Neuromodulatory therapies for patients with prolonged disorders of consciousness

The efficacy and safety of transcutaneous auricular vagus nerve stimulation for patients with minimally conscious state: a sham-controlled randomized double-blind clinical trial

Background

Transcutaneous auricular vagus nerve stimulation (taVNS) has emerged as a potentially effective neuromodulation technique for addressing neurological disorders, including disorders of consciousness. Expanding upon our prior clinical study, which demonstrated the superior effectiveness of a 4-week taVNS treatment in patients with minimally conscious state (MCS) compared to those in a vegetative state/unresponsive wakefulness state, the aim of this investigation was to evaluate the safety and therapeutic efficacy of taVNS in individuals with MCS through a sham-controlled randomized double-blind clinical trial.

Methods

A cohort of 50 adult patients (male = 33, female = 17) diagnosed with a MCS were randomly assigned to either the active taVNS (N = 25) or sham taVNS (N = 25) groups. The treatment period lasted for 4 weeks, followed by an 8-week follow-up period. The Coma Recovery Scale-Revised (CRS-R) and Glasgow Coma Scale (GCS) were administered at baseline and weekly during the initial 4 weeks. Additionally, the Disability Rating Scale (DRS) was used to assess the patients' functional abilities via telephone at week 12. Furthermore, various neurophysiological measures, including electroencephalogram (EEG), upper-limb somatosensory evoked potentials (USEP), brainstem auditory evoked potentials (BAEP), and P300 event-related potentials (P300), were employed to monitor changes in brain activity and neural conduction pathways.

Results

The scores for the active taVNS group in the CRS-R and GCS showed greater improvement over time compared to the sham taVNS group (CRS-R: 1-week, Z = -1.248, p = 0.212; 2-week, Z = -1.090, p = 0.276; 3-week, Z = -2.017, p = 0.044; 4-week, Z = -2.267, p = 0.023. GCS: 1-week, Z = -1.325, p = 0.185; 2-week, Z = -1.245, p = 0.213; 3-week, Z = -1.848, p = 0.065; 4-week, Z = -1.990, p = 0.047). Additionally, the EEG, USEP, BAEP, and P300 also demonstrated significant improvement in the active taVNS group compared to the sham taVNS group at week 4 (EEG, Z = -2.086, p = 0.037; USEP, Z = -2.014, p = 0.044; BAEP, Z = -2.298, p = 0.022; P300 amplitude, Z = -1.974, p = 0.049; P300 latency, t = 2.275, p = 0.027). Subgroup analysis revealed that patients with MCS derived greater benefits from receiving taVNS treatment earlier (CRS-R, Disease duration ≤ 1-month, mean difference = 8.50, 95% CI = [2.22, 14.78], p = 0.027; GCS, Disease duration ≤ 1-month, mean difference = 3.58, 95% CI = [0.14, 7.03], p = 0.044). By week 12, the active taVNS group exhibited lower Disability Rating Scale (DRS) scores compared to the sham taVNS group (Z = -2.105, p = 0.035), indicating a more favorable prognosis for MCS patients who underwent taVNS. Furthermore, no significant adverse events related to taVNS were observed during treatment.

Conclusion

The findings of this study suggest that taVNS may serve as a potentially effective and safe intervention for facilitating the restoration of consciousness in individuals diagnosed with MCS. This therapeutic approach appears to enhance cerebral functioning and optimize neural conduction pathways.

Clinical trial registration

http://www.chictr.org.cn, Identifier ChiCTR2200066629.

Transcutaneous auricular vagus nerve stimulation in the treatment of disorders of consciousness: mechanisms and applications

This review provides an in-depth exploration of the mechanisms and applications of transcutaneous auricular vagus nerve stimulation (taVNS) in treating disorders of consciousness (DOC). Beginning with an exploration of the vagus nerve's role in modulating brain function and consciousness, we then delve into the neuroprotective potential of taVNS demonstrated in animal models. The subsequent sections assess the therapeutic impact of taVNS on human DOC, discussing the safety, tolerability, and various factors influencing the treatment response. Finally, the review identifies the current challenges in taVNS research and outlines future directions, emphasizing the need for large-scale trials, optimization of treatment parameters, and comprehensive investigation of taVNS's long-term effects and underlying mechanisms. This comprehensive overview positions taVNS as a promising and safe modality for DOC treatment, with a focus on understanding its intricate neurophysiological influence and optimizing its application in clinical settings.

Optimizing the modulation paradigm of transcutaneous auricular vagus nerve stimulation in patients with disorders of consciousness: A prospective exploratory pilot study protocol

Background

Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive neuromodulation technique. Several studies have reported the effectiveness of taVNS in patients with disorders of consciousness (DOC); however, differences in the modulation paradigm have led to inconsistent treatment outcomes.

Methods/design

This prospective exploratory trial will include 15 patients with a minimally conscious state (MCS) recruited according to the coma recovery scale-revised (CRS-R). Each patient will receive 5 different frequencies of taVNS (1, 10, 25, 50, and 100 Hz); sham stimulation will be used as a blank control. The order of stimulation will be randomized, and the patients' CRS-R scores and resting electroencephalography (EEG) before and after stimulation will be recorded.

Discussion

The overall study of taVNS used in treating patients with DOC is still in the preliminary stage of exploration. Through this experiment, we aim to explore the optimal stimulation frequency parameters of taVNS for the treatment of DOC patients. Furthermore, we expect to achieve a stable improvement of consciousness in DOC patients by continuously optimizing the neuromodulation paradigm of taVNS for the treatment of DOC patients.

Clinical trial registration

https://www.chictr.org.cn/index.aspx, identifier ChiCTR 2200063828.

¿Es proporcionado suspender la nutrición e hidratación artificial en pacientes con pronóstico incierto?

Para llevar a cabo esta investigación, se revisó la literatura sobre el caso de Terri Schiavo, paciente que se encontraba en estado vegetativo persistente y quien falleció luego de dos semanas, después de que se le suspendiera su alimentación e hidratación; se validó su diagnóstico y se indagó si fue una paciente terminal, así como también se verificó la evidencia disponible, en relación con la hidratación y nutrición artificial en este tipo de pacientes, para determinar la concordancia de estas medidas. Esta información fue analizada desde la perspectiva nutricional y bioética; en la búsqueda bibliográfica se consultaron las bases de datos Scopus, Scielo y PubMed, con los criterios de búsqueda nutrición e hidratación artificial en pacientes terminales y de pronóstico incierto. Estos hallazgos fueron analizados con el modelo de proporcionalidad terapéutica de Calipari. Por lo anterior, se determinó que la nutrición e hidratación artificial configuraban tratamientos de carácter obligatorio u optativo para Terri. Sin embargo, pese a que no existe información concluyente sobre la nutrición e hidratación artificial en pacientes terminales, ni de pronóstico incierto, se recomienda la evaluación caso a caso de parte del equipo médico, para determinar la proporcionalidad de estos procedimientos en conjunto con el paciente y su familia. Cabe resaltar que son necesarios más estudios para proporcionar mejor evidencia que permita contar con elementos objetivos para una mejor toma de decisiones.

Transcutaneous auricular vagus nerve stimulation in disorders of consciousness: A mini-narrative review

In this mini review, 6 studies that investigated the effects of transcutaneous auricular vagus nerve stimulation (taVNS) in patients with disorders of consciousness (DOC) were reviewed. Generally, the application of taVNS in patients with DOC appears to be effective (positive results in 5 of 6 studies) and safe. Furthermore, 4 studies that evaluated changes in the brain following taVNS reported positive results (2 studies, functional magnetic resonance imaging and 2 studies, electroencephalography). Based on our review of the 6 studies, we believe that research and clinical application of taVNS in DOC are in the initial stages and have the following limitations. First, there is a shortage of studies on this topic, with only 6 studies, 2 of which were case reports. Second, 5 studies were performed without control or sham groups. Third, there was no standardization of treatment schedules and electrical stimulation parameters. Therefore, further studies to overcome the above limitations should be encouraged; further original studies involving a larger number of patients in the control or sham groups are needed. However, studies on the optimal conditions (treatment schedule and electrical stimulation parameters) for taVNS in patients with DOC are necessary. Furthermore, neuroimaging studies should be undertaken to elucidate the neurological mechanisms for the recovery of impaired consciousness in DOC and the lasting effects of taVNS on the brain.

Sleep patterns correlates with the efficacy of tDCS on post-stroke patients with prolonged disorders of consciousness

BACKGROUND

The subclassification of prolonged disorders of consciousness (DoC) based on sleep patterns is important for the evaluation and treatment of the disease. This study evaluates the correlation between polysomnographic patterns and the efficacy of transcranial direct current stimulation (tDCS) in patients with prolonged DoC due to stroke.

METHODS

In total, 33 patients in the vegetative state (VS) with sleep cycles or without sleep cycles were randomly assigned to either active or sham tDCS groups. Polysomnography was used to monitor sleep changes before and after intervention. Additionally, clinical scale scores and electroencephalogram (EEG) analysis were performed before and after intervention to evaluate the efficacy of tDCS on the patients subclassified according to their sleep patterns.

RESULTS

The results suggest that tDCS improved the sleep structure, significantly prolonged total sleep time (TST) (95%CI: 14.387-283.527, P = 0.013) and NREM sleep stage 2 (95%CI: 3.157-246.165, P = 0.040) of the VS patients with sleep cycles. It also significantly enhanced brain function of patients with sleep cycles, which were reflected by the increased clinical scores (95%CI: 0.340-3.440, P < 0.001), the EEG powers and functional connectivity in the brain and the 6-month prognosis. Moreover, the changes in NREM sleep stage 2 had a significant positive correlation with each index of the β band.

CONCLUSION

This study reveals the importance of sleep patterns in the prognosis and treatment of prolonged DoC and provides new evidence for the efficacy of tDCS in post-stroke patients with VS patients subclassified by sleep pattern. Trial registration URL: https://www.

CLINICALTRIALS

gov . Unique identifier: NCT03809936. Registered 18 January 2019.