Not myopathic, but autonomic changes in patients with long-COVID syndrome: a case series

Abstract

Introduction Neurological sequelae following SARS-CoV-2 infection still represent a serious concern both for neurologists and neuroscientists. In our paper, we investigated pain, myalgia, and fatigue as symptoms in long-COVID patients with an electrophysiological approach, comprising the evaluation of sympathetic skin responses (SSRs) and quantitative electromyography (qEMG). Materials and methods Twelve patients were enrolled (mean age, 47.7 ± 11.6 years), referred to our attention because of myalgia, pain, or muscle cramps, which persisted about 6 months after the diagnosis of SARS-CoV-2 infection. They underwent conventional electroneurography (ENG), needle electromyography (EMG), and SSRs; moreover, qEMG was performed by sampling at least 20 motor unit potentials (20–30 MUPs) during weak voluntary contraction in deltoid and tibialis anterior muscles. The mean duration, amplitude, and percentage of polyphasic potentials were assessed and compared with healthy and age-matched volunteers. Results ENG did not disclose significant changes compared to healthy subjects; needle EMG did not reveal denervation activity. In addition, qEMG showed MUPs similar to those recorded in healthy volunteers in terms of polyphasia (deltoid: p = 0.24; TA: p = 0.35), MUP area (deltoid: p = 0.45; TA: p = 0.44), mean duration (deltoid: p = 0.06; TA: p = 0.45), and amplitude (deltoid: p = 0.27; TA: p = 0.63). SSRs were not recordable from lower limbs in seven patients (58%) and from the upper ones in three of them (25%). Conclusion Our data suggest an involvement of the autonomic system, with a focus on cholinergic efferent sympathetic activity, without any evidence of myopathic changes.

A Case of Autoimmune Small Fiber Neuropathy as Possible Post COVID Sequelae

“…Moreover, the occurrence of autonomic dysfunction is often related to neuropathy [ 33 ]. Impaired sympathetic skin responses of patients with persistent pain, myalgia, or muscle cramps after COVID-19 were shown to be associated with SFN [ 34 ].…”

Exploring the Pathophysiology of Long COVID: The Central Role of Low-Grade Inflammation and Multisystem Involvement

“…Another aspect of canonical inflammation in LC, which was not included in the aims and objectives of our study, is considering LC as a risk factor for the onset of various inflammatory diseases or the progression of existing inflammatory diseases [ 323 , 324 , 325 , 326 , 327 ]. This primarily concerns immune-dependent diseases, whose association has been established, namely various allergic, autoimmune, and infectious diseases, but also should be taken into account in other pathological conditions as well [ 237 , 238 , 239 , 240 , 241 , 242 , 243 , 244 , 245 , 246 , 247 , 248 , 249 , 250 , 251 , 252 , 253 , 254 , 255 , 256 , 257 , 258 , 259 , 260 , 261 , 262 , 263 , 264 , 265 , 266 , 267 , 268 , 269 , 270 , 271 , 272 , 273 , 274 , 275 , 276 , 277 , 278 , 279 , 280 , 281 ,…”

“…Additionally, mitochondrial alterations, capillary damage, and signs of latent inflammation may remain evident in muscle biopsies for extended periods [ 265 , 268 ]. In some cases, data suggest that muscle weakness and pathological fatigue in LC may involve dysregulation of the autonomic system, focusing on cholinergic and sympathetic efferent activity, even in the absence of overt myopathic changes [ 269 ].…”

Long COVID in Children: A Multidisciplinary Review

“…In the adult, Long COVID patients with suspected cardiovascular symptomatology, ECG (electrocardiograph) aberrations (34%) like non-specific ST-T changes and conduction anomalies were found [ 84 ]. Nonetheless, converging clinical, neurophysiological and anatomopathological, evidence suggests that dysautonomia plays a key role in driving neurological complications in adulthood [ 85 , 86 , 87 ]. Among these, neurophysiology has recently highlighted a specific involvement of the efferent sympathetic activity in chronic pain syndromes following SARS-CoV-2 infection [ 85 ].…”

“…Nonetheless, converging clinical, neurophysiological and anatomopathological, evidence suggests that dysautonomia plays a key role in driving neurological complications in adulthood [ 85 , 86 , 87 ]. Among these, neurophysiology has recently highlighted a specific involvement of the efferent sympathetic activity in chronic pain syndromes following SARS-CoV-2 infection [ 85 ]. These findings are also corroborated by the observation of small-fibre loss applying in vivo corneal confocal microscopy, as well as by changes described in skin biopsies [ 88 , 89 ].…”