Effect of gravity on brain structure as indicated on upright computed tomography

Area of Science:

• Neuroimaging
• Human Physiology
• Biomedical Engineering

Background:

• Gravity influences intracranial pressure and fluid dynamics.
• Understanding posture-related brain changes is crucial for interpreting neuroimaging findings.

Purpose of the Study:

• To quantify posture-related changes in brain structures using upright computed tomography (CT).
• To assess alterations in the pineal body, cerebellar tonsil, pituitary stalk, optic nerve sheath, and lateral ventricles.

Main Methods:

• Thirty-two healthy volunteers underwent upright CT in a sitting position and conventional CT in a supine position.
• Key intracranial structures and cerebrospinal fluid (CSF) spaces were measured and compared between postures.

Main Results:

• Significant ventral and caudal shifts of the pineal body were observed in the sitting position.
• Cerebellar tonsil descended, pituitary stalk length decreased, and optic nerve sheath dimensions reduced.
• Lateral ventricular volume decreased by approximately 5% in the sitting position compared to supine.

Conclusions:

• Intracranial structures and lateral ventricular volume in healthy subjects are significantly affected by posture under normal gravity.
• These findings highlight the importance of considering patient positioning in neuroimaging studies.