Severe subthalamic stimulation-induced dysarthria alleviated by a novel paradigm: A case report

Alternative patterns of deep brain stimulation in neurologic and neuropsychiatric disorders

“…Their VFS paradigm involved 10–50 s trains of alternating HFS and LFS (e.g., 130 Hz for 30 s and 60 Hz for 20 s per 50 s cycle). VFS increased gait speed, mitigated FOG, and improved bradykinesia, while tremor and rigidity either remained stable or further improved compared to HFS alone ( Jia et al, 2015 , 2017 , 2018 ). In two cases, HFS-associated decline in verbal fluency and dysarthria resolved with VFS without diminishing HFS-related improvement in primary appendicular motor symptoms ( Jia et al, 2017 ; Zhang et al, 2019 ).…”

“…VFS increased gait speed, mitigated FOG, and improved bradykinesia, while tremor and rigidity either remained stable or further improved compared to HFS alone ( Jia et al, 2015 , 2017 , 2018 ). In two cases, HFS-associated decline in verbal fluency and dysarthria resolved with VFS without diminishing HFS-related improvement in primary appendicular motor symptoms ( Jia et al, 2017 ; Zhang et al, 2019 ). An additional case report showed improvement in freezing and limb dyskinesia in a single patient with bilateral STN and GPi leads programmed for VFS, which did not occur with HFS alone ( Chang et al, 2021 ).…”

“…Of the excluded studies, nine were non-human animal studies, six did not use paired pulse stimulation, five were reviews, and five were TMS studies without DBS. The search for VFS resulted in 12 studies, five of which were included ( Jia et al, 2015 , 2017 , 2018 ; Zhang et al, 2019 ; Chang et al, 2021 ). Of the excluded studies, two used stimulation modalities other than DBS (e.g., TMS), two were protocols for upcoming studies with no original clinical data, one was a review, one was a non-human animal study, and one did not utilize VFS.…”

Variable High-Frequency Deep Brain Stimulation of the Subthalamic Nucleus for Speech Disorders in Parkinson's Disease: A Case Report

“…It is known that STN-DBS treatment using fixed high frequencies, while being effective in controlling the primary motor symptoms of PD, may induce or aggravate speech and voice dysfunctions (1). VFS containing low frequencies has been reported to relieve severe subthalamic stimulation-induced dysarthria, yet this stimulation has also been found to worsen the tremor (2). Our results confirm the latter observation by showing that VFS containing low frequencies alone worsened the tremor in the present case.…”

“…However, this stimulation at a fixed high frequency does not improve or may even exacerbate the axial symptoms and signs (such as problems with gait, speech, or swallowing) that often emerge over the long-term course of treatment and disease (1). Recent evidence suggests that STN-DBS at a fixed lower frequency (< 100 Hz) could improve speech and gait (2, 3). However, the tremor might worsen significantly with fixed low-frequency stimulation (4).…”