Name:
10.3171/2024.7.FOCVID249
Description:
10.3171/2024.7.FOCVID249
Thumbnail URL:
https://cadmoremediastorage.blob.core.windows.net/45cfb43f-eac9-4f0b-822e-7a3c5d9f3702/videoscrubberimages/Scrubber_194.jpg
Duration:
T00H06M14S
Embed URL:
https://stream.cadmore.media/player/45cfb43f-eac9-4f0b-822e-7a3c5d9f3702
Content URL:
https://cadmoreoriginalmedia.blob.core.windows.net/45cfb43f-eac9-4f0b-822e-7a3c5d9f3702/4. 24-9.mp4?sv=2019-02-02&sr=c&sig=w2fENaoeLIezgEdZp2xCYvXp95mhBWyvROzcD4WBx54%3D&st=2026-03-28T14%3A23%3A12Z&se=2026-03-28T16%3A28%3A12Z&sp=r
Upload Date:
2026-03-28T14:28:12.1003876Z
Transcript:
Language: EN.
Segment:0 .
[MUSIC PLAYING]
SPEAKER: This is a 78-year-old man with a 9-year history of debilitating bilateral hand tremor with features of both essential tremor and Parkinson's disease. He was refractory to propranolol, primidone, and levodopa. We decided to treat with MRI-guided, focused ultrasound thalamotomy. Skull density ratio was found to be 0.31. Although suboptimal, this factor alone does not obviate successful treatment.
SPEAKER: As hair can interfere with the ultrasound focusing, we shave the patient's head and affix the stereotactic frame following injection of local anesthetic. The frame is placed low on the head to maximize the number of ultrasound sources available for the treatment. The patient is brought to the MRI scanner, where a membrane helmet is placed.
SPEAKER: This forms a tight seal with the head. It is filled with cool, degassed water, which completely fills the membrane. Final air bubbles are removed by vigorous tapping. Baseline images are obtained, including a white matter nulled scan for targeting and a 3D FIESTA scan to define the AC-PC landmarks.
SPEAKER: Indirect coordinates for the Vim target are approximately 2 mm above the AC-PC plane. One quarter of the AC-PC distance anterior to PC and 14 mm lateral to midline. The ultrasound transducer is centered around this target. Automated segmentation and tractography that estimates the dentatorubrothalamic tract or DRTT assists with target refinement.
SPEAKER: A white matter- nulled sequence also helps with direct targeting. Vim appears slightly hypointense here. We have also observed that the AP position of the target often lines up with an interruption in the internal capsule, which we use as a landmark. Internal fiducials are placed afterwards. We provide the patient with a safety button that can terminate the sonication.
SPEAKER: In alignment sonication at subthreshold power demonstrates targeting accuracy, as here, MRI thermometry shows heating of the target. We repeat this in three orthogonal planes. After each sonication, we evaluate for any side effects and perform a neurologic exam in which we assess speech sensation in the fingers and face and tremor.
SPEAKER: Here, the patient's postural tremor has already improved. His intention tremor, though, is still severe. We perform pen to paper testing. He can't even attempt to draw the spiral, and he's severely impaired in trying to trace a straight line.
SPEAKER: We then perform a low-energy treatment sonication at the target, which uses high energy than the alignments. MRI thermometry shows a higher and more sustained temperature rise. After treatment, the intention tremor has improved. On pen to paper, he can now follow the spiral and can more precisely trace the straight line.
SPEAKER: We continue to enlarge the lesion with higher energy delivery and additional target points. Here, we use slightly anterior and superior. MRI thermometry showed sustained tissue temperature above 54 to 55 degrees Celsius. The sonication proceeded smoothly despite the patient's low SDR. Testing of the tremor revealed further improvement with subsequent lesioning.
SPEAKER: The patient reported only transient headache and scalp warmth. Pen to paper tests shows continued improvement. The patient is disconnected from the ultrasound apparatus and carefully withdrawn from the MRI. He was discharged to home the same day. We follow-up the next day. The patient's tremor had dramatically improved.
SPEAKER: He did require a cane, given some unsteadiness, which in our experience is typically transient, but otherwise experienced minimal side effects. We obtain an MRI, which demonstrated a 177- cubic-millimeter lesion with surrounding edema at the targeted Vim. We've seen durable response to at least 5 years of follow-up.
SPEAKER: The patient wishes to pursue treatment of the right side, which could be done in a staged fashion in 9 months.
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