Neurosarcoidosis

What neurosarcoidosis is

Sarcoidosis is an inflammatory disease in which immune cells clump into small nodules called granulomas. It most often affects the lungs and chest lymph nodes. When granulomas form in or around the nervous system, they press on, inflame or damage nerve tissue. Granulomas have a strong tendency to involve the base of the brain and the meninges, which explains the typical pattern of cranial nerve and hormone problems.

In about half of people with neurosarcoidosis, neurological symptoms are the first sign of sarcoidosis. Some never show disease elsewhere.

Symptoms by area affected

Facial nerve palsy affects roughly a quarter to half of people with neurosarcoidosis and may come and go. Weakness on both sides of the face, either at the same time or one after the other, is a strong clue. When facial palsy occurs with fever, eye inflammation (uveitis) and swollen parotid glands, it is called Heerfordt syndrome.

Who gets it

Sarcoidosis is most common between ages 20 and 60, in women, and in people of African American and Northern European ancestry. Neurosarcoidosis follows the same pattern. The cause of sarcoidosis is unknown; it is thought to be an abnormal immune response to an environmental trigger in people with a genetic susceptibility.

How neurosarcoidosis is diagnosed

There is no single test. Diagnosis combines typical symptoms, imaging, fluid tests and, ideally, a biopsy showing granulomas. Doctors also exclude infections such as tuberculosis and fungal disease, lymphoma and multiple sclerosis.

1. MRI of the brain and spine with gadolinium contrast: may show thickened, enhancing meninges (especially at the brain's base), enhancing nerves, nodules in the brain, or long inflamed segments of the spinal cord.
2. Lumbar puncture: spinal fluid often shows raised protein and white cells, sometimes low glucose. It also helps rule out infection and cancer cells.
3. Looking for sarcoidosis elsewhere: chest CT and whole-body FDG-PET scans often find inflamed lymph nodes or lung disease, which are easier and safer to biopsy than the brain. Eye exams, skin checks and blood calcium help.
4. Biopsy: usually of a lymph node, lung, skin or eye lesion. A nerve or brain biopsy is reserved for when no other site is available.
5. Hormone tests: if pituitary or hypothalamic involvement is suspected.

Experts classify the diagnosis as definite (granulomas found in nervous system tissue), probable (granulomas found elsewhere in the body plus typical nervous system findings) or possible (typical findings without a biopsy).

Treatment

Treatment aims to control inflammation quickly, prevent permanent nerve damage and limit steroid side effects.

• Corticosteroids (prednisone, or IV methylprednisolone for severe disease) are the first treatment. Isolated facial palsy may need only a short course.
• Steroid-sparing medicines are usually added for brain, spinal cord or optic nerve disease: methotrexate, mycophenolate or azathioprine.
• TNF inhibitors, especially infliximab, are increasingly used early for severe or resistant disease and are often highly effective.
• Symptom treatment: seizure medicines, desmopressin for diabetes insipidus, hormone replacement for pituitary problems, nerve pain medicines, and a shunt for hydrocephalus when needed.
• Monitoring: repeat MRI scans to check response, with bone protection, blood sugar and infection precautions during long-term treatment.

Rehabilitation, including physical, occupational and speech therapy, helps people regain function.

Outlook

The outlook varies. Isolated facial palsy often recovers fully. Disease of the meninges or cranial nerves tends to respond well to treatment. Spinal cord, brain tissue and hypothalamic involvement are more likely to relapse and to leave lasting problems, but early use of strong treatments has improved outcomes. Many people need treatment for several years, and relapses can occur when medicines are reduced. Most people with neurosarcoidosis have a normal or near-normal life expectancy with treatment, though severe brain or spinal cord disease can be disabling.

Frequently asked questions

What are the first symptoms of neurosarcoidosis?

The most common first symptom is weakness of one side of the face, similar to Bell's palsy. Others include double or blurred vision, headaches, numbness or tingling, excessive thirst and urination, and seizures. Symptoms depend on which part of the nervous system the granulomas affect.

How is neurosarcoidosis diagnosed?

Doctors combine an MRI with contrast, spinal fluid tests and scans looking for sarcoidosis elsewhere in the body, such as a chest CT or PET scan. A biopsy showing granulomas, usually taken from a lymph node, lung or skin, supports the diagnosis. Other causes, such as infection, lymphoma and MS, must be excluded.

Can neurosarcoidosis be cured?

There is no guaranteed cure, but many people go into remission with treatment. Isolated facial nerve involvement often resolves completely. Brain and spinal cord disease usually needs years of immune-suppressing treatment and may relapse when medicines are reduced, so long-term follow-up is important.

What is the life expectancy with neurosarcoidosis?

Most people with neurosarcoidosis live a normal or near-normal lifespan with treatment. Serious complications, such as extensive brain involvement, hydrocephalus or heart sarcoidosis, can shorten life, and side effects of long-term treatment need careful management. Early, effective treatment improves outcomes.

Is neurosarcoidosis the same as multiple sclerosis?

No, but they can look alike on MRI and both can cause optic neuritis and spinal cord inflammation. Neurosarcoidosis often involves the meninges and cranial nerves, causes granulomas elsewhere in the body, and responds to different treatments. Spinal fluid tests and body scans help tell them apart.