For 3 decades, sports medicine practitioners have been concerned with the epidemic of sport-related concussion (SRC).1 However, our attention has been redirected to the global pandemic of SARS-Cov-2 and COVID-19, which has spread rapidly across the world and changed life as we know it. Concussion and COVID-19 now intersect in the sports medicine arena because athletes may experience both COVID-19 and concussion.
Early reports of COVID-19 cardiomyopathy resulted in special attention given to the identification of cardiac disease in athletes,2 yet concern for COVID-19 myocarditis has moderated because its prevalence is less than initially feared. SARS Co-V-2 also affects the central nervous system. Angiotensin-converting enzyme-2 receptors, which mediate entry of SARS-Co-V-2 into cells, are present in the brain; however, brain pathological analysis in severe cases and CSF analysis in mild cases of COVID-19 has thus far failed to detect viral DNA, suggesting that immune activation and inflammation3 are the primary drivers of acute and chronic neurological symptoms following COVID-19 infection.4 SARS Co-V-2 brain pathophysiology is believed to involve endothelial dysfunction and disruption of the blood–brain barrier,4 which have also been implicated in the pathophysiology of concussion.5 However, SARS Co-V-2 pathophysiology also involves overwhelming inflammatory cytokine release and neuronal cell death, particularly of the olfactory neurons.6 These mechanisms are not considered to be part of concussion pathophysiology.7 Nevertheless, although the pathophysiology of concussion and of COVID-19 are not identical, some of the common final pathways of their clinical presentation seem to be similar. Thus, recent lessons learned in active concussion neurorehabilitation8 may be applied to some of the neurological consequences of COVID-19 infection.
The emerging COVID-19 population afflicted with symptoms for more than 6 weeks, colloquially called “long haulers,”9 has been labelled post–acute sequelae of COVID-19 (PASC).10 Patients with prolonged neurological symptoms have been labelled post–COVID-19 neurological syndrome (PCNS).11 Recently, it has been appreciated that most patients with persistent neurological symptoms after SRC have the resolution of the acute concussion pathophysiology of ionic shifts and altered cerebral flood flow.12 Patients with persistent postconcussive symptoms (PPCS, symptoms > 4 weeks after concussion)1 are now being characterized as having one or more posttraumatic clinical disorders or phenotypes, including migraine, autonomic, vestibular, oculomotor, cervical, sleep, and psychological impairments that may respond to specific, targeted management strategies.12,13 The same may be said (admittedly to a lesser extent) of patients with COVID-19 neurological syndrome. Nevertheless, and regardless of etiological similarities or differences between the conditions, as clinicians with extensive experience treating concussed patients, we have observed a striking similarity between PCNS/PASC symptoms and those reported by patients with PPCS. Symptoms common to PCNS/PASC9,11 and PPCS1 include headache, brain “fog” (ie, lingering cognitive difficulties, including poor concentration), depression/anxiety, insomnia, blurred vision, tinnitus, noise sensitivity, dizziness, numbness/tingling, fatigue, and reduced exercise capacity (ie, exercise intolerance). Anosmia, ageusia, dysgeusia, and myalgias seem to be more uniquely associated with COVID-19. Patients with COVID-19, much like patients after concussion,1 demonstrate reduced performance on attention and working memory cognitive tasks.9 Some studies suggest that women more often experience PPCS,1 and although early to conclude, one study reported that women experience PASC more often than men.9
With respect to the etiology of the fatigue, “brain fog,” interrupted sleep, and exercise intolerance reported by both PPCS and PASC patients,14 systemic inflammation impairs muscle metabolic homeostasis and exacerbates loss of muscle mass, contributing to fatigue and impaired concentration.15 In addition, COVID-19 and concussion have been associated with a spectrum of autonomic dysfunction that manifests on the mild end as orthostatic intolerance (ie, lightheadedness upon standing)16 to the debilitating postural orthostatic tachycardia syndrome.17–19 Impaired vascular endothelial function in PASC has also been associated with vasoconstriction and impaired organ perfusion,20 which may further exacerbate symptoms such as reduced exercise tolerance. Because some of the symptoms and physical limitations of COVID-19 are related to inflammation, loss of muscle mass, orthostatic intolerance and exercise intolerance, progressive subsymptom threshold aerobic exercise, and appropriate forms of resistance training may be effective for restoring readiness for sport participation.
COVID-19 neurological involvement means that sports medicine and other providers need to adapt their management strategy for athletes with both conditions to mitigate the risk of cumulative brain insult. The American Medical Society for Sports Medicine and the American College of Cardiology have created a cardiac evaluation and treatment algorithm for athletes after COVID-19 infection.2 Patterned after this template, we propose an approach to neurologic complications of COVID-19 in athletes after SRC (Figure) that incorporates the concepts of recovery of normal exercise tolerance (ie, the ability to exercise to the level required of the sport without return of concussion symptoms21) before return to sport, and of using progressive subsymptom threshold aerobic exercise to speed recovery from SRC, that is, the “Buffalo Protocol.”21 In addition, preseason baseline testing is important when interpreting postinjury balance and concentration deficits in concussed athletes1; thus, return-to-sport decisions ideally should incorporate neurologic testing when preseason, preinjury testing results are available for comparison. We recommend that practitioners repeat preseason neurologic testing in athletes with PCNS/PASC to establish a new baseline for comparison with any postconcussion deficits. The timing to repeat baseline testing post COVID-19 is not evidence based; ideally, however, it should be performed close to the start of the sport season to allow for symptom improvement or resolution.
Physicians caring for athletes who develop COVID-19 are uniquely challenged to ensure as much as possible a safe return to sport. Although COVID-19 cardiac complications are of obvious concern, COVID-19 neurologic sequelae, particularly prolonged symptoms, seem to be common and may impact the evaluation of SRC and the approach to safely returning concussed athletes to practice and competition.
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