Vagal nerve stimulation: exploring its efficacy and success for an improved prognosis and quality of life in cerebral palsy patients

The dual effect of vagus nerve stimulation in pediatric patients with drug-resistant epilepsy: Is there more than seizure control?

This is a retrospective and comparative pilot study to investigate the role of vagus nerve stimulation (VNS) in improving cognitive functions in the pediatric age group with drug resistant epilepsy (DRE). It was conducted from January 2018 to February 2023. Children between the ages of 4 and 18 years were divided into two groups, the "VNS group" and the "best medical treatment (BMT) group". Follow up period was 12 months. Demographic, clinical, etiological and investigational data were recorded. Cognitive assessment using the Modified Mini-Mental State Examination for children (MMSE) was recorded at baseline and 12 months later for each group. 76.4 % of patients were classified as epilepsy secondary to cerebral palsy. 75 % of patients showed ≥ 50 % seizure frequency reduction among the VNS group as compared to 12.5 % in the BMT group. None of both groups achieved seizure freedom. At 12 months, both BMT and VNS groups showed statistically significantly improved overall cognitive score from baseline records (p = 0.027) and (p = 0.012), respectively, with a significantly higher improvement in VNS group. Also, statistical sub-analysis of cognitive subscales in cerebral palsy patients in both groups was conducted and revealed a significant improvement (p = 0.02) in the VNS group. We concluded that there is a potential role of VNS in improving cognitive functions which was shown by using a cost-effective screening tool. A significant effect was observed specially in cerebral palsy patients. This is very beneficial in limited-resources countries since VNS has good safety profile, high seizure control, and added value to cognitive functions.

Vagus nerve stimulation to augment recovery from severe traumatic brain injury impeding consciousness: a prospective pilot clinical trial

OBJECTIVES

Traumatic brain injury (TBI) has high morbidity and mortality in both civilian and military populations. Blast and other mechanisms of TBI damage the brain by causing neurons to disconnect and atrophy. Such traumatic axonal injury can lead to persistent vegetative and minimally conscious states (VS and MCS), for which limited treatment options exist, including physical, occupational, speech, and cognitive therapies. More than 60 000 patients have received vagus nerve stimulation (VNS) for epilepsy and depression. In addition to decreased seizure frequency and severity, patients report enhanced mood, reduced daytime sleepiness independent of seizure control, increased slow wave sleep, and improved cognition, memory, and quality of life. Early stimulation of the vagus nerve accelerates the rate and extent of behavioral and cognitive recovery after fluid percussion brain injury in rats.

METHODS

We recently obtained Food and Drug Administration (FDA) approval for a pilot prospective randomized crossover trial to demonstrate objective improvement in clinical outcome by placement of a vagus nerve stimulator in patients who are recovering from severe TBI. Our hypothesis is that stimulation of the vagus nerve results in increased cerebral blood flow and metabolism in the forebrain, thalamus, and reticular formation, which promotes arousal and improved consciousness, thereby improving outcome after TBI resulting in MCS or VS.

DISCUSSION

If this study demonstrates that VNS can safely and positively impact outcome, then a larger randomized prospective crossover trial will be proposed.

Influence of cerebellar stereotactic stimulation on left-right electrodermal information transference in a patient with cerebral palsy

BACKGROUND AND OBJECTIVES

Recent evidence indicates that cerebral palsy is connected to specific autonomic dysregulation between sympathetic and parasympathetic efferent pathways, likely linked to hemispheric influences. These findings suggest a hypothesis that contralateral interhemispheric disinhibition, which may occur on various levels of brain processing including motor functions, could be linked to specific functional dysregulation and structural lesions, which may play a specific role in the modulation of autonomic functions and lead to autonomic dysregulation in cerebral palsy.

METHOD

With the aim of comparing autonomic functions as they relate to interhemispheric modulatory influences during therapeutically indicated stereotactic cerebellar stimulation, we have performed bilateral electrodermal activity measurement and calculations of pointwise transinformation (PTI) in a patient with cerebral palsy. Measurement was performed during therapeutic deep cerebellar stimulation in two cerebellar areas in anterior cerebellar lobe-culmen (left electrode) and central lobule-superior cerebellar peduncle (right electrode).

RESULTS

The results indicate that information transference (PTI) is able to distinguish the states related to specific cerebellar stimulations and that lowest levels of the PTI have been found during stimulation of the central lobule-superior cerebellar peduncle (electrode deepest contact 1), indicating a significantly increased level of inhibition between the left and right sides.

CONCLUSION

The results may present potentially useful clinical findings indicating that increased PTI calculated from electrodermal activity could indirectly indicate disinhibitory activity as a possible indicator of a failure of interhemispheric communication that could explain some specific pathogenetic mechanisms in cerebral palsy. Nevertheless, these results need detailed confirmation in further research, as well as reliable clinical evaluation of their usefulness in the therapy of cerebral palsy.

Long-term results of vagal nerve stimulation for adults with medication-resistant epilepsy who have been on unchanged antiepileptic medication

PURPOSE

Several studies suggest that vagal nerve stimulation (VNS) is an effective treatment for medication-resistant epileptic patients, although patients' medication was usually modified during the assessment period. The purpose of this prospective study was to evaluate the long-term effects of VNS, at 18 months of follow-up, on epileptic patients who have been on unchanged antiepileptic medication.

METHODS

Forty-three patients underwent a complete epilepsy preoperative evaluation protocol, and were selected for VNS implantation. After surgery, patients were evaluated on a monthly basis, increasing stimulation 0.25mA at each visit, up to 2.5mA. Medication was unchanged for at least 18 months since the stimulation was started. The outcome was analysed in relation to patients' clinical features, stimulation parameters, epilepsy type, magnetic resonance imaging (MRI) results, and history of prior brain surgery.

RESULTS

Of the 43 operated patients, 63% had a similar or greater than 50% reduction in their seizure frequency. Differences in the responder rate according to stimulation intensity, age at onset of epilepsy, duration of epilepsy before surgery, previous epilepsy surgery and seizure type, did not reach statistical significance. Most side effects were well tolerated.

CONCLUSIONS

62.8% of our series of 43 medication-resistant epileptic patients experienced a significant long-term seizure reduction after VNS, even in a situation of on unchanged medical therapy. Patient characteristics predictive of VNS responsiveness remain subject to investigation. Controlled studies with larger sample sizes, on VNS for patients with medication-resistant epilepsy on unchanged medication, are necessary to confirm VNS efficacy for drug-resistant epilepsy, and to identify predictive factors.

Dramatic first words spoken in 2 children after vagus nerve stimulation

Vagus nerve stimulation has become an accepted adjunctive treatment for refractory epilepsy with more recent FDA approval in the treatment of depression. Many "positive" effects have been noted in patients with epilepsy namely increased alertness, improved cognition, behavior and mood. These changes appear to be independent of seizure reduction and antiepileptic drug decrease. We present two children (aged 8 and 9 years) who were non-verbal and spoke their first words shortly after vagus nerve stimulators were implanted. The mechanism is unclear although vagus nerve stimulation has been clearly shown to induce neuronal, chemical and perfusion changes in both subcortical and cortical regions of the brain. There is likely a combined effect on primary speech areas as well subcortical and mamillothalamic tracts, and possibly even stimulation and changes at the local vocal cord level contributing to this phenomenon. Our observation has important implications in encephalopathic patients both with and without epilepsy.