Polio-like syndrome

Overview

Polio-like syndrome is a clinical condition that mimics the presentation of poliomyelitis, characterized primarily by sudden onset of limb weakness or paralysis, often affecting one side of the body more than the other. Although it resembles poliomyelitis in its neurological manifestations, polio-like syndrome is not caused by the poliovirus. Instead, it can be triggered by a range of other viral infections or immune-mediated mechanisms. The condition gained increased attention in recent years with outbreaks of acute flaccid myelitis (AFM), a subtype of polio-like illness most commonly affecting children. Due to its potential to cause severe and lasting neurological damage, early recognition and supportive care are crucial.

Causes

Polio-like syndrome can result from various infectious and non-infectious causes. Common triggers include:

• Enteroviruses: Particularly enterovirus D68 (EV-D68) and enterovirus A71, which have been associated with outbreaks of AFM in children.

• West Nile virus: A mosquito-borne virus that can infect the central nervous system and lead to paralysis.

• Adenoviruses and other neurotropic viruses: Occasionally implicated in neurological syndromes with motor involvement.

• Autoimmune response: An abnormal immune reaction may lead to inflammation of the spinal cord or motor neurons, similar to Guillain–Barré syndrome or transverse myelitis.

• Vaccination-related reactions: In very rare cases, post-vaccination neurological reactions may present as polio-like symptoms, although this is extremely uncommon with modern vaccines.

The unifying factor is damage to the anterior horn cells of the spinal cord or motor nerve pathways, resulting in flaccid paralysis.

Symptoms

Symptoms of polio-like syndrome typically develop suddenly and may progress over hours to days. Common features include:

• Sudden onset of limb weakness: Often asymmetrical, affecting one arm or leg more than others.

• Loss of muscle tone: Flaccid (limp) paralysis with decreased reflexes in affected limbs.

• Difficulty walking or using the arms: Depending on the location and severity of nerve involvement.

• Pain in the limbs or neck: Sometimes present before or during the onset of weakness.

• Facial weakness: May occur in some cases, resembling Bell’s palsy.

• Respiratory difficulty: In severe cases, when spinal cord regions controlling the diaphragm are involved.

Systemic symptoms such as fever, sore throat, or gastrointestinal discomfort may precede neurological symptoms, particularly when the condition is triggered by a viral infection.

Diagnosis

Diagnosis of polio-like syndrome is primarily clinical but supported by neurological imaging and laboratory investigations. Steps in the diagnostic process include:

• Neurological examination: To assess muscle tone, reflexes, motor strength, and asymmetry in limb function.

• Magnetic Resonance Imaging (MRI): Especially of the spine, to detect inflammation of the anterior horn cells or gray matter—features seen in AFM.

• Lumbar puncture (spinal tap): Cerebrospinal fluid (CSF) analysis may reveal pleocytosis (increased white cells) and elevated protein levels.

• Viral PCR testing: Throat swabs, nasal samples, stool samples, and CSF are tested for enteroviruses and other pathogens.

• Electromyography (EMG): To assess nerve and muscle function and distinguish from other neuropathies.

It is important to differentiate polio-like syndrome from true poliomyelitis, Guillain–Barré syndrome, and other causes of acute paralysis.

Treatment

There is no specific antiviral treatment for polio-like syndrome. Management is supportive and multidisciplinary, focusing on symptom control, physical recovery, and prevention of complications. Treatment strategies include:

• Hospitalization: For close monitoring, especially in cases with respiratory involvement.

• Respiratory support: Mechanical ventilation may be required if diaphragm paralysis occurs.

• Physical and occupational therapy: Crucial for regaining muscle strength, coordination, and independence in daily activities.

• Pain management: Analgesics and anti-inflammatory medications for discomfort and muscle pain.

• Corticosteroids or IVIG: In selected cases where autoimmune inflammation is suspected, these may help reduce spinal cord inflammation.

• Psychosocial support: Especially for children and families coping with functional disabilities.

Prompt supportive care can help minimize long-term complications and improve outcomes, although full recovery is not always possible.

Prognosis

The prognosis of polio-like syndrome varies depending on the severity of the initial neurological insult and the specific underlying cause. Some individuals, especially those with mild symptoms, may recover fully with time and rehabilitation. Others may experience:

• Persistent limb weakness or paralysis

• Muscle atrophy and decreased motor function

• Orthopedic complications from long-term immobility

• Psychological effects such as anxiety or depression

Children with AFM may regain partial function but often require long-term therapy and assistive devices. Continued research is essential to understand the long-term outcomes and develop targeted treatments. Early intervention, access to rehabilitation services, and comprehensive care remain key to optimizing the prognosis in polio-like syndromes.