Difference of neural connectivity for motor function in chronic hemiparetic stroke patients with intracerebral hemorrhage

A Narrative Review of Stroke of Cortical Hand Knob Area

The cortical hand knob region of the brain is a knob-like segment of the precentral gyrus, projecting into the middle genu of the central sulcus. This anatomic landmark is responsible for intricate control of hand motor movements and has often been implicated in motor weakness following stroke. In some instances, damage to this area has been mistaken for peripheral causes of hand weakness. Our article aims to consolidate clinically relevant information on the cortical hand knob area in a comprehensive review to guide clinicians regarding diagnosis and treatment strategies. We conducted a systematic search within the Medline/PubMed database for reports of strokes in the cortical hand knob region. All studies were published electronically up until December 2023. The search was conducted using the keyword "hand knob". A total of 24 reports containing 150 patients were found. The mean and median ages were 65 and 67 years, respectively. Sixty-two percent of the individuals were male. According to the TOAST criteria for the classification of the stroke, 59 individuals had a stroke due to large-artery atherosclerosis, 8 had small-vessel occlusion, 20 had cardioembolism, 25 were determined, and 38 were undetermined. The most common etiologies for stroke in the hand knob area can be attributed to large vessel occlusions, small vessel occlusions, or cardioembolism. Presentations following damage to this area can mimic ulnar, median, or radial neuropathy as well. Our comprehensive review serves as a resource for recognizing and managing stroke in the cortical hand knob area.

Clinical Effects of Immersive Multimodal BCI-VR Training after Bilateral Neuromodulation with rTMS on Upper Limb Motor Recovery after Stroke. A Study Protocol for a Randomized Controlled Trial

Background and Objectives: The motor sequelae after a stroke are frequently persistent and cause a high degree of disability. Cortical ischemic or hemorrhagic strokes affecting the cortico-spinal pathways are known to cause a reduction of cortical excitability in the lesioned area not only for the local connectivity impairment but also due to a contralateral hemisphere inhibitory action. Non-invasive brain stimulation using high frequency repetitive magnetic transcranial stimulation (rTMS) over the lesioned hemisphere and contralateral cortical inhibition using low-frequency rTMS have been shown to increase the excitability of the lesioned hemisphere. Mental representation techniques, neurofeedback, and virtual reality have also been shown to increase cortical excitability and complement conventional rehabilitation. Materials and Methods: We aim to carry out a single-blind, randomized, controlled trial aiming to study the efficacy of immersive multimodal Brain-Computer Interfacing-Virtual Reality (BCI-VR) training after bilateral neuromodulation with rTMS on upper limb motor recovery after subacute stroke (>3 months) compared to neuromodulation combined with conventional motor imagery tasks. This study will include 42 subjects in a randomized controlled trial design. The main expected outcomes are changes in the Motricity Index of the Arm (MI), dynamometry of the upper limb, score according to Fugl-Meyer for upper limb (FMA-UE), and changes in the Stroke Impact Scale (SIS). The evaluation will be carried out before the intervention, after each intervention and 15 days after the last session. Conclusions: This trial will show the additive value of VR immersive motor imagery as an adjuvant therapy combined with a known effective neuromodulation approach opening new perspectives for clinical rehabilitation protocols.

Integrity of The Hand Fibers of The Corticospinal Tract Shown by Diffusion Tensor Imaging Predicts Hand Function Recovery After Hemorrhagic Stroke

BACKGROUND

Hand motor function is often severely affected in patients with hemorrhagic stroke. The present study aimed to investigate the feasibility of predicting hand function recovery after hypertensive intracerebral hemorrhage using diffusion tensor imaging (DTI).

METHODS

A total of 75 patients with hypertensive intracerebral hemorrhage were prospectively included. DTI of the corticospinal tract (CST) connecting the hand knob area of the precentral gyrus and the cerebral peduncle was performed at around 3 weeks after stroke. Integrity of the CST was evaluated as no disruption, partial disruption, and complete disruption. Hand function was compared by the Brunnstrom recovery stage of hand (BRS-H) at post-stroke 3 weeks and 3 months.

RESULTS

Degrees of integrity of the corticospinal cord was negatively correlated with the BRS-H at both post-stroke 3 weeks (r = -0.77, p < 0.01) and 3 months (r = -0.75, p < 0.01). Patients with intact CST or completely disrupted CST shown by DTI did not show significant improvement in the BRS-H at post-stroke 3 months. However, those with partially disrupted CST showed significant improvement in the BRS-H at post-stroke 3 months compared to 3 weeks (3.79 ± 1.36 vs 2.53 ± 1.58, p = 0.012).

CONCLUSIONS

DTI can be used to visualize the damage to the hand fibers of the CST. Patients with partially disrupted CST may benefit most from rehabilitation therapy for hand function recovery after hypertensive intracerebral hemorrhage.

Intraoperative Transcranial Motor-Evoked Potentials Predict Motor Function Outcome in Intracerebral Hemorrhage Surgery

OBJECTIVE

Prediction of motor function after intracerebral hemorrhage (ICH) often poses a diagnostic challenge. This study was performed to investigate whether intraoperative monitoring of motor-evoked potentials (MEPs) could predict postoperative motor function recovery.

METHODS

We reviewed 16 consecutive patients undergoing evacuation of supratentorial ICH with hemiplegia between June 2011 and October 2014. Patients were categorized according to the results of MEPs before and after evacuation of hematoma. The correlation between detection of MEPs and prognosis of motor function was analyzed.

RESULTS

In 10 of 16 cases (62%), stable MEPs were detected before and after evacuation of hematoma, and postoperative motor function was improved in all cases, including 3 cases with severe preoperative motor impairment on manual muscle test (1-2). In 3 cases (19%) in which MEPs were not detected throughout the procedure, motor function was not improved. In the other 3 cases (19%), MEPs were not measured before evacuation of ICH but were detected after evacuation despite poor prognosis of motor function. The results of postevacuation MEPs were considered false-negative results. Predictions using pre-evacuation MEP results were completely consistent with prognosis for recovery, whereas MEPs obtained during and after evaluation were useful for monitoring.

CONCLUSIONS

Intraoperative MEPs may indicate preservation of pyramidal tracts, and pre-evacuation MEPs can predict motor function outcome after ICH surgery.

Improving Motor Corticothalamic Communication After Stroke Using Real-Time fMRI Connectivity-Based Neurofeedback

BACKGROUND

Two thirds of stroke survivors experience motor impairment resulting in long-term disability. The anatomical substrate is often the disruption of cortico-subcortical pathways. It has been proposed that reestablishment of cortico-subcortical communication relates to functional recovery.

OBJECTIVE

In this study, we applied a novel training protocol to augment ipsilesional cortico-subcortical connectivity after stroke. Chronic stroke patients with severe motor impairment were provided online feedback of blood-oxygenation level dependent signal connectivity between cortical and subcortical regions critical for motor function using real-time functional magnetic resonance imaging neurofeedback.

RESULTS

In this proof of principle study, 3 out of 4 patients learned to voluntarily modulate cortico-subcortical connectivity as intended.

CONCLUSIONS

Our results document for the first time the feasibility and safety for patients with chronic stroke and severe motor impairment to self-regulate and augment ipsilesional cortico-subcortical connectivity through neurofeedback using real-time functional magnetic resonance imaging.

Mouse intracerebral hemorrhage models produce different degrees of initial and delayed damage, axonal sprouting, and recovery

The mechanisms of delayed damage and recovery after intracerebral hemorrhage (ICH) remain poorly defined. Two rodent models of ICH are commonly used: injection of the enzyme collagenase (cICH) and injection of autologous blood (bICH). In mice, we compared the effects of these two models on initial and delayed tissue damage, motor system connections, and behavioral recovery. There is no difference in lesion size between models. Injection of autologous blood causes greater mass effect and early mortality. However, cICH produces greater edema, inflammation, and cell death. Injection of the enzyme collagenase causes greater loss of cortical connections and secondary shrinkage of the striatum. Intracerebral hemorrhage occurs within the motor system connections of the striatum. Mapping of the projections of the forelimb motor area shows a significant sprouting in motor cortex projections only in cICH. Both models of ICH produce deficits in forelimb motor control. Behavioral recovery occurs by 5 weeks in cICH and 9 weeks in bICH. In summary, cICH and bICH differ in almost every facet of initial and delayed stroke pathophysiology, with cICH producing greater initial and secondary tissue damage and greater motor system axonal sprouting than bICH. Motor recovery occurs in both models, suggesting that motor system axonal sprouting in cICH is not causally associated with recovery.