The Optic Nerve Sheath Diameter (ONSD), measured non-invasively by bedside ultrasound, is a well-established surrogate for intracranial pressure (ICP), as the optic nerve sheath is continuous with the intracranial dura mater and its subarachnoid space is filled with cerebrospinal fluid (CSF). While ONSD is typically used to detect elevated ICP (with a cut-off often \> 5.0-5.7 mm for ICP \> 20 mmHg), studies investigating PDPH have paradoxically shown a reduction in ONSD post-spinal anesthesia, correlating with the state of intracranial hypotension.
Previous research has demonstrated that a lower ONSD or a significant decrease in ONSD values 24 hours post-puncture is associated with PDPH development. A study determined that an ONSD at 24 hours of less than 0.40 cm was the best predictor for PDPH. Our study aims to specifically investigate the utility of the immediate change in ONSD to offer a bedside, real-time assessment of risk.
Adult female patients, aged 18-45 years
ASA(American Society of Anesthesiologists) physical status II or III
Scheduled for elective cesarean section
Undergoing surgery under standardized spinal anesthesia
Pre-existing headache disorders (e.g., migraine, chronic tension-type headache)
Known ophthalmic conditions (e.g., optic neuropathy, glaucoma)
Inability to cooperate with ONSD(Optic Nerve Sheath Diameter) ultrasound measurements or follow-up
Allergy to local anesthetics
Target Population: The target population consists of adult female parturients who are medically eligible for spinal anesthesia and are undergoing elective cesarean delivery in a hospital setting. Source Population: The source population is defined as all consecutive adult female patients (aged 18-45 years, ASA II-III) who are admitted to Benha University Hospitals for an elective cesarean section during the study enrollment period (December 2025 - June 2026) and who meet the eligibility criteria. Study Sample (Final Cohort): The study sample will comprise 150 consenting patients drawn consecutively from the source population, forming a single observational cohort. These participants will undergo standardized spinal anesthesia and serial Optic Nerve Sheath Diameter (ONSD) measurements, with follow-up for Post-Dural Puncture Headache development over 72 hours.
Cohort
Prospective
Study Cohort (Single Cohort)
Procedure/SurgeryThis study comprises a single, prospectively enrolled cohort of 150 adult female patients (ASA physical status II-III) scheduled for elective cesarean section under standardized spinal anesthesia. All participants receive the same planned intervention (spinal anesthesia for surgery) and undergo the same standardized measurement protocol for Optic Nerve Sheath Diameter (ONSD). Within this cohort, participants are naturally divided by outcome during follow-up into two groups for analytical purposes: PDPH-Positive Subgroup: Patients who develop Post-Dural Puncture Headache (PDPH) within 72 hours, as diagnosed using the International Classification of Headache Disorders (ICHD-3) criteria. PDPH-Negative Subgroup: Patients who do not develop PDPH within the follow-up period.
Optimal Delta ONSD cut-off value for predicting PDPH
To determine the numerical value of the change in Optic Nerve Sheath Diameter (Delta ONSD = ONSD\<sub\>pre\</sub\> - ONSD\<sub\>post\</sub\>) that best predicts the development of PDPH.
Post-Dural Puncture Headache (PDPH)
To assess the intensity of headache pain. By Numeric Rating Scale (NRS): 0 (no pain) to 10 (worst imaginable pain).
The Need for Epidural Blood Patch (EBP)
The % of patients requiring an Epidural Blood Patch will de determined
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Al-Azhar University
Lead sponsor
Benha University
Collaborator
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