Long COVID Is Not a Functional Neurologic Disorder

Abstract

Long COVID is a common sequela of SARS-CoV-2 infection. Data from numerous scientific studies indicate that long COVID involves a complex interaction between pathophysiological processes. Long COVID may involve the development of new diagnosable health conditions and exacerbation of pre-existing health conditions. However, despite this rapidly accumulating body of evidence regarding the pathobiology of long COVID, psychogenic and functional interpretations of the illness presentation continue to be endorsed by some healthcare professionals, creating confusion and inappropriate diagnostic and therapeutic pathways for people living with long COVID. The purpose of this perspective is to present a clinical and scientific rationale for why long COVID should not be considered as a functional neurologic disorder. It will begin by discussing the parallel historical development of pathobiological and psychosomatic/sociogenic diagnostic constructs arising from a common root in neurasthenia, which has resulted in the collective understandings of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and functional neurologic disorder (FND), respectively. We will also review the case definition criteria for FND and the distinguishing clinical and neuroimaging findings in FND vs. long COVID. We conclude that considering long COVID as FND is inappropriate based on differentiating pathophysiologic mechanisms and distinguishing clinical findings.

Keywords: chronic fatigue syndrome; conversion disorder; dysautonomia; imaging; myalgic encephalomyelitis; neurasthenia; neurology; physical examination; post-COVID-19 condition (PCC); post-acute sequalae of COVID-19 (PASC).

Figure 1

Key time points in the parallel development of disease and illness constructions resulting in myalgic encephalomyelitis/chronic fatigue syndrome (pathobiological illness construction) and functional neurologic disorder (psychosomatic/sociogenic illness construction), based on a common historical root in neurasthenia.

Figure 2

Acrocyanosis in the distal leg in the dependent position (A) that immediately disappears on raising the leg up against gravity (B) in a person with long COVID. She was initially misdiagnosed with functional neurologic disorder based on non-epileptic spells, which were subsequently determined to be pre-syncopal episodes caused by post-COVID-19 postural orthostatic tachycardia syndrome.