FUNDAMENTALS OF TRANSORBITAL SONOGRAPHIC EVALUATION OF OPTIC-NERVE SHEATH EXPANSION UNDER INTRACRANIAL HYPERTENSION .2. PATIENT STUDY

Up to now, the presence of elevated intracranial pressure (ICP) in acu te neurological disorders is suspected by clinical and neuroimaging fi ndings, but its veri fication depends on invasive techniques. Based on our experimental findings of rapid dilatation of human optic nerve sh eaths (ONS), we investigated whether this phenomenon not only happens under chronic, but also under acute conditions of intracranial hyperte nsion. Using optic nerve sonography the ONS was measured at 3 mm behin d the papilla in axial transbulbar view. Thirty-nine children admitted to the intensive care unit (ICU) were examined. Of these 24 were bein g treated for elevated ICP (head trauma, metabolic disorder) and were compared to control patients (outpatients). The ONS diameter (ONSD) fo und in ICU patients with elevated ICP ranged up to 6.8 mm and was sign ificantly enlarged compared with normal data (Wilcoxon's test, P = 0.0 07). The ONSD of ICU patients without pressure elevation was in the sa me range as that of control patients (2.7-4.0 mm). Considering the err or of measurement (0.35 mm), the ONSD is regarded as definitely enlarg ed when 5 mm is exceeded in children above age 4. In younger children, smaller ONSD have to be taken into consideration. We conclude that ul trasound studies of the optic nerve may contribute information about t he acutely increased ICP in critically ill patients.