Die Optikus-Sonografie bildet Papille, Sehnerv sowie dessen perineuralenLiquorraum ab und eröffnet damit u. a. einen diagnostischen Zugang zumintrakraniellen Liquorsystem und dessen Druck(ICP). Auf diese Weise lässt sich eine relevante ICP-Erhöhung über 20 mmHg nicht-invasiv und bettseitig belegen. Mit Einzelmessungen und Verlaufskontrollen hilft die Methode u. a. vor und nach der Etablierung eines invasiven ICP-Monitorings in der Intensiv- und Notfallmedizin sowie bei der Beurteilung chronischer Dysregulationen des ICP.
Abstract
B-Scan ultrasound studies of the optic nerve have focused on the perineural subarachnoidal space and the papillary region to provide information about cerebrospinal fluid dynamics. Enlarged and significantly increasing diameters of the optic nerve sheath (ONSD) are characteristic for established or emerging intracranial hypertension, respectively. Though changes of the ONSD appear earlier than papilledema, diagnostic pitfalls and alternative etiologies of enlarged optic discs must be considered. Orbital ultrasound as a repeatable, non-invasive and bedside procedure can be used for screening purposes in emergency medicine as well as for follow-up studies in the intensive care unit. Negative ONSD-findings allow to exclude intracranial hypertension with a specificity of 85% and higher. In this way potentially stressful transports to the MRI- or CT-scanners become redundant and expenses can be saved. Pathologically wide ONSD or progressively enlarging ONSD (more than 0,3 mm) can predict intracranial hypertension and are useful to identify candidates for invasive ICP-monitoring (ONSD ≥ 5mm in adults accompanies ICP>20 mmHg, sensitivity 85–90%). In cases where invasive techniques are inapplicable, serial ONSD measurements can help to monitor the course of increasing ICP. The restitution of abnormally high ICP, however, is not reliably accompanied by a corresponding decline of ONSD, especially once the ICP exceeded 45 mmHg or more.
Our review discusses the progress of optic nerve ultrasound studies since first reports in intensive care patients. Technical aspects, abnormality criteria according to age, physiological factors influencing the ONSD and interesting applications in acute and chronic conditions of ICP dysregulation are discussed.
Key words
optic nerve sheath - intracranial pressure - cerebrospinal fluid - orbital ultrasound - monitoring
Schlüsselwörter
Sehnervhülle - intrakranieller Druck - Liquor - orbitale Sonografie - Monitoring
