Neurosarcoidosis
Neurosarcoidosis | |
---|---|
Other names | Besnier-Boeck-Schaumann disease |
This condition affects the cranial nerves | |
Specialty | Neurology |
Diagnostic method | Biopsy |
Treatment | immunosuppression |
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.[1] The first case of sarcoidosis involving the nervous system was reported in 1905.[2][3]
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
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.[1]
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 pressure and hydrocephalus.[1]
Involvement of the
Endocrine
Granulomas in the
Mental and other
Other symptoms due to sarcoidosis of other organs may be
Pathophysiology
Sarcoidosis is a disease of unknown cause that leads to the development of granulomas in various organs. While the lungs are typically involved, other organs may equally be affected. Some subforms of sarcoidosis, such as Löfgren syndrome, may have a particular precipitant and have a specific course. It is unknown which characteristics predispose sarcoidosis patients to brain or spinal cord involvement.[1]
Diagnosis
The diagnosis of neurosarcoidosis often is difficult. Definitive diagnosis can only be made by
Only biopsy of suspicious lesions in the brain or elsewhere is considered useful for a definitive diagnosis of neurosarcoidosis. The tissue sample would demonstrate
MRI with gadolinium enhancement is the most useful neuroimaging test. This may show enhancement of the pia mater or white matter lesions that may resemble the lesions seen in multiple sclerosis.[1]
Lumbar puncture may demonstrate raised
Criteria
Some recent papers propose to classify neurosarcoidosis diagnoses by their likelihood of being accurate:[1]
- Definite neurosarcoidosis can only be diagnosed by plausible symptoms, a positive biopsy and no other possible explanations for the symptoms
- Probable neurosarcoidosis can be diagnosed if the symptoms are suggestive, there is evidence of central nervous system inflammation (e.g. CSF and MRI), and other diagnoses have been excluded. A diagnosis of systemic sarcoidosis is not essential.
- Possible neurosarcoidosis may be diagnosed if there are symptoms not due to other conditions, while other criteria are not fulfilled.
Treatment
Neurosarcoidosis, once confirmed, is generally treated with
Prognosis
Of the phenomena occurring in neurosarcoid, only facial nerve involvement is known to have a good prognosis and good response to treatment. Long-term treatment is usually necessary for all other phenomena.[1] The mortality rate is estimated at 10 percent[4]
Epidemiology
Sarcoidosis has a prevalence of 40 per 100,000 in the general population. However, though those with the GG genotype at
The condition most commonly affects young adults of both sexes, although studies have reported more cases in females. Incidence is highest for individuals younger than 40 and peaks in the age-group from 20 to 29 years; a second peak is observed for women over 50.[8][9]
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
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.[9] There may also be differences in the severity of the disease between people of different ethnicities. Several studies suggest that the presentation in people of African origin may be more severe and disseminated than for Caucasians, who are more likely to have asymptomatic disease.[11]
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.[8]
Sarcoidosis is one of the few pulmonary diseases with a higher prevalence in non-smokers.[12]
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.[13]