Neuropsychiatric disorders and COVID-19

We read with interest the Article by Maxime Taquet and colleagues¹ in The Lancet Psychiatry that evaluated a large population (n=236 379) for neurological and psychiatric complications of COVID-19 via analysis of diagnostic codes associated with electronic health notes.¹ The highest hazard ratios (HRs) reported were for myoneural junction or muscle disease (ICD-10 codes G70–73), with HR 5·28 (95% CI 3·71–7·53) after COVID-19 versus after influenza and 4·52 (3·65–5·59) after COVID-19 versus after other respiratory tract infection. These striking findings received little discussion in the manuscript. The incidences of specific disorders within this category were not reported and presumably were not available.

Some of our author group are involved in a project providing weekly syntheses of the neurological and psychiatric sequelae of COVID-19.² We have not yet found any large-scale publication reporting empirical analysis of specific neuromuscular disease in COVID-19. Hence, we were interested to read these new findings. We speculate that critical illness neuromyopathy might partially account for the findings. Critical illness polyneuropathy and critical illness myopathy commonly co-occur, presenting with limb and respiratory muscle weakness, and delayed weaning from mechanical ventilation. Critical illness polyneuropathy and critical illness myopathy are complications of critical illnesses, particularly sepsis, and including severe COVID-19.3, 4 These complications are likely to adversely affect both short-term and long-term patient outcomes, and are of particular concern given the very high numbers of critically ill patients with COVID-19.⁵

Within the ICD-10 system, critical illness myopathy is likely to be coded as other specified myopathy (G72.8), although there could be other possibilities within the myoneural junction or muscle disease coding (G70–73). Other diagnoses, such as myasthenia gravis, muscular dystrophy, and congenital myopathy, are generally less common. The higher risk of myoneural junction or muscle disease for patients with COVID-19 who are hospitalised versus those who are not (HR 7·76 [95% CI 5·15–11·69]) and those who are admitted to the intensive therapy unit versus those who are not (11·53 [6·38–20·83]) are compatible with critical illness polyneuropathy and critical illness myopathy potentially being an important component of this ICD-10 category.

At face value, this specific finding reported by Taquet and colleagues could indicate an important neuromuscular complication in COVID-19. We recommend that COVID-19-related neuromuscular complications are investigated in more detail. Neuromuscular disorders after COVID-19 might have substantial implications for patient recovery and utilisation of physical rehabilitation health-care resources. In our view, critical illness myopathy might be the most likely explanation for this previously unrecognised, important finding.

JR reports honoraria from Alberta Psychiatric Association and has attended an advisory meeting with Promentis Pharmaceuticals, outside of the submitted work. DN is principal investigator on an NIH-funded randomised trial evaluating nutrition and exercise in acute respiratory failure and, related to this trial, is currently in receipt of donated amino acid product from Baxter Healthcare Corporation and an equipment loan from Reck Medical Devices, outside of the submitted work. All other authors declare no competing interests.