# Early Motor Cortex Connectivity and Neuronal Reactivity in Intracerebral Hemorrhage: A Continuous-Wave Functional Near-Infrared Spectroscopy Study

## TL;DR

This study uses near-infrared spectroscopy to show how brain regions connected to movement change in patients with brain bleeds, depending on which side of the brain is affected.

## Contribution

Demonstrates feasibility of cw-fNIRS for assessing motor cortex connectivity and reactivity in acute ICH patients, revealing hemisphere-specific patterns.

## Key findings

- Left hemispheric ICH shows increased connectivity between affected primary motor and premotor cortices.
- Right hemispheric ICH shows decreased connectivity between unaffected primary motor and affected somatosensory cortex.
- Left-hand motor tasks increase oxygenation in the unaffected premotor cortex in right hemispheric ICH.

## Abstract

What are the main findings?
A seed-based resting-state functional connectivity (RSFC) and motor-paradigm-based oxygenation change assessment using continuous-wave functional near-infrared spectroscopy is feasible in patients with acute intracerebral hemorrhage (ICH).In patients with left hemispheric ICH, RSFC may be increased between the affected primary motor cortex (priMC) and the affected premotor cortex (preMC). In contrast, in right hemispheric ICH, RSFC may be decreased between the unaffected priMC and the affected somatosensory cortex.In patients with right hemispheric ICH with left hand finger tapping, there may be increased oxygenation over the unaffected preMC.

A seed-based resting-state functional connectivity (RSFC) and motor-paradigm-based oxygenation change assessment using continuous-wave functional near-infrared spectroscopy is feasible in patients with acute intracerebral hemorrhage (ICH).

In patients with left hemispheric ICH, RSFC may be increased between the affected primary motor cortex (priMC) and the affected premotor cortex (preMC). In contrast, in right hemispheric ICH, RSFC may be decreased between the unaffected priMC and the affected somatosensory cortex.

In patients with right hemispheric ICH with left hand finger tapping, there may be increased oxygenation over the unaffected preMC.

What is the implication of the main finding?
Motor cortex reorganization in patients with acute ICH is based on the side of the stroke.Left preMC connectivity and activity may be affected early in patients with ICH, which may serve as a target for neuromodulation devices.

Motor cortex reorganization in patients with acute ICH is based on the side of the stroke.

Left preMC connectivity and activity may be affected early in patients with ICH, which may serve as a target for neuromodulation devices.

Insights into motor cortex remodeling may enable the development of more effective rehabilitation strategies during the acute phase. We aim to assess the affected and unaffected motor/premotor/somatosensory cortex resting state functional connectivity (RSFC) and reactivity with continuous wave functional near-infrared spectroscopy (cw-fNIRS) in patients with ICH compared to age, sex, and comorbidity-matched subjects. We enrolled patients with acute–subacute hemispheric ICH (n = 37; two were excluded due to artifacts) and grouped them according to the side (right and left) of the stroke. Matched participants or patients with recent transient ischemic attack were enrolled as control subjects for the study (n = 44; five were excluded due to artifacts). RSFC was assessed in both affected and unaffected hemispheres by group-level seed-based (primary motor cortex, priMC) correlation analysis. FT-associated relative oxyhemoglobin (ΔHbO) changes were analyzed in affected and unaffected hemispheres with generalized linear model regression. In left hemispheric ICH, the resting state coherence between the affected priMC and the affected premotor cortex (preMC) increased (β = 0.83, 95% CI = 0.19, 1.47, p = 0.01). In contrast, in right hemispheric ICH, the coherence between the unaffected priMC and the affected preMC decreased (β = −0.6, 95% CI = −1.12, −0.09, p = 0.02). In the left hemispheric ICH, the left-hand FT was associated with increased ΔHbO over the affected preMC (β = 0.01, 95% CI = 0.003, 0.02, p = 0.01). In contrast, in right hemispheric ICH, the left-hand FT was associated with increased ΔHbO over the unaffected preMC (β = 0.02, 95% CI = 0.006, 0.04, p = 0.01). Left hemispheric preMC may be involved in motor cortex reorganization in acute ICH in either hemisphere. Further studies may be required to assess longitudinal changes in motor cortex reorganization to inform acute motor rehabilitation.