Postviral and Postinfectious Syndrome: Symptoms, Diagnosis and Advanced Treatments

Common Symptoms of Postviral Syndrome

• Persistent fatigue unrelieved by rest
• Cognitive dysfunction (“brain fog”)
• Sleep disturbances
• Muscle and joint pain
• Dizziness or orthostatic intolerance
• Gastrointestinal issues
• Autonomic dysfunction (POTS, dysautonomia)
• Sensory hypersensitivity

Causes and Triggers

While the exact mechanisms are still under research, prevailing theories suggest that postviral syndromes may be triggered by:

• A prolonged inflammatory response
• Persistent viral fragments in tissues
• Dysregulation of the immune system
• Connective tissue abnormalities (especially in Ehlers-Danlos Syndrome)
• Structural instability in the craniocervical junction or spinal cord

Beyond Symptoms: Structural and Immunological Investigations

Post-viral or post-infectious syndromes can present with a wide range of systemic and neurological symptoms that often overlap with those of craniocervical instability (CCI), including atlantoaxial instability (AAI). This clinical overlap can lead to underdiagnosis or misinterpretation of underlying structural issues in patients, particularly those with connective tissue disorders (e.g., Ehlers-Danlos Syndrome or other collagenopathies). Recognizing this overlap is crucial for developing an accurate and personalized diagnostic and treatment approach.

Post-viral syndromes, such as those observed following Epstein-Barr virus, Lyme disease, or more recently, SARS-CoV-2 infections (COVID), can lead to long-term dysfunction of the immune, autonomic, and nervous systems. Symptoms such as chronic fatigue, orthostatic intolerance, headaches, cognitive dysfunction (“brain fog”), and widespread pain are common in both post-viral syndromes and craniocervical instability. This convergence of symptoms can make it difficult for clinicians to distinguish whether the origin of the patient’s complaints is immunological, structural, or both.

Craniocervical and atlantoaxial instability refers to excessive motion between the skull and the cervical spine, particularly at the junction between the atlas (C1) and the axis (C2). This instability can cause intermittent compression or stretching of the brainstem, spinal cord, vertebral arteries, and cranial nerves. In patients with connective tissue disorders, the ligamentous laxity inherent in their condition increases the risk of such biomechanical dysfunctions, yet the symptoms may remain subtle or be masked by post-infectious sequelae.

To address this diagnostic challenge, a dual-assessment strategy is recommended:

Biological Evaluation: This component involves the investigation of immunological biomarkers that can reflect ongoing inflammation, immune dysregulation, or autoimmunity. Elevated levels of cytokines, autoantibodies, or persistent immune cell activation may provide evidence that a post-viral or autoimmune process is contributing to the patient’s symptomatology. Understanding the immune profile helps determine whether persistent immune activation could be exacerbating neuroinflammatory processes or autonomic dysfunction and if it coexists with a biomechanical component of the disease.

Biomechanical Evaluation: Parallel to the biological approach, patients should undergo a detailed biomechanical and radiological assessment of the cervical spine, particularly the craniocervical and atlantoaxial regions. Dynamic imaging techniques—such as upright CBCT (flexion-extension), or digital motion X-ray—can reveal abnormal mobility, subluxations, or mechanical compressions that standard static imaging may miss. In individuals with collagenopathies, these biomechanical vulnerabilities may only become apparent under certain postural or dynamic conditions, further emphasizing the need for specific testing protocols.

Combining these two perspectives—biological and biomechanical—allows for a much more nuanced and complete understanding of the patient’s clinical picture. It ensures that the diagnosis does not rely solely on symptom reporting, which may be ambiguous or nonspecific, but rather on objective evidence from both the immune system and structural integrity of the cervical spine. This approach is especially important for identifying cases where structural instability is a hidden driver of chronic symptoms in patients who were initially diagnosed with a post-viral syndrome. We do not know yet, in some cases of CCI-AAI or tethered cord, if they are a cause or a consequence of the so called post-viral-postinfectious syndrome.

Ultimately, this dual-evaluation strategy supports a more integrative and individualized treatment plan, potentially combining immunomodulatory therapies with physical rehabilitation, bracing, or surgical interventions when necessary.

Our experience shows that upright imaging (CBCT, uMRI) is essential for accurately diagnosing these cases. When coupled with comprehensive immunological and neuroinflammatory evaluations, it allows us to detect otherwise “invisible” causes behind persistent postviral symptoms.

We have pioneered an approach in Barcelona that combines upright CBCT and prone lumbar MRI with artificial intelligence to detect instabilities or tethering that are missed in traditional scans as well as a biological evaluation through biomarker testing in order to know whether there is a double component in patients’ disease.

When Postviral Becomes Structural: Our Clinical Approach

In our clinic, we have seen numerous patients who presented with symptoms initially labeled as “post-viral fatigue” or “unexplained chronic fatigue” and were later diagnosed with CCI or Tethered Cord. These patients frequently experience significant improvement in symptoms once the structural condition is addressed. On the other side there also patients that were diagnosed of CCI or Tethered cord that may also improve with immunological based treatment and even in some cases with a combination of both.

We perform a full evaluation which may include:

• Upright CBCT of the cervical spine
• Rotational and dynamic imaging
• Prone/supine lumbar MRI
• Neurophysiological studies
• Inflammatory markers and immunological panels
• Genetic and connective tissue assessments
• Pharmacogenetics

Available Treatments

Each case is unique. Treatments may include:

• Personalized physical rehabilitation and neuromodulation
• Anti-inflammatory and immune-modulating therapies
• Spinal stabilization using orthotics or postural correction
• In selected cases, minimally invasive surgery (tethered cord release surgery) or occipitocervical fusion

Surgery is always a last resort, and we only recommend it when structural pathology clearly correlates with the patient’s clinical presentation and has been confirmed through specialized imaging.

Living with Postviral Syndrome: Hope Through Accurate Diagnosis

Many of our patients come to us after years—sometimes decades—of suffering, misdiagnosis, or being told “everything is normal.” Their symptoms, though life-altering, were often invisible to traditional medicine. We specialize in evaluating these complex cases and giving patients real answers.

When the right diagnosis is finally made, everything changes. Accurate identification of an underlying immunological condition or/and CCI, AAI, or Tethered Cord can lead to life-changing improvements—both with and without surgery.

Would You Like an Expert Evaluation?

If you are experiencing persistent symptoms after a viral illness and suspect a deeper structural or neurological cause, our team can help. We offer:

• Online consultations
• Imaging reviews
• In-person evaluations in Barcelona

Request a remote consultation here or schedule an evaluation with imaging in Barcelona.

FAQs

What is postviral syndrome?

Postviral syndrome is a condition that involves lingering symptoms such as fatigue, brain fog, and dizziness after a viral infection. It may overlap with ME/CFS, Long COVID, or structural spinal issues. Sometimes is also known as post-infectious syndrome, in regards to the initial trigger (bacteria, virus, others…), and some cases have been related to an initial anatomical/biomechanical injury (biomechanical trigger).

How long does postviral fatigue last?

It varies. Some patients recover within weeks, while others experience symptoms for months or even years without a clear resolution.

Is postviral syndrome curable?

There is no universal cure, but when underlying causes (or effects) like spinal instability or immune dysfunction are addressed, many patients experience significant improvement.

Can Dr. Gilete’s team help even if my scans are normal? 

Yes. We specialize in advanced upright and dynamic imaging techniques that detect what standard MRIs may miss. Many of our patients were told their scans were “normal” before coming to us.