# Trigeminal Nerve Stimulation in Chronic Hemiparetic Stroke

> **NIH NIH F31** · NORTHWESTERN UNIVERSITY · 2022 · $42,525

## Abstract

Project Summary
 Emerging research has suggested that chronic stroke induced motor impairments exhibit a dependence on
heighted brainstem mediated monoaminergic drive. Explicitly, an increase in descending monoamines is
believed to increase spinal motoneuron excitability and thus (1) generate spasticity and (2) amplify the diffuse
commands that are responsible for flexion synergy expression. Though modulating this descending
monoaminergic drive yields tremendous potential in affecting both impairments, current pharmacological
approaches prove inadequate and require lengthy titration schedules and elicit burdensome side effects. Thus,
I propose the novel application of transcutaneous electrical ophthalmic trigeminal nerve stimulation (TNS). This
non-invasive stimulus has been shown to attenuate systemic measures of monoamines and is believed to
modulate monoaminergic brainstem areas such as the locus coeruleus. Such an ability to non-invasively reduce
monoamines represents the possibility for substantial improvements in stroke induced movement impairments.
 To investigate this potential, the goal of the proposed project is to elucidate the effects of TNS on (1) upper
limb spinal motoneuron excitability and (2) flexion synergy expression in chronic stroke survivors. Highly
quantitative metrics will be employed for both aims. Spinal motoneuron excitability will be quantified through the
tonic vibration reflex and deep tendon reflex and flexion synergy expression will be quantified with precise robotic
measures of upper extremity work area. These measures will be conducted before, during and after either a real
or sham TNS stimulus condition, with stimulus induced changes in the metrics compared between conditions
and against a quantitative metric of systemic monoamines (salivary α-amylase). Preliminary work has highlighted
the feasibility of the proposed measures and supported the posited rationale. Specifically, initial efforts have
shown a reduction of motor impairments during TNS in individuals with chronic hemiparetic stroke.
 Findings from this study will act to inform an understanding of the functional role of monoaminergic
contributions to human motor control. This will deepen our understanding of human motor control and could
facilitate substantive efforts in the development of neurorehabilitation paradigms. Specifically, through the
application of TNS detailed here, this project will supply initial evidence for a neuromodulatory probe with the
potential to alter monoaminergic drive and reduce chronic stroke induced motor impairments. This will provide
insight into the magnitude of monoaminergic contributions to upper extremity motoneuron excitability and flexion
synergy expression and their susceptibility to changes in monoaminergic drive.

## Key facts

- **NIH application ID:** 10272422
- **Project number:** 5F31NS120500-02
- **Recipient organization:** NORTHWESTERN UNIVERSITY
- **Principal Investigator:** James Andrew Beauchamp
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $42,525
- **Award type:** 5
- **Project period:** 2020-12-01 → 2022-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10272422

## Citation

> US National Institutes of Health, RePORTER application 10272422, Trigeminal Nerve Stimulation in Chronic Hemiparetic Stroke (5F31NS120500-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10272422. Licensed CC0.

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