-
Exercise, Sport & Movement 2023The purpose of this study was to determine the following in persons with midportion Achilles tendinopathy (AT): 1) maximal strength and power; 2) neural drive during...
INTRODUCTION/PURPOSE
The purpose of this study was to determine the following in persons with midportion Achilles tendinopathy (AT): 1) maximal strength and power; 2) neural drive during maximal contractions and contractile function during electrically evoked resting contractions; and 3) whether pain, neural drive, and contractile mechanisms contribute to differences in maximal strength.
METHODS
Twenty-eight volunteers (14 AT, 14 controls) completed isometric, concentric, and eccentric maximal voluntary contractions (MVCs) of the plantar flexors in a Biodex dynamometer. Supramaximal electrical stimulation of the tibial nerve was performed to quantify neural drive and contractile properties of the plantar flexors. Pain sensitivity was quantified as the pressure-pain thresholds of the Achilles tendon, medial gastrocnemius, and upper trapezius.
RESULTS
There were no differences in plantar flexion strength or power between AT and controls (isometric MVC: = 0.95; dynamic MVC: = 0.99; power: = 0.98), nor were there differences in neural drive and contractile function ( = 0.55 and = 0.06, respectively). However, the mechanisms predicting maximal strength differed between groups: neural drive predicted maximal strength in controls ( = 0.02) and contractile function predicted maximal strength in AT ( = 0.001). Although pain did not mediate these relationships (i.e., between maximal strength and its contributing mechanisms), pressure-pain thresholds at the upper trapezius were higher in AT ( = 0.02), despite being similar at the calf ( = 0.24) and Achilles tendon ( = 0.40).
CONCLUSIONS
There were no deficits in plantar flexion strength or power in persons with AT, whether evaluated isometrically, concentrically, or eccentrically. However, the mechanisms predicting maximal plantar flexor strength differed between groups, and systemic pain sensitivity was diminished in AT.
PubMed: 38222444
DOI: 10.1249/esm.0000000000000017 -
American Journal of Veterinary Research Jun 2024The objective of this study was to optimize an MRI-based diffusion tensor imaging (DTI) protocol for imaging the plantar nerves at the level of the tarsus in normal...
OBJECTIVE
The objective of this study was to optimize an MRI-based diffusion tensor imaging (DTI) protocol for imaging the plantar nerves at the level of the tarsus in normal equine limbs.
SAMPLE
12 pelvic cadaver limbs from horses without evidence of proximal suspensory pathology were imaged with a 3T MRI system.
METHODS
For diffusion-weighted imaging, b values of 600, 800, and 1,000 s/mm2 were tested. Data were processed with DSI Studio. Cross-sectional areas of the medial and lateral plantar nerve along the plantar tarsus were recorded. The length and number of fiber tracts, signal-to-noise ratio, and DTI variables were recorded.
RESULTS
At the level of interest, the mean cross-sectional areas of the plantar nerves ranged from 5.03 to 7.42 mm2. The DTI maps consistently generated tracts in the region of the lateral and medial plantar nerves with DTI values in the range of values reported for peripheral nerves in humans. Our findings demonstrate that DTI of the medial and lateral plantar nerves can be performed successfully and used to generate quantitative parameters including fractional anisotropy and mean, axial, and radial diffusivity.
CLINICAL RELEVANCE
Quantitative data generated with this imaging technique can be used to noninvasively characterize the microstructural integrity of neural tissue with possible applications in the evaluation of pathologic changes to the plantar tarsal and metatarsal nerves of horses with proximal suspensory desmopathy.
PubMed: 38889743
DOI: 10.2460/ajvr.24.03.0092 -
Medicine Apr 2024It is essential to understand the considerable variations in bifurcation patterns of the tibial nerve (TN) and its peripheral nerves at the level of the tarsal tunnel to...
It is essential to understand the considerable variations in bifurcation patterns of the tibial nerve (TN) and its peripheral nerves at the level of the tarsal tunnel to prevent iatrogenic nerve injury during surgical nerve release or nerve block. A total of 16 ankles of 8 human cadavers were dissected to investigate the branching patterns of the TN, using 2 imaginary lines passing through the tip of the medial malleolus (MM) as reference lines. Bifurcation patterns and detailed information on the relative locations of the medial plantar, lateral plantar, medial calcaneal, and inferior calcaneal nerves to the reference lines were recorded. The most common bifurcation pattern was Type 1 in 12 ankles (75%), followed by Type 2 in 2 ankles (13%). One medial calcaneal nerve (MCN) was seen in 11 (69%) specimens and 2 MCN branches were seen in 5 (31%) specimen. 88% of the MCN branches bifurcated from the TN, whereas 6% originated from both TN and lateral plantar nerve (LPN). At the level of the tip of the MM, 2 of 7 parameters showed statistically significant difference between both sexes (P < .05). There was a statistically significant difference between left and right ankles in 2 of 7 measurements (P < .05). Further morphometric analysis of the width, distance, and angle between the TN branches and the tip of MM showed a highly variable nature of the location of the peripheral nerve branches.
Topics: Female; Male; Humans; Ankle; Ankle Joint; Tibial Nerve; Tibia; Leg
PubMed: 38608103
DOI: 10.1097/MD.0000000000037745 -
Frontiers in Neuroscience 2023It has been shown that estrogen and progesterone receptors are expressed in the spinal cord; therefore, fluctuation in their concentrations may affect the spinal network...
It has been shown that estrogen and progesterone receptors are expressed in the spinal cord; therefore, fluctuation in their concentrations may affect the spinal network and modulate the control of movement. Herein, we assessed the neuro-modulatory effect of sex hormones on the polysynaptic spinal network by using a flexion reflex network as a model system. Twenty-four healthy eumenorrheic women (age 21-37 years) were tested every other day for one menstrual cycle. Serum estradiol and progesterone were acquired at the time of testing. The flexion reflex of the tibialis anterior was elicited by sending an innocuous electrical stimulus directly to the posterior tibial nerve or plantar cutaneous afferent. Analyses were performed for each menstrual cycle phase: the follicular phase and the luteal phase. Increases in estradiol or progesterone concentrations were not associated with reflex duration or root mean squared (RMS) amplitude in either the follicular or luteal phases. In the luteal phase, an increase in the estradiol concentration was associated with a longer latency of the reflex ( = 0.23, = 0.038). The estradiol × progesterone interaction was found towards significance ( = -0.017, = 0.081). These results highlight the potential synergistic effect of estradiol and progesterone and may provide indirect confirmatory evidence of the observed modulatory effect.
PubMed: 38188036
DOI: 10.3389/fnins.2023.1263756 -
BioRxiv : the Preprint Server For... Sep 2023Following peripheral nerve injury, denervated tissues can be reinnervated via regeneration of injured neurons or via collateral sprouting of neighboring uninjured...
UNLABELLED
Following peripheral nerve injury, denervated tissues can be reinnervated via regeneration of injured neurons or via collateral sprouting of neighboring uninjured afferents into the denervated territory. While there has been substantial focus on mechanisms underlying regeneration, collateral sprouting has received relatively less attention. In this study, we used immunohistochemistry and genetic neuronal labeling to define the subtype specificity of sprouting-mediated reinnervation of plantar hind paw skin in the mouse spared nerve injury (SNI) model, in which productive regeneration cannot occur. Following an initial loss of cutaneous afferents in the tibial nerve territory, we observed progressive centripetal reinnervation by multiple subtypes of neighboring uninjured fibers into denervated glabrous and hairy plantar skin. In addition to dermal reinnervation, CGRP-expressing peptidergic fibers slowly but continuously repopulated the denervated epidermis, Interestingly, GFRα2-expressing nonpeptidergic fibers exhibited a transient burst of epidermal reinnervation, followed by trend towards regression. Presumptive sympathetic nerve fibers also sprouted into the denervated territory, as did a population of myelinated TrkC lineage fibers, though the latter did so less efficiently. Conversely, rapidly adapting Aβ fiber and C fiber low threshold mechanoreceptor (LTMR) subtypes failed to exhibit convincing collateral sprouting up to 8 weeks after nerve injury. Optogenetics and behavioral assays further demonstrated the functionality of collaterally sprouted fibers in hairy plantar skin with restoration of punctate mechanosensation without hypersensitivity. Our findings advance understanding of differential collateral sprouting among sensory neuron subpopulations and may guide strategies to promote the progression of sensory recovery or limit maladaptive sensory phenomena after peripheral nerve injury.
SIGNIFICANCE STATEMENT
Following nerve injury, whereas one mechanism for tissue reinnervation is regeneration of injured neurons, another, less well studied mechanism is collateral sprouting of nearby uninjured neurons. In this study, we examined collateral sprouting in denervated mouse skin and showed that it involves some, but not all neuronal subtypes. Despite such heterogeneity, a significant degree of restoration of punctate mechanical sensitivity is achieved. These findings highlight the diversity of collateral sprouting among peripheral neuron subtypes and reveal important differences between pre- and post-denervation skin that might be appealing targets for therapeutic correction to enhance functional recovery from denervation and prevent unwanted sensory phenomena such as pain or numbness.
PubMed: 37745384
DOI: 10.1101/2023.09.12.557420 -
Plastic and Reconstructive Surgery.... Aug 2023Reconstructing a mangled limb is complex and requires expertise in both bone and soft-tissue reconstruction, particularly when there is significant muscle loss....
Reconstructing a mangled limb is complex and requires expertise in both bone and soft-tissue reconstruction, particularly when there is significant muscle loss. Typically, multistage surgery is necessary, starting with soft-tissue coverage, followed by bone grafting and tendon transfers. Sometimes, microsurgical techniques such as vascularized bone grafts and free functional muscle transfers are necessary, especially when there is a bone defect of over 6 cm; the soft-tissue environment is infected, scarred, or poorly vascularized; or there are extensive musculotendinous injuries. We treated a 34-year-old man who had a crushed left forearm resulting in an 18 × 8 cm open wound, 5-cm radius and 7-cm ulna bone defects, loss of the extensor pollicis longus and brevis muscles, and extensive injuries to the other musculotendinous structures of the forearm. To accomplish a one-stage reconstruction, we used a chimeric fibula osteomyocutaneous flap that included a 20 × 10 cm skin flap, peroneus brevis muscle with its motor nerve, and two segments of fibula. The proximal and distal fibula segments were used for ulnar and radial bone reconstruction, respectively, preserving forearm supination and pronation. The peroneus brevis tendon was sutured to the extensor pollicis longus tendon, and its motor nerve was coaptated with the posterior interosseous nerve to restore thumb extension. The skin flap provided complete coverage of all exposed bone and tendon structures. At the 12-month follow-up, the patient regained full extension of the thumb, and there were no difficulties with forearm supination and pronation or with foot eversion and plantar flexion at the donor leg.
PubMed: 37577248
DOI: 10.1097/GOX.0000000000005182 -
Annals of Indian Academy of Neurology 2024Diabetic peripheral neuropathy (DPN), a complication of diabetes, is detected only in later stages. Medial plantar nerve (MPL) can identify earlier stages of neuropathy....
OBJECTIVE
Diabetic peripheral neuropathy (DPN), a complication of diabetes, is detected only in later stages. Medial plantar nerve (MPL) can identify earlier stages of neuropathy. We evaluated the correlation of MPL sensory nerve action potentials (SNAPs) and severity of DPN measured using the Toronto Clinical Neuropathy Score (TCNS).
METHODS
In this hospital-based, cross-sectional study, we recruited diabetic subjects referred for suspected DPN. Neuropathy was graded with TCNS. Sural nerve conduction studies were performed using standard techniques. MPL studies were conducted using the modified Ponsford technique. All evaluations were performed on Nihon Kohden (model MEB 9200K). Averaged MPL SNAP was correlated with TCNS using Pearson's correlation coefficient. To estimate a correlation of 0.4 with 80% power ( = 0.05), we needed 46 subjects. Linear regression was conducted to adjust for age, duration, and diabetic control. Receiver operating characteristic (ROC) curve analysis was performed to obtain the cutoff for MPL SNAP values using the Youden index.
RESULTS
Fifty-one subjects with a mean age of 53.5 years (8.7) and mean duration of diabetes of 10.2 years (7.2) were included. MPL SNAPs were recordable in 12 patients, and the mean amplitude was 5.15 (2.9) µV. There was correlation between MPL SNAP and TCNS ( = -0.43, = 0.02). No confounding was seen. Use of MPL SNAP resulted in diagnosis of DPN in an additional six (11.8%) patients. The ROC curve suggested that MPL SNAP cutoff of 1.05 µV had an accuracy of 67% in identifying neuropathy as defined by TCNS.
CONCLUSIONS
MPL SNAP has a moderate correlation with clinical score and identifies more diabetic neuropathy than sural nerve.
PubMed: 38751930
DOI: 10.4103/aian.aian_828_23 -
Annals of Indian Academy of Neurology 2024Friedreich's ataxia (FRDA) is a common cause of autosomal recessive cerebellar ataxia. The phenotype is dependent on the repeat size and duration of the disease. We...
BACKGROUND AND AIM
Friedreich's ataxia (FRDA) is a common cause of autosomal recessive cerebellar ataxia. The phenotype is dependent on the repeat size and duration of the disease. We aimed to study the clinical, electrophysiologic, and radiologic profiles in a large Indian cohort of genetically proven FRDA patients.
SUBJECTS AND METHODS
A retrospective cross-sectional, descriptive analysis of genetically proven FRDA patients was performed. A detailed review of all the hospital case records was done to analyze the clinical, radiologic, and electrophysiologic details.
RESULTS
A total of 100 FRDA patients were selected for the analysis. Eighty-six patients had an age at onset between 5 and 25 years. Eight patients (8%) were classified as late-onset FRDA and six patients (6%) as early-onset FRDA. The median age at presentation was 19 years. The median age at onset was 14 years, and the median duration of illness was 4 years. All patients had gait ataxia as the initial symptom. Gait ataxia, loss of proprioception, and areflexia were seen in all patients. Dysarthria, nystagmus, amyotrophy, spasticity, extensor plantars, pes cavus, and scoliosis occurred in one-third of patients. Cardiomyopathy (18%) and diabetes (5%) were less common. Sensory polyneuropathy (87.5%) was the most common nerve conduction abnormality. Cortical somatosensory evoked responses were absent in all 43 tested patients (100%). Brainstem auditory evoked response test was done in 24 patients and it showed absent reactions in six patients (25%). Visual evoked potential was tested in 24 patients and it showed absent P100 responses in five patients (21%). Cerebellar and cord atrophy was seen on magnetic resonance imaging in 50% of patients.
CONCLUSION
Most FRDA patients (86%) had an age at onset of less than 25 years, with typical symptoms of gait ataxia, areflexia, and loss of proprioception found in all patients. Dysarthria, nystagmus, amyotrophy, spasticity, extensor plantars, pes cavus, scoliosis, cardiomyopathy, and diabetes were not seen in all patients. Cerebellar atrophy can occur in FRDA patients. Knowledge regarding the clinical, radiologic, and electrophysiologic profile of FRDA will aid in proper phenotypic characterization.
PubMed: 38751907
DOI: 10.4103/aian.aian_1001_23