Recently, there has been increasing evidence among people infected with coronavirus disease 2019 (COVID-19) of being diagnosed with the typical acute post-infectious inflammatory polyneuroradiculopathy that was formerly known as Guillain-Barré syndrome (GBS), and it is not uncommon that some of them develop chronic inflammatory demyelinating polyneuroradiculopathy (CIDP). However, there is still a large debate and controversy about the link between COVID-19 and polyneuropathy. As a result, a multicentric retrospective cohort study was conducted in Basrah Governorate in the south of Iraq that included 2240 patients over a period of six months. Of those, 1344 patients had a history of COVID-19 in the previous year, and 1.14% of them developed inflammatory polyneuropathy, while only 0.29% (896 patients) of those with no history of COVID-19 had developed inflammatory polyneuropathy. This difference is highly significant, with a relative risk equal to six. The majority of the inflammatory polyneuropathy (44.4%) was diagnosed four to 12 weeks after the COVID-19 infection, with GBS being the most common type (72.2% of cases). Moreover, the nerve conduction velocity, the distal latency, and the amplitude of the most studied nerves were slower, more prolonged, and lower, respectively, among the COVID-19 groups compared with the non-COVID-19 group. Furthermore, there is an inverse correlation between the nerve conduction velocity in the majority of studied nerves and certain inflammatory biomarkers, such as serum ferritin, interleukin-6, and c-reactive protein. Although the occurrence of inflammatory polyneuropathy is more common among the less severe groups of COVID-19, if it occurs in the severe groups, it shows a more aggressive presentation.

Idiopathic inflammatory myopathies, commonly known as myositis, are a diverse group of disorders defined clinically by persistent muscle weakness and reduced muscle endurance, as well as inflammatory cell infiltrates inside the muscle tissue. Myositis as a complication of coronavirus disease 2019 (COVID-19) has been described in an increasing number of reports. An analytical and cross-sectional study was undertaken in Basrah to analyze nerve conduction studies (NCS) and electromyographic (EMG) data in a COVID-19-affected patient. During the evaluation of 2240 patients, three cases of myositis were reported among the COVID-19 population, two of them with new clinical and EMG evidence of inflammatory myositis after the onset of COVID-19 infection, and one patient had a history of polymyositis before the COVID-19 pandemic, but a relapse was triggered by COVID-19, resulting in respiratory failure and death. The study found that the prevalence of myositis among the COVID-19 population was equal to 0.22%, which is 44 times higher than the prevalence of myositis (0.005%) worldwide before the onset of COVID-19 (P < 0.001).

Infection with the novel coronavirus that causes coronavirus disease 2019 results in a variety of clinical symptoms, including various neurological abnormalities. Peripheral nervous system symptoms, such as peripheral neuropathies, were often recorded in the medical literature, primarily as Guillain-Barré syndrome. Mononeuropathy multiplex is a multifocal axonal neuropathy commonly associated with vasculitis or connective tissue disease. Recent evidence about its associations with severe COVID-19 infection and intensive care unit hospitalization is being considered. A 58-year-old man with clinical and electrophysiological confirmation of mononeuropathy multiplex was reported during the peri-COVID-19 illness. He was treated with steroids and achieved a satisfactory response. Therefore, clinical and neurophysiological evaluation is recommended for any patient presenting with neurological manifestations following COVID-19 infection.