Magnetic resonance imaging of the caudal portion of the digastric muscle in canine idiopathic facial neuropathy

Idiopathic is the most common etiology for acute onset of facial neuropathy in dogs with limited number of studies describing MRI characteristics. A retrospective, observational study was performed using archived records, aiming to describe the MRI features of the caudal portion of the digastric muscle in dogs diagnosed with idiopathic facial neuropathy and to determine correlation with prognosis. Client-owned dogs presented to a referral hospital between 2009 and 2019, diagnosed with unilateral idiopathic facial neuropathy and having undergone MRI, with images including the caudal portion of the digastric muscle, were included (n = 19). MRI appearance of the affected muscle, including degree of muscle atrophy, signal intensity, enhancement post-contrast, and enhancement characteristics of the affected facial nerve, was described and compared to the contralateral, clinically unaffected caudal portion of the digastric muscle. Correlation between MRI appearance and outcome at 1-month and 3-months following onset of clinical signs was investigated. The majority of patients demonstrated some degree of muscle atrophy (n = 17, 89%), hyperintensity in T2W (n = 17, 89%), and pre-contrast T1W (n = 15, 79%) images, as well as contrast enhancement of the affected muscle (n = 14, 74%) and affected facial nerve (n = 9, 47%). There was no statistically significant correlation between atrophy or enhancement of the affected caudal portion of the digastric muscle nor between enhancement of the affected facial nerve and outcome. Hyperintensity both in T2W images and pre-contrast T1W images was significantly correlated with a worse prognosis. Ensuring inclusion and evaluation of this muscle in MRI may therefore be indicated in canine idiopathic facial neuropathy.

Lumbar Spondylolisthesis Progression: What is the Effect of Lumbar Medial Branch Nerve Radiofrequency Ablation on Lumbar Spondylolisthesis Progression? A Single-Center, Observational Study

BACKGROUND

Radiofrequency ablation (RFA) is a denervation therapy commonly performed for pain of facet etiology. Degenerative spondylolisthesis, a malalignment of the spinal vertebrae, may be a co-existing condition contributing to pain; yet the effect of RFA on advancing listhesis is unknown. To the extent that denervating RFA may weaken paraspinal muscles that provide stability to the spine, the therapy can potentially contribute to progressive spinal instability.

METHODS

Single-center, prospective, observational pilot study in an interventional pain practice to test the hypothesis that RFA of painful facets in the setting of spondylolisthesis may contribute to advancement of further degenerative spondylolisthesis. Fifteen participants with pre-existing degenerative Grade I or Grade II spondylolisthesis and coexisting axial lumbar pain underwent lumbar RFA encompassing spondylolisthesis level and followed with post-RFA imaging at 12 months and beyond to measure percent change in spondylolisthesis.

RESULTS

The primary outcome was the percent advancement of spondylolisthesis per year measured on post-RFA lateral lumbar spine imaging compared with non-intervention inferred baseline advancement of 2% per very limited observational studies. Among the 15 participants enrolled, 14 completed the study (median age 66; 64.3% women; median BMI 33.5; mean follow-up time 23.9 months). The mean advancement of spondylolisthesis per year after RFA was 1.30% (95% CI -0.14 to 2.78%), with 9/14 below 1.25%.

CONCLUSION

Among patients with lumbar pain originating from facets in the setting of degenerative spondylolisthesis who underwent lumbar RFA, the observed advancement of spondylolisthesis is clinically similar to the estimated maximum baseline of 2% per year change. The study findings did not find a destabilizing effect of lumbar RFA in advancing spondylolisthesis in this patient population.

EphrinB2 and GRIP1 stabilize mushroom spines during denervation-induced homeostatic plasticity

Despite decades of work, much remains elusive about molecular events at the interplay between physiological and structural changes underlying neuronal plasticity. Here, we combined repetitive live imaging and expansion microscopy in organotypic brain slice cultures to quantitatively characterize the dynamic changes of the intracellular versus surface pools of GluA2-containing α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) across the different dendritic spine types and the shaft during hippocampal homeostatic plasticity. Mechanistically, we identify ephrinB2 and glutamate receptor interacting protein (GRIP) 1 as mediating AMPAR relocation to the mushroom spine surface following lesion-induced denervation. Moreover, stimulation with the ephrinB2 specific receptor EphB4 not only prevents the lesion-induced disappearance of mushroom spines but is also sufficient to shift AMPARs to the surface and rescue spine recovery in a GRIP1 dominant-negative background. Thus, our results unravel a crucial role for ephrinB2 during homeostatic plasticity and identify a potential pharmacological target to improve dendritic spine plasticity upon injury.

Development and Description of a New Multifidus-Sparing Radiofrequency Neurotomy Technique for Facet Joint Pain

INTRODUCTION

The technique of radiofrequency neurotomy (RFN) of the facet joints has been used for decades to treat persistent low back pain to good effect in carefully selected patients. Traditionally, the target is the medial branches of the dorsal root supplying the facet joint. An alternative denervation target is the facet joint capsule. Capsule-targeting techniques may spare the multifidus muscle, a possible unintended target of traditional RFN that is thought to be important in recovering from low back pain, and have shown promising results.

METHODS

A modified RFN technique that targets the capsule and spares the multifidus (multifidus-sparing RFN) is described here, along with a brief report of its application in patients with symptomatic facet joint low back pain as compared to traditional medial branch RFN (MBRF).

RESULTS

Over a 2-year period, a total of 401 initial multifidus-sparing RFN and 94 initial MBRF procedures were performed on patients attending a multidisciplinary pain clinic. The proportion of repeat procedures was similar: 28.4% of multifidus-sparing procedures and 23.4% of MBRF procedures. The median repeat interval was 12 months for both groups and interquartile range was 10 months (8-18 months) for multifidus-sparing RFN and 4 months (11-15 months) for MBRF. Effectiveness and safety profiles appear to be similar, although limited, retrospective outcome information prevented robust analysis.

CONCLUSION

Multifidus-sparing RFN represents an intriguing technique to denervate the facet joint pain generator while maintaining normal multifidus function. Further study is warranted, particularly in order to identify the appropriate patient criteria and long-term outcomes.

Surgical Cardiac Sympathetic Denervation for Ventricular Arrhythmias: A Systematic Review

Ventricular arrhythmias are potentially life-threatening disorders that are commonly treated with medications, catheter ablation and implantable cardioverter defibrillator (ICD). Adult patients who continue to be symptomatic, with frequent ventricular arrhythmia cardiac events or defibrillation from ICD despite medical treatment, are a challenging subgroup to manage. Surgical cardiac sympathetic denervation has emerged as a possible treatment option for people refractory to less invasive medical options. Recent treatment guidelines have recommendedcardiac sympathectomy for ventricular tachycardia (VT) or VT/fibrillation storm refractory to antiarrhythmic medications, long QT syndrome, and catecholaminergic polymorphic VT, with much of the data pertaining to pediatric literature. However, for the adult population, the disease indications, complications, and risks of cardiac sympathectomy are less understood, as are the most effective surgical cardiac denervation techniques for this patient demographic. This systematic review navigates available literature evaluating surgical denervation disease state indications, techniques, and sympathectomy risks for medically refractory ventricular arrhythmia in the adult patient population.

Renal Sympathetic Denervation in Patients With Heart Failure With Preserved Ejection Fraction

BACKGROUND

Arterial hypertension is the most common comorbidity in patients with heart failure with preserved ejection fraction (HFpEF) and mediates adverse hemodynamics through related aortic stiffness and increased pulsatile load. We aimed to investigate the clinical and hemodynamic implications of renal sympathetic denervation (RDN) in patients with HFpEF and uncontrolled arterial hypertension.

METHODS

Patients undergoing RDN between 2011 and 2018 in a single-center were retrospectively analyzed and classified as HFpEF (n=99) or no HF (n=65). Stroke volume index and aortic distensibility were measured through cardiac magnetic resonance imaging, and left ventricular (LV) systolic and diastolic properties were assessed echocardiographically.

RESULTS

At baseline, patients with HFpEF had higher stroke volume index (median 40 [interquartile range, 33-48] versus 33 [26-40] mL/m², P=0.002), pulse pressure (69 [63-77] versus 61 [55-67] mm Hg, P<0.001), but lower LV-VPES_100mm Hg (18 [10-28] versus 24 [15-40] mL, P=0.007) and aortic distensibility (1.5 [1.1-2.6] versus 2.7 [1.1-3.5] 10^-3 mm Hg^-1, P=0.013) as compared to no-HF patients. Systolic blood pressure decreased comparable in patients with HFpEF and no-HF patients following RDN (-9 [-16 to -2], P<0.001). After RDN stroke volume index (-3 [-9 to +3] mL/m², P=0.011) decreased and aortic distensibility (0.2 [-0.1 to +1.1] 10^-3 mm Hg^-1, P=0.007) and systolic stiffness (P<0.001) increased in HFpEF patients. LV diastolic stiffness and LV filling pressures as well as NT-proBNP (N-terminal pro-B-type natriuretic peptide) decreased after RDN in patients with HFpEF (P=0.032, P=0.043, and P<0.001, respectively).

CONCLUSIONS

Patients with HFpEF undergoing RDN showed increased stroke volume index, vascular, and LV stiffness as compared to no-HF patients. Following RDN those hemodynamic alterations and reduced systolic and diastolic LV stiffness were partly normalized, implying RDN might be a potential therapeutic strategy for arterial hypertension and HFpEF.

Cardiac intramural arteriovenous malformations presented as ventricular tachycardia and fibrillation storm

We report a case of cardiac intramural arteriovenous malformations (AVMs) misdiagnosed as hypertrophic cardiomyopathy and presented as life-threatening ventricular arrhythmia storm that was successfully controlled by cardiac sympathetic denervation. A 46-year-old male patient with an implantable cardioverter-defibrillator was admitted for recurrent ventricular tachycardia requiring repeated shock refractory to antiarrhythmic drugs. Although the patient was previously diagnosed with hypertrophic cardiomyopathy, multimodality imaging studies showed large left ventricular intramural AVMs, potentially representing arrhythmogenic substrates. Life-threatening ventricular arrhythmia storm, which could not be controlled by radiofrequency catheter ablation and therapeutic hypothermia. However, cardiac sympathetic denervation surgery successfully controlled the ventricular arrhythmia storm.

Wide Pulse Width Electroacupuncture Ameliorates Denervation-Induced Skeletal Muscle Atrophy in Rats via IGF-1/PI3K/Akt Pathway

OBJECTIVE

To evaluate the effect of the pulse width of electroacupuncture (EA) in the treatment of denervation-induced skeletal muscle atrophy in rats and examine the role of insulin-like growth factor 1 (IGF-1)/phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway during EA.

METHODS

Sciatic nerve functional index (SFI), muscle wet weight and the cross-sectional area (CSA) of the gastrocnemius muscle were analyzed after treatment in model rats with EA of various pulse widths (0.5, 50, 100 and 200 ms). The apoptosis index (AI) and paired box (PAX)3 and PAX7 protein expression were also determined. Further, the mRNA and protein expressions of components of IGF-1/PI3K/Akt pathway and their downstream targets were determined, along with the inhibiting effect of the pathway with a PI3-specific inhibitor.

RESULTS

EA with a pulse width of 200 ms was found to have the best effect with regard to increasing SFI, CSA and muscle weight, decreasing AI, and increasing the expression of PAX3 and PAX7. The IGF-1/PI3K/Akt pathway was found to be activated by denervation, although the downstream forkhead box O (FoxO) pathway was not suppressed by its activation. The PI3K/Akt pathway and its downstream molecule mammalian target of rapamycin (mTOR) were up-regulated further by EA to promote muscle protein synthesis. Meanwhile, the expressions of downstream FoxO and F-box protein 32 (ATROGIN-1) were down-regulated to reduce protein degradation.

CONCLUSIONS

EA with 200-ms pulse width was found to have a more significant effect than 0.5-ms EA. The positive effects of EA disappeared after inhibition of the PI3K/Akt pathway.

Increase in Bioavailability of Nitric Oxide After Renal Denervation Improves Kidney Function in Sheep With Hypertensive Kidney Disease

[Figure: see text].

Magnetic resonance spectroscopy reveals mitochondrial dysfunction in amyotrophic lateral sclerosis

Mitochondrial dysfunction is postulated to be central to amyotrophic lateral sclerosis (ALS) pathophysiology. Evidence comes primarily from disease models and conclusive data to support bioenergetic dysfunction in vivo in patients is currently lacking. This study is the first to assess mitochondrial dysfunction in brain and muscle in individuals living with ALS using 31P-magnetic resonance spectroscopy (MRS), the modality of choice to assess energy metabolism in vivo. We recruited 20 patients and 10 healthy age and gender-matched control subjects in this cross-sectional clinico-radiological study. 31P-MRS was acquired from cerebral motor regions and from tibialis anterior during rest and exercise. Bioenergetic parameter estimates were derived including: ATP, phosphocreatine, inorganic phosphate, adenosine diphosphate, Gibbs free energy of ATP hydrolysis (ΔGATP), phosphomonoesters, phosphodiesters, pH, free magnesium concentration, and muscle dynamic recovery constants. Linear regression was used to test for associations between brain data and clinical parameters (revised amyotrophic functional rating scale, slow vital capacity, and upper motor neuron score) and between muscle data and clinico-neurophysiological measures (motor unit number and size indices, force of contraction, and speed of walking). Evidence for primary dysfunction of mitochondrial oxidative phosphorylation was detected in the brainstem where ΔGATP and phosphocreatine were reduced. Alterations were also detected in skeletal muscle in patients where resting inorganic phosphate, pH, and phosphomonoesters were increased, whereas resting ΔGATP, magnesium, and dynamic phosphocreatine to inorganic phosphate recovery were decreased. Phosphocreatine in brainstem correlated with respiratory dysfunction and disability; in muscle, energy metabolites correlated with motor unit number index, muscle power, and speed of walking. This study provides in vivo evidence for bioenergetic dysfunction in ALS in brain and skeletal muscle, which appears clinically and electrophysiologically relevant. 31P-MRS represents a promising technique to assess the pathophysiology of mitochondrial function in vivo in ALS and a potential tool for future clinical trials targeting bioenergetic dysfunction.

Obstructive Sleep Apnea-Induced Neurogenic Nocturnal Hypertension: A Potential Role of Renal Denervation?

There is a bidirectional, causal relationship between obstructive sleep apnea (OSA) and hypertension. OSA-related hypertension is characterized by high rates of masked hypertension, elevated nighttime blood pressure, a nondipper pattern of nocturnal hypertension, and abnormal blood pressure variability. Hypoxia/hypercapnia-related sympathetic activation is a key pathophysiological mechanism linking the 2 conditions. Intermittent hypoxia also stimulates the renin-angiotensin-aldosterone system to promote hypertension development. The negative and additive cardiovascular effects of OSA and hypertension highlight the importance of effectively managing these conditions, especially when they coexist in the same patient. Continuous positive airway pressure is the gold standard therapy for OSA but its effects on blood pressure are relatively modest. Furthermore, this treatment did not reduce the cardiovascular event rate in nonsleepy patients with OSA in randomized controlled trials. Antihypertensive agents targeting sympathetic pathways or the renin-angiotensin-aldosterone system have theoretical potential in comorbid hypertension and OSA, but current evidence is limited and combination strategies are often required in drug resistant or refractory patients. The key role of sympathetic nervous system activation in the development of hypertension in OSA suggests potential for catheter-based renal sympathetic denervation. Although long-term, randomized controlled trials are needed, available data indicate sustained and relevant reductions in blood pressure in patients with hypertension and OSA after renal denervation, with the potential to also improve respiratory parameters. The combination of lifestyle interventions, optimal pharmacological therapy, continuous positive airway pressure therapy, and perhaps also renal denervation might improve cardiovascular risk in patients with OSA.

Early Lipid Raft-Related Changes: Interplay between Unilateral Denervation and Hindlimb Suspension

Muscle disuse and denervation leads to muscle atrophy, but underlying mechanisms can be different. Previously, we have found ceramide (Cer) accumulation and lipid raft disruption after acute hindlimb suspension (HS), a model of muscle disuse. Herein, using biochemical and fluorescent approaches the influence of unilateral denervation itself and in combination with short-term HS on membrane-related parameters of rat soleus muscle was studied. Denervation increased immunoexpression of sphingomyelinase and Cer in plasmalemmal regions, but decreased Cer content in the raft fraction and enhanced lipid raft integrity. Preliminary denervation suppressed (1) HS-induced Cer accumulation in plasmalemmal regions, shown for both nonraft and raft-fractions; (2) HS-mediated decrease in lipid raft integrity. Similar to denervation, inhibition of the sciatic nerve afferents with capsaicin itself increased Cer plasmalemmal immunoexpression, but attenuated the membrane-related effects of HS. Finally, both denervation and capsaicin treatment increased immunoexpression of proapoptotic protein Bax and inhibited HS-driven increase in antiapoptotic protein Bcl-2. Thus, denervation can increase lipid raft formation and attenuate HS-induced alterations probably due to decrease of Cer levels in the raft fraction. The effects of denervation could be at least partially caused by the loss of afferentation. The study points to the importance of motor and afferent inputs in control of Cer distribution and thereby stability of lipid rafts in the junctional and extrajunctional membranes of the muscle.

The Metabolic Stability of the Nicotinic Acetylcholine Receptor at the Neuromuscular Junction

The clustering and maintenance of nicotinic acetylcholine receptors (AChRs) at high density in the postsynaptic membrane is a hallmark of the mammalian neuromuscular junction (NMJ). The regulation of receptor density/turnover rate at synapses is one of the main thrusts of neurobiology because it plays an important role in synaptic development and synaptic plasticity. The state-of-the-art imaging revealed that AChRs are highly dynamic despite the overall structural stability of the NMJ over the lifetime of the animal. This review highlights the work on the metabolic stability of AChRs at developing and mature NMJs and discusses the role of synaptic activity and the regulatory signaling pathways involved in the dynamics of AChRs.

NRG/ErbB signaling regulates neonatal muscle growth but not neuromuscular contractures in neonatal brachial plexus injury

Neonatal brachial plexus injury (NBPI) causes disabling and incurable muscle contractures that are driven by impaired growth of denervated muscles. A rare form of NBPI, which maintains afferent muscle innervation despite motor denervation, does not cause contractures. As afferent innervation regulates various aspects of skeletal muscle homeostasis through NRG/ErbB signaling, our current study investigated the role of this pathway in modulating contracture development. Through pharmacologic modification with an ErbB antagonist and NRG1 isoforms, we discovered that NRG/ErbB signaling does not modulate the development of contractures in neonatal mice. Instead, ErbB inhibition impeded growth in nondenervated skeletal muscles, whereas increased ErbB activation exacerbated denervation‐induced skeletal muscle atrophy. This potential regulatory effect of NRG/ErbB signaling on neonatal muscle growth warrants deeper investigation.

[Abdominal pseudohernia: diagnosis and treatment]

OBJECTIVE

To present an effective treatment strategy for abdominal pseudohernia considering own clinical experience and literature data.

MATERIAL AND METHODS

The authors report surgical treatment of 2 patients and therapeutic management of 1 patient with abdominal pseudohernia. Moreover, current state of this problem is analyzed according to literature data in Pubmed, Google and e-library databases.

RESULTS. P

Seudohernia is followed by asymmetrical protrusion of abdominal wall, prolapsed site is not involved in breathing; patients cannot tense muscles in the affected area. T8-L2 skin sensitivity impairment or hyperesthesia may be observed. Denervation is confirmed by electroneuromyography. Ultrasound, CT and MRI reveal no defect in abdominal wall. However, its thinning within denervation area is visualized. Treatment is determined by the cause and reversibility of denervation. If mechanical damage (intersection) of T8-L2 nerves following trauma or any manipulation is absent, the main cause is herpes zoster neuropathy. Surgical treatment is not indicated. Antiherpetic therapy and physical therapy result functional restoration of abdominal wall muscles within 2-4 months. In case of mechanical cause of pseudohernia, it is advisable to wait at least a year after denervation for real assessment of situation. Partial or complete re-innervation is possible throughout this period. Surgical treatment is indicated if re-innervation is absent. An effective technique presented in this manuscript is reconstruction of the prolapsed area with several imbrication sutures in several planes up to symmetry with contralateral area with subsequent reinforcement with a mesh implant if necessary. There were no relapses in 2 our patients within 5 and 7 years, respectively.

CONCLUSION

In our opinion, this report is the first manuscript devoted to systematic analysis of diagnosis and treatment of abdominal pseudohernia in available literature. Surgical treatment is not indicated for postherpetic pseudohernia. It is carried out for pseudohernia persisting for more than 1 year if its cause is trauma or any manipulation.

Motor function recovery: deciphering a regenerative niche at the neuromuscular synapse

The coordinated movement of many organisms relies on efficient nerve–muscle communication at the neuromuscular junction (NMJ), a peripheral synapse composed of a presynaptic motor axon terminal, a postsynaptic muscle specialization, and non‐myelinating terminal Schwann cells. NMJ dysfunctions are caused by traumatic spinal cord or peripheral nerve injuries as well as by severe motor pathologies. Compared to the central nervous system, the peripheral nervous system displays remarkable regenerating abilities; however, this capacity is limited by the denervation time frame and depends on the establishment of permissive regenerative niches. At the injury site, detailed information is available regarding the cells, molecules, and mechanisms involved in nerve regeneration and repair. However, a regenerative niche at the final functional step of peripheral motor innervation, i.e. at the mature neuromuscular synapse, has not been deciphered. In this review, we integrate classic and recent evidence describing the cells and molecules that could orchestrate a dynamic ecosystem to accomplish successful NMJ regeneration. We propose that such a regenerative niche must ensure at least two fundamental steps for successful NMJ regeneration: the proper arrival of incoming regenerating axons to denervated postsynaptic muscle domains, and the resilience of those postsynaptic domains, in morphological and functional terms. We here describe and combine the main cellular and molecular responses involved in each of these steps as potential targets to help successful NMJ regeneration.

Sensory innervation of the human shoulder joint: the three bridges to break

BACKGROUND

Painful shoulders create a substantial socioeconomic burden and significant diagnostic challenge for shoulder surgeons. Consensus with respect to the anatomic location of sensory nerve branches is lacking. The aim of this literature review was to establish consensus with respect to the anatomic features of the articular branches (ABs) (1) innervating the shoulder joint and (2) the distribution of sensory receptors about its capsule and bursae.

MATERIALS AND METHODS

Four electronic databases were queried, between January 1945 and June 2019. Thirty original articles providing a detailed description of the distribution of sensory receptors about the shoulder joint capsule (13) and its ABs (22) were reviewed.

RESULTS

The suprascapular, lateral pectoral, axillary, and lower subscapular nerves were found to provide ABs to the shoulder joint. The highest density of nociceptors was found in the subacromial bursa. The highest density of mechanoreceptors was identified within the insertion of the glenohumeral ligaments. The most frequently identified innervation pattern comprised 3 nerve bridges (consisting of ABs from suprascapular, axillary, and lateral pectoral nerves) connecting the trigger and the identified pain generator areas rich in nociceptors.

CONCLUSION

Current literature supports the presence of a common sensory innervation pattern for the human shoulder joint. Anatomic studies have demonstrated that the most common parent nerves supplying ABs to the shoulder joint are the suprascapular, lateral pectoral, and axillary nerves. Further studies are needed to assess both the safety and efficacy of selective denervation of the painful shoulders, while limiting the loss of proprioceptive function.

Cardiac sympathetic denervation in wild-type transthyretin amyloidosis

BACKGROUND

Tissue accumulation of misfolded transthyretin (TTR) may occur because of TTR gene mutations (variant amyloid TTR amyloidosis, ATTRv), or as an age-related phenomenon (wild-type ATTR, ATTRwt). Cardiac sympathetic denervation has been reported in ATTRv, but has never been investigated in ATTRwt.

METHODS

Fifteen consecutive patients with ATTRwt cardiomyopathy (81% men, median age 82 years, no one with prior myocardial infarction) underwent Cadmium Zinc Telluride tomographic imaging for amyloid burden (^99mTc-hydroxymethylene diphosphonate - ^99mTc-HMDP), innervation (¹²³I-metaiodobenzylguanidine - ¹²³I-MIBG), and perfusion (^99mTc-tetrofosmin).

RESULTS

Median summed ^99mTc-HMDP score was 60 (58-62), denoting a severe and diffuse amyloid burden. Planar ¹²³I-MIBG examination showed decreased early and late H/M ratios (late H/M ratio: 1.5 [1.3-1.6], range 1.2-1.9, reference value ≥2.0). Summed ¹²³I-MIBG score was 12 (6-22), with the most prominent denervation in the infero-septal, inferior, and infero-lateral regions; summed rest score was 7 (5-11), with lowest degrees of myocardial perfusion in the inferior and infero-septal regions. The correlation between amyloid burden (as relative ^99mTc-HMDP uptake) and innervation (as relative ¹²³I-MIBG uptake) did not achieve statistical significance at both segmental (p = .252) and regional level (p = .251). Nevertheless, denervation tended to worsen in parallel with the amyloid burden, and ¹²³I-MIBG scores increased with ^99mTc-HMDP scores. Segments and regions with prominent hypoperfusion also showed a higher degree of denervation (r = 0.500 and 0.591, respectively; both p < .001).

CONCLUSIONS

Patients with ATTRwt cardiomyopathy display cardiac sympathetic denervation, particularly in the inferior and septal myocardial wall. Myocardial hypoperfusion has a similar regional pattern, while the amyloid burden is more extensive.

Comment on: "Thumb carpometacarpal joint osteoarthritis: Is there a role for denervation? A systematic review"

We read with great interest the recent systematic review by Teo I. and Riley N. on denervation in thumb carpometacarpal joint osteoarthritis. Undoubtedly, denervation of the first carpometacarpal (CMC-1) joint does represent a promising surgical treatment alternative for patients suffering from persistent CMC-1-joint osteoarthritis. A surgical standard, however, has not yet been implemented, as technical approach and indication of this procedure still show great variances. In order to contribute to an evidence-based standardization of CMC-1-joint denervation, we would like to share our considerations, approaches and anatomical findings in this comment.

Timing of proteasome inhibition as a pharmacologic strategy for prevention of muscle contractures in neonatal brachial plexus injury

Neonatal brachial plexus injury (NBPI) causes disabling and incurable contractures, or limb stiffness, which result from proteasome‐mediated protein degradation impairing the longitudinal growth of neonatally denervated muscles. We recently showed in a mouse model that the 20S proteasome inhibitor, bortezomib, prevents contractures after NBPI. Given that contractures uniquely follow neonatal denervation, the current study tests the hypothesis that proteasome inhibition during a finite window of neonatal development can prevent long‐term contracture development. Following neonatal forelimb denervation in P5 mice, we first outlined the minimum period for proteasome inhibition to prevent contractures 4 weeks post‐NBPI by treating mice with saline or bortezomib for varying durations between P8 and P32. We then compared the ability of varying durations of longer‐term proteasome inhibition to prevent contractures at 8 and 12 weeks post‐NBPI. Our findings revealed that proteasome inhibition can be delayed 3‐4 days after denervation but is required throughout skeletal growth to prevent contractures long term. Furthermore, proteasome inhibition becomes less effective in preventing contractures beyond the neonatal period. These therapeutic effects are primarily associated with bortezomib‐induced attenuation of 20S proteasome β1 subunit activity. Our collective results, therefore, demonstrate that temporary neonatal proteasome inhibition is not a viable strategy for preventing contractures long term. Instead, neonatal denervation causes a permanent longitudinal growth deficiency that must be continuously ameliorated during skeletal growth. Additional mechanisms must be explored to minimize the necessary period of proteasome inhibition and reduce the risk of toxicity from long‐term treatment.

Neurohormonal Modulation as a Therapeutic Target in Pulmonary Hypertension

The autonomic nervous system (ANS) and renin-angiotensin-aldosterone system (RAAS) are involved in many cardiovascular disorders, including pulmonary hypertension (PH). The current review focuses on the role of the ANS and RAAS activation in PH and updated evidence of potential therapies targeting both systems in this condition, particularly in Groups 1 and 2. State of the art knowledge in preclinical and clinical use of pharmacologic drugs (beta-blockers, beta-three adrenoceptor agonists, or renin-angiotensin-aldosterone signaling drugs) and invasive procedures, such as pulmonary artery denervation, is provided.

Microscopic spermatic cord denervation for chronic orchialgia/chronic scrotal content pain: operative outcomes and predictors of failure

Background

To describe our institutional outcomes with microscopic spermatic cord denervation (MSCD) for chronic scrotal content paint (CSCP) and identify predictors of treatment failure.

Methods

Retrospective chart review was performed to identify all MSCD performed by two surgeons at a single institution from 2010–2019. Patient demographic data and operative outcomes were collected. Patients were excluded from analysis if no post-operative follow up was available. Success was defined as complete resolution of bothersome pain. Multivariable logistic regression was utilized to identify predictors of treatment failure.

Results

During the study period, 101 patients were identified in which 113 MSCD procedures were performed. Final analysis included 103 procedures across 93 patients. Mean age was 41.8 years (SD 13.2), mean BMI was 29.2 kg/m² (SD 5.96) and median months of pain preceding surgery were 24 (range, 3–300 months). Overall, 75/103 (73%) MSCD were successful. Of the failures, 5 patients had recurrence of pain greater than 6 months after surgery. Only the presence of pelvic floor muscle spasm (PFMS) independently predicted MSCD failure (OR 3.95, P=0.02). 9 of 19 (47%) patients with PFMS experienced treatment failure, while 19 of 84 (23%) without PFMS experienced failure.

Conclusions

MSCD offers a therapeutic option for patients with refractory CSCP. The presence of PFMS is associated with lower surgical success rates. Patients with pre-operatively identified PFMS should be counseled regarding a higher risk of treatment failure.

Daily Oral Administration of Protease-Treated Royal Jelly Protects Against Denervation-Induced Skeletal Muscle Atrophy

Honeybees produce royal jelly (RJ) from their cephalic glands. Royal jelly is a source of nutrition for the queen honey bee throughout its lifespan and is also involved in fertility and longevity. Royal jelly has long been considered beneficial to human health. We recently observed that RJ delayed impairment of motor function during aging, affecting muscle fiber size. However, how RJ affects skeletal muscle metabolism and the functional component of RJ is as of yet unidentified. We demonstrate that feeding mice with RJ daily prevents a decrease in myofiber size following denervation without affecting total muscle weight. RJ did not affect atrophy-related genes but stimulated the expression of myogenesis-related genes, including IGF-1 and IGF receptor. Trans-10-hydroxy-2-decenoic acid (10H2DA) and 10-hydroxydecanoic acid (10HDAA), two major fatty acids contained in RJ. After ingestion, 10H2DA and 10HDAA are metabolized into 2-decenedioic acid (2DA) and sebacic acid (SA) respectively. We found that 10H2DA, 10HDAA, 2DA, and SA all regulated myogenesis of C2C12 cells, murine myoblast cells. These novel findings may be useful for potential preventative and therapeutic applications for muscle atrophy disease included in Sarcopenia, an age-related decline in skeletal muscle mass and strength.

Anatomic surface landmarks to guide injection for posterior interosseous nerve block

Proper injection of the posterior interosseous nerve (PIN) is important for both the therapeutic and diagnostic management of wrist pain. However, no anatomical study exists describing the site of injection based on individual wrist width. We sought to develop a reproducible anthropometric ratio utilizing external wrist surface anatomy to predict a safe and accurate injection site for the PIN. Fresh frozen cadaver forearms were dissected at the University of Louisville tissue lab. Several anthropometric measurements were obtained in order to develop a reproducible ratio to calculate location of injection. A total of 16 cadaver forearms of equal male to female ratio were obtained. On average, the male forearm had a greater mean wrist circumference obtained at the level of Lister's tubercle compared to female forearms, 17.1 cm vs. 13.5 cm. An injection given ulnar to proximal edge of Lister's tubercle at a length of one-fourth the distance between Lister's tubercle and radial aspect of ulnar styloid resulted in 100% accurate perineural injection without intraneural injection. An anthropometric ratio of one-fourth the distance from Lister's tubercle to the ulnar styloid was able to predict accurate injection sites for the distal PIN in cadaveric specimens of varying anatomical proportions.