pressure and hydrocephalus. Involvement of the spinal cord is rare, but can lead to abnormal sensation or weakness in one or more limbs, or cauda equina symptoms (incontinence to urine or stool, decreased sensation in the buttocks). Endocrine Granulomas in the pituitary gland, which produces numerous hormones, is rare but leads to any of the symptoms of hypopituitarism: amenorrhoea (cessation of the menstrual cycle), diabetes insipidus (dehydration due to inability to concentrate the urine), hypothyroidism (decreased activity of the thyroid) or hypocortisolism (deficiency of cortisol). Mental and other Psychiatric problems occur in 20 percent of cases; many different disorders have been reported, e.g. depression and psychosis. Peripheral neuropathy has been reported in up to 15 percent of cases of neurosarcoidosis. Other symptoms due to sarcoidosis of other organs may be uveitis (inflammation of the uveal layer in the eye), dyspnoea (shortness of breath), arthralgia (joint pains), lupus pernio (a red skin rash, usually of the face), erythema nodosum (red skin lumps, usually on the shins), and symptoms of liver involvement (jaundice) or heart involvement (heart failure). 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. Diagnosis The diagnosis of neurosarcoidosis 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