Aberrant central plasticity underlying synchronous sensory phenomena in brachial plexus injuries after contralateral cervical seventh nerve transfer

Harnessing the uninjured hemisphere for treatment of the stroke or brain-injured patient - evolution of the contralateral C7 transfer

This article presents a comprehensive review of contralateral C7 (cC7) transfer surgery, tracing its evolution from treating brachial plexus injuries to its transfer to ipsilateral C7 transfer surgery in treating upper motor neurone injuries. The cC7 was initially postulated to restore function by replacing injured nerves at the peripheral level, but dynamic cortical reorganization has since been demonstrated post-surgery, which potentially allows harnessing of the cC7 procedure to expand the span of control of the uninjured hemisphere in conditions like hemiplegic stroke. By integrating principles of nerve regeneration and brain plasticity through phased rehabilitation programmes, published clinical results have demonstrated significant improvements in upper limb function, confirming the procedure's safety and efficacy, with donor site morbidity that is typically mild and transient. The cC7 procedure may play a major role in the future of restoring upper limb function in patients who have suffered upper motor neurone lesions.

Dynamic alternations of interhemispheric functional connectivity in brachial plexus avulsion injury patients with nerve transfer: a resting state fMRI study

Brachial plexus avulsion injury (BPAI) is a severe peripheral nerve injury that leads to functional reorganization of the brain. However, the interhemispheric coordination following contralateral cervical 7 nerve transfer remains unclear. In this study, 69 BPAI patients underwent resting-state functional magnetic resonance imaging examination to assess the voxel-mirrored homotopic connectivity (VMHC), which reveals the interhemispheric functional connection. The motor function of the affected upper extremity was measured using the Fugl-Meyer Assessment of Upper Extremity (FMA-UE) scale. The VMHC analysis showed significant differences between the bilateral precentral gyrus, supplementary motor area (SMA), middle frontal gyrus (MFG), and insula. Compared to the preoperative group, the VMHC of the precentral gyrus significantly increased in the postoperative short-term group (PO-ST group) but decreased in the postoperative long-term group (PO-LT group). Additionally, the VMHC of the SMA significantly increased in the PO-LT group. Furthermore, the VMHC of the precentral gyrus in the PO-ST group and the SMA in the PO-LT group were positively correlated with the FMA-UE scores. These findings highlight a positive relationship between motor recovery and increased functional connectivity of precentral gyrus and SMA, which provide possible therapeutic targets for future neuromodulation interventions to improve rehabilitation outcomes for BPAI patients.

Donor complications of contralateral C7 nerve transfer in Brachial Plexus Birth Injury: a systematic review

PURPOSE

Contralateral C7 (CC7) nerve transfer is a reconstructive option in the upper limb when there are limited donor options. Promising results have been reported in the adult population but its role in Brachial Plexus Birth Injury (BPBI) is unclear. A major concern with this technique is the potential impact on the contralateral, unaffected limb. Our aim was to review the available literature on the use of this transfer in BPBI, to determine the incidence of short- and long-term deficits at the donor site.

METHODS

The relevant literature was identified from searches of Embase, Ovid Emcare and Ovid MEDLINE, for combinations of terms relating to CC7 nerve transfer and BPBI.

RESULTS

Seventy-five patients were included in this review, from the eight papers that were eligible for inclusion, from a total of 16 papers identified. Patient age ranged from three to 93 months and the shortest follow-up period was six months. Post-operative motor deficits at the donor site included reduced range of shoulder abduction; triceps weakness; and phrenic nerve palsy. All motor deficits recovered within six months. The only sensory deficit reported was reduced sensation in the median nerve distribution which, in all cases, resolved within four weeks. Finally, synchronous donor limb motion and sensation were reported in 46.6% of patients.

CONCLUSION

CC7 nerve transfer in BPBI appears to have few long-term donor limb complications. Sensory and motor deficits are reportedly transient. The impact of synchronous motion and sensation on upper limb function in this patient cohort is not yet known.

Value of High-Resolution MRI in the Diagnosis of Brachial Plexus Injury in Infants and Young Children

Purpose

To investigate the value of high-resolution MRI based on 3D-short inversion time inversion recovery sampling perfection with application-optimized contrasts (3D-STIR SPACE) sequence for the diagnosis of brachial plexus injury in infants and young children.

Methods

Physical examination, electromyography (EMG) and MRI data of 26 children with brachial plexus injury were retrospectively analyzed. Sensitivity, specificity, and accuracy were calculated for the three tests. The agreement among these examinations was analyzed with the Kappa test. P<0.05 was considered statistically significant.

Results

Of the 26 children, 3 cases had normal MRIs, 23 cases had unilateral brachial plexus injury diagnosed with MRI, and a total of 73 nerve roots and/or sheaths were involved. Among the 23 cases with aberrant MRI findings, there were 19 cases of nerve root thickening (42 nerve roots), 4 cases of nerve root sleeve expansion (5 nerve roots), 17 cases of pseudomeningeal cysts (34 nerve roots), 2 cases of nerve root loosening (2 nerve roots), 8 cases of nerve root dissection (11 nerve roots), 19 cases with increased nerve signal (43 nerve roots), and 9 cases with an increased signal of the muscles on the affected side. As for the diagnosis of brachial plexus injury, the sensitivity and the accuracy of physical examination, EMG and MRI were 0.92, 0.86, and 0.88, respectively. The agreement between MRI and physical examination was substantial (κ=0.780, P=0.000), as did the agreement between MRI and EMG (κ=0.611, P=0.005).

Conclusion

High-resolution MRI based on 3D-STIR SPACE sequence plays a role in the diagnosis and evaluation of brachial plexus injury in infants and young children. It can accurately identify the injured nerve and characterize related pathological alterations. Besides EMG and physical examination, it can be used as a valuable tool for screening and monitoring of brachial plexus injury in infants and children.

Identifying Oscillations under Multi-site Sensory Stimulation for High-level Peripheral Nerve Injured Patients：A Pilot Study

OBJECTIVE

For high-level peripheral nerve injured (PNI) patients with severe sensory dysfunction of upper extremities, identifying the multi-site tactile stimulation is of great importance to provide neurorehabilitation with sensory feedback. In this pilot study, we showed the feasibility of identifying multi-site and multi-intensity tactile stimulation in terms of electroencephalography (EEG).

APPROACH

Three high-level PNI patients and eight non-PNI participants were recruited in this study. Four different sites over the upper arm, forearm, thumb finger and little finger were randomly stimulated at two intensities (both sensory-level) based on the transcutaneous electrical nerve stimulation (TENS). Meanwhile, 64-channel EEG signals were recorded during the passive tactile sense stimulation on each side.

MAIN RESULTS

The spatial-spectral distribution of brain oscillations underlying multi-site sensory stimulation showed dominant power attenuation over the somatosensory and prefrontal cortices in both alpha-band (8-12 Hz) and beta-band (13-30 Hz). But there was no significant difference among different stimulation sites in terms of the averaged power spectral density over the region of interest (ROI). By further identifying different stimulation sites using temporal-spectral features, we found the classification accuracies were all above 89% for the affected arm of PNI patients, comparable to that from their intact side and that from the non-PNI group. When the stimulation site-intensity combinations were treated as eight separate classes, the classification accuracies were ranging from 88.89% to 99.30% for the affected side of PNI subjects, similar to that from their non-affected side and that from the non-PNI group. Other performance metrics, including Specificity, Precision, and F1-Score, also showed a sound identification performance for both PNI patients and non-PNI subjects.

SIGNIFICANCE

These results suggest that reliable brain oscillations could be evoked and identified well, even though induced tactile sense could not be discerned by the PNI patients. This study have implication for facilitating bidirectional neurorehabilitation systems with sensory feedback.

Contralateral C7 nerve transfer in the treatment of upper-extremity paralysis: a review of anatomical basis, surgical approaches, and neurobiological mechanisms

The previous three decades have witnessed a prosperity of contralateral C7 nerve (CC7) transfer in the treatment of upper-extremity paralysis induced by both brachial plexus avulsion injury and central hemiplegia. From the initial subcutaneous route to the pre-spinal route and the newly-established post-spinal route, this surgical operation underwent a series of innovations and refinements, with the aim of shortening the regeneration distance and even achieving direct neurorrhaphy. Apart from surgical efforts for better peripheral nerve regeneration, brain involvement in functional improvements after CC7 transfer also stimulated scientific interest. This review summarizes recent advances of CC7 transfer in the treatment of upper-extremity paralysis of both peripheral and central causes, which covers the neuroanatomical basis, the evolution of surgical approach, and central mechanisms. In addition, motor cortex stimulation is discussed as a viable rehabilitation treatment in boosting functional recovery after CC7 transfer. This knowledge will be beneficial towards improving clinical effects of CC7 transfer.

Aberrant central plasticity underlying synchronous sensory phenomena in brachial plexus injuries after contralateral cervical seventh nerve transfer

BACKGROUNDS

Contralateral cervical seventh (C7) nerve transfer aids motor and sensory recovery in total brachial plexus avulsion injuries (TBPI), but synchronous sensation often persists postoperatively. The mechanism underlying synchronous sensory phenomena remain largely unknown.

OBJECTIVE

To investigate the role of central plasticity in sensory recovery after contralateral C7 nerve transfer.

METHODS

Sixteen right TBPI patients who received contralateral C7 nerve transfer for more than 2 years were included. Sensory evaluations included Semmes-Weinstein monofilament assessment (SWM), synchronous sensation test, and sensory evoked action potential (SNAP) test. Smaller value in the SWM assessment and larger amplitude of SNAP indicates better tactile sensory. Functional magnetic resonance imaging was performed while stimulations delivered to each hand separately in block-design trials for central plasticity analysis.

RESULTS

The SWM value of the injured right hand was increased compared with the healthy left side (difference: 1.76, 95% confidence interval: 1.37-2.15, p < .001), and all 16 patients developed synchronous sensation. In functional magnetic resonance imaging analysis, sensory representative areas of the injured right hand were located in its ipsilateral S1, and 23.4% of this area overlapped with the representative area of the left hand. The ratio of overlap for each patient was significantly correlated with SWM value and SNAP amplitude of the right hand.

CONCLUSION

The tactile sensory functioning of the injured hand was dominated by its ipsilateral SI in long-term observation, and its representative area largely overlapped with the representative area of the intact hand, which possibly reflected a key mechanism of synchronous sensation in patients with TBPI after contralateral C7 transfer.