Background: Magnetic resonance-guided high-intensity focused ultrasound (MRgHIFU) is an incisionless neurosurgical procedure to treat essential tremor (ET) and tremor-dominant Parkingson's disease (TDPD). While MRgHIFU is an effective neurosurgical procedure to suppress tremor in ET and TDPD, recurrence of tremor symptoms after a first MRgHIFU ablative procedure have been reported. We present 3 cases to report the utilization of deterministic tractography and digitized stereotactic atlases to identify variables that contribute to recurrent tremor and to plan retreatment MRgHIFU thalamotomies. Methods: 2 patients with ET and 1 patient with TDPD underwent a successful MRgHIFU thalamotomy procedure with standard indirect targeting. All 3 patients had recurrent tremor at 1-6 months post-ablation. Following this period, all patients received postoperative magnetic resonance imaging (MRI) scans with dentato-rubro-thalamic-tract (DRTT) two tensor deterministic tracking (FT2) and a computerized stereotactic atlas superimposed onto the lesion site of thermoablation. Results: In the TDPD patient, the DRTT was shown to be anterior to the high-intensity focused ultrasound lesion (HIFU) from the first ablation. Retreatment with anterior targeting permanently supressed tremor. In 2 patients the DRTT fully reconstituted after the first ablation. The original target was retreated with increased-temperature sonications, resulting in permanent tremor suppression. Conclusions: Postoperative image processing with DRTT deterministic tractography and computerized stereotactic atlases is an effective way to plan MRgHIFU thalamotomies for recurrent tremor. The target for TDPD may be anterior to the standard thalamotomy coordinates.
This work was supervised by Dr. Gordon Baltuch at Columbia Neurosurgery.