Studies that assessed the diagnostic accuracy of ultrasonography of optic nerve sheath diameter versus intraventricular or intraparenchymal intracranial pressure monitoring for the assessment of intracranial hypertension were eligible for inclusion.
The included studies were prospective cross-sectional design. Studies were of adult patients (older than 18 years) with traumatic brain injury, subarachnoid haemorrhage, stroke, intracranial haemorrhage, intracranial haematoma, severe brain injury and spontaneous or primary intracerebral haemorrhage. Four studies used ultrasonography of optic nerve sheath diameter and intraventricular or intraparenchymal intracranial pressure monitoring simultaneously. Two studies had less than a one hour delay between the two tests. The threshold ranged from 5.0mm to 5.9mm. Studies were published between 2007 and 2009.
Three reviewers independently undertook study selection. Disagreements were resolved by consensus.