Neurosarcoidosis is a form of sarcoidosis that involves the central nervous system. Sarcoidosis refers to the formation of growths made up of immune cells and in 5% to 15% of cases, these growths or granulomas occur in the brain and spinal cord.
Neurosarcoidosis usually occurs as a result of sarcoidosis that already involves other parts of the body and only about 1% of sarcoidosis patients will have neurosarcoidosis alone.
Neurosarcoidosis manifests in many different ways, but the most common problem is cranial abnormality which occurs in about 50% to 70% of those affected. The most common feature is abnormality of the facial nerve, which can lead to weakness in one or both sides of the face. Eyesight may also be affected due to involvement of the optic nerve.
Less common features that may manifest include:
- Double vision due to involvement of the oculomotor nerve, trochlear nerve or abducens nerve.
- Involvement of the trigeminal nerve may reduced facial sensation.
- Involvement of the vestibulocochlear nerve may lead to hearing loss and dizziness.
- Involvement of the glossopharyngeal nerve may lead to swallowing problems.
- Involvement of the hypoglossal nerve may affect the tongue.
- Involvement of the accessory nerve may affect arm and shoulder muscles.
- Seizures occur in about 15% of cases.
- Meningitis or inflammation of the meninges is also seen in some patients, causing headache and neck rigidity.
- If granulomas form in the pituitary gland where various hormones are produced, conditions that may develop include diabetes, amenorrhea, jaundice or even heart failure.
Diagnosis and treatment
A diagnosis of neuroscarcoidosis can only be confirmed by biopsy. However, a biopsy is avoided where possible due to the risks associated with the procedure. In cases of the above symptoms, other tests that may be performed include a computed tomography (CT) scan, magnetic resonance imaging (MRI) scan, lumbar puncture, and electroencephalography (EEG).
Once a diagnosis is confirmed, most cases are treated with glucocorticoids such as prednisolone. Other agents that have also proved effective in some studies include methotrexate, hydroxychloroquine, cyclophosphamide, thalidomide and infliximab.
Reviewed by Sally Robertson, BSc