Transorbital Ultrasound of Optic Nerve Sheath Diameter Between Healthy Pregnant Women and Those With Severe Preeclampsia.

Study Overview
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Brief Summary
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The neurological alterations associated with preeclampsia depend on cerebral autoregulation, a theory that outlines the mechanisms by which the nervous system controls cerebral perfusion. However, with the loss of autoregulation, increased blood flow, edema and eventually increased intracranial pressure are triggered and may be translated into neurological manifestations such as symptoms of vasospasm, one of the criteria for severity in preeclampsia. Nervous system manifestations frequently found in preeclampsia are headache, blurred vision, scotomas and hyperreflexia. Although uncommon, temporary blindness (lasting a few hours to a week) may also accompany severe preeclampsia and eclampsia. The optic nerve, as part of the central nervous system, is surrounded by cerebrospinal fluid and dura mater, which forms the optic nerve sheath. Due to the connection with the intracranial subarachnoid space, the diameter of the optic nerve sheath is influenced by variations in cerebrospinal fluid pressure. Increased intracranial pressure is transmitted to the subarachnoid space surrounding the optic nerve, causing its expansion. Recent studies suggest that an optic nerve sheath diameter greater than 5 mm correlates 100% with ICP (intracerebral pressure) greater than 20 mm Hg. Due to the simple nature of the test and the limited time required to perform it, it is an ideal non-invasive test to assess changes in mental status, severe headache, and to take the necessary measures aimed at reducing intracranial pressure. The diagnosis of elevated intracranial pressure is challenging and critical, because early recognition and treatment are essential to prevent brain damage or death since preeclampsia with severe data remains one of the most frequent complications in our institution. These values are not taken from the obstetric population, so this study proposes the description of a standard value for the pregnant population. There are few studies that describe a value to help us define cases of this pathology and correlate it with the signs and symptoms of severity in patients with preeclampsia.

Official Title
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Transorbital Ultrasound Measurement of Optic Nerve Sheath Diameter Between Pregnant Women With Severe Preeclampsia and Normal Gestations. Prospective, Controlled Trial.

Conditions
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Preeclampsia Severe

Intervention / Treatment
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* Procedure: Transorbital ultrasound of the optic nerve sheet


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age between 15-44 years. Gestational age between 34-40 weeks of gestation. Exclusion Criteria: Eye disease (Glaucoma, diabetic neuropathy, optic neuritis). Nervous disorders. Psychiatric disorders Diabetes

Ages Eligible for Study
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Minimum Age: 15 Years
Maximum Age: 44 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: A transorbital ultrasound to measure the optic nerve sheet will be performed in patients with severe preeclampsia and then compared with normal controls.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Preeclampsia<br>Patients with severe preeclampsia and gestational age between 34-40 weeks. | Procedure: Transorbital ultrasound of the optic nerve sheet<br>* Measurement of the optic nerve sheet with a linear transducer (7,5 MHz).<br>|
| Active Comparator: Control<br>Patients with normal gestations between 34-40 weeks. | Procedure: Transorbital ultrasound of the optic nerve sheet<br>* Measurement of the optic nerve sheet with a linear transducer (7,5 MHz).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Optic nerve sheet measurement | The diameter of the optic nerve sheath was measured three millimeters behind the eyeball, and one axis perpendicular to the optic nerve. Three measurements were taken in each eye. The resulting six measurements were averaged to give a mean of the optic nerve sheet measurement, to minimize measurement variability. | 24 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Severe preeclampsia, Optic nerve sheet, Intracranial pressure