Neurosarcoidosis (sometimes shortened to neurosarcoid) refers to a type of sarcoidosis, a condition of unknown cause featuring granulomas in various tissues, in this type involving the central nervous system (brain and spinal cord). Neurosarcoidosis can have many manifestations, but abnormalities of the cranial nerves (a group of twelve nerves supplying the head and neck area) are the most common. It may develop acutely, subacutely, and chronically. Approximately 5–10 percent of people with sarcoidosis of other organs (e.g. lung) develop central nervous system involvement. Only 1 percent of people with sarcoidosis will have neurosarcoidosis alone without involvement of any other organs. Diagnosis can be difficult, with no test apart from biopsy achieving a high accuracy rate. Treatment is with immunosuppression. The first case of sarcoidosis involving the nervous system was reported in 1905. Signs and symptoms Neurological Abnormalities of the cranial nerves are present in 50–70 percent of cases. The most common abnormality is involvement of the facial nerve, which may lead to reduced power on one or both sides of the face (65 percent resp 35 percent of all cranial nerve cases), followed by reduction in visual perception due to optic nerve involvement. Rarer symptoms are double vision (oculomotor nerve, trochlear nerve or abducens nerve), decreased sensation of the face (trigeminal nerve), hearing loss or vertigo (vestibulocochlear nerve), swallowing problems (glossopharyngeal nerve) and weakness of the shoulder muscles (accessory nerve) or the tongue (hypoglossal nerve). Visual problems may also be the result of papilledema (swelling of the optic disc) due to obstruction by granulomas of the normal cerebrospinal fluid (CSF) circulation. Seizures (mostly of the tonic-clonic/"grand mal" type) are present in about 15 percent and may be the presenting phenomenon in 10 percent. Meningitis (inflammation of the lining of the brain) occurs in 3–26 percent of cases. Symptoms may include headache and nuchal rigidity (being unable to bend the head forward). It may be acute or chronic. Accumulation of granulomas in particular areas of the brain can lead to abnormalities in the function of that area. For instance, involvement of the internal capsule would lead to weakness in one or two limbs on one side of the body. If the granulomas are large, they can exert a mass effect and cause headache and increase the risk of seizures. Obstruction of the flow of cerebrospinal fluid, too, can cause headaches, visual symptoms (as mentioned above) and other features of raised intracranial