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.
Epidemiology
Sarcoidosis has a prevalence of 40 per 100,000 in the general population. However, though those with the GG genotype at rs1049550 in the ANXA11 gene were found to have 1.5–2.5 times higher odds of sarcoidosis compared to those with the AG genotype, while those with the AA genotype had about 1.6 times lower odds. Furthermore, those with Common Variable Immunodeficiency (CVID) may be at even higher risk. One study of 80 CVID patients found eight of these had sarcoidosis, suggesting as high a prevalence in CVID populations as one in 10. Given that less than 10 percent of those with sarcoidosis will have neurological involvement, and possibly later on in their disease course, neurosarcoidosis has a prevalence of less than four per 100,000.
Sarcoidosis occurs throughout the world in all races with an average incidence of 16.5/100,000 in men and 19/100,000 in women. The disease is most prevalent in Northern European countries and the highest annual incidence of 60/100,000 is found in Sweden and Iceland. In the United States sarcoidosis is more common in people of African descent than Caucasians, with annual incidence reported as 35.5 and 10.9/100,000, respectively.
The variable incidence of neurosarcoidosis over the world may be at least partially attributable to the lack of screening programs in certain regions of the world and the overshadowing presence of other granulomatous diseases, such as tuberculosis, that may interfere with the diagnosis of sarcoidosis where they are prevalent.
Manifestation appears to be slightly different according to race and sex. Erythema nodosum is far more common in men than in women and in Caucasians than in other races. In Japanese patients, ophthalmologic and cardiac involvement are more common than in other races.
Notable cases
The American television personality and actress Karen Duffy wrote Model Patient: My Life As an Incurable Wise-Ass on her experiences with neurosarcoidosis.