Effects of Cervical Hyperextension on Cervical Blood Flow, Cerebral Oximetry and Cognitive Functions.

Study Overview
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Brief Summary
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The goal of this observational study is to determine the effects of cervical hyperextension on cerebral oximetry and cognitive functions in healthy individuals without other additional factors such as anesthesia and surgical stress. The main questions it aims to answer are: Can cervical hyperextension cause changes in cerebral oxygenation in non-anesthetized healthy individuals? Can cervical hyperextension cause changes in cervical and cerebral blood flow in non-anesthetized healthy individuals? Can cervical hyperextension cause changes in cognitive functions in non-anesthetized healthy individuals? Can cervical hyperextension cause changes in optic nerve sheath diameter in non-anesthetized healthy individuals? Participants will be monitored with cerebral oximeter device and asked to answer Montreal cognitive function test before and during cervical hyperextension position. The researchers will evaluate the changes in cervical and cerebral blood flow ultrasonographically before and during cervical hyperextension position.

Detailed Description
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Some operations are performed in the cervical hyperextension position. During the cervical hyperextension position, changes in neck blood flow as a result of stretching of neck vessels can occur. These changes can be observed as an increase or decrease in cerebral blood flow. Changes in cerebral blood flow can lead to changes in brain oxygenation and affect cognitive functions. Aim: This study aims to show the effects of cervical hyperextension on cerebral oximetry and cognitive functions in healthy individuals without other additional factors such as anesthesia and surgical stress. Method: Healthy volunteers who meet the specified criteria and sign informed consent will be included in the study. All volunteers will be asked to answer validated Montreal cognitive assessment test in Turkish. Cerebral oximetry will be monitored by 2 probes placed on the frontal bone while all volunteers are lying in a supine position with the neck in a neutral position. Basal cerebral oximetry values will be recorded. In the same position cervical blood flow values and optic nerve sheath diameter will be measured by the same and experienced researcher non-invasively with a Doppler ultrasonography device and recorded. Optimum cervical hyperextension position will be obtained by placing the standard pad under the neck of the volunteers. In the meantime cerebral oximetry values will be recorded. Cervical blood flow will be re-measured in this position non-invasively with a Doppler ultrasonography device and recorded. Cerebral oximeter values will be recorded every 5 minutes for 30 minutes. In the end of 30 minutes period of hyperextension position the cervical blood flow and optic nerve sheath diameter will be measured again non-invasively with a Doppler ultrasonography device and recorded. Immediately afterwards, the Montreal cognitive assessment test will be repeated without changing the position. After all measurements are completed, the procedure will be terminated by resting the volunteer in neutral position for 15 minutes.

Official Title
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The Effects of Neck Hyperextension on Neck Blood Flow, Cerebral Oximetry and Cognitive Functions in Adult Healthy Volunteers

Conditions
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Hyperextension Injury of Neck

Intervention / Treatment
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* Other: Doppler ultrasonography


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18-65 years, healthy volunteers Exclusion Criteria: diabetes mellitus, chronic obstructive pulmonary disease, Liver failure, Kidney failure, Past coronary arteria by-pass graft history, Hemoglobinopathies, Anemia, hypertensive patients, Alzheimer's disease, neurodegenerative diseases, mental retardation, Vertebrobasilar system anomalies detected in magnetic resonance-angiography

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Other: Doppler ultrasonography|All volunteers will be monitored with cerebral oximeter, asked to answer the Montreal cognitive assessment test and cervical blood flow values and optic nerve sheath diameter will be determined with Doppler ultrasonography.|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline in the cervical blood flow rates | Cervical blood flow measurement will be performed 3 times by the same and experienced researcher with the same Doppler ultrasonography device; before cervical hyperextension in neutral position, in the first 5 minutes of cervical hyperextension, in the end of 30 minutes period of cervical hyperextension position. | Cervical blood flow measurement will be performed 3 times in 30 minute period. | 
| Change from baseline in the optic nerve sheath diameter | Optic nerve sheath diameter measurement will be performed 2 times by the same and experienced researcher with the same Doppler ultrasonography device: before cervical hyperextension in neutral position, in the end of 30 minutes period of cervical hyperextension position. | Optic nerve sheath diameter measurement will be performed 3 times in 30 minute period. | 
| Change from baseline in the cerebral oximeter values | Cerebral oxygenisation values will be measured continuously before and during the cervical hyperextension position with a transcutaneous near infrared spectroscope device (NIRS) via two transcutaneous probes placed on the frontal bone non-invasively and recorded. | Cerebral oxygenisation values will be measured continuously before and during the cervical hyperextension position and recorded in every 5 minutes in 30 minute period. | 
| Change from baseline in the Montreal cognitive assessment test | All volunteers will be asked to answer the Montreal cognitive assessment test 2 times by the same researcher; before cervical hyperextension in neutral position, in the end of 30 minutes period of cervical hyperextension position. | Montreal cognitive assessment test will be performed 2 times in 30 minute period. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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optic nerve sheath, hyperextension of neck, cervical blood flow, cerebral oxygen saturation