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The Journal of Neuroscience : the... Apr 2024Following peripheral nerve injury, denervated tissues can be reinnervated via regeneration of injured neurons or collateral sprouting of neighboring uninjured afferents...
Following peripheral nerve injury, denervated tissues can be reinnervated via regeneration of injured neurons or collateral sprouting of neighboring uninjured afferents into denervated territory. While there has been substantial focus on mechanisms underlying regeneration, collateral sprouting has received less attention. Here, we used immunohistochemistry and genetic neuronal labeling to define the subtype specificity of sprouting-mediated reinnervation of plantar hindpaw skin in the mouse spared nerve injury (SNI) model, in which productive regeneration cannot occur. Following 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 of male mice. In addition to dermal reinnervation, CGRP-expressing peptidergic fibers slowly but continuously repopulated denervated epidermis, Interestingly, GFRα2-expressing nonpeptidergic fibers exhibited a transient burst of epidermal reinnervation, followed by a trend towards regression. Presumptive sympathetic nerve fibers also sprouted into denervated territory, as did a population of myelinated TrkC lineage fibers, though the latter did so inefficiently. Conversely, rapidly adapting Aβ fiber and C fiber low threshold mechanoreceptor (LTMR) subtypes failed to exhibit convincing sprouting up to 8 weeks after nerve injury in males or females. Optogenetics and behavioral assays in male mice 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.
Topics: Female; Mice; Male; Animals; Peripheral Nerve Injuries; Nerve Regeneration; Skin; Neurogenesis; Neurons, Afferent
PubMed: 38471780
DOI: 10.1523/JNEUROSCI.1494-23.2024 -
Journal of Nippon Medical School =... 2024Tarsal tunnel syndrome (TTS) is a common entrapment neuropathy that is sometimes elicited by ganglia in the tarsal tunnel.
BACKGROUND
Tarsal tunnel syndrome (TTS) is a common entrapment neuropathy that is sometimes elicited by ganglia in the tarsal tunnel.
METHODS
Between August 2020 and July 2022, we operated on 117 sides with TTS. This retrospective study examined data from 8 consecutive patients (8 sides: 5 men, 3 women; average age 67.8 years) with an extraneural ganglion in the tarsal tunnel. We investigated the clinical characteristics and surgical outcomes for these patients.
RESULTS
The mass was palpable through the skin in 1 patient, detected intraoperatively in 1 patient, and visualized on MRI scanning in the other 6 patients. Symptoms involved the medial plantar nerve area (n = 5), lateral plantar nerve area (n = 1), and medial and lateral plantar nerve areas (n = 2). The interval between symptom onset and surgery ranged from 4 to 168 months. Adhesion between large (≥20 mm) ganglia and surrounding tissue and nerves was observed intraoperatively in 4 patients. Of the 8 patients, 7 underwent total ganglion resection. There were no surgery-related complications. On their last postoperative visit, 3 patients with a duration of symptoms not exceeding 10 months reported favorable outcomes.
CONCLUSIONS
Because ganglia eliciting TTS are often undetectable by skin palpation, imaging studies may be necessary. Early surgical intervention appears to yield favorable outcomes.
Topics: Male; Humans; Female; Aged; Tarsal Tunnel Syndrome; Retrospective Studies; Magnetic Resonance Imaging; Skin
PubMed: 38462440
DOI: 10.1272/jnms.JNMS.2024_91-203 -
The Journal of Emergency Medicine Feb 2024
Topics: Humans; Fasciitis, Plantar; Emergency Service, Hospital; Tibial Nerve
PubMed: 38432710
DOI: 10.1016/j.jemermed.2023.10.035 -
Brain Research Jun 2024Chronic pain is linked to cognitive impairment; however, the underlying mechanisms remain unclear. In the present study, we examined these mechanisms in a...
BACKGROUND
Chronic pain is linked to cognitive impairment; however, the underlying mechanisms remain unclear. In the present study, we examined these mechanisms in a well-established mouse model of Alzheimer's disease (AD).
METHODS
Neuropathic pain was modeled in 5-month-old transgenic APPswe/PS1dE9 (APP/PS1) mice by partial ligation of the sciatic nerve on the left side, and chronic inflammatory pain was modeled in another group of APP/PS1 mice by injecting them with complete Freund's adjuvant on the plantar surface of the left hind paw. Six weeks after molding, the animals were tested to assess pain threshold (von Frey filament), learning, memory (novel object recognition, Morris water maze, Y-maze, and passive avoidance), and depression-like symptoms (sucrose preference, tail suspension, and forced swimming). After behavioral testing, mice were sacrificed and the levels of p65, amyloid-β (residues 1-42) and phospho-tau in the hippocampus and cerebral cortex were assayed using western blotting, while interleukin (IL)-1β levels were measured by enzyme-linked immunosorbent assay.
RESULTS
Animals subjected to either type of chronic pain showed lower pain thresholds, more severe deficits in learning and memory, and stronger depression-like symptoms than the corresponding control animals. Either type of chronic pain was associated with upregulation of p65, amyloid-β (1-42), and IL-1β in the hippocampus and cerebral cortex, as well as higher levels of phosphorylated tau.
CONCLUSIONS
Chronic pain may exacerbate cognitive deficits and depression-like symptoms in APP/PS1 mice by worsening pathology related to amyloid-β and tau and by upregulating signaling involving IL-1β and p65.
Topics: Animals; Mice; Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Chronic Pain; Disease Models, Animal; Maze Learning; Memory Disorders; Mice, Transgenic; Presenilin-1
PubMed: 38430996
DOI: 10.1016/j.brainres.2024.148843 -
Scandinavian Journal of Medicine &... Mar 2024The enigmatic benefits of acute limb ischemic preconditioning (IP) in enhancing muscle force and exercise performance have intrigued researchers. This study sought to...
The enigmatic benefits of acute limb ischemic preconditioning (IP) in enhancing muscle force and exercise performance have intrigued researchers. This study sought to unravel the underlying mechanisms, focusing on increased neural drive and the role of spinal excitability while excluding peripheral factors. Soleus Hoffmann (H)-reflex /M-wave recruitment curves and unpotentiated supramaximal responses were recorded before and after IP or a low-pressure control intervention. Subsequently, the twitch interpolation technique was applied during maximal voluntary contractions to assess conventional parameters of neural output. Following IP, there was an increase in both maximum normalized force and voluntary activation (VA) for the plantar flexor group, with negligible peripheral alterations. Greater benefits were observed in participants with lower VA levels. Despite greater H-reflex gains, soleus volitional (V)-wave and sEMG amplitudes remained unchanged. In conclusion, IP improves muscle force via enhanced neural drive to the muscles. This effect appears associated, at least in part, to reduced presynaptic inhibition and/or increased motoneuron excitability. Furthermore, the magnitude of the benefit is inversely proportional to the skeletal muscle's functional reserve, making it particularly noticeable in under-recruited muscles. These findings have implications for the strategic application of the IP procedure across diverse populations.
Topics: Male; Humans; Electromyography; Muscle, Skeletal; Muscle Contraction; Motor Neurons; Isometric Contraction; Ischemic Preconditioning; H-Reflex; Electric Stimulation
PubMed: 38429941
DOI: 10.1111/sms.14591 -
Journal of Orthopaedic Case Reports Feb 2024The main differentials of non-traumatic heel pain are plantar fasciitis (PF), plantar heel fat pad atrophy, worn-out footwear, especially asymmetric wear and tear,...
INTRODUCTION
The main differentials of non-traumatic heel pain are plantar fasciitis (PF), plantar heel fat pad atrophy, worn-out footwear, especially asymmetric wear and tear, hyperuricemia, corns, callosities, tumors of the calcaneum, osteomyelitis, calcaneal stress fractures due to overweight or unaccustomed over usage, radiating pain from S1 nerve root compression, and seronegative spondyloarthropathies. Compression of the tibial nerve or the medial calcaneal nerve at or around the flexor retinaculum is the other possibility. In this case report, we want to highlight a sparsely known pathology, caused due to the entrapment of the first branch of the lateral plantar nerve or inferior calcaneal nerve, also known as Baxter's nerve that may present independently or accompany the common PF. Non-steroidal anti-inflammatory medications or injections of local steroids are typically used for conservative management. However, hydro-dissection or surgical release may be needed in non-responsive cases.
CASE REPORT
We present the case of a 57-year-old female with complaints of chronic pain and tenderness in the middle of the heel radiating laterally. She underwent magnetic resonance imaging that revealed chronic denervation changes in the form of marked atrophy and near complete fatty replacement of abductor digiti minimi muscle suggesting chronic Baxter neuropathy. A mildly thickened and hyperintense plantar fascia adjacent to the calcaneal spur and significant heel fat pad edema were seen too. The patient responded well to a local steroid injection and remains pain-free at the 1-year follow-up.
CONCLUSION
When heel pain is present, Baxter's nerve impingement presents as a challenging clinical diagnosis that may accompany the common PF and is often overlooked. MRI can be used to assess the denervation effects of both the acute and chronic stages of Baxter's nerve impingement by identifying abnormalities of the abductor digiti minimi muscle belly.
PubMed: 38420250
DOI: 10.13107/jocr.2024.v14.i02.4252 -
Diagnosis (Berlin, Germany) Feb 2024Intraneural ganglionic cysts are non-neoplastic cysts that can cause signs and symptoms of peripheral neuropathy. However, the scarcity of such cases can lead to...
OBJECTIVES
Intraneural ganglionic cysts are non-neoplastic cysts that can cause signs and symptoms of peripheral neuropathy. However, the scarcity of such cases can lead to cognitive biases. Early surgical exploration of space occupying lesions plays an important role in identification and improving the outcomes for intraneural ganglionic cysts.
CASE PRESENTATION
This patient presented with loss of sensation on the right sole with tingling numbness for six months. A diagnosis of tarsal tunnel syndrome was made. Nerve conduction study revealed that the mixed nerve action potential (NAP) was absent in the right medial and lateral plantar nerves. The magnetic resonance imaging (MRI) found a cystic lesion measuring 1.4×1.8×3.8 cm as the presumed cause of the neuropathy. Surgical exploration revealed a ganglionic cyst traversing towards the flexor retinaculum with baby cysts. The latter finding came as a surprise to the treating surgeon and was confirmed to be an intraneural ganglionic cyst based on the histopathology report.
CONCLUSIONS
Through integrated commentary by a case discussant and reflection by an orthopedician, this case highlights the significance of the availability heuristic, confirmation bias, and anchoring bias in a case of rare disease. Despite diagnostic delays, a medically knowledgeable patient's involvement in their own care lead to a more positive outcome. A fish-bone diagram is provided to visually demonstrate the major factors that contributed to the diagnostic delay. Finally, this case provides clinical teaching points in addition to a pitfall, myth, and pearl related to availability heuristic and the sunk cost fallacy.
PubMed: 38401131
DOI: 10.1515/dx-2023-0161 -
Plantar compartment block for hallux valgus surgery: a proof-of-concept anatomic and clinical study.Regional Anesthesia and Pain Medicine Feb 2024Hallux valgus surgery is associated with moderate to severe postoperative pain. We hypothesized that a plantar compartment block may be a good technique for...
BACKGROUND
Hallux valgus surgery is associated with moderate to severe postoperative pain. We hypothesized that a plantar compartment block may be a good technique for postoperative analgesia. We describe an anatomic approach to ultrasound-guided plantar compartment block and assess the clinical efficacy of the block for outpatient surgery.
METHODS
The anatomic study was aimed to describe the plantar compartment, using both dissection methods and imaging, and to define a volume of local anesthetic. Patients scheduled for hallux valgus surgery with a popliteal sciatic nerve block, and combined plantar compartment and peroneal blocks were included in the clinical study. Data on attaining the criteria for rapid exit from the outpatient center, duration of sensory and analgesic block, visual analog scale (VAS) values for postoperative pain at rest and during movement, and the consumption of morphine as rescue analgesia were recorded.
RESULTS
Plane-by-plane dissections and cross-sections were done in five cadaveric lower limbs. The medial calcaneal nerve divides into medial plantar and lateral plantar nerves in the upper part of the plantar compartment. These nerves were surrounded by 5 mL of colored gelatin, and 10 mL of injectates dye spread to the medial calcaneal branches. Thirty patients (26 women) were included in the clinical study. There were no failures of surgical block. Ninety per cent of patients successfully passed functional testing for ambulatory exit from the center within 5 hours (25th-75th centiles, 3.8-5.5 hours). The median duration of plantar compartment sensory block was 17.3 hours (10.5-21.5 hours), and the first request for rescue analgesic was 11.75 hours (10.5-23 hours) after surgery. The median VAS score for maximum pain reported within the 48-hour period was 2 (1-6). Twelve patients received 2.5 mg (0-5 mg) of morphine on day 1. Patients were highly satisfied and no adverse events were noted.
CONCLUSIONS
This anatomic description of the ultrasound-guided plantar compartment block reported the injection area to target the medial and lateral plantar nerves with 5 mL of local anesthetic. Normal walking without assistance is attained rapidly with this regional anesthesia technique, and the time to request postoperative analgesia after hallux valgus surgery is long.
TRIAL REGISTRATION NUMBER
NCT03815422.
PubMed: 38373818
DOI: 10.1136/rapm-2023-105246 -
JBJS Essential Surgical Techniques 2023Painful neuromas of the foot and ankle frequently pose a treatment dilemma because of persistent pain or recurrence after resection. Primary surgical treatment of...
BACKGROUND
Painful neuromas of the foot and ankle frequently pose a treatment dilemma because of persistent pain or recurrence after resection. Primary surgical treatment of painful neuromas includes simple excision with retraction of the residual nerve ending to a less vulnerable location. The use of a collagen conduit for recurrent neuromas is advantageous, particularly in areas with minimal soft-tissue coverage options, and is a technique that has shown 85% patient satisfaction regarding surgical outcomes. Additionally, the use of a collagen conduit limits the need for deep soft-tissue dissection and reduces the morbidity typically associated with nerve burial.
DESCRIPTION
Specific steps include appropriate physical examination, preoperative planning, and supine patient positioning. The patient is placed supine with a lower-extremity bolster under the ipsilateral extremity in order to allow improved visualization of the plantar surface of the foot. A nonsterile tourniquet is placed on the thigh. The incision site is marked out, and a longitudinal plantar incision is made until proximal healthy nerve is identified-typically approximately 1 to 2 cm, but the incision can be extended up to 6 cm. The incision is made between the metatarsals, with blunt dissection carried down to the neuroma. The neuroma is sharply excised distally through healthy nerve, and a whip stitch is placed to facilitate the collagen conduit placement. The collagen conduit is passed dorsally into the intermetatarsal space and secured to the dorsal fascia of the foot. The wound is closed with 3-0 nylon horizontal mattress sutures. Postoperatively, a soft dressing is applied to the operative extremity, and patients are advised to be non-weight-bearing for two weeks. At two weeks, patients begin partial weight-bearing with use of a boot, and physical therapy is initiated. No antibiotics are necessary, and 300 mg of gabapentin is prescribed and tapered off by the six-week follow-up visit. Follow-ups are conducted at 2, 6, 12, 24, and fifty-two weeks. It is necessary to monitor for signs and symptoms of infection, surgical complications, and neuroma recurrence during follow-up appointments.
ALTERNATIVES
Simple excision of the neuroma with proximal burial into muscle or bone is a common surgical technique. However, inadequate resection of the nerve or poor surgical technique can lead to recurrent neuromas. For neuromas not responding to simple excision, other techniques have been utilized, including cauterization, chemical agents, nerve capping, and muscle or bone burial. The results of these techniques have varied, and none has gained clinical superiority over the other.
RATIONALE
A study analyzing the use of collagen conduits for painful neuromas of the foot and ankle has shown this technique to be a safe and successful alternative to the previously discussed methods of resection. That study by Gould et al. found that 85% of patients had a substantial reduction in pain, with mean visual analog scale (VAS) pain scores reducing from 8 to 10 preoperatively to 0 to 4 postoperatively. Moreover, alternative biological conduits, such as the greater saphenous vein, have proven to be costly in time and resources, as this structure is often utilized in cardiovascular bypass surgery and its harvest conveys a risk of iatrogenic nerve injury to the patient.Numerous studies focusing on excision of recurrent Morton neuromas via a plantar approach have found variable success rates. Of the patients surveyed in those studies, 75% reported substantial pain improvement. However, <50% of these queried patients reported complete pain relief. Studies analyzing the dorsal approach for revision Morton neuroma excision found similar success rates. Approximately 78% of patients reported good or excellent postoperative outcomes, and significant improvements were observed in patient postoperative Patient-Reported Outcomes Measurement Information System (PROMIS) scores for pain interference, intensity, and global physical health. One study comparing outcomes following plantar versus dorsal approaches for recurrent Morton neuroma found no significant difference in postoperative patient outcomes. That study suggested that surgeons utilize the approach with which they are most comfortable. Gould et al. reported an 85% success rate with collagen conduit, which was similar to if not slightly improved compared with the other prior studies. The utilization of a collagen conduit technique thus offers comparable patient outcomes for patients with difficult neuromas.
EXPECTED OUTCOMES
Recurrent neuroma resection with the use of a collagen conduit has proven to provide satisfactory patient outcomes regarding pain and neuritis symptoms. The goal of any neuroma resection is to greatly diminish or entirely eliminate nerve pain. Based on the available evidence, there has been no proven clinical superiority of any particular technique over the others. However, in the present example case, the location of the patient's neuroma in this video makes it 85% likely that the patient will report satisfactory outcomes and 50% likely that the patient will be entirely symptom-free. At two weeks postoperatively, the patient reported well controlled pain, absence of burning or tingling sensation, full range of movement in the foot, and intact sensation throughout all major nerve distributions, including the saphenous; superficial peroneal nerve; deep peroneal nerve; and sural, medial, and lateral plantar nerves. However, sensation is absent distal to the site of a neuroma resection.
IMPORTANT TIPS
Careful preoperative planting is of utmost importance.Ruling out other potential pathologies is necessary to ensure proper outcomes.Meticulous dissection should be carried out, with delicate handling of the proximal nerve ending.Excision of the nerve should be done sharply through the healthy portion of the nerve.Appropriate sizing of the nerve conduit (with a commercially available industry sizer) should be performed.The nerve conduit should be passed dorsally and secured to the dorsal fascia without any tension.
ACRONYMS AND ABBREVIATIONS
MRI = magnetic resonance imagingUS = ultrasoundVAS = visual analog scale.
PubMed: 38357467
DOI: 10.2106/JBJS.ST.22.00065