[History of neurovascular ultrasonography]

History of diagnostic ultrasound begins with the Austrian physicist Christian Doppler, who described in 1842 the Doppler principle. 40 years later, the Curies discovered the reverse piezoelectric effect that produces ultrasound. The first ultrasonic devices were designed at the beginning of the 20th century and were used among other things for detection of submarines. Development during World War II permitted the construction of the first transcranial (1940) and extracranial (1949) ultrasound imaging units. Continuous-wave Doppler sonography was introduced in clinical practice 20 to 30 years later. Due to its high validity, this technique has become the standard method for evaluation of extracranial occlusive cerebrovascular disease. Further ultrasonic developments like duplex and color duplex sonography have increased the diagnostic possibilities but did not replace continuous-wave sonography in many European ultrasound laboratories. Transcranial ultrasound studies are performed by means of pulsed-wave Doppler or color duplex sonography. It is likely that power Doppler and transpulmonary contrast agents will further increase diagnostic confidence in neurovascular ultrasound. The search for a source of arterio-arterial embolism in case of ocular and cerebral ischemia remains the main indication for neurovascular ultrasonography. Additional indications are repetitive studies in dissection, vasospasm, endovascularly treated vascular malformations and stenoses, intracranial pressure monitoring, examination of cerebrovascular reactivity in suspicion of hemodynamic ischemia, and diagnostic work-up of cough syncope, pulsatile tinnitus and cardiac right-left shunt.