TCD (transcranial Doppler) is an adjunctive test for neurological disorders and is widely used to assess the presence of stenosis, occlusion or regurgitation by measuring the velocity of blood flow in intracranial vessels and the pulsatility index of the vessels. TCD (transcranial Doppler) can also be used for the early assessment of cerebral vasospasm, especially after subarachnoid hemorrhage, and can be used to monitor patients for microemboli, especially in patients with headaches. If microemboli are monitored, transesophageal cardiac ultrasound can be checked if necessary. Currently, TCD can also be used to monitor for increased intracranial pressure.