Ultrasonographic ONSD as a Predictor of PDPH in Spinal Anesthesia for Cesarean Delivery

Al-Azhar University

Status: Not yet enrolling

Conditions: Cesarean Section Complications

Treatments: Procedure: Study Cohort (Single Cohort)

Study type: Observational

Funder types: Other

Identifiers

NCT07360756

RC. 1.12.2025

Details and patient eligibility

About

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.

Enrollment: 150 estimated patients

Sex: Female

Ages: 18 to 45 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• 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

Exclusion criteria

• 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

• Emergency cesarean section

• Contraindications to spinal anesthesia:

  • Coagulopathy
  • Infection at the puncture site

• Preexisting hypertension on medication

• Pre-eclampsia with severe features (suggested for separate study)

• Known cardiac disease with hemodynamic instability

• Allergy to study drugs

• Fetal distress or non-reassuring cardiotocography (CTG)

• Body Mass Index (BMI) >40 kg/m²

• Refusal to sign informed consent

Trial design

150 participants in 1 patient group

Study Cohort (Single Cohort)

Description:

This 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.

Treatment:

Procedure: Study Cohort (Single Cohort)