Transcranial Doppler (TCD) is a diagnostic tool that can provide a real-time picture of brain hemodynamics. Known in clinical practice for the first time in 1986, currently TCD is one of the tools most often used to perform examinations, diagnostics or evaluation of therapy, in patients with cerebrovascular (cerebrovascular) disorders.
The application of TCD is non-invasive, without giving side effects so that it is convenient for patients to do, although in some cases it is necessary to carry out repeated examinations at short intervals.
TCD works by using low-frequency (2 MHz) ultrasonic waves that penetrate the skull and target the blood vessels to be evaluated. The procedure for examining TCD is to place the probe in a location that allows ultrasonic waves to assess the speed of blood circulation in the arteries of the brain, or is called a window .
There are at least three windows for performing TCD, namely the area between the eyes and ears ( transtemporal window), above the eyelids ( transorbital window ), and between the occipital and cervical bones ( transforaminal/suboccipital window) . Each window can show different blood vessels according to their anatomical location. The transtemporal window approach can evaluate waves from the middle cerebral artery, anterior cerebral artery, posterior cerebral artery, and posterior communicating artery; transorbital window for the ophthalmic artery, and carotid siphon artery; transforaminal window for the vertebral and basilar arteries.
One of the cerebrovascular disorders that often utilize TCD is ischemic stroke. Ischemic stroke occurs when there is a blockage in the blood vessels of the brain which causes reduced blood flow to certain parts of the brain. TCD examination plays a role both in the screening phase / before the occurrence of a stroke, during a stroke, after stroke therapy, to determine the post-stroke prognosis.
TCD can provide valuable information regarding the presence of microemboli, the presence of blood vessel obstruction (atheroma stenosis) to the degree of blockage which will be related to the incidence of stroke in patients. It was found that the sensitivity of TCD is more than 90% in indicating the presence of blockage of the blood vessels of the brain, especially those that occur in the middle cerebral artery.
In its role in determining the prognosis of patients with acute ischemic stroke, TCD shows the severity of the blockage that occurs in the blood vessels involved. This level of prognosis varies from good with a possible short post-stroke recovery time, to death due to stroke.
In cases of ischemic stroke patients who have received therapy and recanalized blood flow, TCD will be useful in monitoring the effectiveness of therapy, including evaluation in determining dose adjustments, and the duration of antifibrinolytic agents given in cases of rapid recanalization.
Not only ischemic stroke, the application of TCD can also be useful in diagnosing migraine headaches, assessing the presence of post-subarachnoid hemorrhage vasospasm, thrombosis in the cerebral venous system, intracranial hypertension to the diagnosis of brain death ( brain death ).
In some cases, such as carotid artery stenosis, syncope, or transient ischemic attack (TIA), TCD examination should be accompanied by Carotid Doppler (CD) examination to support the conclusion of the diagnosis.
Even though the TCD examination is a simple and non-invasive examination, the results of the examination are highly dependent on the operator, in this case a neurologist/neurologist. Good TCD examination results, accompanied by a clear medical history and a good neurological physical examination, will certainly help in determining the appropriate follow-up for the patient so that the clinical outcome can be achieved as optimally as possible.
Article written by dr. Rineke Twistixa Arandita Sp.N (Neurologist / Nerve Specialist at EMC Pulomas Hospital).