Stroke is the second leading cause of death and the third leading cause of disability worldwide. The cause is usually either a blockage or a severe narrowing of a cerebral artery. An important part of stroke prevention is the diagnosis and clarification of stenosis in the arteries supplying the brain, both inside and outside the skull, in order to diagnose a high-grade stenosis at an early stage and offer the patient revascularization. In particular, asymptomatic carotid artery stenosis confronts the diagnosing physician with the question of whether revascularisation is necessary.

Risk factors for stroke in asymptomatic carotid artery stenosis include contralateral TIA or cerebral infarction, male gender, rapid progression of the degree of stenosis, plaque morphology, clinically silent cerebral infarctions, Doppler sonographic evidence of microemboli or reduced vasomotor reserve. An established biomarker does not exist at this time. A candidate for such a biomarker in the blood is the protein "neurofilament light chain" (NFL), which is already established in the diagnosis of dementia. As a component of the cytoskeleton of neurons, it is released into the patient's blood when the cells are damaged and can be measured there. Another candidate is glial fibrillary acid protein (GFAP), a part of the cytoskeleton of glial cells that is also released into the blood when glial cells are damaged. A systematic investigation of the value of neurofilament light chain and the glial fibrillary acidic protein in the blood of patients with asymptomatic carotid stenosis is still lacking. VANGAS determines the value of NFL and GFAP from the blood of patients with asymptomatic carotid stenosis to determine associations with the degree of stenosis, the natural course of the stenosis (increase or decrease) and possible symptoms of the stenosis as well as the functional outcome after symptomatic stenosis.

Inclusion Criteria:

• Age 60- 80 years
• 0-100 % stenosis of the internal carotid artery

Exclusion Criteria:

• Neurodegenerative diseases such as any form of dementia or Parkinson's disease
• Polyneuropathy
• Multiple sclerosis
• Stroke (ischaemic or haemorrhagic) within the last 12 months
• Transient ischaemic attack within the last 12 months
• Neurotrauma within the last 12 months
• Atrial fibrillation

Patients are included from our and the cooperating neurological clinics and practices