| **Efficacy for Bilateral Tremor** | Limited (unilateral only) | Effective                     |
| **Side Effects**            | Heat-related (e.g., numbness) | Device-related risks (e.g., infection) |

===== Future Prospects =====
Ongoing research is exploring:
  * Expanding indications for other neurological and psychiatric conditions (e.g., OCD, depression).
  * Enhancing technology to allow bilateral treatments.
  * Integrating with other imaging modalities for better targeting.

This technique represents a promising advancement in functional neurosurgery, particularly for patients seeking a less invasive alternative to traditional surgical interventions.

----


[[Magnetic resonance guided focused ultrasound]] (MRgHIFU) [[thalamotomy]] destroyed tissues by focusing a high-energy beam on the [[ventralis intermedius nucleus]] of the [[thalamus]]. 


===== Case reports =====

A single case report of MR-guided focused ultrasound thalamotomy for [[tremor]] in [[fragile X associated tremor ataxia syndrome]]
((Cerquera C, Rumià J, Herrera JM, Moreno V, Bargalló N, Valldeoriola F. A
single case report of MR-guided focused ultrasound thalamotomy for tremor in
fragile X-associated tremor/ataxia. Parkinsonism Relat Disord. 2016 Apr 4. pii:
S1353-8020(16)30080-3. doi: 10.1016/j.parkreldis.2016.04.002. [Epub ahead of
print] PubMed PMID: 27066991.
)).