![]() The fasciculations were mainly in the lower limbs, which had normal muscle strength. 9 Fourteen of them were very concerned about being diagnosed with ALS. 11 An interesting Australian prospective study published recently examined the cases of 20 physicians (20 consecutive cases) complaining of fasciculations. 8 Since then, several authors have explored this topic, defining a benign fasciculation syndrome (BFS), that most frequently affects young healthcare professionals, 9, 10 who, in some cases, have already developed dyspnea. In 1963, Reed and Kurland warned that the presence of fasciculations was not necessarily a prelude to the onset of a progressive and lethal disease, due to the involvement of the lower motor neuron. The objective of this study based on the current literature is to describe various causes of fasciculations and to discuss the pathophysiological skeletal involvement, when present ( Table 1).įasciculations can also be found in individuals with no neurological disease. 5 reported the case of a young man with benign fasciculations, triggered by the use of oral corticosteroids administered in immunosuppressive doses in patients with immune-mediated kidney disease, which subside completely after medication tapering. ![]() A similar mechanism also occurs during induction of anesthesia with succinylcholine endotracheally. Discharges are caused by the direct effect of acetylcholine in the motor nerve terminals. 1 With regard to fasciculations potentials induced by drugs, Masland and Wigiton, 6 in a pioneering experimental study, concluded that neostigmine can cause fasciculation potentials by increasing the concentration of acetylcholine at the neuromuscular junction in felines. 5 Also healthy individuals can have fasciculations, although they are generally located in well-defined sites, such as the brachial distal third, the crural area and the eyelids. It is also important to consider that several conditions may trigger them, such as other diseases of the fore tip of the spinal cord (benign monomelic amyotrophy, progressive spinal muscular atrophies, Hirayama disease and others), neuromuscular junction disorders, electrolyte disorders, systemic diseases and use of certain medications. However they are known to be associated with a hypersensitivity of denervated muscles. This suggests that fasciculation potentials may originate anywhere in the axon, probably within the distal axonal arborization. Potential fasciculations may also persist after a distal nerve block. In short, it is incorrect to associate fasciculations directly to the injury of fore tip of the spinal cord, because the skeletal pathophysiological involvement can be quite broad. 3 No one knows whether the origin of ALS is central, in the first or second motor neurons, in the peripheral, or even in the terminal motor nerve − which is an even more intriguing aspect for experts. The presence of fasciculations, however, is not a sign of ALS when no other symptoms or signs of involvement of the fore tip and the pyramidal bundle are identified. Undoubtedly, this finding in a neurological examination is of concern, given its close relationship with amyotrophic lateral sclerosis (ALS), a disease that leads to a depletion of neurons in the fore tip and the pyramidal bundle. Some neurologists call them verminosis, because they look like worms moving below the dermis. The fasciculations can be defined as visible fast, fine, spontaneous and intermittent contractions of muscle fibers.
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