Bedside Ultrasound Measurement of Optic Nerve Sheath Diameter for Detecting Raised Intracranial Pressure

Raised intracranial pressure (ICP) is a serious medical emergency that requires prompt recognition to prevent brain damage. While invasive pressure monitoring and brain CT scans are commonly used, bedside transorbital ultrasonography to measure optic nerve sheath diameter (ONSD) offers a rapid, non-invasive alternative. The purpose of this study is to evaluate the diagnostic accuracy of bedside ultrasound measurement of ONSD in detecting raised ICP in adult patients, using brain CT scan findings as the reference standard. Adult patients clinically suspected of having elevated intracranial pressure and referred for a brain CT scan will undergo a non-invasive bedside ocular ultrasound examination. The optic nerve sheath diameter will be measured in both eyes and compared with independent CT brain interpretations to assess sensitivity, specificity, and the optimal diagnostic cut-off value.

Inclusion Criteria: * Adults aged ≥ 18 years * Clinical suspicion of acutely raised intracranial pressure (e.g., altered level of consciousness, papilledema, progressive headache, vomiting, or focal neurological deficits) * Referred to undergo a brain CT scan * Hemodynamically stable at the time of ultrasound examination Exclusion Criteria: * Pre-existing orbital or ocular trauma * Known history of optic nerve disease (e.g., optic neuritis or glaucoma) * Previous ocular or intraorbital surgery * Severe ocular pathology preventing safe transorbital ultrasonographic assessment * Refusal to participate or lack of informed consent from the patient or legal guardian