Cortico-Cerebellar Connectivity Underlying Motor Control in Chronic Poststroke Individuals

Efficacy and safety of deep brain stimulation in mesencephalic locomotor region for motor function in patients with post-stroke hemiplegia: a study protocol for a multi-center double-blind crossover randomized controlled trial

Background

Deep brain stimulation (DBS) is a potential treatment for improving movement disorder. However, few large-sample studies can reveal its efficacy and safety. This study aims to initially explore the efficacy and safety of DBS in the mesencephalic locomotor region (MLR) on motor function in patients with post-stroke hemiplegia.

Methods/design

This multicenter, prospective, double-blind, randomized crossover clinical trial aims to assess the safety and effectiveness of Deep Brain Stimulation (DBS) in the mesencephalic locomotor region (MLR) for patients with moderate to severe post-stroke hemiplegia. Sixty-two patients with stable disease after a year of conservative treatment will be enrolled and implanted with deep brain electrodes. Post-surgery, patients will be randomly assigned to either the DBS group or the control group, with 31 patients in each. The DBS group will receive electrical stimulation 1 month later, while the control group will undergo sham stimulation. Stimulation will be discontinued after 3 and 6 months, followed by a 2-week washout period. Subsequently, the control group will receive electrical stimulation, while the DBS group will undergo sham stimulation. Both groups will resume electrical stimulation at the 9th and 12th-month follow-ups. Post-12-month follow-up, motor-related scores will be collected for analysis, with the Fugl-Meyer Assessment Upper Extremity Scale (FMA-UE) as the primary metric. Secondary outcomes include balance function, neuropsychiatric behavior, fall risk, daily living activities, and quality of life. This study aims to provide insights into the therapeutic benefits of DBS for post-stroke hemiplegia patients.

Result/conclusion

We proposed this study for the first time to comprehensively explore the effectiveness and safety of DBS in improving motor function for post-stroke hemiplegia, and provide evidence for DBS in the treatment of post-stroke hemiplegia. Study limitations are related to the small sample size and short study period.

Clinical Trial Registration

Clinicaltrials.gov, identifier NCT05968248.

Electrophysiological Correlates of Dentate Nucleus Deep Brain Stimulation for Poststroke Motor Recovery

While ipsilesional cortical electroencephalography has been associated with poststroke recovery mechanisms and outcomes, the role of the cerebellum and its interaction with the ipsilesional cortex is still largely unknown. We have previously shown that poststroke motor control relies on increased corticocerebellar coherence (CCC) in the low beta band to maintain motor task accuracy and to compensate for decreased excitability of the ipsilesional cortex. We now extend our work to investigate corticocerebellar network changes associated with chronic stimulation of the dentato-thalamo-cortical pathway aimed at promoting poststroke motor rehabilitation. We investigated the excitability of the ipsilesional cortex, the dentate (DN), and their interaction as a function of treatment outcome measures. Relative to baseline, 10 human participants (two women) at the end of 4-8 months of DN deep brain stimulation (DBS) showed (1) significantly improved motor control indexed by computerized motor tasks; (2) significant increase in ipsilesional premotor cortex event-related desynchronization that correlated with improvements in motor function; and (3) significant decrease in CCC, including causal interactions between the DN and ipsilesional cortex, which also correlated with motor function improvements. Furthermore, we show that the functional state of the DN in the poststroke state and its connectivity with the ipsilesional cortex were predictive of motor outcomes associated with DN-DBS. The findings suggest that as participants recovered, the ipsilesional cortex became more involved in motor control, with less demand on the cerebellum to support task planning and execution. Our data provide unique mechanistic insights into the functional state of corticocerebellar-cortical network after stroke and its modulation by DN-DBS.

No Additional Effects of Sequential Facilitatory Cerebral and Cerebellar rTMS in Subacute Stroke Patients

The aim of this study was to investigate the additional effects of cerebellar rTMS on the motor recovery of facilitatory rTMS over affected primary motor cortex (M1) in subacute stroke patients. Twenty-eight subacute stroke patients were recruited in this single-blind, randomized, controlled trial. The Cr-Cbll group received Cr-Cbll rTMS stimulation consisting of high-frequency rTMS over affected M1 (10 min), motor training (10 min), and high-frequency rTMS over contralesional Cbll (10 min). The Cr-sham group received sham rTMS instead of high-frequency rTMS over the cerebellum. Ten daily sessions were performed for 2 weeks. A Fugl-Meyer Assessment (FMA) was measured before (T0), immediately after (T1), and 2 months after the intervention (T2). A total of 20 participants (10 in the Cr-Cbll group and 10 in the Cr-sham group) completed the intervention. There was no significant difference in clinical characteristics between the two groups at T0. FMA was significantly improved after the intervention in both Cr-Cbll and Cr-sham groups (p < 0.05). However, there was no significant interaction in FMA between time and group. In conclusion, these results could not demonstrate that rTMS over the contralesional cerebellum has additional effects to facilitatory rTMS over the affected M1 for improving motor function in subacute stroke patients.

Suicide Attempt in a Poststroke Patient After Undergoing Deep Brain Stimulation: A Case Report

Deep brain stimulation (DBS) is a type of therapy involving electrical stimulation of the brain and is primarily used to treat movement disorders. While perhaps beneficial, DBS has also been shown to have some potential major side effects, including increased risk for depression and suicide. In the present article, we report a case of a suicide attempt in a depressed patient two months after undergoing DBS for treatment of acute dystonia the patient had suffered from a prior ischemic stroke. This manuscript serves as a reminder of the negative ramifications that can be associated with DBS and why we should be cautious in providing DBS to patients who are either currently depressed or have a history of depression.

Paired DBS and TMS Reveals Dentato-Cortical Facilitation Underlying Upper Extremity Movement in Chronic Stroke Survivors

BACKGROUND

Cerebellum shares robust di-synaptic dentato-thalamo-cortical (DTC) connections with the contralateral motor cortex. Preclinical studies have shown that DTC are excitatory in nature. Structural integrity of DTC is associated with better upper extremity (UE) motor function in people with stroke, indicating DTC are important for cerebellar influences on movement. However, there is a lack of understanding of physiologic influence of DTC in humans, largely due to difficulty in accessing the dentate nucleus.

OBJECTIVE

Characterize DTC physiology using dentate nucleus deep brain stimulation (DBS) combined with transcranial magnetic stimulation (TMS) in stroke.

METHODS

Nine chronic stroke survivors with moderate-to-severe UE impairment (Fugl-Meyer 13-38) underwent a paired DBS-TMS experiment before receiving experimental dentate nucleus DBS in our first-in-human phase I trial (Baker et al., 2023, Nature Medicine). Conditioning DBS pulses were given to dentate nucleus 1 to 10 ms prior to supra-threshold TMS pulses given to ipsilesional motor cortex. Effects were assessed on motor evoked potentials (MEPs). Size of DBS-conditioned MEPs was expressed relative to TMS MEPs, where values >1 indicate facilitation.

RESULTS

Dentate nucleus DBS led to facilitation of MEPs at short-latency intervals (3.5 and 5 ms, P = .049 and .021, respectively), a phenomenon we have termed dentato-cortical facilitation (DCF). Higher DCF was observed among patients with more severe UE impairment. Diffusion tensor imaging revealed microstructure of thalamo-cortical portion of DTC was related to higher corticomotor excitability.

CONCLUSIONS

Our in vivo investigation reveals for the first time in humans the intrinsic excitatory properties of DTC, which can serve as a novel therapeutic target for post-stroke motor recovery.