COVID-19 and the Nervous System: Northwestern Medicine Review
Summary: A comprehensive review finds that roughly half of patients hospitalized with COVID-19 experience neurological symptoms. These range from headaches, dizziness, and loss of smell or taste to seizures and stroke. Evidence indicates that SARS‑CoV‑2 can affect the entire nervous system—brain, spinal cord, peripheral nerves and muscles—and neurological signs may appear before the classic respiratory symptoms such as fever and cough.
Source: Northwestern University
Key finding: A new review of current scientific literature, led by investigators at Northwestern Medicine and published in Annals of Neurology, concludes that COVID‑19 represents a global threat to the entire nervous system. The review synthesizes reported neurologic manifestations, likely pathological mechanisms, diagnostic considerations, and implications for clinical management.
Clinical reports indicate that about 50% of hospitalized patients with COVID‑19 exhibit one or more neurological manifestations. Common symptoms include headache, dizziness, reduced alertness or altered mental status, difficulty concentrating, and disordered smell (anosmia) or taste (ageusia). More serious complications documented in hospitalized patients include seizures, ischemic and hemorrhagic strokes, neuromuscular weakness, and muscle pain.
“It is essential that both the public and clinicians recognize that SARS‑CoV‑2 infection can begin with neurological symptoms, before any fever, cough, or respiratory distress becomes evident,” said Dr. Igor Koralnik, chief of neuro‑infectious diseases and global neurology at Northwestern Medicine and lead author of the review. Early awareness can prompt timely evaluation and appropriate care when neurologic signs are the presenting feature.
The review outlines multiple mechanisms by which COVID‑19 may damage nervous system structures. First, systemic complications of the infection—such as severe lung disease, impaired oxygen delivery, kidney or cardiac dysfunction—can secondarily injure the brain by causing hypoxia or metabolic disturbance. Second, COVID‑19 frequently triggers a hypercoagulable state that increases the risk of blood clots, contributing to ischemic stroke, cerebral venous sinus thrombosis, or hemorrhagic events. Third, the virus may directly invade the central nervous system, producing encephalitis or meningitis in some patients. Finally, an excessive or dysregulated immune response to infection can produce inflammatory, post‑infectious or immune‑mediated conditions that harm brain, spinal cord, nerves, and muscle.
Examples of central nervous system disorders described in the review include encephalopathy, encephalitis, acute disseminated encephalomyelitis (ADEM), meningitis, ischemic and hemorrhagic stroke, venous sinus thrombosis, and endothelialitis. Peripheral nervous system and neuromuscular complications reported in association with COVID‑19 include loss of smell and taste, muscle injury, and immune‑mediated neuropathies such as Guillain‑Barré syndrome and its variants.
To better characterize the frequency, spectrum and outcomes of neurologic complications, Koralnik and colleagues have established a Neuro‑COVID research team. They are conducting a retrospective analysis of all COVID‑19 patients hospitalized at Northwestern Medicine to quantify how often neurological complications occur, describe their clinical features, and evaluate responses to therapies used in routine care.
Given the limited data on long‑term outcomes, the team is also following some patients prospectively through a dedicated outpatient Neuro‑COVID clinic. This follow‑up will help determine whether neurological problems resolve over time or persist as chronic deficits, and will inform recommendations on rehabilitation and long‑term management.
“Understanding the range of neurologic involvement and the underlying mechanisms is crucial for directing clinical decisions, selecting appropriate diagnostic tests, and choosing treatments that can improve outcomes,” Koralnik said.
About this research
Source: Northwestern University
Media contact: Marla Paul – Northwestern University
Image source: The image is in the public domain.
Original research (open access): “COVID‑19: a global threat to the nervous system” by Igor J. Koralnik, M.D., and Kenneth L. Tyler, M.D., published in Annals of Neurology. DOI: 10.1002/ana.25807
Abstract (summary)
In less than six months after its emergence, SARS‑CoV‑2 spread globally, infecting nearly 6 million people and contributing to over 350,000 deaths. Initially characterized as a respiratory pathogen, it is now clear that COVID‑19 affects multiple organ systems, including the central and peripheral nervous systems. Reported neurologic manifestations are expanding rapidly and appear to arise from several mechanisms: virus‑induced hyperinflammatory and hypercoagulable states, direct viral infection of nervous tissue, and post‑infectious immune‑mediated processes. Central nervous system involvement may present as encephalopathy, encephalitis, acute disseminated encephalomyelitis, meningitis, ischemic or hemorrhagic stroke, venous sinus thrombosis, and endothelialitis. Peripheral nervous system complications include dysfunction of smell and taste, muscle injury, and Guillain‑Barré syndrome and its variants. Because of its global reach and multifactorial neuropathogenic mechanisms, COVID‑19 poses a widespread threat to nervous system health. Although knowledge of SARS‑CoV‑2 neuropathogenesis continues to evolve, this review provides a framework to help neurologists and clinicians recognize, diagnose, and manage the diverse neurologic facets of COVID‑19.
Share responsibly: This summary aims to inform clinicians, patients and the public about neurologic aspects of COVID‑19. For clinical decisions, consult current guidance from health authorities and specialty societies, and consider individual patient circumstances.