Objective: The objective is to present the first reported case of a patient with post-hypoxic myoclonus (PHM) who underwent noninvasive MR-guided Focused Ultrasound Treatment (MRgFUS).

Background: Lance-Adams syndrome is a condition characterized by myoclonus  which occurs days or weeks after hypoxic brain injury. The therapy is ineffective very often. Deep brain stimulation (DBS) has been used to treat PHM with different results.

Method: A 55-year-old woman developed severe generalized myoclonus and anarthria in 8 weeks after an episode of prolonged anoxia due to traumatic asphyxia (2019). She could not stand, and was dependent on feeding, and grooming.
Clonazepam, levetiracetam, levodopa, pregabalin, normokineztine at the maximum tolerated doses were not effective. She was consulted by several neurosurgeons for consideration of DBS, but the operation was not offered due to the lack of experience in treating patients with PHM.
On examination, there were mild spontaneous myoclonic jerks in her right arm. Action myoclonus emerged during every active action in every limb. Stimulus-induced myoclonus with tactile stimulation of the right arm and leg was revealed. She required assistance to stand with triggered negative myoclonus in her legs.
Pallidothalamic tractotomy (PTT) by MRgFUS was performed in January 2022. We chose PTT due to its safety and efficacy in the treatment of dystonia based on a literature review.

Results: The Unified Dystonia Rating Scale (UDRS) improved from 20 to 14 score, and Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) score improved from 16 to 20 after the treatment. Myoclonus Unified Myoclonus Rating Scale (UMRS) decreased from 100 to 60 after the treatment. During the MRgFUS treatment, she started to communicate using simple words. Only mild action myoclonus in her right limbs registered after the treatment. Her lower extremity negative myoclonus showed improvement which allowed her to stand by pushing off with both hands and walk several meters with one-person assistance. She was able to hold items with each hand.

Conclusion: Our experience shows that MRgFUS treatment is a safe, effective treatment for PHM. Additional clinical trials with a more number of patients and structured protocol for patient selection are needed. As MRgFUS becomes one of the effective neurosurgical techniques, we anticipate that its application to the treatment of rare movement disorders will continue to grow.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/transcranial-magnetic-resonance-guided-focused-ultrasound-in-lance-adams-syndrome/