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Brain : a Journal of Neurology Apr 2024The most frequent neurodegenerative proteinopathies include diseases with deposition of misfolded tau or α-synuclein in the brain. Pathological protein aggregates in...
The most frequent neurodegenerative proteinopathies include diseases with deposition of misfolded tau or α-synuclein in the brain. Pathological protein aggregates in the PNS are well-recognized in α-synucleinopathies and have recently attracted attention as a diagnostic biomarker. However, there is a paucity of observations in tauopathies. To characterize the involvement of the PNS in tauopathies, we investigated tau pathology in cranial and spinal nerves (PNS-tau) in 54 tauopathy cases [progressive supranuclear palsy (PSP), n = 15; Alzheimer's disease (AD), n = 18; chronic traumatic encephalopathy (CTE), n = 5; and corticobasal degeneration (CBD), n = 6; Pick's disease, n = 9; limbic-predominant neuronal inclusion body 4-repeat tauopathy (LNT), n = 1] using immunohistochemistry, Gallyas silver staining, biochemistry, and seeding assays. Most PSP cases revealed phosphorylated and 4-repeat tau immunoreactive tau deposits in the PNS as follows: (number of tau-positive cases/available cases) cranial nerves III: 7/8 (88%); IX/X: 10/11 (91%); and XII: 6/6 (100%); anterior spinal roots: 10/10 (100%). The tau-positive inclusions in PSP often showed structures with fibrillary (neurofibrillary tangle-like) morphology in the axon that were also recognized with Gallyas silver staining. CBD cases rarely showed fine granular non-argyrophilic tau deposits. In contrast, tau pathology in the PNS was not evident in AD, CTE and Pick's disease cases. The single LNT case also showed tau pathology in the PNS. In PSP, the severity of PNS-tau involvement correlated with that of the corresponding nuclei, although, occasionally, p-tau deposits were present in the cranial nerves but not in the related brainstem nuclei. Not surprisingly, most of the PSP cases presented with eye movement disorder and bulbar symptoms, and some cases also showed lower-motor neuron signs. Using tau biosensor cells, for the first time we demonstrated seeding capacity of tau in the PNS. In conclusion, prominent PNS-tau distinguishes PSP from other tauopathies. The morphological differences of PNS-tau between PSP and CBD suggest that the tau pathology in PNS could reflect that in the central nervous system. The high frequency and early presence of tau lesions in PSP suggest that PNS-tau may have clinical and biomarker relevance.
Topics: Humans; Supranuclear Palsy, Progressive; tau Proteins; Pick Disease of the Brain; Alzheimer Disease; Tauopathies; Spinal Nerves; Biomarkers
PubMed: 37972275
DOI: 10.1093/brain/awad381 -
Arquivos de Neuro-psiquiatria Sep 2023The distinction between sensory neuronopathies (SN), which is by definition purely sensory, and sensory polyneuropathies (SP) and sensory multineuropathies (SM) is...
BACKGROUND
The distinction between sensory neuronopathies (SN), which is by definition purely sensory, and sensory polyneuropathies (SP) and sensory multineuropathies (SM) is important for etiologic investigation and prognosis estimation. However, this task is often challenging in clinical practice. We hypothesize that F-wave assessment might be helpful, since it is able to detect subtle signs of motor involvement, which are found in SP and SM, but not in SN.
OBJECTIVE
The aim of the present study was to determine whether F-waves are useful to distinguish SN from SP and SM.
METHODS
We selected 21 patients with SP (12 diabetes mellitus, 4 transthyretin familial amyloid polyneuropathy, 4 others), 22 with SM (22 leprosy), and 26 with SN (13 immune-mediated, 10 idiopathic, 3 others) according to clinical-electrophysiological-etiological criteria. For every subject, we collected data on height and performed 20 supramaximal distal stimuli in median, ulnar, peroneal, and tibial nerves, bilaterally, to record F-waves. Latencies (minimum and mean) and persistences were compared across groups using the Kruskal-Wallis and Bonferroni tests. -values < 0.05 were considered significant.
RESULTS
All groups were age, gender, and height-matched. Overall, there were no significant between-group differences regarding F-wave latencies. In contrast, F-wave persistence was able to stratify the groups. Peroneal F-wave persistence was higher, bilaterally, in the SN group compared to SM and SP ( < 0.05). In addition, F-waves persistence of the ulnar and tibial nerves was also helpful to separate SN from SP ( < 0.05).
CONCLUSION
F-wave persistence of the peroneal nerves might be an additional and useful diagnostic tool to differentiate peripheral sensory syndromes.
Topics: Humans; Neural Conduction; Median Nerve; Ulnar Nerve; Tibial Nerve; Peroneal Nerve; Polyneuropathies; Syndrome; Peripheral Nerves
PubMed: 37793400
DOI: 10.1055/s-0043-1772599 -
Neuroscience Dec 2023Neuropathic pain is a debilitating chronic pain condition and is refractory to the currently available treatments. Emerging evidence suggests that melatonin exerts...
Neuropathic pain is a debilitating chronic pain condition and is refractory to the currently available treatments. Emerging evidence suggests that melatonin exerts analgesic effects in rodent models of neuropathic pain. Nevertheless, the exact underlying mechanisms of the analgesic effects of melatonin on neuropathic pain are largely unknown. Here, we observed that spinal nerve ligation (SNL) in rats L5 and L6 induced an obvious decrease in the 50% paw withdrawal threshold (PWT) and paw withdrawal latency (PWL), indicating the induction of mechanical allodynia and the hyperalgesia, and melatonin prevented the genesis and maintenance of mechanical allodynia and the hyperalgesia. Notably, the inhibitory action of melatonin on SNL-induced mechanical allodynia and heat hypersensitivity was inhibited by a SIRT1 inhibitor (EX527). Melatonin treatment increased the expression of neuronal sirtuin1 (SIRT1) in DRGs following nerve injury. Furthermore, melatonin treatment restored the injury-dependent decrease in mitochondrial membrane potential and peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) and reduced the injury-dependent increase in hydrogen peroxide and 8-hydroxy-2-deoxyguanosine (8-OHdG), which was inhibited by EX527. In addition, we found that EX527 impeded the inhibitory effects of melatonin on the SNL-induced increased expression of cytokines tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β). In conclusion, the above data demonstrated that melatonin alleviated mechanical allodynia and hyperalgesia induced by peripheral nerve injury via SIRT1 activation. Melatonin resolved mitochondrial dysfunction-oxidative stress-dependent and neuroinflammation mechanisms that were driven by SIRT1 after nerve injury.
Topics: Rats; Animals; Hyperalgesia; Sirtuin 1; Melatonin; Rats, Sprague-Dawley; Ganglia, Spinal; Neuralgia; Spinal Nerves; Mitochondria; Analgesics
PubMed: 37832908
DOI: 10.1016/j.neuroscience.2023.10.005 -
Handchirurgie, Mikrochirurgie,... Feb 2024Complex brachial plexus injuries with multiple or complete root avulsions make intraplexic reconstruction impossible in some cases. Such cases necessitate the use of...
Complex brachial plexus injuries with multiple or complete root avulsions make intraplexic reconstruction impossible in some cases. Such cases necessitate the use of extraplexic nerve donors such as the spinal accessory nerve or intercostal nerves. The contralateral C7 root represents a donor with a high axon count and can be used as an axon source in such cases. We summarise current indications, surgical technique and functional results after a contralateral C7 transfer in cases of brachial plexus injury, describing some of our own cases and including a selective literature review.
Topics: Humans; Nerve Transfer; Brachial Plexus; Brachial Plexus Neuropathies; Axons
PubMed: 38408481
DOI: 10.1055/a-2246-1704 -
Surgical and Radiologic Anatomy : SRA Sep 2023The current cadaveric case series evaluates the coracobrachialis muscle morphology, the related musculocutaneous nerve origin, course, and branching pattern, as well as...
PURPOSE
The current cadaveric case series evaluates the coracobrachialis muscle morphology, the related musculocutaneous nerve origin, course, and branching pattern, as well as associated adjacent neuromuscular variants.
MATERIALS AND METHODS
Twenty-seven (24 paired and 3 unpaired) cadaveric arms were dissected to identify the coracobrachialis possible variants with emphasis on the musculocutaneous nerve course and coexisted neural variants.
RESULTS
Four morphological types of the coracobrachialis were identified: a two-headed muscle in 62.96% (17/27 arms), a three-headed in 22.2% (6/27), a one-headed in 11.1% (3/27), and a four-headed in 3.7% (1 arm). A coracobrachialis variant morphology was identified in 37.04% (10/27). A three-headed biceps brachii muscle coexisted in 23.53% (4/17). Two different courses of the musculocutaneous nerve were recorded: 1. a course between coracobrachialis superficial and deep heads (in cases of two or more heads) (100%, 24/24), and 2. a medial course in case of one-headed coracobrachialis (100%, 3/3). Three neural interconnections were found: 1. the lateral cord of the brachial plexus with the medial root of the median nerve in 18.52%, 2. the musculocutaneous with the median nerve in 7.41% and 3. the radial with the ulnar nerve in 3.71%. Duplication of the lateral root of the median nerve was identified in 11.1%.
CONCLUSIONS
The knowledge of the morphology of the muscles of the anterior arm compartment, especially the coracobrachialis variant morphology and the related musculocutaneous nerve variable course, is of paramount importance for surgeons. Careful dissection and knowledge of relatively common variants play a significant role in reducing iatrogenic injury.
Topics: Humans; Arm; Musculocutaneous Nerve; Brachial Plexus; Median Nerve; Muscle, Skeletal; Cadaver
PubMed: 37464221
DOI: 10.1007/s00276-023-03207-7 -
Journal of Neurosurgery. Spine Mar 2024Tarlov perineurial spinal cysts (TCs) are an underrecognized cause of spinal neuropathic symptoms. TCs form within the sensory nerve root sleeves, where CSF extends...
Tarlov perineurial spinal cysts (TCs) are an underrecognized cause of spinal neuropathic symptoms. TCs form within the sensory nerve root sleeves, where CSF extends distally and can accumulate pathologically. Typically, they develop at the sacral dermatomes where the nerve roots are under the highest hydrostatic pressure and lack enclosing vertebral foramina. In total, 90% of patients are women, and genetic disorders that weaken connective tissues, e.g., Ehlers-Danlos syndrome, convey considerable risk. Most small TCs are asymptomatic and do not require treatment, but even incidental visualizations should be documented in case symptoms develop later. Symptomatic TCs most commonly cause sacropelvic dermatomal neuropathic pain, as well as bladder, bowel, and sexual dysfunction. Large cysts routinely cause muscle atrophy and weakness by compressing the ventral motor roots, and multiple cysts or multiroot compression by one large cyst can cause even greater cauda equina syndromes. Rarely, giant cysts erode the sacrum or extend as intrapelvic masses. Disabling TCs require consideration for surgical intervention. The authors' systematic review of treatment analyzed 31 case series of interventional percutaneous procedures and open surgical procedures. The surgical series were smaller and reported somewhat better outcomes with longer term follow-up but slightly higher risks. When data were lacking, authorial expertise and case reports informed details of the specific interventional and surgical techniques, as well as medical, physical, and psychological management. Cyst-wrapping surgery appeared to offer the best long-term outcomes by permanently reducing cyst size and reconstructing the nerve root sleeves. This curtails ongoing injury to the axons and neuronal death, and may also promote axonal regeneration to improve somatic and autonomic sacral nerve function.
Topics: Humans; Axons; Spinal Nerve Roots; Spine; Tarlov Cysts
PubMed: 38100766
DOI: 10.3171/2023.9.SPINE23559 -
Experimental Neurology Oct 2023Moderate acute intermittent hypoxia (mAIH) elicits plasticity in both respiratory (phrenic long-term facilitation; pLTF) and sympathetic nerve activity (sympLTF) in...
HYPOTHESES
Moderate acute intermittent hypoxia (mAIH) elicits plasticity in both respiratory (phrenic long-term facilitation; pLTF) and sympathetic nerve activity (sympLTF) in rats. Although mAIH produces pLTF in normal rats, inconsistent results are reported after cervical spinal cord injury (cSCI), possibly due to greater spinal tissue hypoxia below the injury site. There are no reports concerning cSCI effects on sympLTF. Since mAIH is being explored as a therapeutic modality to restore respiratory and non-respiratory movements in humans with chronic SCI, both effects are important. To understand cSCI effects on mAIH-induced pLTF and sympLTF, partial or complete C2 spinal hemisections (C2Hx) were performed and, 2 weeks later, we assessed: 1) ipsilateral cervical spinal tissue oxygen tension; 2) ipsilateral & contralateral pLTF; and 3) ipsilateral sympLTF in splanchnic and renal sympathetic nerves.
METHODS
Male Sprague-Dawley rats were studied intact, or after partial (single slice) or complete C2Hx (slice with ∼1 mm aspiration). Two weeks post-C2Hx, rats were anesthetized and prepared for recordings of bilateral phrenic nerve activity and spinal tissue oxygen pressure (PtO). Splanchnic and renal sympathetic nerve activity was recorded in intact and complete C2Hx rats.
RESULTS
Spinal PtO near phrenic motor neurons was decreased after C2Hx, an effect most prominent with complete vs. partial injuries; baseline PtO was positively correlated with mean arterial pressure. Complete C2Hx impaired ipsilateral but not contralateral pLTF; with partial C2Hx, ipsilateral pLTF was unaffected. In intact rats, mAIH elicited splanchnic and renal sympLTF. Complete C2Hx had minimal impact on baseline ipsilateral splanchnic or renal sympathetic nerve activity and renal, but not splanchnic, sympLTF remained intact.
CONCLUSION
Greater tissue hypoxia likely impairs pLTF and splanchnic sympLTF post-C2Hx, although renal sympLTF remains intact. Increased sympathetic nerve activity post-mAIH may have therapeutic benefits in individuals living with chronic SCI since anticipated elevations in systemic blood pressure may mitigate hypotension characteristic of people living with SCI.
Topics: Humans; Rats; Male; Animals; Rats, Sprague-Dawley; Motor Neurons; Spinal Cord Injuries; Hypoxia; Oxygen; Phrenic Nerve
PubMed: 37451584
DOI: 10.1016/j.expneurol.2023.114478 -
Burns : Journal of the International... Dec 2023Although several studies have investigated models of nerve electrical injury, only a few have focused on electrical injury to peripheral nerves, which is a common and...
INTRODUCTION
Although several studies have investigated models of nerve electrical injury, only a few have focused on electrical injury to peripheral nerves, which is a common and intractable problem in clinical practice. Here, we describe an experimental rat model of peripheral nerve electrical injury and its assessment.
METHODS
A total of 120 animals were subjected to short-term corrective electrostimulation (50 Hz, 1-s duration) applied at varying voltages (control, 65, 75, 100, 125, and 150 V) to the exposed left sciatic nerve. Behavioural testing, electrophysiological measurements, and histopathological observation of the sciatic nerve were conducted at 1-, 2-, 4-, and 8-w follow-ups.
RESULTS
No functional defects were noted in the groups that received 65-V stimulation at any time point. Sciatic nerve functional defects were found after 2 w in animals that received 75-V stimulation, but function returned to normal after 4 w. In animals that received 100-V and 125-V stimulation, functional defects were observed at 4 w, but had partially recovered by 8 w. Conversely, animals that received 150-V stimulation did not show recovery after 8 w.
CONCLUSION
We presented a model of peripheral nerve electrical injury that avoided the interference of various external factors, such as current instability, compression of the surrounding tissues, and altered blood supply. The model allowed quantitation and ranking of the nerve injury into four degrees. It facilitated effective evaluation of nerve function impairment and repair after injury. It can be used post-surgically to evaluate peripheral nerve impairment and reconstruction and enables translational interpretation of results, which may improve understanding of the mechanisms underlying the progression of peripheral nerve electrical injury.
Topics: Rats; Animals; Rats, Sprague-Dawley; Burns; Peripheral Nerve Injuries; Sciatic Nerve; Electric Injuries; Nerve Regeneration
PubMed: 37821288
DOI: 10.1016/j.burns.2023.03.004 -
Skeletal Radiology Oct 2023The T12 to S4 spinal nerves form the lumbosacral plexus in the retroperitoneum, providing sensory and motor innervation to the pelvis and lower extremities. The... (Review)
Review
The T12 to S4 spinal nerves form the lumbosacral plexus in the retroperitoneum, providing sensory and motor innervation to the pelvis and lower extremities. The lumbosacral plexus has a wide range of anatomic variations and interchange of fibers between nerve anastomoses. Neuropathies of the lumbosacral plexus cause a broad spectrum of complex pelvic and lower extremity pain syndromes, which can be challenging to diagnose and treat successfully. In their workup, selective nerve blocks are employed to test the hypothesis that a lumbosacral plexus nerve contributes to a suspected pelvic and extremity pain syndrome, whereas therapeutic perineural injections aim to alleviate pain and paresthesia symptoms. While the sciatic and femoral nerves are large in caliber, the iliohypogastric and ilioinguinal, genitofemoral, lateral femoral cutaneous, anterior femoral cutaneous, posterior femoral cutaneous, obturator, and pudendal nerves are small, measuring a few millimeters in diameter and have a wide range of anatomic variants. Due to their minuteness, direct visualization of the smaller lumbosacral plexus branches can be difficult during selective nerve blocks, particularly in deeper pelvic locations or larger patients. In this setting, the high spatial and contrast resolution of interventional MR neurography guidance benefits nerve visualization and targeting, needle placement, and visualization of perineural injectant distribution, providing a highly accurate alternative to more commonly used ultrasonography, fluoroscopy, and computed tomography guidance for perineural injections. This article offers a practical guide for MR neurography-guided lumbosacral plexus perineural injections, including interventional setup, pulse sequence protocols, lumbosacral plexus MR neurography anatomy, anatomic variations, and injection targets.
Topics: Humans; Magnetic Resonance Imaging; Lumbosacral Plexus; Nerve Block; Lower Extremity; Pain
PubMed: 37495713
DOI: 10.1007/s00256-023-04384-7