Intracranial Hypertension and Optic Nerve Sheath Diameter

Intracranial hypertension (ICH) is a mortality risk factor in severe traumatic brain injury (TBI), in purulent meningitis, in hepatic encephalopathy and in Reye's syndrome. It is also a risk factor for severe neurologic sequelae in survivors. Intracranial pressure (ICP) monitoring is likely to guide therapeutics, and certain research on adults or on children, suggest that IH therapeutic approach, for instance for bacterial meningitis, would improve the prognosis. Two monitoring techniques are currently recommended. They are reference methods for ICP measure : * monitoring with intraventricular catheter, * intra-parenchymal monitoring using optical fiber catheter. Non invasive methods have been suggested, including ultrasound measurement of optic nerve sheath diameter (ONSD) which is the most interesting one. The ONSD measured ultrasonically is correlated with ICP level in adults with severe TBI. A diameter over 5,9 mm predicts ICH within the first 24 hours. In children, ONSD average values have been worked out, and an ONSD increase is found in children suffering from hydrocephalus with IH and in children with TBI. ICH precocious detection is fundamental in children sensitive to ICH because their cerebral development is not finished yet. Difficulties met for ICP monitoring implementation in infants and its invasive nature are often disliked by clinicians. A non-invasive exam is then essential to allow a better care of children with ICH in intensive care unit.