The use of Trans Cranial Dopper (TCD), in Neurology

Updated: Sep 1, 2023

Transcranial Doppler (TCD) ultrasound is a non-invasive, real-time measure of cerebrovascular function.

It is a commonly available and inexpensive diagnostic tool that can detect, localize, and grade the severity of cerebrovascular diseases.

The Indications for TCD

Transcranial Doppler (TCD) ultrasound is a useful tool in diagnosing neurological disorders, particularly those involving cerebrovascular abnormalities. Some common neurological disorders that can be diagnosed using TCD include:

1. Cerebral sinus venous thrombosis (CSVT) : TCD is effective in diagnosing CSVT, which is a rare but potentially life-threatening condition caused by blood clots in the veins that drain blood from the brain.

2. Acute ischemic stroke : TCD can be used to assess blood flow velocity in the major cerebral arteries and detect changes in blood flow patterns that may indicate an acute ischemic stroke.

Blood supply to the brain

3. Intracranial atherosclerotic stenosis : TCD can be used to detect and grade the severity of intracranial atherosclerotic stenosis, which is a narrowing of the arteries in the brain caused by the buildup of plaque

4. Cerebral vasospasm : TCD can be used to monitor blood flow velocity in patients with subarachnoid hemorrhage and detect cerebral vasospasm, which is a potentially life-threatening complication that can occur after a brain hemorrhage.

5. Raised intracranial pressure : TCD can be used to monitor patients with raised ICP, pre and even post operatively.

It is also useful for day-to-day bedside assessment of critical conditions including vasospasm in subarachnoid hemorrhage and intracranial pressure monitoring

Advantages

The advantages of transcranial Doppler (TCD) in diagnosing neurological disorders include:

1. Non-invasive and safe : TCD is a non-invasive and safe diagnostic technique that does not involve ionizing radiation or the need for contrast agents. It uses ultrasound technology to assess cerebral blood flow velocity and pulsatility index.

2. Cost-effective and portable : TCD is a relatively inexpensive diagnostic tool compared to other imaging modalities. It is also portable, allowing for bedside assessments and monitoring in acute emergency settings.

3. Real-time assessment of cerebral blood flow : TCD provides real-time information about cerebral blood flow patterns, allowing for immediate assessment and monitoring of blood flow velocity in the major basal cerebral arteries. This can be particularly useful in acute conditions such as ischemic stroke.

4. Complementary information to other imaging modalities: TCD provides physiological information about cerebral hemodynamics that can complement the anatomical details obtained from other neuroimaging modalities. It can provide additional insights into the degree of cerebral vessel stenosis, microemboli, and other cerebrovascular abnormalities.

5. Bedside assessment and monitoring: TCD can be performed at the bedside, making it a convenient tool for assessing and monitoring patients in various clinical settings. It allows for repeated measurements and can be used for continuous monitoring in critical care units.

While TCD has its limitations, such as operator dependency and the inability to provide direct anatomical information, its advantages make it a valuable tool in the diagnosis and monitoring of neurological disorders, particularly those involving cerebrovascular abnormalities

It can be used in conjunction with other imaging modalities to provide a comprehensive evaluation of patients.

It is a bedside procedure that can be performed quickly and easily, making it a useful tool in emergency situations

How is TCD done ?

The technique of TCD involves placing a transducer on the temporal bone to measure blood flow velocity via cerebral circulation and pulsatility index

.The transducer emits high-frequency sound waves that bounce off red blood cells and return to the transducer, creating a waveform that can be analyzed to determine blood flow velocity.

In summary, TCD is a useful diagnostic tool for cerebrovascular diseases and can provide additional information as part of a multimodal imaging protocol in many clinical settings.