Sub Arachnoid Hemorrhage (SAH) is a public health concern because of its high incidence
(7/100 000 inhab.), its mortality rate (25%), and its morbidity rate (50%).
Prognostic tools are indispensable in guiding and optimizing the care of these patients.
Some diagnostic factors have been identified (e.g. age, comorbidities, ACSOS , GCS, ICP,
occurrence of complications) as well as some classification schemes used for grading
seriousness of the disease (Hunt and Hess, World Federation of NeuroSurgery).
A tool that is simple, reliable, reproducible, non costly, non invasive, and simple to
perform (including remote methods and without changing planned patient care) would be ideal.
The measurement of the Optic Nerve Sheath Diameter (ONSD,) correlated by MRI and ultrasound
in previous studies, with intra-cranial pressure (ICP: a fundamental prognostic factor for
SAH) could be one of these tools.
This measurement, previously demonstrated using ultrasound, could be carried out at the time
of the patient's initial cerebral scan.
In practice, at admission each patient undergoes a cerebral CT scan much more often than an
ultrasound (faster, less costly, less technical training required).
Two preliminary studies seem to suggest that this measurement of ONSD on CTc is a predictive
factor for morbi-morbidity in patients having serious traumatic skull fractures.The
measurement is reliable, reproducible, non invasive, and non costly, with good sensitivity
Proving that it is also applicable to SAH could be particularly useful.