Longitudinal study of speech and dual-task performance in Parkinson's disease patients treated with subthalamic nucleus deep brain stimulation

Impact of Stimulation Frequency on Verbal Fluency Following Bilateral Subthalamic Nucleus Deep Brain Stimulation in Parkinson's Disease

OBJECTIVE

The effects of stimulation frequency on verbal fluency (VF) following subthalamic nucleus deep brain stimulation (STN-DBS) in Parkinson's disease (PD) are not well understood. The present study examines the impact stimulation frequency has on VF following bilateral STN-DBS in PD.

METHODS

Prospective study of 38 consecutive patients with PD with low frequency STN-DBS (LFS) (n = 10) and high frequency STN-DBS (HFS) (n = 14), and a non-operated PD control group consisting of patients with fluctuating response to dopaminergic medication (n = 14) homogeneous in age, education, disease duration, and global cognitive function. Patients were evaluated on VF tasks (letter, semantic, action verbs, alternating). A one-way analysis of variance (ANOVA) was conducted to assess distinctions between groups. Pre- and post-surgical comparisons of fluencies were performed for operated groups. A mixed ANOVA was applied to the data to evaluate the interaction between treatment (HFS vs. LFS) and time (pre- vs. post-surgery). Strategy use (clustering and switching) was evaluated.

RESULTS

Semantic and letter fluency performance revealed significant differences between HFS and LFS groups. Pre- and post-surgical comparisons revealed HFS negatively affected letter, semantic, and action fluencies, but LFS had no effect on VF. No interaction effect or main effect of treatment was found. Main effect of time was significant for semantic and action fluencies indicating a decrease in postoperative fluency performance. Patients with LFS produced larger average cluster sizes than patients with HFS.

CONCLUSION

LFS may be less detrimental to VF, but these findings suggest that VF decline following STN-DBS is not caused by stimulation frequency alone.

Speech, voice, and language outcomes following deep brain stimulation: A systematic review

BACKGROUND

Deep brain stimulation (DBS) reliably ameliorates cardinal motor symptoms in Parkinson's disease (PD) and essential tremor (ET). However, the effects of DBS on speech, voice and language have been inconsistent and have not been examined comprehensively in a single study.

OBJECTIVE

We conducted a systematic analysis of literature by reviewing studies that examined the effects of DBS on speech, voice and language in PD and ET.

METHODS

A total of 675 publications were retrieved from PubMed, Embase, CINHAL, Web of Science, Cochrane Library and Scopus databases. Based on our selection criteria, 90 papers were included in our analysis. The selected publications were categorized into four subcategories: Fluency, Word production, Articulation and phonology and Voice quality.

RESULTS

The results suggested a long-term decline in verbal fluency, with more studies reporting deficits in phonemic fluency than semantic fluency following DBS. Additionally, high frequency stimulation, left-sided and bilateral DBS were associated with worse verbal fluency outcomes. Naming improved in the short-term following DBS-ON compared to DBS-OFF, with no long-term differences between the two conditions. Bilateral and low-frequency DBS demonstrated a relative improvement for phonation and articulation. Nonetheless, long-term DBS exacerbated phonation and articulation deficits. The effect of DBS on voice was highly variable, with both improvements and deterioration in different measures of voice.

CONCLUSION

This was the first study that aimed to combine the outcome of speech, voice, and language following DBS in a single systematic review. The findings revealed a heterogeneous pattern of results for speech, voice, and language across DBS studies, and provided directions for future studies.

Continuous theta burst stimulation over right cerebellum for speech impairment in Parkinson's disease: study protocol for a randomized, sham-controlled, clinical trial

Background

Speech impairment is a common symptom of Parkinson's disease (PD) that worsens with disease progression and affects communication and quality of life. Current pharmacological and surgical treatments for PD have inconsistent effects on speech impairment. The cerebellum is an essential part of sensorimotor network that regulates speech production and becomes dysfunctional in PD. Continuous theta-burst stimulation (cTBS) is a non-invasive brain stimulation technique that can modulate the cerebellum and its connections with other brain regions.

Objective

To investigate whether cTBS over the right cerebellum coupled with speech-language therapy (SLT) can improve speech impairment in PD.

Methods

In this randomized controlled trial (RCT), 40 patients with PD will be recruited and assigned to either an experimental group (EG) or a control group (CG). Both groups will receive 10 sessions of standard SLT. The EG will receive real cTBS over the right cerebellum, while the CG will receive sham stimulation. Blinded assessors will evaluate the treatment outcome at three time points: pre-intervention, post-intervention, and at a 12-week follow-up. The primary outcome measures are voice/speech quality and neurobehavioral parameters of auditory-vocal integration. The secondary outcome measures are cognitive function, quality of life, and functional connectivity determined by resting-state functional magnetic resonance imaging (fMRI).

Significance

This trial will provide evidence for the efficacy and safety of cerebellar cTBS for the treatment of speech impairment in PD and shed light on the neural mechanism of this intervention. It will also have implications for other speech impairment attributed to cerebellar dysfunctions.

Clinical trial registration

www.chictr.org.cn, identifier ChiCTR2100050543.

Impacts of motor phenotype on cognitive function in patients with Parkinson's disease 1 year after subthalamic-nucleus deep brain stimulation

BACKGROUND

Parkinson's disease (PD) is a neurological disorder that affects both motor and cognitive functioning. This study aimed to examine the impact of motor phenotype on cognitive function 1 year after subthalamic-nucleus deep brain stimulation (STN-DBS).

METHODS

The prospectively collected data of 37 patients with PD were retrospectively analyzed. The patients were divided into two group according to their motor phenotype: the postural instability and gait disturbance (PIGD) group comprised 16 patients, and the tremor-dominant (TD) group comprised 21 patients. The clinical characteristics and cognitive functions of all patients were examined at baseline and at the 1-year follow-up after STN-DBS.

RESULTS

The data showed that STN-DBS significantly improved motor functions (P < 0.05). A repeated-measures analysis of variance indicated a considerable group × time interaction impact on the memory quotient score (P < 0.001) and T_min (P = 0.033).

CONCLUSIONS

A distinct relationship between the neuropsychological spectrum and motor phenotype of PD patients was observed at the 1-year follow-up after STN-DBS, with worse cognitive outcomes in patients with the PIGD phenotype. Geriatr Gerontol Int 2023; 23: 85-90.

Attentional Demand of Motor Speech Encoding: Evidence From Parkinson's Disease

PURPOSE

While the involvement of attention in utterance planning is well established at the conceptual and lexical levels, the attentional demands of postlexical processes are still debated. This study investigates the involvement of attentional resources on motor speech encoding during utterance production in the context of Parkinson's disease (PD), a population allowing to assess if the attentional demands observed in a dual-task paradigm (the dual-task costs [DTCs]) are explained by postlexical difficulties and not solely by executive impairment.

METHOD

Speech production was analyzed in a dual-task paradigm with 30 participants presenting with motor speech disorders due to hypokinetic dysarthria in the context of PD. The dual-task comprised an automatic speech task in which participants recited the days of the week and two nonverbal tasks evaluating processing speed and inhibition. The severity of dysarthria and performance in several executive tests (inhibition, verbal fluency, and cognitive shifting) were used as potential predictors of the DTCs.

RESULTS

Individuals with PD exhibited a DTC on the nonverbal tasks and on the speech task when the secondary task was inhibition (the most difficult one). Additionally, the severity of dysarthria and a poorer performance in cognitive shifting predicted a more severe DTC on speech rate. Finally, modulation of the magnitude of the DTCs was observed, depending on the difficulty of the nonverbal secondary task.

CONCLUSION

The results suggest that, in PD, postlexical processes require attentional resources and cognitive shifting is related to dual-task performance in speech.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21265893.