Eosinophilic Meningitis: Symptoms, Causes, Treatment

What are the symptoms of eosinophilic meningitis?

The symptoms of eosinophilic meningitis can vary depending on the underlying cause, but they generally resemble those of other types of meningitis, with specific characteristics related to the immune response involving eosinophils. Common symptoms include:

General symptoms:

• Severe headache: One of the most common and prominent symptoms.
• Fever: Elevated body temperature, often indicating infection or inflammation.
• Neck stiffness: Difficulty or pain when moving the neck, a hallmark of meningitis.
• Nausea and vomiting: Often accompanying the headache and fever.
• Photophobia: Sensitivity to light.
• Muscle weakness or pain: In some cases, due to nerve involvement.
• Neurological symptoms:
• Confusion or altered mental state.
• Seizures (in severe cases).
• Dizziness or unsteadiness.

Other possible symptoms:

• Tingling or numbness: Especially in the limbs, due to nerve irritation.
• Facial nerve palsy: Paralysis or weakness of facial muscles.
• Skin rashes: Rare but possible, particularly with allergic or parasitic causes.

Symptoms specific to parasitic infections (e.g., Angiostrongylus cantonensis):

• Abdominal pain: May occur with parasitic causes due to migration of parasites from the digestive system.
• Eosinophilia in blood: An elevated count of eosinophils in the bloodstream, which may be detected through blood tests.

If any symptoms of meningitis are present, it is crucial to seek immediate medical attention, as meningitis can lead to serious complications without timely treatment.

What are the causes of eosinophilic meningitis?

Eosinophilic meningitis is caused by a variety of factors, but the most common cause is parasitic infection. Other causes can include allergic reactions, autoimmune conditions, certain medications, and rarely, bacterial or fungal infections. Here are the primary causes:

1. Parasitic Infections

Parasitic infections are the leading cause of eosinophilic meningitis. The parasites can invade the central nervous system and trigger an immune response, leading to an increased number of eosinophils in the cerebrospinal fluid (CSF).

• Angiostrongylus cantonensis (rat lungworm): The most common cause of eosinophilic meningitis, especially in tropical and subtropical regions. Infection typically occurs through ingestion of raw or undercooked snails, slugs, or contaminated produce.
• Gnathostoma spinigerum: A parasitic worm that can cause eosinophilic meningitis, primarily found in Southeast Asia and Latin America. Infection occurs through ingestion of raw or undercooked fish, poultry, or frogs.
• Toxocara species: Parasitic roundworms that can lead to eosinophilic meningitis, typically transmitted through ingestion of contaminated soil or food.
• Baylisascaris procyonis: A parasitic infection transmitted by raccoons, which can also cause severe neurological symptoms.
• Strongyloides stercoralis: A parasitic roundworm that can cause hyperinfection syndrome and eosinophilic meningitis, particularly in immunocompromised individuals.

2. Fungal Infections

• Coccidioides immitis: A fungus that can cause eosinophilic meningitis, primarily in endemic areas such as the southwestern United States. Coccidioidomycosis (Valley Fever) can lead to eosinophilia in the CSF in some cases.

3. Allergic Reactions

• Drugs: Certain medications, including nonsteroidal anti-inflammatory drugs (NSAIDs), antibiotics, and vaccines, can cause allergic reactions leading to eosinophilic meningitis.
• Immunologic reactions: In rare cases, an autoimmune or allergic response can trigger eosinophil production, leading to eosinophilic meningitis.

4. Autoimmune Disorders

• Hypereosinophilic syndrome: A rare condition characterized by persistently high levels of eosinophils in the body, which can lead to tissue inflammation, including in the brain and spinal cord.

5. Other Causes

• Idiopathic eosinophilic meningitis: In some cases, the cause is unknown, and no specific infectious or inflammatory trigger can be identified.

Summary of common causes:

• Parasitic infections: Especially Angiostrongylus cantonensis (rat lungworm).
• Fungal infections: Such as Coccidioides immitis.
• Allergic reactions: To drugs or environmental factors.
• Autoimmune conditions: Such as hypereosinophilic syndrome.

Early diagnosis and treatment are crucial for managing eosinophilic meningitis, especially if caused by a parasitic infection.

What is the treatment for eosinophilic meningitis?

The treatment for eosinophilic meningitis depends on the underlying cause, typically focusing on addressing the infection (if present), reducing inflammation, and managing symptoms. Here is an overview of common treatments:

1. Parasitic Infections

• Antiparasitic medications: If eosinophilic meningitis is caused by parasites such as Angiostrongylus cantonensis (rat lungworm) or Gnathostoma spinigerum, antiparasitic drugs like albendazole or mebendazole may be prescribed to kill the parasites. However, their use in A. cantonensis infections is debated due to concerns about worsening inflammation when parasites die in the brain.
• Steroids: Corticosteroids (such as prednisone) are often used to reduce inflammation and swelling in the brain caused by the immune response to parasites. They are commonly prescribed in combination with antiparasitic drugs or alone in certain cases.

2. Fungal Infections

• Antifungal medications: If a fungal infection (like Coccidioides immitis) is the cause, antifungal drugs such as fluconazole or amphotericin B are used to treat the underlying fungal infection.

3. Allergic or Drug Reactions

• Stopping the triggering medication: If eosinophilic meningitis is caused by an allergic reaction to a drug, discontinuing the medication is the first step.
• Corticosteroids: Steroids may also be used to reduce inflammation caused by an allergic or immune reaction.

4. Symptomatic Treatment

• Pain management: Pain relievers like acetaminophen or ibuprofen may be prescribed to help manage headaches and other discomforts associated with the condition.
• Management of neurological symptoms: If seizures or other neurological symptoms occur, additional medications may be given to manage these issues.

5. Supportive Care

• Hospitalization: In more severe cases, hospitalization may be necessary to monitor the patient, especially if there is increased intracranial pressure, seizures, or other complications.
• Lumbar puncture: Sometimes repeated lumbar punctures are performed to relieve pressure from the buildup of cerebrospinal fluid (CSF) and help alleviate headaches.

Key Points:

• Steroids: Frequently used to reduce inflammation, especially in parasitic cases.
• Antiparasitic or antifungal medications: Prescribed based on the underlying cause of the infection.
• Supportive care: Symptom management, pain relief, and hospitalization when necessary.

It’s essential to diagnose the specific cause of eosinophilic meningitis accurately to provide the appropriate treatment. Seeking early medical care is important for reducing complications and improving outcomes.

What happens if I don’t treat eosinophilic meningitis?

If eosinophilic meningitis is left untreated, the condition can lead to serious complications depending on the underlying cause, the severity of the inflammation, and how long the condition progresses without intervention. Here are potential outcomes:

1. Increased Brain and Spinal Cord Damage

• Chronic inflammation: The prolonged presence of eosinophils in the cerebrospinal fluid (CSF) can lead to sustained inflammation in the brain and spinal cord, damaging the tissues and increasing the risk of permanent neurological deficits.
• Brain damage: Severe cases can result in long-term damage to brain tissue, leading to cognitive impairments, memory loss, or personality changes.

2. Neurological Complications

• Seizures: Untreated inflammation can trigger seizures, which may become recurrent and difficult to control over time.
• Paralysis or muscle weakness: Damage to nerves may result in paralysis, muscle weakness, or loss of motor control, particularly in the limbs.
• Hearing and vision loss: Cranial nerves can be affected, leading to hearing or vision impairment, especially if pressure builds up in the brain.

3. Hydrocephalus

• Increased intracranial pressure: In some cases, eosinophilic meningitis can cause a buildup of cerebrospinal fluid (CSF), leading to hydrocephalus (excess fluid in the brain). This can cause severe headaches, nausea, vomiting, and potential damage to the brain from the increased pressure.
• Coma: In extreme cases, untreated hydrocephalus may lead to loss of consciousness or coma.

4. Persistent Symptoms

• Chronic headaches: Untreated inflammation often results in persistent, severe headaches that can be debilitating.
• Neurological symptoms: Persistent dizziness, confusion, difficulty concentrating, and altered mental status may worsen without treatment.

5. Systemic Complications

• Worsening of parasitic or fungal infections: If caused by an infection, particularly a parasitic one like Angiostrongylus cantonensis (rat lungworm), the infection may continue to spread, causing further damage to the nervous system and potentially other organs.
• Secondary infections: In cases where the immune system is compromised, untreated meningitis can lead to other infections or systemic complications.

6. Death

• Severe cases of eosinophilic meningitis can be fatal if left untreated, particularly if caused by parasitic infections or if it leads to complications such as hydrocephalus, severe seizures, or coma.

Summary of Risks:

• Permanent neurological damage (seizures, paralysis, vision or hearing loss).
• Hydrocephalus (fluid buildup in the brain), potentially leading to coma.
• Increased risk of fatal outcomes, particularly in severe or untreated infections.

Early diagnosis and appropriate treatment are essential to prevent these complications. If eosinophilic meningitis is suspected, medical attention should be sought immediately.