Transverse myelitis (TM) is an inflammatory disorder of the spinal cord characterized by acute or subacute development of bilateral motor, sensory, and autonomic dysfunction attributable to focal spinal cord inflammation. Although historically associated with viral infections, systemic autoimmune disorders, demyelinating diseases, and idiopathic immune-mediated mechanisms, the emergence of SARS-CoV-2 has introduced a new context in which inflammatory spinal cord injury has been reported following both acute infection and, less commonly, after immunization. The COVID-19 pandemic has provided unprecedented insight into the complex interactions between viral infection, host immunity, vascular biology, and neuroinflammation.<\/p>\n\n\n\n
Reported cases of COVID-19\u2013associated transverse myelitis have occurred during acute infection, during the postinfectious period, and in the setting of multisystem inflammatory responses. Clinical presentations range from isolated sensory disturbances and weakness to severe paraplegia with bowel and bladder dysfunction. Magnetic resonance imaging (MRI) typically demonstrates longitudinally extensive or focal spinal cord lesions, while cerebrospinal fluid (CSF) analysis frequently reveals inflammatory abnormalities, including pleocytosis and elevated protein concentrations. However, considerable heterogeneity exists, suggesting that COVID-19\u2013associated TM represents a spectrum of immunologic disorders rather than a single disease entity.<\/p>\n\n\n\n
Current evidence supports several possible pathogenic pathways, including immune-mediated demyelination, molecular mimicry between viral antigens and neural proteins, dysregulated T-cell and B-cell activation, cytokine-driven inflammation, endothelial injury, complement activation, and disruption of the blood\u2013spinal cord barrier. Direct invasion of spinal cord tissue by SARS-CoV-2 remains controversial, with limited pathological evidence supporting true viral neurotropism compared with indirect immune-mediated mechanisms.<\/p>\n\n\n\n
Genetic susceptibility is likely to influence individual risk. Variations in human leukocyte antigen (HLA) genes, interferon signaling pathways, innate immune regulators, and autoimmune susceptibility loci may determine whether an individual mounts a protective antiviral response or develops pathological inflammation. Advances in genomics, single-cell immune profiling, and molecular biomarker discovery are beginning to clarify why rare individuals develop severe neurologic complications after SARS-CoV-2 exposure.<\/p>\n\n\n\n
Treatment strategies remain based primarily on established approaches for inflammatory myelitis, including high-dose intravenous corticosteroids, plasma exchange, intravenous immunoglobulin, and targeted immunotherapy for refractory disease. Early recognition and aggressive treatment are associated with improved neurological recovery, although persistent sensory abnormalities, neuropathic pain, gait impairment, and autonomic dysfunction may occur.<\/p>\n\n\n\n
Long-term outcome data remain limited but suggest that COVID-19\u2013associated TM can follow diverse trajectories. Some patients experience substantial neurological recovery, whereas others develop chronic disability consistent with incomplete spinal cord injury. Future research integrating clinical phenotyping, immunology, genomics, and longitudinal follow-up will be essential to determine mechanisms, identify susceptible individuals, and develop precision therapies.<\/p>\n\n\n\n
The spinal cord represents one of the most biologically complex structures in the human nervous system, integrating descending motor pathways, ascending sensory systems, autonomic networks, and segmental reflex circuits. Injury to this highly organized structure can produce profound functional impairment, including paralysis, sensory loss, chronic neuropathic pain, and irreversible disturbances of bladder and bowel control. Among inflammatory disorders affecting the spinal cord, transverse myelitis occupies a unique position because it represents not a single disease but a clinical syndrome produced by multiple convergent biological mechanisms.<\/p>\n\n\n\n
The classical definition of transverse myelitis describes an inflammatory lesion involving the spinal cord that produces bilateral neurological dysfunction attributable to spinal cord involvement, with evidence of inflammation demonstrated clinically, radiologically, or through cerebrospinal fluid analysis. The disorder may involve a short segment of the spinal cord or extend across multiple vertebral levels, producing the syndrome known as longitudinally extensive transverse myelitis (LETM). Historically, TM has been recognized following viral infections, vaccinations, autoimmune diseases, malignancies, and systemic inflammatory states.\u00b9<\/p>\n\n\n\n
Before the COVID-19 pandemic, transverse myelitis was considered a rare neurological condition, with estimated annual incidence rates ranging from approximately 1 to 8 cases per million persons depending on diagnostic criteria and population studied.\u00b2 The rarity of the disorder creates substantial challenges in establishing causation when cases appear after a new biological exposure. A temporal relationship alone cannot determine whether an exposure caused the event, because rare neurological disorders occur spontaneously within any large population.<\/p>\n\n\n\n
The emergence of SARS-CoV-2 fundamentally altered understanding of infection-associated neurological disease. Although initially characterized primarily as a respiratory pathogen, SARS-CoV-2 rapidly became recognized as a multisystem inflammatory virus capable of affecting the nervous system through immune activation, vascular injury, endothelial dysfunction, and systemic inflammatory pathways. Neurological manifestations reported during COVID-19 include encephalopathy, cerebrovascular disease, seizures, peripheral neuropathies, dysautonomia, anosmia, cognitive dysfunction, and inflammatory demyelinating disorders.\u00b3<\/p>\n\n\n\n
Transverse myelitis emerged as one of the rare but biologically important neurological complications associated with SARS-CoV-2 infection. The earliest reports described patients developing rapidly progressive weakness, sensory abnormalities, and autonomic dysfunction during or shortly after COVID-19 illness. Some patients had evidence of spinal cord inflammation despite minimal respiratory disease, suggesting that neurological injury may occur through immune mechanisms rather than through the severity of pulmonary infection alone.\u2074<\/p>\n\n\n\n
Several observations support an immune-mediated model of COVID-associated TM. First, many patients develop neurological symptoms after the peak of viral replication, during a period when adaptive immune responses are activated. Second, CSF studies often reveal inflammatory patterns without detectable viral RNA. Third, many patients respond to immunomodulatory therapies such as corticosteroids and plasma exchange, consistent with an inflammatory rather than purely degenerative process.\u2075<\/p>\n\n\n\n
Nevertheless, the pathogenesis remains incompletely understood. SARS-CoV-2 possesses several biological properties capable of triggering immune dysregulation. Viral proteins may activate innate immune pathways through pattern-recognition receptors, stimulating production of interferons, interleukins, tumor necrosis factor, and chemokines. In susceptible individuals, these responses may become excessive, resulting in immune-mediated injury to neural tissue.\u2076<\/p>\n\n\n\n
The concept of molecular mimicry has received particular attention. In this model, structural similarities between viral proteins and host neural antigens may generate cross-reactive immune responses. Activated T cells or antibodies initially directed against SARS-CoV-2 antigens may inadvertently recognize components of myelin, oligodendrocytes, neurons, or vascular structures within the spinal cord. Similar mechanisms have been proposed in other postinfectious neurological disorders, including Guillain\u2013Barr\u00e9 syndrome and acute disseminated encephalomyelitis.\u2077<\/p>\n\n\n\n
Another emerging mechanism involves vascular and endothelial dysfunction. SARS-CoV-2 infection can induce widespread endothelial activation, platelet abnormalities, complement activation, and microvascular inflammation. The spinal cord has a particularly vulnerable microvascular architecture, and disruption of spinal cord perfusion or the blood\u2013spinal cord barrier may permit immune-cell infiltration and inflammatory injury.\u2078<\/p>\n\n\n\n
The genetic basis of susceptibility remains an important area of investigation. Most individuals infected with SARS-CoV-2 do not develop inflammatory neurological complications, suggesting that host factors strongly influence disease expression. Variants affecting antigen presentation, interferon signaling, immune regulation, and inflammatory pathways may determine whether immune responses remain protective or become pathogenic.\u2079<\/p>\n\n\n\n
The study of COVID-associated transverse myelitis therefore provides a broader window into neuroimmunology. It illustrates how a viral infection can act as a trigger for complex interactions between genetic predisposition, immune activation, vascular biology, and neural vulnerability. Understanding these mechanisms may improve not only management of COVID-associated TM but also treatment of other immune-mediated neurological diseases.<\/p>\n\n\n\n
This review examines current evidence regarding COVID-19\u2013associated transverse myelitis, integrating epidemiology, immunopathogenesis, genomics, physiology, neuropathology, diagnostic approaches, therapeutic strategies, and long-term outcomes. Particular emphasis is placed on distinguishing established evidence from evolving hypotheses and identifying areas where future research is needed.<\/p>\n\n\n\n
Determining the true incidence of COVID-19\u2013associated transverse myelitis (TM) represents a significant epidemiological challenge. Transverse myelitis is itself a rare neurological syndrome, and the additional requirement of establishing a temporal or mechanistic relationship with SARS-CoV-2 infection introduces further complexity. Unlike common complications of COVID-19, such as respiratory failure, thromboembolic disease, or acute kidney injury, inflammatory spinal cord syndromes occur infrequently and are often identified through individual case reports, institutional series, and neurological surveillance systems.<\/p>\n\n\n\n
Prior to the COVID-19 pandemic, population-based studies estimated the annual incidence of acute transverse myelitis to be approximately 1\u20138 cases per million persons per year, although estimates vary according to diagnostic criteria, geographic region, and ascertainment methodology.\u00b9 In pediatric populations, incidence estimates are generally lower but may vary substantially because of differences in recognition and classification of acute inflammatory demyelinating syndromes.\u00b2<\/p>\n\n\n\n
The appearance of TM following SARS-CoV-2 infection was first recognized during the early months of the pandemic. Published reports described patients developing neurological deficits during active infection or within several days to weeks after respiratory symptoms had resolved. These cases raised the possibility that SARS-CoV-2 could function as a trigger for inflammatory spinal cord injury, similar to other viral infections historically associated with postinfectious myelitis.<\/p>\n\n\n\n
However, the rarity of reported cases makes precise risk estimation difficult. Large observational studies examining neurological complications after COVID-19 infection have identified increased risks of multiple neurological disorders, but transverse myelitis remains uncommon relative to other manifestations.\u00b3 The available evidence suggests that while SARS-CoV-2 infection may increase the probability of inflammatory neurological disease, the absolute risk of developing TM remains extremely low.<\/p>\n\n\n\n
A critical methodological issue is distinguishing increased recognition from increased incidence. During the pandemic, clinicians were highly alert to neurological complications of COVID-19, potentially increasing reporting of rare events that may previously have been attributed to idiopathic causes. Conversely, some cases may have been missed because neurological symptoms occurred after mild or asymptomatic infection.<\/p>\n\n\n\n
Reported cases of COVID-associated TM demonstrate three broad temporal patterns:<\/p>\n\n\n\n
Some individuals develop spinal cord inflammation during active SARS-CoV-2 infection. These patients may present with respiratory symptoms, fever, systemic inflammation, and rapidly progressive neurological deficits.<\/p>\n\n\n\n
The simultaneous presence of infection and neurological disease raises several possibilities:<\/p>\n\n\n\n
However, direct detection of SARS-CoV-2 within spinal cord tissue has been uncommon, and most cases do not demonstrate evidence of viral replication within the central nervous system.<\/p>\n\n\n\n
The majority of reported cases appear to follow a postinfectious pattern, occurring days to weeks after recovery from acute COVID-19.<\/p>\n\n\n\n
This timing resembles classic postviral autoimmune neurological disease. The immune system, after successfully responding to infection, may remain activated and generate inflammatory responses directed against host tissues.<\/p>\n\n\n\n
Typical features include:<\/p>\n\n\n\n
This pattern supports an autoimmune mechanism rather than direct viral destruction.<\/p>\n\n\n\n
A subset of patients with persistent post-COVID symptoms have reported sensory disturbances, weakness, autonomic dysfunction, neuropathic pain, and gait abnormalities. In some individuals, inflammatory spinal cord disease has been proposed as a contributor to long COVID neurological syndromes.<\/p>\n\n\n\n
However, it is important to distinguish confirmed inflammatory myelitis from broader post-COVID neurological dysfunction. Many patients with long COVID have symptoms related to:<\/p>\n\n\n\n
without evidence of structural spinal cord inflammation.<\/p>\n\n\n\n
COVID-associated TM does not present as a uniform disorder. Published cases demonstrate substantial variation in severity, anatomical localization, and recovery.<\/p>\n\n\n\n
Weakness is among the most common presenting features. Depending on lesion location and severity, patients may experience:<\/p>\n\n\n\n
The neurological pattern reflects interruption of corticospinal pathways within the spinal cord.<\/p>\n\n\n\n
Damage to descending motor tracts produces:<\/p>\n\n\n\n
Early in the disease process, however, patients may demonstrate flaccid weakness because of spinal shock, in which reflex activity temporarily decreases below the level of injury.<\/p>\n\n\n\n
Sensory abnormalities are highly characteristic of TM and often provide important diagnostic clues.<\/p>\n\n\n\n
Patients may report:<\/p>\n\n\n\n
A sensory level on neurological examination\u2014the point below which sensation becomes impaired\u2014is a key finding suggesting spinal cord localization.<\/p>\n\n\n\n
Commonly reported sensory levels include:<\/p>\n\n\n\n
Persistent sensory symptoms are among the most frequent long-term complications, even in patients with substantial motor recovery.<\/p>\n\n\n\n
The spinal cord contains critical pathways controlling bladder, bowel, and sexual function. Consequently, autonomic impairment is common in moderate-to-severe cases.<\/p>\n\n\n\n
Clinical manifestations include:<\/p>\n\n\n\n
Autonomic recovery often occurs more slowly than motor recovery and may remain incomplete.<\/p>\n\n\n\n
Magnetic resonance imaging is central to diagnosis.<\/p>\n\n\n\n
Typical findings include:<\/p>\n\n\n\n
These represent increased water content associated with:<\/p>\n\n\n\n
Some COVID-associated cases demonstrate lesions extending over three or more vertebral segments.<\/p>\n\n\n\n
These lesions raise consideration of:<\/p>\n\n\n\n
Gadolinium enhancement may indicate active inflammation and breakdown of the blood\u2013spinal cord barrier.<\/p>\n\n\n\n
Patterns include:<\/p>\n\n\n\n
A central challenge in interpreting COVID-associated TM is determining whether SARS-CoV-2 caused the disease or whether cases represent coincidental occurrence.<\/p>\n\n\n\n
The evaluation of causality requires consideration of:<\/p>\n\n\n\n
Applying these criteria suggests that SARS-CoV-2 infection can plausibly trigger inflammatory myelitis in rare individuals. However, the absolute frequency remains very low, and the precise magnitude of increased risk remains uncertain.<\/p>\n\n\n\n
Current evidence indicates:<\/p>\n\n\n\n
The biological mechanisms responsible for COVID-19\u2013associated transverse myelitis (TM) remain incompletely defined, but current evidence strongly favors a model in which immune-mediated injury<\/strong>, rather than direct viral destruction of spinal cord tissue, represents the dominant pathway. SARS-CoV-2 possesses multiple properties capable of initiating profound immunological activation, including stimulation of innate immune receptors, induction of inflammatory cytokines, endothelial injury, complement activation, and prolonged immune dysregulation.<\/p>\n\n\n\n The spinal cord is particularly vulnerable to immune-mediated injury because neurological function depends on highly organized networks of neurons, axons, oligodendrocytes, myelin sheaths, astrocytes, microglia, and vascular structures. Even limited inflammatory injury can disrupt conduction through major ascending and descending pathways, producing profound neurological deficits.<\/p>\n\n\n\n COVID-19\u2013associated TM likely represents a convergence of several mechanisms:<\/p>\n\n\n\n These mechanisms are not mutually exclusive. A genetically susceptible individual may experience viral exposure, develop excessive innate immune activation, generate cross-reactive adaptive immunity, and subsequently sustain inflammatory spinal cord injury.<\/p>\n\n\n\n Early during the COVID-19 pandemic, concern arose that SARS-CoV-2 might directly invade the central nervous system (CNS) and infect neural tissue. Several observations supported this possibility:<\/p>\n\n\n\n However, evidence for direct spinal cord infection remains limited.<\/p>\n\n\n\n In most reported cases of COVID-associated TM:<\/p>\n\n\n\n These findings suggest that the spinal cord is usually injured indirectly through immune mechanisms.<\/p>\n\n\n\n The difficulty in demonstrating viral invasion is partly related to the biology of SARS-CoV-2. Unlike viruses such as poliovirus or West Nile virus, which have established neuroinvasive patterns, SARS-CoV-2 appears to produce neurological injury predominantly through systemic inflammation, endothelial dysfunction, immune activation, and vascular mechanisms.<\/p>\n\n\n\n Molecular mimicry occurs when microbial proteins contain molecular structures sufficiently similar to host proteins that immune responses generated against the pathogen cross-react with human tissues.<\/p>\n\n\n\n This mechanism has been proposed in:<\/p>\n\n\n\n In SARS-CoV-2 infection, antibodies and T cells directed against viral proteins may theoretically recognize:<\/p>\n\n\n\n The spike protein has received particular attention because it contains multiple immunogenic regions capable of stimulating strong antibody and T-cell responses.<\/p>\n\n\n\n Candidate targets include:<\/p>\n\n\n\n Possible immune targets include:<\/p>\n\n\n\n Damage to these structures can impair saltatory conduction and produce neurological deficits.<\/p>\n\n\n\n Oligodendrocytes maintain CNS myelin. Immune-mediated injury may result in:<\/p>\n\n\n\n Astrocytes regulate:<\/p>\n\n\n\n Astrocytic injury may amplify spinal cord inflammation.<\/p>\n\n\n\n Adaptive cellular immunity is central to inflammatory myelitis.<\/p>\n\n\n\n After SARS-CoV-2 exposure, antigen-presenting cells activate T lymphocytes through major histocompatibility complex (MHC) pathways.<\/p>\n\n\n\n Several T-cell populations may participate:<\/p>\n\n\n\n CD4+ cells coordinate immune responses through cytokine production.<\/p>\n\n\n\n Important subsets include:<\/p>\n\n\n\n Produce:<\/p>\n\n\n\n These cytokines promote macrophage activation and inflammatory tissue injury.<\/p>\n\n\n\n Produce:<\/p>\n\n\n\n Th17 responses have been implicated in autoimmune neurological diseases because they promote:<\/p>\n\n\n\n Regulatory T cells normally suppress excessive immunity.<\/p>\n\n\n\n Impaired regulatory function may permit uncontrolled inflammation.<\/p>\n\n\n\n Severe COVID-19 is characterized by abnormal cytokine signaling, sometimes referred to as a “cytokine storm.”<\/p>\n\n\n\n Although TM patients do not necessarily experience systemic cytokine storms, localized immune activation may occur within the nervous system.<\/p>\n\n\n\n Important cytokines include:<\/p>\n\n\n\n IL-6 promotes:<\/p>\n\n\n\n Elevated IL-6 has been associated with severe COVID-19 and neurological complications.<\/p>\n\n\n\n TNF-\u03b1 contributes to:<\/p>\n\n\n\n TNF signaling has long been implicated in inflammatory demyelinating disease.<\/p>\n\n\n\n Type I interferons (IFN-\u03b1 and IFN-\u03b2) represent critical antiviral defenses.<\/p>\n\n\n\n However, abnormal timing or intensity of interferon responses may contribute to tissue injury.<\/p>\n\n\n\n Early interferon activation is protective, whereas delayed excessive activation may promote inflammation.<\/p>\n\n\n\n The blood\u2013spinal cord barrier (BSCB) is essential for maintaining neural homeostasis.<\/p>\n\n\n\n It consists of:<\/p>\n\n\n\n Inflammation can disrupt this barrier, allowing:<\/p>\n\n\n\n SARS-CoV-2 infection promotes endothelial activation through:<\/p>\n\n\n\n Loss of BSCB integrity provides a pathway through which systemic immune activation can become spinal cord injury.<\/p>\n\n\n\n The complement system is an ancient component of innate immunity that recognizes pathogens and promotes immune defense.<\/p>\n\n\n\n However, excessive complement activation can damage host tissue.<\/p>\n\n\n\n Mechanisms include:<\/p>\n\n\n\n Studies of severe COVID-19 have demonstrated complement activation in vascular tissues.<\/p>\n\n\n\n Similar pathways may contribute to inflammatory spinal cord injury in susceptible individuals.<\/p>\n\n\n\n B-cell activation following SARS-CoV-2 infection may produce antibodies directed against:<\/p>\n\n\n\n Potentially relevant antibodies include:<\/p>\n\n\n\n Importantly, COVID-associated TM must be differentiated from established autoimmune disorders.<\/p>\n\n\n\n A patient developing TM after SARS-CoV-2 infection may actually have:<\/p>\n\n\n\n Therefore, comprehensive antibody testing is essential.<\/p>\n\n\n\n Another proposed mechanism involves vascular injury.<\/p>\n\n\n\n SARS-CoV-2 can produce:<\/p>\n\n\n\n The spinal cord has a vulnerable arterial supply, particularly in watershed regions.<\/p>\n\n\n\n Microvascular dysfunction may cause:<\/p>\n\n\n\n Some cases initially diagnosed as inflammatory TM may include a vascular component.<\/p>\n\n\n\n A unified model of COVID-associated transverse myelitis can be summarized as follows:<\/p>\n\n\n\n Step 1: Viral exposure<\/strong><\/p>\n\n\n\n \u2193<\/p>\n\n\n\n Step 2: Innate immune activation<\/strong><\/p>\n\n\n\n Activation of macrophages, dendritic cells, interferons, and inflammatory pathways<\/p>\n\n\n\n \u2193<\/p>\n\n\n\n Step 3: Adaptive immune stimulation<\/strong><\/p>\n\n\n\n Activation of T cells and B cells<\/p>\n\n\n\n \u2193<\/p>\n\n\n\n Step 4: Loss of immune tolerance<\/strong><\/p>\n\n\n\n Molecular mimicry and autoimmune activation<\/p>\n\n\n\n \u2193<\/p>\n\n\n\n Step 5: Blood\u2013spinal cord barrier disruption<\/strong><\/p>\n\n\n\n Immune cells and antibodies enter CNS tissue<\/p>\n\n\n\n \u2193<\/p>\n\n\n\n Step 6: Spinal cord inflammation<\/strong><\/p>\n\n\n\n Demyelination, axonal injury, edema, neuronal dysfunction<\/p>\n\n\n\n \u2193<\/p>\n\n\n\n Step 7: Clinical syndrome<\/strong><\/p>\n\n\n\n Weakness, sensory loss, autonomic dysfunction<\/p>\n\n\n\n Current evidence suggests that COVID-19\u2013associated transverse myelitis represents a rare but biologically plausible immune-mediated complication of SARS-CoV-2 infection. The dominant mechanisms appear to involve dysregulated host immunity rather than direct viral destruction of spinal cord tissue.<\/p>\n\n\n\n The disorder likely emerges from interaction between:<\/p>\n\n\n\n Understanding these pathways is essential because it may allow future development of targeted therapies aimed not only at suppressing inflammation but at correcting specific immune abnormalities responsible for neurological injury.<\/p>\n\n\n\n One of the most fundamental unanswered questions in COVID-19\u2013associated transverse myelitis (TM) is why only a very small proportion of individuals exposed to SARS-CoV-2 develop inflammatory spinal cord disease. Hundreds of millions of people worldwide have experienced SARS-CoV-2 infection, yet inflammatory myelitis remains exceedingly uncommon. This discrepancy strongly suggests that infection alone is insufficient to produce spinal cord injury and that additional factors\u2014genetic susceptibility, immune regulation, environmental exposures, age, comorbid conditions, and stochastic immune events\u2014shape individual risk.<\/p>\n\n\n\n Modern genomic research has demonstrated that severe infectious and autoimmune diseases are rarely determined by a single gene mutation. Rather, they arise from complex interactions among multiple genetic variants that influence:<\/p>\n\n\n\n COVID-19\u2013associated TM therefore provides an opportunity to study a broader principle in medicine: the transition from a protective antiviral immune response to pathological autoimmunity.<\/p>\n\n\n\n At present, no single genetic variant has been proven to cause COVID-associated TM. However, several genomic pathways have biological plausibility based on knowledge from autoimmune neurological disease, inflammatory demyelination, and severe COVID-19.<\/p>\n\n\n\n The human leukocyte antigen (HLA) system represents the major genetic determinant of adaptive immune recognition.<\/p>\n\n\n\n Located on chromosome 6, HLA genes encode molecules responsible for presenting peptide fragments to T lymphocytes.<\/p>\n\n\n\n Two major pathways are relevant:<\/p>\n\n\n\n Including:<\/p>\n\n\n\n These present intracellular peptides to CD8+ cytotoxic T cells.<\/p>\n\n\n\n Including:<\/p>\n\n\n\n These present extracellular peptides to CD4+ helper T cells.<\/p>\n\n\n\n Because SARS-CoV-2 infection produces extensive viral protein exposure, HLA variation may influence:<\/p>\n\n\n\n HLA associations have been identified in multiple neuroinflammatory disorders.<\/p>\n\n\n\n Examples include:<\/p>\n\n\n\n Strong associations exist with:<\/p>\n\n\n\n This allele enhances presentation of myelin-derived peptides and increases susceptibility to CNS demyelination.<\/p>\n\n\n\n Associations include:<\/p>\n\n\n\n Specific HLA backgrounds appear to influence antibody generation against myelin oligodendrocyte glycoprotein.<\/p>\n\n\n\n These observations are relevant because some cases of COVID-associated TM may represent activation of previously silent autoimmune tendencies.<\/p>\n\n\n\n Different HLA types bind SARS-CoV-2 peptides with different efficiency.<\/p>\n\n\n\n Some variants may produce:<\/p>\n\n\n\n Others may promote:<\/p>\n\n\n\n Computational studies have suggested that some HLA alleles may present SARS-CoV-2 peptides that share similarity with human proteins, potentially increasing the theoretical risk of molecular mimicry.<\/p>\n\n\n\n However, these findings remain hypothesis-generating and require confirmation in patients with documented inflammatory neurological disease.<\/p>\n\n\n\n Type I interferons represent one of the earliest antiviral defense mechanisms.<\/p>\n\n\n\n The pathway includes:<\/p>\n\n\n\n Important genes include:<\/p>\n\n\n\n Research has demonstrated that some patients with severe COVID-19 possess inherited or acquired defects in type I interferon immunity.<\/p>\n\n\n\n These defects may produce:<\/p>\n\n\n\n A defective interferon response may theoretically contribute to neurological complications through two opposing mechanisms:<\/p>\n\n\n\n leading to greater antigen exposure.<\/p>\n\n\n\n leading to uncontrolled inflammatory responses.<\/p>\n\n\n\n Signal transducer and activator of transcription (STAT) proteins regulate cytokine responses.<\/p>\n\n\n\n Important pathways include:<\/p>\n\n\n\n Alterations in STAT signaling may influence:<\/p>\n\n\n\n In the spinal cord, abnormal cytokine signaling may amplify activation of:<\/p>\n\n\n\n Beyond HLA and interferon pathways, multiple genes influence autoimmune risk.<\/p>\n\n\n\n Important categories include:<\/p>\n\n\n\n Genes affecting immune tolerance include:<\/p>\n\n\n\n These pathways regulate whether activated immune cells are suppressed or allowed to persist.<\/p>\n\n\n\n Variants affecting:<\/p>\n\n\n\n may influence inflammatory intensity.<\/p>\n\n\n\n Complement activation is increasingly recognized as a component of COVID-associated inflammation.<\/p>\n\n\n\n Genes influencing complement regulation include:<\/p>\n\n\n\n Alterations could modify susceptibility to inflammatory vascular or neural injury.<\/p>\n\n\n\n Genetic sequence alone does not determine immune behavior.<\/p>\n\n\n\n Epigenetic mechanisms modify gene expression through:<\/p>\n\n\n\n Viral infections can produce long-lasting epigenetic changes in immune cells.<\/p>\n\n\n\n Potential consequences include:<\/p>\n\n\n\n This concept may be particularly relevant to long COVID, where persistent immune abnormalities have been observed months after infection.<\/p>\n\n\n\n MicroRNAs are small RNA molecules that regulate gene expression after transcription.<\/p>\n\n\n\n SARS-CoV-2 infection alters expression of multiple microRNAs involved in:<\/p>\n\n\n\n Certain microRNA profiles may influence whether immune activation resolves or persists.<\/p>\n\n\n\n Potential future applications include:<\/p>\n\n\n\n A major research question is whether COVID-associated TM represents a new disease entity or whether SARS-CoV-2 triggers known autoimmune pathways.<\/p>\n\n\n\n Several similarities exist with established disorders:<\/p>\n\n\n\n Shared mechanisms:<\/p>\n\n\n\n Differences:<\/p>\n\n\n\n Shared mechanisms:<\/p>\n\n\n\n Differences:<\/p>\n\n\n\n Shared mechanisms:<\/p>\n\n\n\n Differences:<\/p>\n\n\n\n The most likely model is not a single susceptibility gene but a cumulative threshold effect.<\/p>\n\n\n\n An individual may possess:<\/p>\n\n\n\n Individually, each factor may be insufficient.<\/p>\n\n\n\n Together, they may create a biological environment where SARS-CoV-2 exposure triggers pathological inflammation.<\/p>\n\n\n\n A conceptual model:<\/p>\n\n\n\n Genetic predisposition<\/strong><\/p>\n\n\n\n Viral immune activation<\/strong><\/p>\n\n\n\n Environmental modifiers<\/strong><\/p>\n\n\n\n Failure of immune regulation<\/strong><\/p>\n\n\n\n =<\/p>\n\n\n\n Inflammatory spinal cord injury<\/strong><\/p>\n\n\n\n Future studies should incorporate:<\/p>\n\n\n\n to identify rare variants.<\/p>\n\n\n\n to detect common susceptibility loci.<\/p>\n\n\n\n to characterize immune-cell states.<\/p>\n\n\n\n to determine where inflammatory pathways occur within nervous tissue.<\/p>\n\n\n\n Combining:<\/p>\n\n\n\n These approaches may eventually allow prediction of which patients are most vulnerable to neurological complications after infection.<\/p>\n\n\n\n The genomic basis of COVID-19\u2013associated transverse myelitis remains an emerging field. Current evidence suggests that susceptibility is likely determined by a complex interaction among antigen presentation genes, interferon pathways, autoimmune risk variants, inflammatory regulators, and epigenetic modifications.<\/p>\n\n\n\n The rarity of the disorder despite widespread SARS-CoV-2 exposure strongly supports the existence of host susceptibility factors. Identifying these factors may ultimately transform management from reactive treatment to predictive, preventive neuroimmunology.<\/p>\n\n\n\n Understanding the neurological consequences of COVID-19\u2013associated transverse myelitis (TM) requires an appreciation of the highly specialized physiology of the spinal cord. The spinal cord is not merely a passive communication pathway between the brain and peripheral nervous system; it is an active computational structure responsible for integrating sensory information, coordinating movement, maintaining posture, regulating autonomic function, and supporting complex reflex networks.<\/p>\n\n\n\n Inflammatory injury associated with SARS-CoV-2 infection can disrupt this delicate organization through multiple mechanisms:<\/p>\n\n\n\n The clinical manifestations of COVID-associated TM\u2014weakness, sensory loss, neuropathic pain, gait impairment, bladder dysfunction, and autonomic abnormalities\u2014reflect interruption of specific spinal cord pathways.<\/p>\n\n\n\n The spinal cord consists of:<\/p>\n\n\n\n The central gray matter contains neuronal cell bodies and interneurons, while the surrounding white matter contains heavily myelinated axons traveling between the brain and peripheral nervous system.<\/p>\n\n\n\n Inflammation can affect all components simultaneously.<\/p>\n\n\n\n The corticospinal tracts are the principal pathways controlling voluntary movement.<\/p>\n\n\n\n Origin:<\/p>\n\n\n\n Course:<\/p>\n\n\n\n Function:<\/p>\n\n\n\n Inflammation affecting corticospinal fibers produces:<\/p>\n\n\n\n The severity depends on:<\/p>\n\n\n\n The dorsal columns transmit:<\/p>\n\n\n\n Damage produces:<\/p>\n\n\n\n Many patients with spinal inflammatory disorders describe a sensation of “walking on foam” or uncertainty about foot position because proprioceptive information is disrupted.<\/p>\n\n\n\n The spinothalamic pathways transmit:<\/p>\n\n\n\n Inflammatory injury can produce:<\/p>\n\n\n\n Neuropathic pain may persist even after inflammation resolves because damaged sensory pathways undergo abnormal electrical remodeling.<\/p>\n\n\n\n The term “transverse” refers to involvement across the width of the spinal cord.<\/p>\n\n\n\n Unlike a peripheral nerve injury affecting a single nerve distribution, a transverse spinal cord lesion can interrupt multiple systems simultaneously.<\/p>\n\n\n\n A single inflammatory lesion may affect:<\/p>\n\n\n\n This explains why patients may simultaneously experience:<\/p>\n\n\n\n Myelin is produced in the central nervous system by oligodendrocytes.<\/p>\n\n\n\n Its functions include:<\/p>\n\n\n\n Myelin allows saltatory conduction, where electrical impulses rapidly jump between nodes of Ranvier.<\/p>\n\n\n\n When inflammation damages myelin:<\/p>\n\n\n\n Clinical consequences include:<\/p>\n\n\n\n Early in disease, conduction failure may be reversible.<\/p>\n\n\n\n Later, axonal degeneration can produce permanent disability.<\/p>\n\n\n\n Oligodendrocytes are particularly vulnerable during inflammatory attacks.<\/p>\n\n\n\n Potential mechanisms include:<\/p>\n\n\n\n Important inflammatory mediators include:<\/p>\n\n\n\n Loss of oligodendrocytes reduces remyelination capacity and may contribute to chronic neurological deficits.<\/p>\n\n\n\n A central concept in inflammatory spinal cord disease is the difference between:<\/p>\n\n\n\n and<\/p>\n\n\n\n Patients with preserved axons may recover substantially after inflammation decreases.<\/p>\n\n\n\n Patients with extensive axonal loss may experience:<\/p>\n\n\n\n MRI abnormalities do not always perfectly predict disability because functional outcome depends more on microscopic axonal integrity than lesion size alone.<\/p>\n\n\n\n Microglia are the resident immune cells of the central nervous system.<\/p>\n\n\n\n Under normal conditions, they:<\/p>\n\n\n\n During inflammatory disease, microglia become activated and release:<\/p>\n\n\n\n Activated microglia can have dual roles:<\/p>\n\n\n\n\n
Direct Viral Neuroinvasion: A Controversial Mechanism<\/h4>\n\n\n\n
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Molecular Mimicry and Autoimmune Cross-Reactivity<\/h4>\n\n\n\n
Conceptual Basis<\/h4>\n\n\n\n
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Potential Neural Targets<\/h4>\n\n\n\n
Myelin-associated proteins<\/h4>\n\n\n\n
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Oligodendrocytes<\/h4>\n\n\n\n
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Astrocytes<\/h4>\n\n\n\n
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T-Cell\u2013Mediated Neuroinflammation<\/h4>\n\n\n\n
CD4+ Helper T Cells<\/h4>\n\n\n\n
Th1 cells<\/h4>\n\n\n\n
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Th17 cells<\/h4>\n\n\n\n
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Regulatory T Cells<\/h4>\n\n\n\n
Cytokine Dysregulation and the Inflammatory Cascade<\/h4>\n\n\n\n
Interleukin-6 (IL-6)<\/h4>\n\n\n\n
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Tumor Necrosis Factor-\u03b1 (TNF-\u03b1)<\/h4>\n\n\n\n
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Interferon Signaling<\/h4>\n\n\n\n
Blood\u2013Spinal Cord Barrier Dysfunction<\/h4>\n\n\n\n
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Complement Activation<\/h4>\n\n\n\n
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Autoantibodies and Humoral Immunity<\/h4>\n\n\n\n
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Microvascular Injury and Spinal Cord Ischemia<\/h4>\n\n\n\n
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Integrated Pathogenic Model<\/h4>\n\n\n\n
Conclusions<\/h4>\n\n\n\n
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Genomics of Susceptibility in COVID-19\u2013Associated Transverse Myelitis: HLA Biology, Interferon Networks, Autoimmune Predisposition, and Precision Neuroimmunology<\/h1>\n\n\n\n
Overview<\/h2>\n\n\n\n
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Human Leukocyte Antigen (HLA) System and Antigen Presentation<\/h4>\n\n\n\n
Central Role of HLA Biology<\/h4>\n\n\n\n
Class I HLA molecules<\/h4>\n\n\n\n
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Class II HLA molecules<\/h4>\n\n\n\n
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HLA and Autoimmune Neurological Disease<\/h4>\n\n\n\n
Multiple sclerosis<\/h4>\n\n\n\n
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Neuromyelitis optica spectrum disorder<\/h4>\n\n\n\n
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MOG antibody-associated disease<\/h4>\n\n\n\n
HLA and SARS-CoV-2 Immune Responses<\/h4>\n\n\n\n
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Type I Interferon Pathway Genetics<\/h4>\n\n\n\n
Importance of Interferon Signaling<\/h4>\n\n\n\n
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Interferon Defects and COVID-19 Neurological Disease<\/h4>\n\n\n\n
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STAT Pathway Regulation<\/h4>\n\n\n\n
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Autoimmune Susceptibility Genes<\/h4>\n\n\n\n
Immune checkpoint regulation<\/h4>\n\n\n\n
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\n\n\n\nCytokine regulation genes<\/h4>\n\n\n\n
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\n\n\n\nComplement pathway genes<\/h4>\n\n\n\n
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\n\n\n\nEpigenetic Regulation<\/h4>\n\n\n\n
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\n\n\n\nMicroRNA Regulation<\/h4>\n\n\n\n
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\n\n\n\nGenomic Similarities Between COVID-19 TM and Other Demyelinating Disorders<\/h4>\n\n\n\n
Multiple Sclerosis<\/h4>\n\n\n\n
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\n\n\n\nNeuromyelitis Optica Spectrum Disorder<\/h4>\n\n\n\n
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\n\n\n\nMOG Antibody Disease<\/h4>\n\n\n\n
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\n\n\n\nThe Concept of Genetic Thresholds<\/h4>\n\n\n\n
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\n\n\n\nFuture Directions in Genomic Research<\/h4>\n\n\n\n
Whole-genome sequencing<\/h4>\n\n\n\n
Genome-wide association studies<\/h4>\n\n\n\n
Single-cell RNA sequencing<\/h4>\n\n\n\n
Spatial transcriptomics<\/h4>\n\n\n\n
Multi-omics approaches<\/h4>\n\n\n\n
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\n\n\n\nConclusions<\/h4>\n\n\n\n
Physiology and Neurobiology of COVID-19\u2013Associated Transverse Myelitis: Spinal Cord Pathways, Demyelination, Axonal Injury, Neurovascular Dysfunction, and Mechanisms of Recovery<\/h4>\n\n\n\n
Overview<\/h4>\n\n\n\n
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\n\n\n\nFunctional Organization of the Spinal Cord<\/h4>\n\n\n\n
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\n\n\n\nThe Major Motor Pathways<\/h4>\n\n\n\n
Corticospinal Tracts<\/h4>\n\n\n\n
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\n\n\n\nThe Major Sensory Pathways<\/h4>\n\n\n\n
Dorsal Column System<\/h4>\n\n\n\n
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\n\n\n\nSpinothalamic Tracts<\/h4>\n\n\n\n
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\n\n\n\nWhy Transverse Myelitis Produces Bilateral Symptoms<\/h4>\n\n\n\n
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\n\n\n\nDemyelination: The Central Physiological Event<\/h4>\n\n\n\n
Normal Myelin Function<\/h4>\n\n\n\n
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\n\n\n\nConsequences of Demyelination<\/h4>\n\n\n\n
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\n\n\n\nOligodendrocyte Injury<\/h4>\n\n\n\n
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\n\n\n\nAxonal Injury: The Determinant of Long-Term Disability<\/h4>\n\n\n\n
Reversible conduction block<\/h4>\n\n\n\n
Irreversible axonal destruction.<\/h4>\n\n\n\n
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\n\n\n\nNeuroinflammation and Microglial Activation<\/h4>\n\n\n\n
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Harmful effects<\/h4>\n\n\n\n
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