MRI findings (T1-weighted images) in a patient with<unk>  showing thickening of infundibulum and both optic nerves (white signal marked with yellow arrows; width 6 mm). Right image: MRI brain with contrast showing near resolution of enhancement after treatment. The diagnosis of<unk>  often is difficult. Definitive diagnosis can only be made by biopsy (surgically removing a tissue sample). Because of the risks associated with brain biopsies, they are avoided as much as possible. Other investigations that may be performed in any of the symptoms mentioned above are computed tomography (CT) or magnetic resonance imaging (MRI) of the brain, lumbar puncture, electroencephalography (EEG) and evoked potential (EP) studies. If the diagnosis of sarcoidosis is suspected, typical X-ray or CT appearances of the chest may make the diagnosis more likely; elevations in angiotensin-converting enzyme and calcium in the blood, too, make sarcoidosis more likely. In the past, the Kveim test was used to diagnose sarcoidosis. This now obsolete test had a high (85 percent) sensitivity, but required spleen tissue of a known sarcoidosis patient, an extract of which was injected into the skin of a suspected case. Only biopsy of suspicious lesions in the brain or elsewhere is considered useful for a definitive diagnosis of neurosarcoid. This would demonstrate granulomas (collections of inflammatory cells) rich in epithelioid cells and surrounded by other immune system cells (e.g. plasma cells, mast cells). Biopsy may be performed to distinguish mass lesions from tumours (e.g. gliomas). 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. Lumbar puncture may demonstrate raised protein level, pleiocytosis (i.e. increased presence of both lymphocytes and neutrophil granulocytes) and oligoclonal bands. Various other tests (e.g. ACE level in CSF) have little added value. Criteria Some recent papers propose to classify<unk>  by likelihood: * Definite<unk>  can only be diagnosed by plausible symptoms, a positive biopsy and no other possible causes for the symptoms * Probable<unk>  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<unk>  may be diagnosed if there are symptoms not due to other conditions but other criteria are not fulfilled.
Neurosarcoidosis
Malignant multiple sclerosis
Sarcoidosis
Gamasoidosis
Amyloidosis
Melioidosis
Multiple sclerosis
Tumefactive multiple sclerosis