C7 nerve root sensory distribution in peripheral nerves: a bold functional magnetic resonance imaging investigation at 9.4 T

Retro Oesophageal Transfer of Contralateral C7 in Birth Brachial Plexus Injury - A Retrospective Study

Background: Presence of available healthy nerve roots on the injured side determines the outcome after nerve reconstruction. Paucity of nerve roots warrants contralateral C7 harvest for optimal results. We aim to study the risks and benefits of retro oesophageal transfer of contralateral C7 root in infants with birth brachial plexus injury. Methods: Study was carried out from 2017 to 2022 in 13 children who have undergone retro oesophageal transfer of contralateral C7 root to affected side. Follow-up period ranged from 8 to 60 months after the surgery. Motor power assessment was done using by active movement scale. Results: Average active movement score for abduction was found to be 6, elbow flexion 5.7, elbow extension 5.8, wrist extension 3, wrist flexion 4, finger flexion 4.8 and finger extension 3.8, respectively. No neurological deficits, limb length anomaly noted in the normal upper limb after contralateral C7 harvest. Conclusions: Retro oesophageal transfer of contralateral C7 is a safe technique in birth brachial plexus injury. The advantage of retro oesophageal transfer is reduction in the length of nerve grafts, thus helping in early neurotisation of distal forearm and hand muscles. The large axonal output from contralateral C7 can be used to reconstruct different nerves without any residual deficits on the normal side. Level of Evidence: Level IV (Therapeutic).

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.

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.

Autobiography of James S. Hyde

The papers, book chapters, reviews, and patents by James S. Hyde in the bibliography of this document have been separated into EPR and MRI sections, and within each section by topics. Within each topic, publications are listed chronologically. A brief summary is provided for each patent listed. A few publications and patents that do not fit this schema have been omitted. This list of publications is preceded by a scientific autobiography that focuses on selected topics that are judged to have been of most scientific importance. References to many of the publications and patents in the bibliography are made in the autobiography.

Effect of Collateral Sprouting on Donor Nerve Function After Nerve Coaptation: A Study of the Brachial Plexus

Background

The aim of the present study was to evaluate the donor nerve from the C7 spinal nerve of the rabbit brachial plexus after a coaptation procedure. Assessment was performed of avulsion of the C5 and C6 spinal nerves treated by coaptation of these nerves to the C7 spinal nerve.

Material/Methods

After nerve injury, fourteen rabbits were treated by end-to-side coaptation (ETS), and fourteen animals were treated by side-to-side coaptation (STS) on the right brachial plexus. Electrophysiological and histomorphometric analyses and the skin pinch test were used to evaluate the outcomes.

Results

There was no statistically significant difference in the G-ratio proximal and distal to the coaptation in the ETS group, but the differences in the axon, myelin sheath and fiber diameters were statistically significant. The comparison of the ETS and STS groups distal to the coaptation with the controls demonstrated statistically significant differences in the fiber, axon, and myelin sheath diameters. With respect to the G-ratio, the ETS group exhibited no significant differences relative to the control, whereas the G-ratio in the STS group and the controls differed significantly. In the electrophysiological study, the ETS and STS groups exhibited major changes in the biceps and subscapularis muscles.

Conclusions

The coaptation procedure affects the histological structure of the nerve donor, but it does not translate into changes in nerve conduction or the sensory function of the limb. The donor nerve lesion in the ETS group is transient and has minimal clinical relevance.

Donor-side morbidity after contralateral C-7 nerve transfer: results at a minimum of 6 months after surgery

OBJECT Donor-side morbidity associated with contralateral C-7 (CC7) nerve transfer remains controversial. The purpose of this study was to evaluate functional deficits in the donor limb resulting from prespinal route CC7 nerve transfer. METHODS A total of 63 patients were included. Forty-one patients had undergone CC7 nerve transfer surgery at least 6 months previously and were assigned to one of 2 groups based on the duration of postoperative follow-up. Group 1 (n = 21) consisted of patients who had undergone surgery between 6 months and 2 years previously, and Group 2 (n = 20) consisted of patients who had undergone surgery more than 2 years previously. An additional 22 patients who underwent CC7 nerve transfer surgery later than those in Groups 1 and 2 were included as a control group (Group 3). Results of preoperative testing in these patients and postoperative testing in Groups 1 and 2 were compared. Testing included subjective assessments and objective examinations. An additional 3 patients had undergone surgery more than 6 months previously but had severe motor weakness and were therefore evaluated separately; these 3 patients were not included in any of the study groups. RESULTS The revised Short-Form McGill Pain Questionnaire (SF-MPQ-2) was the only subjective test that showed a significant difference between Group 3 and the other 2 groups, while no significant differences were found in objective sensory, motor, or dexterity outcomes. The interval from injury to surgery for patients with a normal SF-MPQ-2 score in Groups 1 and 2 was significantly less than for those with abnormal SF-MFQ-2 scores (2.4 ± 1.1 months vs 4.6 ± 2.9 months, p = 0.002). The 3 patients with obvious motor weakness showed a tendency to gradually recover. CONCLUSIONS Although some patients suffered from long-term sensory disturbances, resection of the C-7 nerve had little effect on the function of the donor limb. Shortening preoperative delay time can improve sensory recovery of the donor limb.

Functional connectivity in rat brain at 200 μm resolution

The somatosensory functional magnetic resonance imaging (fMRI) response to electrical stimulation of the middle phalange of the second digit of four rats at a spatial resolution of 200 μm cubic at 9.4 T is reported. At high threshold (p<0.002), activated voxels encompass a penetrating vein that passes across the gray matter. These voxels lie mostly in three contiguous slices perpendicular to the pial surface. This activation is assigned to the representation in the forepaw barrel subfield (FBS) of a single cortical column of this phalange. In addition, the activation of the indusium griseum (IG) is visualized robustly. Voxels revealed by fMRI were used to observe functional connectivity to other voxels of the sensorimotor cortex using fcMRI. Results of this experiment were analyzed as a function of decreasing threshold, which exhibited spreading connectivity that revealed S2, M1/M2, and contralateral S1. Noting that every cubic millimeter of tissue contains 125 voxels, connectivity patterns are complex. It is hypothesized that they reflect connections within gray matter by association fibers. S2 and IG revealed connectivities with many voxels across the sensorimotor cortex. These regions also showed subregional variation of connectivity. A 1-cm-diameter surface coil with a local low-noise RF amplifier was used in these studies. The usual region of sensitivity (ROS) of such a coil is 1 cm diameter by 0.5 cm depth. Significant connectivity was observed between time courses of voxels that were within the ROS and voxels that were outside, which extends the volume of tissue that can be observed by the methods of this article.

The current perception threshold test differentiates categories of mechanical neck disorder

STUDY DESIGN

Cross-sectional discriminative analysis.

OBJECTIVE

To determine whether current perception threshold (CPT) can differentiate between categories of patients with mechanical neck disorders (MNDs).

BACKGROUND

Neck pain is the third most common musculoskeletal disorder and affects a third of all adults each year. It can present as neck pain without musculoskeletal signs, neck pain with musculoskeletal signs but no neurological signs, or neck pain with neurological signs. CPT testing can assess altered sensory perception that may reflect neurological changes.

METHODS

Patients with MNDs (n = 106) were classified into 3 groups, based on a standardized musculoskeletal examination process performed by an experienced physiotherapist who was blinded to CPT scores. The 3 groups were defined as neck pain without musculoskeletal signs (MND I) (n = 60), neck pain with musculoskeletal signs (MND II) (n = 29), and neck pain with neurological signs (MND III) (n = 17). A rapid protocol of CPT testing was performed at 3 frequencies (5, 250, and 2000 Hz), using 3 dermatomal locations on the hand. A 1-way analysis of variance with post hoc comparison and effect sizes was calculated to compare the mean CPT scores between the groups. A binary logistic-regression model was used to predict probability of higher CPT in MND III and to create a receiver-operating-characteristic curve.

RESULTS

Mean CPT differed significantly across the 3 MND groups (MND I, 9.7; MND II, 10.6; and MND III, 11.8; P<.001; η(2) = 0.6). Post hoc comparisons indicated differences between MND I and MND II (P = .05) and between MND II and MND III (P = .01) that had large effect sizes (MND I versus II, d = 1 and MND II versus III, d = 2.2). CPT testing was able to distinguish between MND II and III when a threshold value of greater than 11 was used to indicate MND III. The predicted probability of abnormal CPT in MND III had an estimated 73% sensitivity and 81% specificity; the odds ratio was 11.5 (P = .001) for the differentiation capacity of CPT between MND II and III, with a cutoff of 11. The area under the receiver-operating-characteristic curve was 0.84 (95% confidence interval: 0.72, 0.96; P<.001).

CONCLUSION

CPT testing has moderate discriminatory accuracy, specificity, and sensitivity for classification of MND categories into neck pain with or without neurological signs. J Orthop Sports Phys Ther 2014;44(7):532-540. Epub 10 May 2014. doi:10.2519/jospt.2014.4691.

The Current Perception Threshold Test Differentiates Categories of Mechanical Neck Disorder

Study Design Cross-sectional discriminative analysis. Objective To determine whether current perception threshold (CPT) can differentiate between categories of patients with mechanical neck disorders (MNDs). Background Neck pain is the third most common musculoskeletal disorder, affecting a third of all adults each year. It can present as neck pain without musculoskeletal signs; neck pain with musculoskeletal signs but no neurological signs; neck pain with neurological signs. CPT testing can assess altered sensory perception that may reflect neurological changes. Methods Patients with MNDs (n=106) were classified into 3 groups based on a standardized musculoskeletal examination process performed by an experienced physiotherapist blinded to CPT scores. The 3 groups were defined as: MND-I, neck pain without musculoskeletal signs (n=60); MND-II, neck pain with musculoskeletal signs (n=29); MND-III, neck pain with neurological signs (n=17). A rapid protocol of CPT testing was performed at 3 frequencies (5, 250, 2000 Hz), using 3 dermatomal locations on the hand. A 1-way ANOVA with post hoc comparison and effect sizes were calculated to compare the mean CPT score between the groups. A binary logistic regression model was used to predict probability of higher CPT in MND-III and used to create a receiver operating characteristic (ROC) curve. Results Mean CPT differed significantly across the 3 MND groups (MND-I, 9.7; MND-II, 10.6; and MND-III, 11.8; P < .001, η2 = .6). Post hoc comparisons indicated differences between MND-I and MND-II (P = .05) and between MND-II and MND-III (P = .01), that were large effect sizes (MND I versus II, d = 1 and MND II versus III, d = 2.2). CPT testing was able to distinguish between MND II and III when a threshold value of greater than 11 was used to indicate MND-III. The predicted probability of abnormal CPT in MND-III had an estimated 73% sensitivity and 81% specificity; the odds ratio was 11.5 (P =.001) for the differentiation capacity of CPT between MND-II and III with a cut-off of 11. The area under the ROC curve (AUC) was .84 (95% CI =.72 to .96, P < .001). Conclusions CPT testing has moderate discriminatory accuracy, specificity, and sensitivity for classification of MND categories into neck pain with or without neurological signs. J Orthop Sports Phys Ther, Epub 10 May 2014. doi:10.2519/jospt.2014.5691.