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

Condition(s) studied

Investigational drug(s) / intervention(s)

Study Cohort (Single Cohort): 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.

Study summary

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.

Eligibility

Primary outcome measure(s)

• Optimal Delta ONSD cut-off value for predicting PDPH — 72 hours post-spinal.
  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.

Trial sites (1)

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