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QShould I see a neurologist for sarcoidosis?
DR. JEFFREY GELFAND RESPONDS:
A The immune system is the body's way of protecting against infection and injury. In sarcoidosis, the immune system becomes misdirected and attacks part of the patient's own body as if it were a foreign invader, causing inflammation and tissue damage. What causes the immune system to go awry in people with sarcoidosis is unknown. What is known is that in sarcoidosis, tiny clusters of immune cells, called granulomas, form in certain parts of the body, including the lungs, lymph nodes, eyes, skin, and other tissues. Why are certain organs affected in some patients with sarcoidosis and not others? That is an important question, but one that remains unanswered.
Infiltration of the nervous system by sarcoidosis—neurosarcoidosis—occurs in up to 10 percent of people with the disease. For example, sarcoidosis can infiltrate the central nervous system, including the brain, spinal cord, pituitary gland, optic nerves, and meninges, which are the membranes that envelope the central nervous system. (This is typically assessed by clinical examination, MRI, spinal fluid examination, neuro-ophthalmologic testing, and tests of nerve function.) In this case of central nervous system involvement, the neurologic problems may be the first sign that a patient has sarcoidosis.
The disease can also invade the peripheral nervous system, which consists of the nerves outside of the brain and spinal cord. (This is typically assessed by clinical examination, nerve conduction studies, electromyography, and, sometimes, additional testing for involvement of small nerve fibers in the skin.)
But a much larger proportion of sarcoidosis patients without direct evidence of central or peripheral nervous system involvement still report neurologic symptoms, such as thinking problems, mood changes, pain, fatigue, headaches, sensory changes, weakness, and imbalance. Neurologic consultation can be helpful for these individuals in order to sort out the cause of the symptoms and provide expert recommendations for treatment. It is important to remember that the presence of neurologic symptoms in a patient with sarcoidosis does not necessarily mean that the person has neurosarcoidosis—he or she may have sarcoidosis in addition to another neurologic condition.
Diagnosis and treatment of neurosarcoidosis can be challenging, so consultation with a neurologist with expertise in sarcoidosis is advised. Because sarcoidosis can affect so many different parts of the body, it is also critical that the various doctors and providers involved in the patient's care communicate with one another.
MRI of the brain of a patient with neurosarcoidosis. The brighter areas show involvement of the optic nerves and hypothalamus. MRI COURTESY JEFFREY M. GELFAND, M.D.
More research is needed to understand why neurosarcoidosis occurs, how to improve diagnosis, and how to make treatment more effective and tolerable. We have created a neurosarcoidosis referral and research program (sarcoidosis.ucsf.edu ) with these aims in mind. Our hope is to work closely with clinicians and other experts worldwide to aid in successfully diagnosing, treating—and curing—this mysterious disease.