ocular ultrasound for elevated ICP

22 Jan

(re-post of an old review, but came up again recently, worth a refresher)

 

from sonoguide.com:

Evaluation of the optic nerve sheath diameter (ONSD) can detect EICP.

On ultrasound a normal optic nerve sheath measures up to 5.0 mm in diameter.

The ONSD is measured 3 mm posterior to the globe for both eyesA position of 3 mm behind the globe is recommended because the ultrasound contrast is greatest, the results are more reproducible

Two measurements are averaged.

An average ONSD greater than 5 mm is considered abnormal and elevated intracranial pressure should be suspected.

 

STUDY 1:

35 patients, 14 with elevated ICP on CT

all 14 with elevated ICP were detected with ONSD >5.0mm (mean ONSD was 6.27mm)

 

STUDY 2:

50 patients with brain injury + 26 controls

ultrasounded ONSD, then intraparenchymal catheter to measure ICP

severe brain injured patients (ONSD 6.1 +/- 0.7 mm; ICP 26.2 +/- 8.7 mmHg)

moderate brain injury (ONSD 4.2 +/- 1.2 mm; ICP 12.0 +/- 3.6 mmHg)

controls (ONSD 3.6 +/- 0.6 mm; ICP 10.3 +/- 3.1 mmHg).

best cut-off value of ONSD for predicting elevated ICP was 5.7 mm (sensitivity = 74.1% and specificity = 100%)

 

 

 

References: sonoguide; study 1; study 2; picture

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