Chronic Denervation Myopathy
Maher Kurdi in Neuromuscular Pathology Made Easy, 2021
Long-standing neurogenic disease may result in denervation of the target musculature. This is rare in clinical practice and usually referred to as chronic denervation myopathy. The spectrum of potential causes ranges from hereditary or sporadic genetic mutations to neurodegenerative, inflammatory, and neoplastic processes. In addition, aging of muscle and some metabolic conditions are also accompanied by neuropathy. The most common sporadic or hereditary cause is anterior horn cell degeneration of the central nervous system. Amyotrophic lateral sclerosis (ALS) in adulthood and spinal muscular atrophy (SMA) in childhood are the best examples of denervation myopathies. Secondary acquired causes include any disease with severe peripheral neuropathy, due to any cause, affecting the innervated muscle. Table 21.1 lists the common denervation diseases in muscle pathology practice.
Spinal Cord Disease
Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw in Hankey's Clinical Neurology, 2020
Macroscopically, brain and spinal cord often appear normal; the precentral gyrus and corticospinal tracts may show atrophy (Figures 23.28–23.32). Microscopic findings (Figures 23.33, 23.34) are: Loss of Betz’ cells of the motor cortex.Degeneration and gliosis of the corticospinal tracts.Degeneration of lower brainstem motor nuclei (not oculomotor nuclei) in most cases.Cytoplasmic eosinophilic inclusions (Bunina's bodies) and ubiquitin immunoreactive inclusion bodies (containing TAR DNA binding protein 43 [TDP-43]) in degenerating cranial motor nuclei, anterior horn cells, and Betz’ cells.Muscle shows features of denervation.Nonmotor pathways also demonstrate pathologic changes, including sensory pathways and peripheral sensory nerves.
Histology and Pathology of the Human Neuromuscular Junction with a Description of the Clinical Features of the Myasthenic Syndromes
Marc H. De Baets, Hans J.G.H. Oosterhuis in Myasthenia Gravis, 2019
The toxins produced by different strains of Clostridium botulinum have the common property of blocking of ACh release. Botulinum toxin A (BoA) binds to binding sites on the presynaptic plasma membrane of peripheral, cholinergic nerves and is incorporated into the terminals.100 It supposedly lowers the Ca2+ sensitivity of the release mechanism. Stimulated quantal release is blocked completely and spontaneous quantal and nonquantal release are blocked partially.101 Blocking of ACh release has consequences both for the muscle fibers and the innervating nerves. The muscle fibers react as if denervated (see for review references 58 and 102). The resting membrane potential decreases and extrajunctional receptors appear on the muscle fiber membrane. Sprouts originating from nerve terminals or terminal axons and intramuscular nodes of Ranvier start to develop two days after local injection of botulinum toxin and form new NMJs.103,104 The signal for sprouting is generally considered to be a muscle-derived factor produced under conditions of inactivity.105,106 Denerva-tion-like changes of the muscle fibers and sprouting are also seen when inactivity is induced by other means, e.g., by nerve conduction blockade with tetrodotoxin. Most, if not all, denervation changes can be prevented or reversed by appropriate direct stimulation of muscle.58
Bilateral peroneal nerve palsy due to prolonged squatting in farmers: clinical and electrophysiological outcome
Published in Neurological Research, 2023
NCS and needle EMG studies were conducted at admission. The demographic characteristics of the patients, time to admission to the hospital, type of neural injury and muscle strength are summarized in Table 1. In two patients (three limbs, 18.75%), there was a pure conduction block due to neuropraxia caused by long-term compression. In addition to conduction block, denervation findings were observed in TA, EHL, and PL muscles in four (five limbs) patients. These findings were consistent with the mixed-type neural injury. In Some of the patients although axonal degeneration was observed in the other limbs, the conduction block could not be demonstrated due to the long-term duration of the first admission after symptom onset. NCS and needle EMG results are demonstrated in Table 2 and Table 3.
Genetic and epigenetic disease modifiers in an Italian C9orf72 family expressing ALS, FTD or PD clinical phenotypes
Published in Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration, 2022
Antonia Ratti, Silvia Peverelli, Elisabetta D'Adda, Claudia Colombrita, Michele Gennuso, Alessandro Prelle, Vincenzo Silani
The proband’s mother (ND230) did not report any neurological sign or family history of neurodegenerative diseases. Recently, also the proband’s sister (ND439) came to our attention at the age of 47 because in the last two years she started to show a disorder of deambulation due to muscle weakness in the legs with bilateral steppage. She presented a spinal form of ALS, more severe in lower limb. Spasticity was present in upper and lower limbs. Bilateral hand muscle wasting was evident, bulbar muscles were still spared. EMG showed active denervation in all limb muscles examined. Cerebral and cervical MRI were normal. She started oral therapy with riluzole. Neuropsychological testing showed a constructive apraxia with no global cognitive impairment. She did not develop extrapyramidal signs, at least at the last follow-up two years after disease onset.
Preliminary evaluation of the reliability and validity of the 3D printed Toronto Rehabilitation Institute-Hand Function Test in individuals with spinal cord injury
Published in The Journal of Spinal Cord Medicine, 2021
Naaz Kapadia, Lazar Jovanovic, Kristin Musselman, Rosalie Wang, Cesar Marquez-Chin, Milos R. Popovic
The current study was designed to evaluate the psychometric properties of the 3D TRI-HFT in sub-acute and chronic SCI populations. This study was a sub-study conducted within two single arm interventional studies that aimed at assessing the feasibility and efficacy of EEG-Triggered Functional Electrical Stimulation Therapy for Upper Limb Rehabilitation.22 Inclusion criteria for study 1 were: (a) traumatic SCI classified as American Spinal Injury Association Impairment Scale (AIS) B-D, (b) SCI less than six months prior to baseline assessment, (c) neurological level of injury between C4 to C7 and (d) expected length of stay of at least 80 days at the time of study initiation. The exclusion criteria were (a) history of seizure disorder not effectively managed by seizure medications, (b) an existing electrical stimulation device (e.g. Implantable Cardioverter Defibrillator, Pacemaker, Spinal Stimulation), (c) rash or open wound at electrode site, (d) denervation of the targeted muscles, (e) poorly controlled autonomic dysreflexia, (f) botulinum toxin injection into affected upper extremity within three months prior to the study start, and (g) currently enrolled in another upper limb study. Inclusion criteria for study 2 were: (a) traumatic SCI classified as AIS B-D and (b) SCI at least 24 months prior to the baseline assessment. The exclusion criteria were same as the sub-acute study.
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