The diagnosis of<unk>  is primarily based on the patient's history with its typical features as well as the findings of nail fold capillaroscopy. This test shows an excessive constriction (narrowing) in the smallest blood vessels (capillaries) of the fingers in response to being exposed to cold. Patients with vasospastic symptoms characteristic of<unk>  have shown a unique gene expression when their lymphocytes underwent gene expression profiling. Clinical significance Having<unk>  does not necessarily mean that an individual is sick. Most of those affected are and remain healthy. Certain diseases such as arteriosclerosis and its consequences are probably even rarer. Best known is the higher risk of normal tension glaucoma, a disease with an impaired regulation of blood flow in a large number of patients. If glaucomatous damage occurs despite normal eye pressure or if glaucomatous damage is progressive despite normalized intraocular pressure, frequently<unk>  is the cause. In these eyes, an elevated pressure in the retinal veins has been observed. Glaucoma patients with<unk>  show some specific clinical signs like increased frequency of optic disc haemorrhages, activated retinal astrocytes, elevated retinal venous pressure, optic nerve compartmentalization, and fluctuating diffuse visual field defects. The association of normal tension glaucoma with the syndrome has recently been confirmed by a group of Chinese researchers. In a 2016 review on the risk factors for normal tension glaucoma by ophthalmologists from Asia (where this form of glaucoma is much more prevalent than in Europe or North America),<unk>  has been attributed to increase the likelihood of ganglion cell damage in these patients, with disc hemorrhages as a characteristic clinical sign. Migraine attacks, a common feature of<unk> , have been described as a risk factor for glaucoma progression, in open-angle glaucoma as well as in normal tension glaucoma.<unk>  may also predispose to other eye diseases such as vascular occlusion (especially retinal vein occlusion) in relatively young people or central serous retinopathy. Muscle spasms and tension are common among individuals with<unk> . Tinnitus and sometimes even acute hearing loss can occur. There is currently insufficient data available on cases where<unk>  is suspected like in the sudden, unexpected deaths of young athletes. People suffering from retinitis pigmentosa seem to have<unk>  quite frequently, and possible associations with the vascular factor endothelin-1 are under investigation.
Flammer syndrome
Fryns-Aftimos syndrome
Bogart–Bacall syndrome
Teunissen–Cremers syndrome
Char syndrome
Helsmoortel-Van der Aa syndrome
Jeavons syndrome
Keutel syndrome