Neurosarcoidosis is a chronic disease affecting the central nervous system. The condition is characterized by inflammation that can affect the spinal cord, brain, or optic nerve. The inflammation can destroy the myelin sheath that protects the nerve fibers, which can ultimately lead to a loss of body function.
Definition & Facts
Neurosarcoidosis can manifest in various ways depending on the part of the central nervous system that is affected. The condition most often occurs in the facial nerves and cranial nerves, the hypothalamus, and the pituitary gland; however, it can also affect the optic and auditory nerves.
Neurosarcoidosis can cause permanent loss of neurological function in some people. It can be life-threatening if the brainstem is affected, but this is extremely rare.
Symptoms & Complaints
Neurosarcoidosis affecting the pituitary gland may result in fatigue, excessive thirst, excessive urination, and changes in menstrual periods in women. If the peripheral nerves are affected, the patient may experience numbness and tingling, muscle weakness, and loss of movement.
Neurosarcoidosis of the brain and cranial nerves is characterized by a wide range of symptoms, including:
- Confusion, disorientation, or delirium
- Changes in hearing, vision, or sense of smell or taste
- Dizziness or vertigo
- Facial palsy
- Speech impairment
- Changes in appetite and sleep cycle
- Psychiatric disturbances
In some patients, neurosarcoidosis can affect the autonomic nervous system. This can result in decreased sensitivity to temperature, extreme sensitivity to touch, and unexplained pain. Neurologic symptoms typically develop within two years of the onset of systemic symptoms of sarcoidosis, which include fatigue, malaise, weight loss, joint pain, and fever.
Although the exact cause is unknown, neurosarcoidosis occurs in approximately 5 to 15 percent of patients with sarcoidosis of the lungs. Sarcoidosis is considered a rare disease in that it affects fewer than 200,000 people in the U.S. annually. Sarcoidosis is the result of a heightened immune response that can eventually damage various organs within the body. Sarcoidosis causes clumps of cells called granulomas to develop within an organ that can hamper its function. The disease most often attacks the lungs, but it can affect any organ including the lymph nodes, eyes, and even the skin.
Fewer than 10 percent of patients with neurosarcoidosis have a strictly neurological form of the condition. Genetic factors, infections, and autoimmune diseases may increase the risk of developing neurosarcoidosis. While sarcoidosis of the lungs is normally seen in patients between the ages of 20 and 40, the onset of neurosarcoidosis most often occurs during a person’s 40s or 50s and is an extension of the existing sarcoidosis. Neurosarcoidosis can occur in anyone; however, it is most common in those of Swedish and African-American descent.
Diagnosis & Tests
A patient with a history of sarcoidosis who subsequently develops neurological issues is likely to have neurosarcoidosis. Diagnosis of the condition typically starts with a medical history and neurological examination. A chest X-ray will typically show evidence of pulmonary sarcoidosis. It is also important to rule out other potential causes of neuropathy, including diabetes mellitus, vitamin deficiencies, exposure to heavy metals or toxins, and tumors.
While blood tests may not be useful in providing a definitive diagnosis, they can be used to identify elevated blood glucose levels, vitamin deficiencies, and metabolic conditions that can cause similar symptoms. Calcium levels and erythrocyte sedimentation rates are often elevated in cases of systemic sarcoidosis. Blood tests may also identify potential pituitary/hypothalamic involvement. A lumbar puncture (also known as a spinal tap) will often show signs of inflammation and elevated levels of a specific enzyme.
A magnetic resonance imaging (MRI) scan may indicate lesions or masses along specific nerves, the brain, or the spinal cord. An electromyography/nerve conduction study will demonstrate motor and sensory nerve conduction deficits. A biopsy of the affected nerve tissue can be used to confirm the diagnosis. Neurosarcoidosis is extremely rare in children, so other conditions must be carefully excluded before arriving at a diagnosis.
Treatment & Therapy
There is no known cure for neurosarcoidosis. Some patients do experience spontaneous remission within 4 to 6 months; however, most patients do require long-term therapy. The principal method of treatment is immunosuppressive drugs and corticosteroid therapy. The most common immunosuppressants used include cyclosporine, methotrexate, and cyclophosphamide.
Relapses typically require long-term steroid therapy. It is important to note that long-term use of immunosuppressants and steroids does present significant side effects, such as an increased risk of infections, weight gain, and osteoporosis, so patients should discuss the benefits and risks with their doctor before beginning therapy. Low-dose radiation therapy may have some benefit for patients with brain involvement.
Ancillary therapies may be needed depending on the patient’s specific neurologic symptoms. Patients experiencing symptoms of dementia may require interventions to ensure safety and assistance with basic daily care. Hormone replacement therapy may be beneficial for patients suffering from hypopituitarism. Risperidone and antipsychotic medications may help patients experiencing psychosis.
Physical therapy and occupational therapy may help patients manage their symptoms and make it easier to perform activities of daily living. Patients with balance problems may be able to reduce their risk of falls with balance exercises and assistive devices, such as canes and walkers. Management of neurosarcoidosis typically requires consultation with a team of specialists, including rheumatologists, pulmonologists, endocrinologists, and neurosurgeons.
Prevention & Prophylaxis
Individuals who seek aggressive treatment for their sarcoidosis may be able to turn off the body’s immune response before neurological damage can occur. The National Institute of Neurological Disorders and Strokes is working in conjunction with other agencies within the National Institutes of Health to develop new ways to diagnose, treat, and cure both sarcoidosis and neurosarcoidosis.