What Is Pachymeningitis?

Pachymeningitis is a rare medical condition in which the outer layer of the brain or spinal cord, called the dura mater, thickens and becomes inflamed. Symptoms vary based on the location of the affected area of dura mater but can include headaches and face pain.

The dura mater is the tough, outermost layer of tissue surrounding the brain and spinal cord. It is one of the three layers that make up the meninges.

This article will cover pachymeningitis symptoms, causes, diagnosis, and treatment.

Symptoms

Symptoms of pachymeningitis vary based on where the dura mater has thickened and the amount of pressure placed on the brain or spinal cord. In some cases, there are no symptoms at all.

Pachymeningitis symptoms can include:

• Chronic headaches
• Face pain
• Vision changes, including papilledema
• Hearing loss
• Stroke
• Blood clots
• Increased pressure around the brain

Damage of the brain and spinal cord can occur with increased pressure from pachymeningitis. The brain is surrounded by the skull, which is a fixed space. When the size of the brain increases beyond the available space within the skull, it can result in elevated intracranial pressure (ICP).

ICP is a medical emergency. If you are experiencing symptoms of ICP—which can include headache, nausea, fatigue, and vision changes—call your healthcare provider immediately.

Causes

What causes pachymeningitis is not always clear. Experts speculate that it is an autoimmune response, the result of an infection, or the result of another condition. In some people, the true cause of pachymeningitis may never be found. This is called idiopathic hypertrophic meningitis.

The following three conditions are usually the cause:

• Neurosarcoidosis: A variation of sarcoidosis in which swelling and abnormal deposits in parts of the nervous system develop
• Granulomatosis with polyangiitis: An autoimmune disease with inflammation of blood vessels that results in damage to the body's organs
• Immunoglobulin G4-related disease (IgG4-RD): An autoimmune disease that causes inflammatory fibrosis (thickening and tissue scarring)

Pachymeningitis may also be associated with other inflammatory diseases, such as rheumatoid arthritis and lupus.

Diagnosis

The gold standard for diagnosing pachymeningitis is a biopsy of the dura mater. In this procedure, a sample of tissue is surgically removed for analysis in a lab. The biopsy test results can help determine the cause. This procedure is often used along with other forms of diagnostic testing, including:

• CT scan: Short for "computed tomography," a CT scan looks at structures in the body, such as muscles, bones, and blood vessels. A CT scan is a series of X-ray images and is, therefore, more detailed than a single X-ray.
• MRI: Short for "magnetic resonance imaging," an MRI is a very detailed test that uses magnetic fields and computer-generated radio waves to produce pictures of structures in the body. Unlike a CT, an MRI does not use radiation.
• Blood test: A blood test may be conducted to look for autoimmune conditions and hormone changes.

Treatment

To prevent damage to the brain and spinal cord, early diagnosis and treatment are necessary. Pachymeningitis is typically treated with a steroid medication (such as prednisone) and immunosuppressive therapy.

Immunosuppressants used to treat pachymeningitis include:

• Azasan (azathioprine) 
• Cytoxan (cyclophosphamide)
• Otrexup (methotrexate)
• Rituxan (rituximab)

People with severe pachymeningitis may need surgery to relieve the pressure caused by the thickened dura mater.

Patient-specific treatment varies based on the underlying condition. For example, if it is discovered that an infection is causing pachymeningitis, treatment would be focused on relieving the infection.

Prognosis

The prognosis after diagnosis varies from person to person and is dependent upon the underlying cause of the pachymeningitis.

According to a 2018 study, approximately 30% of people who had idiopathic hypertrophic pachymeningitis continued to have symptoms after completing treatment.

It is possible to develop pachymeningitis after treatment. A relapse can occur from one week to several years after treatment. Anyone who has had pachymeningitis should be monitored by their healthcare provider after treatment for signs of recurrence.

Summary

Pachymeningitis is a rare condition that causes areas of a layer of tissue that surrounds the spinal cord and brain (dura mater) to thicken and become inflamed. This thickening can cause different symptoms based on its location. Some people may have vision changes, headaches, or hearing loss. Treatment is based on the underlying cause and generally involves medications and, in some cases, surgery.

A Word From Verywell

Any condition that puts pressure on the spinal cord or brain, including pachymeningitis, is very serious and can even be life-threatening. If you have vision changes, headaches, hearing loss, or other neurological symptoms, contact your healthcare provider immediately.