Noninvasive Sonographic Evaluation of the Intracranial Pressure in Brain-Injured Adults

Abstract

The optic nerve sheath diameter (ONSD) may be increased in brain-injured patients with elevated intracranial pressure (ICP). We investigated whether ONSD measurements correlated with noninvasive and invasive ICP measurements in brain-injured adults. We examined 106 brain-injured patients and 67 control subjects without intracranial pathology. Brain-injured patients were evaluated clinically (Glasgow coma scale, GCS) and using a semiquantitative (I–VI) neuroimaging scale (Marshall Scale, MS), and were divided into those with moderate (MS = I and GCS>8, n = 35) and severe (MS = II–VI and GCS≤8, n = 71) brain injury. During Hospitalization, patients with severe brain injury underwent three measurements of the ONSD and noninvasive ICP (eICP), using optic nerve sonography and transcranial Doppler sonography, respectively. Upon admission, 32 severely brain-injured patients additionally underwent invasive ICP measurement. In severely brain-injured patients, the ONSD correlated with the MS (r = 0.76–0.82) and the eICP (r = 0.53–0.80) in all three evaluations (P<0.001), whereas ONSD and eICP were significantly increased (6.2±0.7mm and 27.5±6.9mmHg, P<0.0001) as compared with moderately brain-injured patients (4.2±0.9mm and 12.2±3.7mmHg) and controls (3.5±0.8mm and 9.9±3.7mmHg). Invasive ICP measurements also correlated with ONSD measurements (r = 0.68, P = 0.002). The best cut-off ONSD value for predicting elevated ICP was 5.7 mm (sensitivity = 74.1%, specificity = 100%). ONSD measurements correlate with noninvasive and invasive ICP measurements, and with neuroimaging findings in brain-injured adults. Optic nerve sonography could alert clinicians to the presence of elevated ICP, whenever invasive ICP evaluation is contraindicated and/or is unavailable.