ONSD ultrasound
OtherDescription of the ONSD ultrasound: ONSD is measured 3 mm behind the globe and perpendicularly to the optic nerve axis (2 dimensions mode).
For each optic nerve, 2 measures are performed: 1 sagittal and 1 transverse. The patient is positioned in 30° dorsal elevation. Gel is applied on the eyelid and a 7,5 MHz probe is used.
At the same time and on the same side, a transcranial Doppler is performed using a 2 MHz probe placed on the temple. Are measured: systolic velocity, mean velocity, diastolic velocity, resistance index and pulsatility index.
As ONSD measures cannot be done blinded (regarding ICP monitoring), a centralised evaluation (by 2 experts) of the recorded sonograms is planned.