Abstract

The myodural bridge (MDB) is a dense connective tissue bridge connecting the suboccipital muscles to the spinal dura mater, and it has been proven to be a normal common existing structure in humans and mammals. Some scholars believe that the suboccipital muscles can serve as a dynamic cerebrospinal fluid (CSF) pump via the MDB, and they found head rotations promote the CSF flow in human body, which provided evidence for this hypothesis. Head movement is a complex motion, but the effects of other forms of head movement on CSF circulation are less known. The present study explored the effects of head-nodding on CSF circulation. The CSF flow of 60 healthy volunteers was analyzed via cine phase-contrast magnetic resonance imaging at the level of the occipitocervical junction before and after one-minute-head-nodding period. Furthermore, the CSF pressures of 100 volunteers were measured via lumbar puncture before and after 5 times head-nodding during their anesthetizing for surgical preparation. As a result, it was found that the maximum and average CSF flow rates at the level of the upper border of atlas during ventricular diastole were significantly decreased from 1.965 ± 0.531 to 1.839 ± 0.460 ml/s and from 0.702 ± 0.253 to 0.606 ± 0.228 ml/s respectively. In the meantime, the changes in the ratio of cranial and caudal orientation of the net flow volume were found differed significantly after the one-minute-head-nodding period (p = 0.017). And on the other hand, the CSF pressures at the L3–L4 level were markedly increased 116.03 ± 26.13 to 124.64 ± 26.18 mmH2O. In conclusion, the head-nodding has obvious effects on CSF circulation and head movement is one of the important drivers of cerebrospinal fluid circulation. We propose that the suboccipital muscles, participating in various head movements, might pull the dura sac via the myodural bridge, and thus, head movement provides power for the CSF circulation.

Highlights

  • The myodural bridge (MDB) is a dense connective tissue bridge connecting the suboccipital muscles to the spinal dura mater, and it has been proven to be a normal common existing structure in humans and mammals

  • In order to verify relationships between the cerebrospinal fluid (CSF) circulation dynamics and head movements, and to provide physiological data for revealing the role of MDB, the present study explored the effects of head-nodding movement on CSF circulations

  • It was well known that they were connected to the upper cervical spinal dura mater via the MDBs through the posterior atlanto-occipital and atlanto-axial ­interspaces[1,2,3,4,5,6]

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Summary

Materials and methods

Approval from the Ethics Committee for Research at the Basic Medical College of Dalian Medical University was obtained for this study. A cine-PC MR imaging ­method[21] was used to measure the cardiac-gated CSF flow through the transverse plane at the level of the upper border of atlas with a peripheral pulse trigger Volunteers lied on an MR bed with a cushion pillow, One head-nodding cycle was counted when a head extended from the neutral position to the largest range and back to the origin and flexed from the neutral position to the largest range and back to the neutral position Volunteers nodded their heads according to the researcher’s instructions for one-minute-head-nodding normalization of 30 times within 1 min. When the fluid level in the piezometer tube slowly rose and stabilized, the CSF pressure ­(mmH2O), blood pressure (mmHg), and heart rate (times/min) were recorded. Statistical significance was calculated using a paired sample t test, rank sum test and Chi-square test in SPSS 17.0. p value of less than 0.05 indicated a statistically significant difference

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