Neurosarcoidosis
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Neurosarcoidosis refers to sarcoidosis involving the central nervous system. Approximately 5-10% of people with sarcoidosis develop central nervous system involvement. Only 1% of people with sarcoidosis will have neurosarcoidosis alone.
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[edit] Signs and Symptoms
Neurosarcoidosis can present with any neurologic finding. Signs and symptoms are dependent on the area of the brain involved. The base of the brain is most commonly affected. Possible presentations include persistent headache, nerve palsy, weakness, dysphagia, seizure, psychiatric problems, etc. If the hypothalamus is involved, a person may develop endocrine abnormalities such as hypothyroidism, central diabetes insipidus, irregular periods or adrenal insufficiency.
[edit] Diagnosis
The diagnosis of neurosarcoidosis often is difficult. Definitive diagnosis can only be made by biopsy. Because of the risks associated with brain biopsies, frequently they are not done.
In an individual with known sarcoidosis, the development of suggestive symptoms with collaborative imaging on MRI is often considered enough for diagnosis. The diagnosis is not definitive, in this case, as other conditions may mimic the disease. For instance, cryptococcus is associated with sarcoid patients, even those not on immunosuppressive therapy, and should be a consideration in any person with sarcoidosis who develops neurological symptoms. In addition, some lymphomas cannot be differentiated from sarcoidosis on MRI.
There is no definitive lab test to make the diagnosis, however, several can be helpful. In cerebral spinal fluid, protein concentration is usually elevated, a pleocytosis is present and the glucose may be normal to high. In the CSF, the ACE level is elevated in 50% of neurosarcoid patients and has a specificity greater than 90%. Serum and urine calcium are occasionally elevated.
In individuals found to have brain lesions consistent with sarcoidosis but who have no known systemic involvement, an evaluation for involvement of other organs is warranted. A chest x-ray and possibly a high resolution CT of the lungs should be done as the lungs are most frequently affected by sarcoidosis. In addition, a thorough examination of the skin and lymph nodes should be done. An examination of the eye by an ophthalmologist is also indicated. Any tissue suggestive of sarcoid should be biopsied to help confirm the diagnosis.
If only the brain appears affected, however, a biopsy is not necessarily indicated, depending on the area involved and degree of suspicion. If infection and tumor have been ruled out, the lesions on imaging are suggestive of sarcoid and the symptoms improve on steroids, it may reasonable to make the diagnosis without a biopsy.
[edit] Treatment
Because of the rarity of the disease, little evidence exists to guide treatment. High dose steroids are considered the treatment of choice followed by a slow taper. Two thirds of patients will have remission of the disease and not require further treatment.
Recurrent or chronic disease may require long term treatment with steroids which is frequently limited by side effects. In this case, a trial of a non-steroidal immunosuppressive is warranted. Their use has been reported in numerous case studies; however, no randomized controlled studies have been done to show their efficacy. Thalidomide may have a role in treatment as well.
