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(64) Targeted Deep Brain Stimulation of Motor Thalamus Improves Motor Speech and Swallowing After Cerebral Lesions

Thursday, June 12, 2025
5:10 PM - 5:50 PM ET
Location: Grand Foyer
Introduction: Speech and swallowing are intricate motor functions that require intact neural signals from motor cortical regions to control the muscles of the head and neck. Lesions of the corticospinal and corticobulbar tracts from traumatic brain injury (TBI) or stroke impair communication between the motor cortex and these muscles, causing dysarthria and dysphagia. Here, we demonstrate that deep brain stimulation of the motor thalamus (mThal-DBS) improves speech and swallowing function in two participants.

Methods: We assessed speech function with and without mThal-DBS in two participants with mild (TBI02) or severe (TBI01) dysarthria after TBI. Specifically, we instructed the participants to perform speech and oromotor tasks, including single-word, two-word, or sentence repetitions and Frenchay Dysarthria Assessment (FDA-2). We quantified changes in the four speech subsystems (respiration, phonation, resonance, and articulation) as well as intelligibility and quality as assessed by blinded speech language pathologists (SLPs) and naive listeners. In one participant with moderate dysphagia (TBI01), we also evaluated swallowing function during a videofluoroscopic study (i.e., modified barium swallow, MBS) with and without mThal-DBS. A blinded SLP performed a clinical evaluation and interpretation of the MBS.

Results: During mThal-DBS, speech improved across all subsystems in TBI01. Specifically, vocal intensity increased with mThal-DBS across most words (65.4% of increases were statistically significant), suggesting that stimulation improves breath support for volume control. Similarly, mThal-DBS significantly decreased the number of voice breaks, indicating improved respiratory and phonatory control. Finally, mThal-DBS improved articulatory control in both TBI01 and TBI02. In TBI01, we found an increased perceptual presence of several consonant sounds during mThal-DBS relative to no stimulation. In the two-word task, TBI02 produced significantly less errors (i.e., speech arrest, distorted/incorrect phonemes, slurring, and stuttering) during mThal-DBS.

Swallowing function improved during mThal-DBS as compared to the no stimulation condition. Without stimulation, TBI01 presented with moderate oral and mild pharyngeal dysphagia. The SLP reported improvements in the oral and pharyngeal phases of swallowing, reduced difficulty initiating volitional swallows, and decreased oral residue during mThal-DBS. Mthal-DBS also reduced the total duration and amounts of residue in the oral and pharyngeal phases of the swallow, indicating improved swallowing efficiency.

Conclusion: Our results demonstrate that mThal-DBS immediately enhances speech production in two participants with mild to severe dysarthria. Additionally, we show that mThal-DBS improves swallowing function, enabling a participant with moderate dysphagia to swallow more efficiently. These preliminary results highlight the potential of this approach as an innovative treatment for dysarthria and dysphagia.