Dual Innervation Research Articles

Dual versus Single Innervation of Gracilis Free Functional Muscle Transfer in Facial Paralysis: Long-Term Resting and Dynamic Outcomes.

The purpose of this study was to compare long-term tone and excursion in single- versus dual-innervated free functional muscle transfer (FFMT) in patients with longstanding facial paralysis. Patients with longstanding facial palsy treated with an FFMT innervated either by a nerve-to-masseter graft (single-innervation group) or nerve-to-masseter and cross-facial-nerve grafts (dual-innervation group) were included. One-year minimum follow-up was required. Outcome measures, based on standardized photographs, included excursion, smile angle, teeth exposure, commissure height deviation, and upper lip height deviation in repose and in closed and open-teeth smile preoperatively and at 3 months, 1 year, and 3 years postoperatively. Emotrics software and ImageJ software were used to take measurements. Between-group and within-group longitudinal comparisons were analyzed. At 3 years (single, n = 24; dual, n = 13), significance was found between groups in commissure position (single, 26.42 mm versus dual, 31.51 mm; P < 0.0001) and excursion with open-mouth smile (single, 31.32 mm versus dual, 26.59 mm; P < 0.001). Single-innervation FFMT within-group analysis lacked significant improvement in commissure height deviation and upper lip height deviation at 3 years in repose, whereas the dual-innervation group revealed significant improvements (3.67 mm [ P < 0.001], 3.17 mm [ P < 0.001], respectively). Teeth exposure revealed an increase in the dual-innervation group (single, 35.753 mm 2 versus dual, 64.177 mm 2 ), but significance was not observed. Dual-innervated FFMT revealed improvements in resting tone and teeth exposure with minimal decrease in smile excursion compared with single-innervated FFMT. Therapeutic, III.

Dynamic Repair Surgery for Late-Stage Facial Paralysis: Advances in Restoring Movement and Function.

Purpose: Facial paralysis results from congenital or acquired facial nerve damage, leading to significant cosmetic and functional deficits. Surgical resection of parotid and midface tumors can cause facial paralysis, necessitating effective treatment strategies. This review addresses the challenge of restoring movement and function in late-stage facial paralysis, focusing on dynamic repair techniques involving nerve and muscle transplantation. Methods: The review encompasses studies on dynamic repair surgery for late facial paralysis, including techniques such as local muscle flap with pedicle transfer, vascularized nerve flap with pedicle transfer, and multiple muscle flap procedures. A systematic literature search was conducted using PubMed, Web of Science, and Google Scholar, covering studies from 2000 to 2024. Keywords included "dynamic repair", "late-stage facial paralysis", "nerve and muscle transplantation", "muscle flap", and "tendon transposition". Included were clinical studies, systematic reviews, and meta-analyses reporting surgical outcomes. Exclusion criteria included studies with insufficient data and non-peer-reviewed articles. Results: Dynamic repair techniques involving nerve and muscle transplantation are essential for treating late-stage facial paralysis. Each surgical method has strengths and limitations. The masseter muscle flap demonstrates high success rates, although it can cause horizontal tension and jaw contour issues. The temporalis muscle flap is effective for smile restoration but may lead to temporal concavity. The gracilis muscle flap is widely used, especially with dual nerve innervation, showing high success in spontaneous smiles but requiring a longer recovery period. The latissimus dorsi flap is effective but can cause edema and shoulder issues. The serratus anterior free flap offers flexibility with precise vector positioning but may not achieve adequate lip elevation and can cause cheek swelling. Combined multi-flap surgeries provide more natural facial expressions but increase surgical complexity and require advanced microsurgical skills. Conclusions: Dual nerve innervation shows promise for restoring spontaneous smiles. One-stage surgery offers faster recovery and reduced financial burden. Comprehensive patient evaluation is crucial to select the most suitable surgical method. Dynamic repair techniques involving nerve and muscle transplantation provide effective solutions for restoring function and aesthetics in late-stage facial paralysis. Future research should focus on long-term outcomes, patient satisfaction, and standardizing surgical protocols to optimize treatment strategies.

Functionally linked amygdala and prefrontal cortical regions are innervated by both single and double projecting cholinergic neurons.

Cholinergic cells have been proposed to innervate simultaneously those cortical areas that are mutually interconnected with each other. To test this hypothesis, we investigated the cholinergic innervation of functionally linked amygdala and prefrontal cortical regions. First, using tracing experiments, we determined that cholinergic cells located in distinct basal forebrain (BF) areas projected to the different nuclei of the basolateral amygdala (BLA). Specifically, cholinergic cells in the ventral pallidum/substantia innominata (VP/SI) innervated the basal nucleus (BA), while the horizontal limb of the diagonal band of Broca (HDB) projected to its basomedial nucleus (BMA). In addition, cholinergic neurons in these two BF areas gave rise to overlapping innervation in the medial prefrontal cortex (mPFC), yet their axons segregated in the dorsal and ventral regions of the PFC. Using retrograde-anterograde viral tracing, we demonstrated that a portion of mPFC-projecting cholinergic neurons also innervated the BLA, especially the BA. By injecting retrograde tracers into the mPFC and BA, we found that 28% of retrogradely labeled cholinergic cells were double labeled, which typically located in the VP/SI. In addition, we found that vesicular glutamate transporter type 3 (VGLUT3)-expressing neurons within the VP/SI were also cholinergic and projected to the mPFC and BA, implicating that a part of the cholinergic afferents may release glutamate. In contrast, we uncovered that GABA is unlikely to be a co-transmitter molecule in HDB and VP/SI cholinergic neurons in adult mice. The dual innervation strategy, i.e., the existence of cholinergic cell populations with single as well as simultaneous projections to the BLA and mPFC, provides the possibility for both synchronous and independent control of the operation in these cortical areas, a structural arrangement that may maximize computational support for functionally linked regions. The presence of VGLUT3 in a portion of cholinergic afferents suggests more complex functional effects of cholinergic system in cortical structures.

The Dual Innervation of the Gluteus Maximus Associated with Other Anatomical Variations of the Gluteal Region

The Dual Innervation of the Gluteus Maximus Associated with Other Anatomical Variations of the Gluteal Region

Dual innervation method to preserve erectile function following prostatectomy

Prostate cancer is the second most prevalent cancer in men. Robot-assisted radical prostatectomy (RARP) has altered the landscape of prostate cancer treatment. Despite the excellent oncological outcomes associated with RARP, the rate of erectile dysfunction (ED) remains high. Primary repair of disrupted cavernous nerves with interpositional nerve grafts has been described; however, the outcomes have been inconsistent. We hypothesize that this is attributed to Schwann cell atrophy and axonal regeneration limitations caused by long nerve grafts. We proposed the use of nerve transfer to support axonal regrowth via an inter-positional graft with additional donor axons. A cadaveric study was performed to evaluate the anatomical feasibility of a vastus lateralis nerve (VLN) transfer to the distal recipient cavernous nerve stump. The VLN is long with multiple branching patterns that allow tension-free coaptation of the cavernous nerve. We postulate that a dual innervation method using VLN nerve transfer together with interpositional nerve graft repair of the transacted cavernous nerves may improve the outcomes of ED post-RARP.

Nodose afferent fibers require PIEZO2 for esophageal mechanosensation

The esophagus receives dual innervation of extrinsic afferent fibers from both the dorsal root ganglia as well as the vagal ganglia. These are polymodal sensory afferents that are able to sense a variety of stimuli that include chemical and mechanical stimuli. Previous research has demonstrated that the esophagus is innervated by low threshold mechanoreceptors arising from the nodose ganglia, which provide critical peripheral feedback that is required for proper swallowing and peristaltic reflexes. We know that in the vagal system, PIEZO2 plays a critical role in lung inflation and baroreceptor function in the aorta and carotid sinus. Hence, we hypothesize that PIEZO2 is the mechanotransducer in these nodose esophageal low threshold mechanoreceptors. We used a two-pronged approach to elucidate PIEZO2’s role in esophageal mechanosensation: first, GCaMP6s imaging and then single fiber electrophysiology to understand the kinetics of nodose esophageal afferent fiber activation. Both of these approaches used our ex-vivo intact vagal esophageal preparation. Our proof-of-principle studies were conducted in PIRT-GCaMP6s mice, obtained through the crossbreeding of Pirt-Cre (Cre expressed in all sensory neurons) mice with Cre-dependent, ROSA26 based, GCaMP6s reporter (B6.129S6-Gt(ROSA)26Sor-tm96(CAG-CGaMP6s)Hze). Our preliminary data in Pirt-GCaMP6s mice showed a profound increase in the Ca2+ influx in a subset of nodose neurons in response to mechanical distention of the esophagus at 5, 10, and 30mmHg pressures. For our knockout group, we obtained nodose-specific knockout of PIEZO2 by crossing P2X2-Cre mice (P2X2 is expressed in all nodose neurons) with PIEZO2fl/fl mice (P2X2/PIEZO2 KO mice). Upon performing our GCaMP6s imaging experiments in this group, we saw that there was a significant reduction in the number of nodose neurons that were responsive to esophageal distention (58% down to 17%). Comparing the fluorescence intensities of all esophageal neurons between the control and KO groups, we observed a significant reduction at all three intraesophageal pressures (p&lt;0.05, n=458 and 395 neurons in control and KO groups, respectively). In our single fiber electrophysiology experiments, our control and KO groups were PIEZO2fl/fl mice and P2X2/PIEZO2 KO respectively. We were able to successfully record APs from A-fiber mechanosensitive esophageal neurons. The number of APs recorded from KO group was reduced at all the three intraesophageal pressures when compared to the control PIEZO2fl/fl mice. Our findings support the hypothesis that PIEZO2 is the mechanotransduction protein involved in vagal nodose afferent fibers innervating the esophagus. NIH. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The 3D muscle morphology and intramuscular innervation of the digital bellies of flexor digitorum profundus: Clinical implications for botulinum toxin injection sites.

Spasticity of flexor digitorum profundus is frequently managed with botulinum toxin injections. Knowledge of the 3D morphology and intramuscular innervation of the digital bellies of flexor digitorum profundus is necessary to optimize the injections. The purpose of this study was to digitize and model in 3D the contractile and connective tissue elements of flexor digitorum profundus to determine muscle morphology, model and map the intramuscular innervation and propose sites for botulinum toxin injection. Fiber bundles (FBs)/aponeuroses and intramuscular nerve branches were dissected and digitized in 12 formalin embalmed cadaveric specimens. Cartesian coordinate data were reconstructed into 3D models as insitu to visualize and compare the muscle morphology and intramuscular innervation patterns of the bellies of flexor digitorum profundus. The 3rd, 4th and 5th digital bellies were superficial to the 2nd digital belly and located adjacent to each other in all specimens. Each digital belly had distinct intramuscular innervation patterns. The 2nd digital belly received intramuscular branches from the anterior interosseus nerve (AIN). The superior half of the 3rd digital belly was innervated intramuscularly by the ulnar nerve (n = 4) or by both the anterior interosseus and ulnar nerves (n = 1). The inferior half of the belly received dual innervation from the anterior interosseus and ulnar nerves in 2 specimens, or exclusively from the AIN (n = 2) or the ulnar nerve (n = 1). The 4th digital belly was innervated by intramuscular branches of the ulnar nerve. One main branch, after coursing through the 4th digital belly, entered the lateral aspect of the 5th digital belly and arborized intramuscularly. The morphology of the FBs, aponeuroses and intramuscular innervation of the digital bellies of FDP were mapped and modelled volumetrically in 3D as insitu. Previous studies were not volumetric nor identified the course of the intramuscular nerve branches within each digital belly. Based on the intramuscular innervation of each of the digital bellies, one possible optimized botulinum toxin injection location was proposed. This injection location, at the junction of the superior and middle thirds of the forearm, would be located in dense nerve terminal zones of the anterior interosseus and ulnar nerves. Future anatomical and clinical investigations are necessary to evaluate the efficacy of these anatomical findings in the management of spasticity.

Novel Method of Dual-innervated Free Gracilis Muscle Transfer for Facial Reanimation: A Case Series.

Dynamic facial reanimation is the gold standard treatment for a paralyzed face. The use of the cross-face nerve graft (CFNG) in combination with the masseteric nerve to innervate the free gracilis muscle has been reported to provide both spontaneity and strong neural input. We report a case series of dual innervation, using a novel method where the branch to masseter is coapted to the side of the CFNG. Eight patients received free gracilis muscle transfer using the new dual innervation method between September 2014 and December 2017. The CFNG, which was performed nine months prior, was sutured in an end-to-end fashion to the obturator nerve. A nerve graft was coapted to the ipsilateral masseteric nerve and then sutured in an end-to-side fashion to the CFNG proximal to its coaptation to the obturator nerve. All patients recovered smile function with and without teeth clenching around the same time period. Smiles without teeth clenching appeared later in two of eight patients and earlier in one of eight patients, being noted at an average of 8.25 months of follow-up versus 7.6 months. The estimate of true attainment is limited by the spacing of follow-up dates. Average follow-up time was 36.07 months (range: 10-71.5). FACE-Gram software smile analysis with and without biting demonstrated similar excursion on average (7.64 mm versus 8.6 mm respectively, P = 0.93), both of which are significantly improved from preoperation. This novel method of a dual-innervated free gracilis muscle transfer offers a viable technique that achieves a symmetric, strong, and emotional smile.

Restoring the spontaneous smile through free functional muscle transfer. A systematic review and meta-analysis of the last twenty years’ experience

The recovery of the spontaneous smile has become a primary focus in facial reanimation surgery and its major determinant is the selected neurotizer. We aimed to compare the spontaneity outcomes of the most preferred neurotization methods in free functional muscle transfer for long-standing facial paralysis. The Embase, Ovid Medline, and PubMed databases were queried with 21 keywords. All clinical studies from the last 20 years reporting the postoperative spontaneity rate for specified neurotization strategies [cross-face nerve graft (CFNG), contralateral facial nerve (CLFN), motor nerve to the masseter (MNM), and dual innervation (DI)] were included. A meta-analysis of prevalence was performed using Freeman-Tukey double arcsine transformation, I2 statistic, and generic inverse variance with a random-effects model. Risk Of Bias In Non-randomized Studies of Interventions and Newcastle-Ottawa scale were used to assess bias and study quality. The literature search produced 2613 results and 473 unique citations for facial reanimation. Twenty-nine studies including 2046 patients were included in the systematic review. A meta-analysis of eligible data (1952 observations from 23 studies) showed statistically significant differences between the groups (CFNG: 0.94; 95% confidence interval [CI], 0.76-1.00, CLFN: 0.91; 95% CI, 0.49-1.00, MNM: 0.26; 95% CI, 0.05-0.54, DI: 0.98; 95% CI, 0.90-1.00, P<0.001). In pairwise comparisons, statistically significant differences were found between MNM and other neurotization strategies (P<0.001 in CFNG compared with MNM, P=0.013 for CLFN compared with MNM, P<0.001 for DI compared with MNM). DI- and CLFN-driven strategies achieved the most promising outcomes, whereas MNM showed the potential to elicit spontaneous smile at a lower extent. Our meta-analysis was limited primarily by incongruency between spontaneity assessment systems. Consensus on a standardized tool would enable more effective comparisons of the outcomes.

Alterations in synapses and mitochondria induced by acute or chronic intermittent hypoxia in the pre-Bötzinger complex of rats: an ultrastructural triple-labeling study with immunocytochemistry and histochemistry.

The pre-Bötzinger complex (pre-BötC), a kernel of inspiratory rhythmogenesis, is a heterogeneous network with excitatory glutamatergic and inhibitory GABAergic and glycinergic neurons. Inspiratory rhythm generation relies on synchronous activation of glutamatergic neuron, whilst inhibitory neurons play a critical role in shaping the breathing pattern, endowing the rhythm with flexibility in adapting to environmental, metabolic, and behavioral needs. Here we report ultrastructural alterations in excitatory, asymmetric synapses (AS) and inhibitory, symmetric synapses (SS), especially perforated synapses with discontinuous postsynaptic densities (PSDs) in the pre-BötC in rats exposed to daily acute intermittent hypoxia (dAIH) or chronic (C) IH. We utilized for the first time a combination of somatostatin (SST) and neurokinin 1 receptor (NK1R) double immunocytochemistry with cytochrome oxidase histochemistry, to reveal synaptic characteristics and mitochondrial dynamic in the pre-BötC. We found perforated synapses with synaptic vesicles accumulated in distinct pools in apposition to each discrete PSD segments. dAIH induced significant increases in the PSD size of macular AS, and the proportion of perforated synapses. AS were predominant in the dAIH group, whereas SS were in a high proportion in the CIH group. dAIH significantly increased SST and NK1R expressions, whereas CIH led to a decrease. Desmosome-like contacts (DLC) were characterized for the first time in the pre-BötC. They were distributed alongside of synapses, especially SS. Mitochondria appeared in more proximity to DLC than synapses, suggestive of a higher energy demand of the DLC. Findings of single spines with dual AS and SS innervation provide morphological evidence of excitation-inhibition interplay within a single spine in the pre-BötC. In particular, we characterized spine-shaft microdomains of concentrated synapses coupled with mitochondrial positioning that could serve as a structural basis for synchrony of spine-shaft communication. Mitochondria were found within spines and ultrastructural features of mitochondrial fusion and fission were depicted for the first time in the pre-BötC. We provide ultrastructural evidence of excitation-inhibition synapses in shafts and spines, and DLC in association with synapses that coincide with mitochondrial dynamic in their contribution to respiratory plasticity in the pre-BötC.

Neural innervation in adipose tissue, gut, pancreas, and liver

Abstract Efficient communication between the brain and peripheral organs is indispensable for regulating physiological function and maintaining energy homeostasis. The peripheral nervous system (PNS) in vertebrates, consisting of the autonomic and somatic nervous systems, bridges the peripheral organs and the central nervous system (CNS). Metabolic signals are processed by both vagal sensory nerves and somatosensory nerves. The CNS receives sensory inputs via ascending nerves, serves as the coordination and integration center, and subsequently controls internal organs and glands via descending nerves. The autonomic nervous system consists of sympathetic and parasympathetic branches that project peripheral nerves into various anatomical locations to regulate the energy balance. Sympathetic and parasympathetic nerves typically control the reflexive and involuntary functions in organs. In this review article, we outline the innervation of adipose tissue, gut, pancreas, and liver, to illustrate the neurobiological basis of central–peripheral interactions. We emphasize the importance of understanding the functional atlas of neural control of energy metabolism, and more importantly, provide potential avenues for further research in this area.

(087) Why Should Pelvic Floor Physical Therapy be Included in Treatment of Vestibulodynia?

Abstract Introduction Vestibulodynia, vulvar pain localized to the vestibule without an identifiable cause, has a multifactorial etiology including neurologic, hormonal, inflammatory, psychologic, and musculoskeletal factors. Key pathophysiologic drivers likely vary from patient to patient. Published studies demonstrate that compared to controls, patients with provoked vestibulodynia are more likely to have pelvic floor hypertonicity and decreased pelvic floor strength, as measured by dynamometric speculum and ultrasound. Further, observational studies describe improvement of vestibulodynia symptoms with pelvic floor physical therapy, suggesting a causal relationship between pelvic floor hypertonicity and vestibulodynia. Objective To describe the pathophysiologic mechanism by which pelvic floor dysfunction and myofascial trigger point development could cause vestibuoldynia, with a focus on pelvic floor anatomy. Methods Literature about vestibulodynia, pelvic floor dysfunction, and pelvic floor anatomy was reviewed and synthesized in conjunction with expert clinical experience of pelvic floor physical therapists and gynecologists. Results The pelvic floor consists of the levator ani muscles (iliococcygeus, pubococcygeus, and puborectalis) and ischiococcygeus, which form a basket to support the pelvic organs. The puborectalis inserts in the posterior vestibule, and hypertonicity can cause allodynia in this region. The levator ani are innervated by the levator ani nerve, which originates from S3-S5 and traverses the visceral surface of the muscles. Some cadaveric studies suggest dual innervation of the levator ani by the pudendal nerve, which originates from S2-S4 and courses over the inferior surface of the muscles. Pelvic floor hypertonicity, increased resting tone of the pelvic floor muscles, can result from many factors including stress, bladder and rectum voiding habits, and painful pelvic processes (i.e. interstitial cystitis, endometriosis). Increased muscle tone can promote sensitization of muscle afferent fibers and neuropathic upregulation. This may be perceived as vestibulodynia because the vestibule contains visceral and somatic sensory nerve fibers, whose signals are integrated at the same spinal levels as those from the levator ani. This anatomy allows for somatovisceral convergence of afferent signals, and thus perception of vestibular pain. Hypertonicity of the pelvic floor muscles decreases circulation creating localized hypoxia that can promote development of myofascial trigger points (tender nodules) in the pelvic floor. These trigger points can cause allodynia, perceived in the vestibule. In some cases, vestibulodynia may develop first and promote pelvic floor hypertonicity. Conclusions As pelvic floor hypertonicity can contribute to the pathogenesis of vestibulodynia, it is imperative for clinicians to include pelvic floor tone evaluation in their assessment of vestibulodynia. If pelvic floor hypertonicity is present, it should be treated concurrently with vestibular pain through a combination of pelvic floor physical therapy, trigger point injections, and botulinum toxin injections as pelvic floor hypertonicity and vestibulodynia may each perpetuate the other. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: Johnson &amp; Johnson.

Letter to "The Split Hypoglossal Nerve and Cross-Face Nerve Graft for Dual Innervation of the Functional Muscle Transfer in Facial Reanimation".

Gurbuz, Canberk MD*; Dursun, Buket MD†; Alagöz, Murat Şahin MD, PHD* Author Information

Artificial intelligence-based numerical analysis of the quality of facial reanimation: A comparative retrospective cohort study between one-stage dual innervation and single innervation

This study aimed to investigate the difference in facial reanimation surgery using functional gracilis muscle transfer between the masseteric nerve alone and its combined use with cross face nerve graft (CFNG), which has not been explored before. A novel analysis method based on artificial intelligence (AI) was employed to compare the outcomes of the two approaches.Using AI, 3-dimensional facial landmarks were extracted from 2-dimensional photographs, and distance and angular symmetry scores were calculated. The patients were divided into two groups, with Group 1 undergoing one-stage CFNG and masseteric nerve dual innervation, and Group 2 receiving only masseteric nerve. The symmetry scores were obtained before and 1 year after surgery to assess the degree of change.Of the 35 patients, Group 1 included 13 patients, and Group 2 included 22 patients. The analysis revealed that, in the resting state, the change in the symmetry score of the mouth corner showed distance symmetry (2.55 ± 2.94, 0.52 ± 2.75 for Group 1 and Group 2, respectively, p = 0.048) and angle symmetry (1.21 ± 1.43, 0.02 ± 0.22 for Group 1 and Group 2, respectively, p = 0.001), which were significantly improved in Group 1, indicating a more symmetric pattern after surgery. In the smile state, only the angle symmetry was improved more symmetrically in Group 1 (3.20 ± 2.38, 1.49 ± 2.22 for Group 1 and Group 2, respectively, p = 0.041).Within the limitations of the study it seems that this new analysis method enabled a more accurate numerical symmetry score to be obtained, and while the degree of mouth corner excursion was sufficient with only the masseteric nerve, accompanying CFNG led to further improvement in symmetry in the resting state.

D32. Long-term Outcomes Comparing Between Single Versus Dual Innervated Free Functional Gracilis Muscle Transfer in Longstanding Facial Paralysis Patients

PURPOSE: Comparing long-term outcomes between single versus dual innervated free functional muscle transfer (FFMT) in patients with longstanding facial paralysis. METHODS: Included were longstanding flaccid facial palsy patients between 2013-2020 treated with a FFMT innervated either by a nerve-to-masseter (single innervation group - SIG) or by nerve-to-masseter and cross-facial-nerve graft (dual innervation group - DIG). One year minimal follow up was required. Outcome measures, based on professional standardized photos, included excursion, smile angle, teeth exposure in repose and in closed and open teeth smile preoperatively, and at 3 months, 1-year, 3-years, and 5-years postoperatively as available. Emotrics software (Massachusetts Eye and Ear Infirmary, Boston, MA) and ImageJ (Rasband, W.S., ImageJ, U.S, National Institutes of Health, Bethesda, MD) were used for all measurements. Between group and within group longitudinal comparisons at each timepoint were analyzed using Wilcoxon Two-Sample Testing. RESULTS: Preoperatively (SIG=33, DIG=14) and 3-months-postoperatively (SIG=28, DIG=14) parameters were similar between groups. At one-year (SIG=32, DIG=13) modiolus angle in repose was increased in the DIG (SIG=99.245 degrees, DIG=105.91 degrees, p=0.0146). At three years (SIG=24, DIG=13),significance was found in modiolus position (SIG=26.42mm, DIG=31.51mm, p=0.0001), commissure excursion with open mouth smile (SIG=31.21mm, DIG=30.915mm, p=0.0005), modiolus angle in repose (SIG=98.14 degrees, DIG=105.06 degrees, p=0.0344), and modiolus angle with open mouth smile(SIG=111.025 degrees, DIG=99.47 degrees, p=0.0001). Midface parameters at 5-year follow up (SIG=14, DIG=6) were similar between groups. CONCLUSION: Dually innervated FFMT did not reveal any clear long-term measurable benefit for midface reanimation albeit synchrony and spontaneity were not assessed.

Donor Nerve Selection in Free Gracilis Muscle Transfer; Systematic Review and Meta-Analysis

Introduction: One of the crucial factors in facial reanimation surgery is the donor nerve selection. There have been several neurotizers to reinnervate the free gracilis muscle flap (FGMT). Currently the cross-face nerve graft (CFNG) and motor nerve to masseter are the most favored options. The “dual innervation” is described as potential way to combine the advantages of individual donor nerves and has shown successful results. Materials and Methods: Two databases were searched for the CFNG, masseteric nerve and dual innervation of FGMT. Defined primary measures were applied to the results to compare the extent of commissure excursion, facial symmetry at rest and smile, spontaneity, time to flap contraction for each neurotizer. Meta-analysis was conducted for studies including quantitative data for commissure excursion and facial symmetry. We included all study types except the animal studies. Only articles written in English language from 2001 were taken into consideration. We followed PRISMA guidelines. ROBINS-I and Newcastle-Ottawa tools were used to assess the risk of bias and quality for each study included in the meta-analysis. Results: 147 articles on FGMT were systematically reviewed and 13 studies were evaluated in the meta-analysis. All studies were high in quality. Heterogeneity was high among the studies, limiting the efficiency of our meta-analysis. Conclusion: CFNG is the most frequently utilized reinnervation technique. Masseteric nerve is very reliable and has the potential to provide more commissural excursion and higher success rate. Dual innervation is an effective alternative leading to effective clinical outcomes. A globalized and quantitative measurement method will contribute to the future of facial reanimation surgery.

Clinically Relevant Anatomical Variations in the Brachial Plexus.

Anatomical variation in the brachial plexus may result in a variety of clinically relevant patterns, including various neuralgias of the upper extremity and differing nerve territories. Some conditions can be debilitating in symptomatic patients, resulting in paresthesia, anesthesia, or weakness of the upper extremity. Others may simply result in cutaneous nerve territories that deviate from a traditional dermatome map. This study evaluated the frequency and anatomical presentations of a large number of clinically relevant brachial plexus nerve variations in a sample of human body donors. We identified a high frequency of various branching variants, of which clinicians, especially surgeons, should be aware. The medial pectoral nerves in 30% of the sample were found to originate from either the lateral cord, or both the medial and lateral cords of the brachial plexus rather than exclusively from the medial cord. The dual cord innervation pattern greatly increases the number of spinal cord levels traditionally believed to innervate the pectoralis minor muscle. The thoracodorsal nerve arose as a branch of the axillary nerve 17% of the time. The musculocutaneous nerve sent branches to the median nerve in 5% of specimens. The medial antebrachial cutaneous nerve shared a common trunk with the medial brachial cutaneous nerve in 5% of individuals and derived from the ulnar nerve in 3% of specimens.

Comparison of Outcomes of Smile Reanimation Between Dual- Versus Single-Innervation Technique in Single-Stage Latissimus Dorsi Neuromuscular Transfer in Facial Paralysis Patients.

Background: Although a dual-innervation technique has emerged in single-stage functional latissimus dorsi (LD) muscle transfer for smile reanimation, its benefits over conventional techniques have not been elucidated. Objective: To compare outcomes of dual-innervation technique with those of single-innervation. Methods: Patients with facial palsy treated with single-stage functional LD muscle transfer were identified, and categorized into two groups: single and dual innervation. Outcomes were assessed using clinical examination based on the Terzis grading system and using automated software (Emotrics). Results: Fifty-nine patients (mean age 37.6 years; male/female 30/29) were analyzed, including 40 in single (35.1 years, 23/17) and 19 in dual-innervation group (43.0 years, 7/12), with a median follow-up of 34 months (range, 9-165) (single: 41.5, 12-165, dual: 23.0, 9-41). Tumor-related paralysis was the most common etiology in both groups (overall: 45.8%, single: 40.0%, dual: 57.9%). The dual group had a significantly higher rate of cases with Terzis grade IV or V postoperatively. In the Emotrics-based evaluation, the dual group exhibited significantly enhanced improvements in smile excursion in the dynamic state compared with the single. The degree of improvement in the resting state did not differ between groups. Conclusion: The dual-innervation technique might provide promising results in achieving enhanced smile excursion.

A three-component model of the spinal nerve ramification: Bringing together the human gross anatomy and modern Embryology.

Due to its long history, the study of human gross anatomy has not adequately incorporated modern embryological findings; consequently, the current understanding has often been incompatible with recent discoveries from molecular studies. Notably, the traditional epaxial and hypaxial muscle distinction, and their corresponding innervation by the dorsal and ventral rami of the spinal nerve, do not correspond to the primaxial and abaxial muscle distinction, defined by the mesodermal lineages of target tissues. To resolve the disagreement between adult anatomy and embryology, we here propose a novel hypothetical model of spinal nerve ramification. Our model is based on the previously unknown developmental process of the intercostal nerves. Observations of these nerves in the mouse embryos revealed that the intercostal nerves initially had superficial and deep ventral branches, which is contrary to the general perception of a single ventral branch. The initial dual innervation pattern later changes into an adult-like single branch pattern following the retraction of the superficial branch. The modified intercostal nerves consist of the canonical ventral branches and novel branches that run on the muscular surface of the thorax, which sprout from the lateral cutaneous branches. We formulated the embryonic branching pattern into the hypothetical ramification model of the human spinal nerve so that the branching pattern is compatible with the developmental context of the target muscles. In our model, every spinal nerve consists of three components: (1) segmental branches that innervate the primaxial muscles, including the dorsal rami, and short branches and long superficial anterior branches from the ventral rami; (2) plexus-forming intramural branches, the serial homolog of the canonical intercostal nerves, which innervate the abaxial portion of the body wall; and (3) plexus-forming extramural branches, the series of novel branches located outside of the body wall, which innervate the girdle and limb muscles. The selective elaboration or deletion of each component successfully explains the reasoning for the standard morphology and variability of the spinal nerve. Therefore, our model brings a novel understanding of spinal nerve development and valuable information for basic and clinical sciences regarding the diverse branching patterns of the spinal nerve.

Effects of Spinal Cord Injury Site on Cardiac Autonomic Regulation: Insight from Analysis of Cardiovascular Beat by Beat Variability during Sleep and Orthostatic Challenge.

The goal of this study on Spinal Cord Injury (SCI) patients with cervical or thoracic lesion was to assess whether disturbances of ANS control, according to location, might differently affect vagal and sympatho-vagal markers during sleep and orthostatic challenge. We analyzed with linear and nonlinear techniques beat-by-beat RR and arterial pressure (and respiration) variability signals, extracted from a polysomnographic study and a rest-tilt test. We considered spontaneous or induced sympathetic excitation, as obtained shifting from non-REM to REM sleep or from rest to passive tilt. We obtained evidence of ANS cardiac (dys)regulation, of greater importance for gradually proximal location (i.e., cervical) SCI, compatible with a progressive loss of modulatory role of sympathetic afferents to the spinal cord. Furthermore, in accordance with the dual, vagal and sympathetic bidirectional innervation, the results suggest that vagally mediated negative feedback baroreflexes were substantially maintained in all cases. Conversely, the LF and HF balance (expressed specifically by normalized units) appeared to be negatively affected by SCI, particularly in the case of cervical lesion (group p = 0.006, interaction p = 0.011). Multivariate analysis of cardiovascular variability may be a convenient technique to assess autonomic responsiveness and alteration of functionality in patients with SCI addressing selectively vagal or sympathetic alterations and injury location. This contention requires confirmatory studies with a larger population.