OPTIC-NERVE SHEATH ENLARGEMENT IN ACUTE INTRACRANIAL HYPERTENSION

B-scan sonography can image the optic nerve and allows to measure the sheath diameter on-line. For 20 adult control subjects the optic nerve sheath (ONS) diameter ranged between 2.9 and 4.3 mm (mean 3.6) In the follow-up of I6 severe acutely brain injured patients (cerebrovascula r and traumatic disease) leading to elevated intracranial pressure, ON S-diameters were significantly enlarged (mean 5.5 mm). The underlying ONS dilatations can be explained by cerebrospinal fluid shift from the intracranial subarachnoidal compartment. Markedly enlarged ONS were f ound in nearly all cases and the recorded maximum diameters ranged bet ween 3.8 and 6.9 mm. Usually papilledema was not detectable on the day of maximum ONS-diameter, but ONS dilatations were recorded as early a s four hours after trauma. Optic nerve sheath diameters exceeding 5.0 mm bilaterally always corresponded with elevated intracranial pressure and can serve as a marker for intracranial hypertension provided othe r neuropathies can be excluded. In this way, the authors currently use this non-invasive technique in the evaluation of acute neurological d isorders at the bedside.