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Muscle and Nerve Fibers Classification
Published in Maher Kurdi, Neuromuscular Pathology Made Easy, 2021
Based on their diameter and conduction velocity (CV), nerve fibers are also subclassified into A, B, and C types (Figure 2.2). A-type is subdivided into alpha, beta, gamma, and delta fibers. This classification is known as Erlanger and Gasser classification. The CV is considered the main cutoff factor in this classification, which depends on the extent of nerve myelination. In myelinated fibers, depolarization initiates faster than in unmyelinated fibers. Therefore, the CVs in group A myelinated fibers are higher than group B and C fibers (Table 2.2). These changes can be detected only during electrophysiological studies. The pathological changes associated with these abnormal fibers can be detected by examining the nerve fibers themselves.
Neurologic Diagnosis
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Within 4–5 days, both the axon and myelin distal to the site of injury degenerate. The degenerating myelin forms linear arrays of ovoids and globules along the degenerating axon. The axon of the proximal segment regenerates by forming sprouts that grow distally, and some reinnervate the surviving distal neurilemmal tubes of the Schwann cell basement membrane, inside which the Schwann cells have divided and arranged themselves in line. The regenerating axons are then myelinated by the Schwann cells, but the nerve fibers are smaller in diameter and have shorter internodal lengths than original.
Etiopathogenesis
Published in Vineet Relhan, Vijay Kumar Garg, Sneha Ghunawat, Khushbu Mahajan, Comprehensive Textbook on Vitiligo, 2020
Dario Didona, Biagio Didona, Giovanni Paolino, Raffaele Dante Caposiena Caro
Pathologically, degenerative changes in dermal nerves and sweat glands have been reported in vitiligo patients [44]. In addition, thicker Schwann cell basement membranes have been found surrounding the nerve fibers when compared with healthy controls [44]. Furthermore, Bose found a reduction in Merkel cells, which was associated with a destruction of melanocytes [45].
Efficient simulations of stretch growth axon based on improved HH model
Published in Neurological Research, 2023
Xiao Li, Xianxin Dong, Xikai Tu, Hailong Huang
Neuronal cell is composed of three components: a cell body, an axon, and a dendrite. These components are responsible for receiving, integrating, and delivering information. In general, neurons receive and integrate information from other neurons via their dendrites and cell bodies, and then transfer it to other neurons via their axons. Nerve fibers have great excitability and conductivity, and their primary role is to transmit information between neurons. When a sufficient stimulus excites a nerve fiber, it immediately generates a propagable action potential. Chemical synapses allow action potentials to be passed from one neuron to the next by transporting neurotransmitters through synaptic vesicles. The action potential-induced shift in membrane potential causes the calcium channel on the synaptic terminal membrane to open, allowing a substantial number of calcium ions to flow into the membrane, resulting in an abrupt increase in calcium ions in the synaptic membrane. When synaptic vesicles detect an increase in the number of calcium ions in the surrounding environment, they fuse with the presynaptic membrane and spit neurotransmitters into the synaptic gap. After binding to a protein receptor on the postsynaptic membrane, the neurotransmitter causes excitement or inhibition.
Feasibility of robot-assisted radical prostatectomy in men at senior age ≥75 years: perioperative, functional, and oncological outcomes of a high-volume center
Published in The Aging Male, 2022
Sami-Ramzi Leyh-Bannurah, Christian Wagner, Andreas Schuette, Nikolaos Liakos, Theodoros Karagiotis, Mikolaj Mendrek, Pawel Rachubinski, Matthias Oelke, Zhe Tian, Jorn H. Witt
Fourth, our 36-months erectile function recovery rate of 27% is comparable to 33% reported by other high-volume centres [4,5,14,15]. Specifically, several series, which mostly relied on animal models, clearly demonstrated that increasing age negatively affects the regeneration and reinnervation of peripheral nerve fibers after injury, being delayed and less effective [33–35]. Moreover, with increasing age the neuroimmune profile usually becomes pro-inflammatory, potentially further contributing to nerve decline after RARP [36]. Thus, even at the same baseline erectile function and after matching, our MVA findings are highly conceivable, i.e. that younger PCa patients have a significantly faster and/or better recovery of erectile function after RARP compared to senior patients. This is in line with senior age as the strongest predictor of erectile dysfunction and impaired nerve regeneration even beyond the context of RARP [37].
Clinical and apparative investigation of large and small nerve fiber impairment in mixed cohort of ATTR-amyloidosis: impact on patient management and new insights in wild-type
Published in Amyloid, 2022
Aikaterini Papagianni, Sandra Ihne, Daniel Zeller, Caroline Morbach, Nurcan Üçeyler, Claudia Sommer
By applying a comprehensive set of clinical and six apparative investigations of function and morphology of peripheral nerve fibers in our mixed cohort, we yield useful insights regarding peripheral nervous system involvement. In particular, not only including large fiber, but also small fiber and autonomic fiber dysfunction was diagnosed, thereby highlighting new pathways to accelerate and improve a diagnostic approach to these patients. Applying this set of examinations in a mixed study population, we aimed to move a step forward from merely reporting small-fiber involvement in ATTRv amyloidosis using single or few apparative tests as already previously done [10,11] but to explore comprehensively (large-, small- and autonomic) peripheral nervous involvement in combination with skin punch biopsies in order to identify early disease manifestation and progression in ATTRv amyloidosis. This comprehensive approach of the peripheral nervous system in cases of ATTRwt amyloidosis arose after recent sporadic reports in the literature [17]. The exploration of this cohort provides data indicating that a comprehensive diagnostic test battery of the peripheral nervous system in patients with ATTRv amyloidosis can provide evidence of early-stage disease manifestation or progression (three ATTRv patients in our sample). We suggest therefore the implementation of apparative tests for small somatic and autonomic fibers in the screening and follow-up assessments of all patients with ATTRv amyloidosis.