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Focal neurological deficit
Published in Sherif Gonem, Ian Pavord, Diagnosis in Acute Medicine, 2017
Table 23.1 lists the disorders that may affect the brain and spinal cord, while the causes of peripheral neuropathy, neuromuscular junction disease and myopathy are shown in Table 23.2. Nerve root damage (radiculopathy) is most commonly caused by compression within the spinal canal, due to the same pathologies that cause spinal cord compression. However, it is possible for the systemic pathologies that cause peripheral neuropathy to affect a nerve root and thus cause a radiculopathy.
Plasmablasts and neuroimmunological disorders
Published in Immunological Medicine, 2019
Norio Chihara, Riki Matsumoto, Takashi Yamamura
As an example of inhibition of neurotransmitter, Myasthenia gravis (MG) is a neuromuscular junction disease, where the autoantibodies against the acetylcholine receptor (AChR) inhibit post-synaptic neurotransmission, which results in muscle weakness and fatigue. Anti-AChR antibodies mainly consist of IgG1 and IgG3 subclass, thus their function is complement-dependent cytotoxicity as well as antibody-dependent cellular cytotoxicity. The antibodies also make AChR cross-link together and physically inhibit acetylcholine (Ach) binding to the receptors, and lesser extent functionally block Ach-binding site [5]. On the other hand, there is another autoantibody that causes MG, anti-muscle-specific kinase (MuSK) antibody consists of IgG4 subclass that rarely causes complement-dependent cytotoxicity but decreases AChR clustering required for prompt neurotransmission. Recently, it is reported that IgG4 autoantibodies targeting Ranvier's node protein NF155 or contactin-1 in the peripheral nerves causes loss of paranodal transverse bands and demyelinating polyneuropathy which is found in less than 10% of chronic inflammatory demyelinating polyneuropathy [6,7].
Longstanding and Refractory Anti-Muscle Specific Tyrosine Kinase Antibody-Associated Myasthenia Gravis (Anti-MuSK-MG) in a Child Successfully Treated with Rituximab
Published in Journal of Binocular Vision and Ocular Motility, 2019
Steven Weger, Juan Pablo Appendino, Ian H. Clark
A jitter response from SFEMG performed in the orbicularis oculi muscle is abnormal in over 95% of patients with myasthenia gravis, followed by frontalis and extensor digitorum communis in around 85% of patients (even when the patient is taking anticholinesterase inhibitors). A jitter response measures the variation in the time interval between two action potentials of the same motor unit following a single stimulus for depolarization. Although it does not correlate with disease severity, it confirms disturbed neuromuscular transmission, with reported higher sensitivity (up to 99%) than acetylcholine receptor antibodies. The least sensitive test is repetitive stimulation (76%).6 Our patient showed a severely delayed MCD and MSD when compared with normal values (16–26 µsec), confirming the clinical suspicion of neuromuscular junction disease despite seronegative results for AChR. These results guided further serum investigations, leading to the confirmation of anti-MuSK-MG.
Diagnostic approach to neuropsychiatric lupus erythematosus: what should we do?
Published in Postgraduate Medicine, 2018
Enrico Maria Zardi, Chiara Giorgi, Domenico Maria Zardi
The use of electromyography and electroneurography is mandatory when there is a sudden weakness in different nerve territories; with these techniques it is possible to obtain precise measurements concerning amplitude and onset of muscle activity and motor and sensory nerve conduction velocities, respectively, thus discriminating between presence and absence of peripheral nerve disease, plexopathy, and neuromuscular junction disease. Moreover, both techniques may definitely influence the process of clinical decision-making in patients with dramatic clinical presentation, rapidly evolving toward paraparesis or sensory deficits and sphincter dysfunction [75].