Transcranial Doppler Versus Computed Tomography In Evaluation Of Brain Edema In Patients With Traumatic Brain Injury

Computed Tomography (CT) scan of the brain will be done on admission to the ICU and 48-72 hours after starting hyperosmolar therapy. The cerebral oedema will be scored as follows: 0 = no brain oedema, 1 = mild brain oedema, 2 = moderate brain oedema, and 3 = severe brain oedema. Oedema is defined as mild when the ventricles and cisterns are narrow in the CT in the acute stage; moderate, when in addition to the mild form, the sylvian fissure and cortical gyri are not visualized; and severe, when in addition to mild and moderate, the perimesencephalic cisterns can not be visualized.

Transcranial doppler ultrasonography will be performed immediately after CT scan then after 48-72 hours of starting hyperosmolar therapy according to the following protocol:

• The examination will be done using phased array probe using (Versana active, general electric medical systems china Co.Ltd) ultrasound (US) device.
• Standing behind the head of the patient, the 2 Mega Hertz (MHz) transducer will be placed over the temporal area just above the zygomatic arch and in front of the tragus of the ear and oriented slightly upward and anteriorly.
• A red color signal (i.e. flow towards the probe) at a depth between 40-65 mm will represent the flow in the ipsilateral middle cerebral artery.
• The angle and position of insonation will be adjusted to provide the highest quality Doppler signal.
• By applying pulsed wave on the insonated segment, Peak Systolic Velocity (PSV) and End Diastolic Velocity (EDV) will be measured and recorded on US machine.
• Mean flow velocity (MFV) will be calculated using the formula:

(PSV+(EDVx 2))/3.

• Pulsatility index (PI) is calculated using the formula: (PSV-EDV)/ MFV.
• Intracranial pressure (ICP) will be calculated as follows: