Sarcoidosis is an inflammatory disease characterized by the formation of microscopic clumps of inflammatory cells, called granulomas. A rarer form, neurosarcoidosis, occurs when this inflammation impacts the nervous system, causing granulomas to develop in the brain, spinal cord, or peripheral nerves. While sarcoidosis most commonly involves the lungs and lymph nodes, neurological involvement is a significant manifestation that presents unique challenges.
Neurological Manifestations of Sarcoidosis
The symptoms of neurosarcoidosis are diverse and depend on the location of the granulomas within the nervous system. When the cranial nerves are affected, the most frequent sign is facial palsy, which causes a sudden drooping or weakness on one side of the face. This can also extend to other cranial nerves, leading to vision problems like double vision, hearing loss, or a diminished sense of smell or taste.
Involvement of the central nervous system, which includes the brain and spinal cord, can produce a different set of symptoms. Patients may experience persistent headaches, seizures, or cognitive difficulties often described as “brain fog.” In some instances, the inflammation can obstruct the flow of cerebrospinal fluid, leading to hydrocephalus, where fluid builds up in the brain. The symptoms can sometimes mimic those of other neurological disorders, like multiple sclerosis.
When granulomas form along the spinal cord, they can cause weakness, numbness, or paralysis in the limbs. The peripheral nerves can also be a target, resulting in peripheral neuropathy, characterized by sensations of pain, numbness, or tingling, typically in the hands and feet. The course of these symptoms can vary, with some individuals experiencing a single episode, while others may have a relapsing-remitting pattern.
Muscle involvement in sarcoidosis is often asymptomatic, but in rare cases, it can lead to pain, muscle weakness, or atrophy. Laboratory tests may show elevated levels of muscle enzymes, and the onset can be either acute or subacute.
The Diagnostic Pathway
Diagnosing neurosarcoidosis is a complex process that involves ruling out other conditions with similar symptoms, as there isn’t a single definitive test. The process begins with a neurological examination to assess motor and sensory functions, coordination, and mental status. This initial step helps pinpoint the areas of the nervous system that may be affected and guides further testing.
Magnetic Resonance Imaging (MRI) of the brain and spinal cord is a common diagnostic tool. When administered with a contrast agent, an MRI can highlight areas of inflammation or reveal characteristic lesions on the brain, its protective outer layers (meninges), or the spinal cord.
A lumbar puncture, or spinal tap, is another procedure used in the diagnostic process. This involves collecting a small sample of cerebrospinal fluid (CSF), the fluid that surrounds the brain and spinal cord. Analysis of the CSF can reveal elevated protein levels or an increased number of white blood cells, which are indicators of inflammation.
The most conclusive evidence for a neurosarcoidosis diagnosis comes from a biopsy. A small sample of affected tissue is surgically removed and examined under a microscope. Finding noncaseating granulomas—a specific type of inflammatory cell cluster—in the tissue confirms the diagnosis. This tissue can be taken from a nerve or, more commonly, from a non-neurological site where sarcoidosis is also present, such as the lungs or skin.
Therapeutic Interventions
The primary goal of treating neurosarcoidosis is to manage inflammation, reduce symptoms, and prevent long-term damage to the nervous system. Treatment is tailored to the individual, considering the severity of symptoms and the specific parts of the nervous system involved.
The first line of defense is high-dose corticosteroids, such as prednisone. These medications are effective at quickly reducing inflammation and can lead to a rapid improvement in symptoms. However, long-term use of corticosteroids can have significant side effects, so they are usually prescribed for the shortest duration possible at the lowest effective dose.
For patients who do not respond well to corticosteroids or who require long-term treatment, immunosuppressant medications are often introduced. Drugs like methotrexate or azathioprine work by suppressing the immune system, thereby reducing the formation of granulomas. These are sometimes referred to as steroid-sparing agents because they can help lower the required dose of corticosteroids.
In cases that are resistant to both corticosteroids and conventional immunosuppressants, biologic therapies may be used. These newer, more targeted treatments include TNF-alpha inhibitors, such as infliximab. They work by blocking a specific protein in the immune system that promotes inflammation. This approach is generally reserved for more severe or refractory cases of neurosarcoidosis.
Living with Neurosarcoidosis
Neurosarcoidosis is often a chronic condition with periods of relapse and remission, requiring a long-term perspective focused on maintaining quality of life. The unpredictable nature of the condition, with symptoms that can flare up unexpectedly, means that ongoing medical supervision is a part of the patient’s journey.
Effective management involves a multidisciplinary care team to ensure all aspects of the disease are monitored and treated. This team may include:
- A neurologist who specializes in neurosarcoidosis
- A pulmonologist to monitor for lung involvement
- A rheumatologist
- An ophthalmologist, as eye involvement is common in sarcoidosis
Beyond medication, managing the chronic symptoms of neurosarcoidosis is a large part of the daily experience. Physical therapy can help with muscle weakness and mobility issues, while occupational therapy can assist patients in adapting their daily activities. Pain management strategies may also be needed for those who experience chronic pain from nerve damage.