Objective: To describe a case of disabling essential tremor (ET) treated with unilateral MRI-Guided Focused Ultrasound (FUS) thalamotomy as rescue treatment after deep brain stimulation (DBS).

Background: Approximately 25–55% of ET patients develop medication-refractory tremor. DBS of the thalamic ventralis intermedius (VIM) nucleus is the standard treatment for medication-refractory ET. Loss of tremor control can occur gradually over the years in up to 30% of patients treated with VIM-DBS, due to tolerance and disease progression. FUS has demonstrated a significant improvement of ET patients.

Method: We present a patient with disabling action tremor previously treated with DBS, in which unilateral FUS thalamotomy was subsequently used to regain tremor control.

Results: A 55-year-old right-handed male presented with bilateral medically-refractory action tremor treated with bilateral VIM-DBS at the age of 45. After a good initial response, the tremor reappeared. At the beginning tremor improved after changes in DBS programming, but those changes were no longer effective. Ten years after DBS there was complete recurrence of tremor, despite múltiple adjustments of stimulation parameters. We removed the DBS system and the patient subsequently underwent left-side FUS thalamotomy (3-Tesla-MRI (General Electrics), ExAblate Neuro (InSightec)). Stereotactic planning was performed for the left VIM and tractography was used to localize the adjacent anatomical structures. After one treatment sonication, with a mean temperature of 58 degrees, a significant action tremor persisted, so the target was moved 2mm lateral where a significant cavitation appeared, possible due to the scar of the previous DBS led. Finally, we performed two thalamic lesions (L15/A6/S2 and L16/A5/S2) with a total number of 7 treatment sonications, delivering 59900J over 90 seconds. The maximum temperature reached was 62ºC(range 55ºC-63ºC). He suffered a transient mild dysarthria and dysmetria of the right extremities. We observed an abolition of right-upper extremity tremor, which maintains three months later.

Conclusion: We demonstrate the feasibility and safety to perform FUS thalamotomy as a rescue treatment of disabling tremor after DBS. The dramatic improvement of tremor in our patient after FUS supports the hypothesis of different mechanisms underlying neuromodulation and ablation.

« Back to 2023 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/focused-ultrasound-as-rescue-treatment-of-essential-tremor-after-deep-brain-stimulation/