Assessment of optic nerve sheath diameter using ultrasonography in patients with clinical and radiological suspicion of elevated ıntracranial pressure in the ıntensive care unit.

OBJECTIVE

The aim of this study was to evaluate optic nerve sheath diameter using ultrasonography in patients with clinical and radiological suspicion of elevated intracranial pressure in the intensive care unit. Elevated intracranial pressure is a critical condition resulting from various intracranial pathologies and constitutes a major cause of morbidity and mortality.

METHODS

Several invasive and noninvasive methods are available for detecting elevated intracranial pressure. Although invasive methods are regarded as the gold standard, they are associated with certain disadvantages. Ultrasonographic measurement of optic nerve sheath diameter, a noninvasive technique, has gained prominence owing to its repeatability, bedside applicability, and cost-effectiveness. From June to December 2023, 50 patients with suspected elevated intracranial pressure based on cranial computed tomography findings and clinical presentation, along with 36 healthy volunteers, were included in the study.

RESULTS

Optic nerve sheath diameter was significantly greater in patients (right 6.13±0.50 mm, left 6.13±0.51 mm) compared with controls (right 4.23±0.22 mm, left 4.23±0.21 mm; p<0.001). Moreover, optic nerve sheath diameter was significantly correlated with mortality, as well as with Glasgow Coma Scale, Full Outline of UnResponsiveness, Acute Physiology and Chronic Health Evaluation II, and Sequential Organ Failure Assessment scores. Patients with computed tomography findings such as brain edema and midline shift also exhibited significantly elevated optic nerve sheath diameter values.

CONCLUSION

Ultrasonographic measurement of optic nerve sheath diameter represents a reliable adjunctive modality for identifying patients with radiological signs of elevated intracranial pressure and for prognostic assessment in the intensive care unit. Nevertheless, the lack of invasive intracranial pressure monitoring as the gold standard constitutes a major limitation, and validation against direct intracranial pressure measurements is warranted in future studies. This technique may be particularly useful in hemodynamically unstable patients who cannot be safely transferred for computed tomography imaging.