Research on Spinal Cord Injury by Andrew K Fletcher
Respiration and Posture Link To Cerebrospinal fluid circulation
- Spinal cord injury (SCI) Inclined Bed Therapy Research
CEREBROSPINAL FLUID STASIS AND ITS CLINICAL SIGNIFICANCE
"Respiratory Influences on CSF Fluctuation
The systolic pulse wave is well established as the primary impetus for CSF circulation, but there is evidence that the respiratory rhythm also plays a significant role. A recent study of CSF pressure oscillations in anesthetized rats found that the strongest oscillations were coincident with ventilatory chest movement (both spontaneous and mechanically assisted) rather than arterial pulse pressure. CSF pressure oscillations were found to be only weakly entrained to heart rate.29
Maier et al observed that normal respiration may induce periodic brainstem motion as strongly as systolic phase arterial expansion. The respiratory cycle drives a low frequency oscillation of the brainstem, in which caudal brain displacement corresponds with expiration and cephalad rebound corresponds with inspiration. The effect is more pronounced with forced respiration. This respiratory phase pulse, superimposed upon the higher frequency cardiovascular pulse, appears to influence cerebrospinal fluid fluctuation. Modified respiratory efforts affect CSF fluctuation in peculiar ways. Valsalva maneuver quickly causes caudad and then cephalad brainstem movement. Coughing causes a cephalad impulse in CSF flow.30"
Yoga practice may enhance CSF flow. CSF flow appears to be related to postural changes in pressure measurements, which correspond closely with the degree of inclination of the body. In the prone position, cranial and lumbar CSF pressures are approximately equal. Standing posture reduces cephalad flow of CFS, lowers cervical SAS pressure, and increases lumbar pressure.71 With cervical spine flexion, the ventral SAS narrows up to 43%, and the dorsal SAS widens up to 89%. In extension, the ventral cervical SAS increase up to 9%, and the dorsal SAS is reduced up to 17%, as compared with the neutral position. These changes are associated with changes in the sagittal diameter of the cervical cord, which is decreased 14% in flexion and increased 15% in extension, compared with neutral.72 Because CSF flow appears to follow the path of least resistance,14 yoga postures of spinal flexion, extension and inversion, as well as patient positioning for structural and energetic therapies, can be expected to affect CFS flow. Alternating spinal flexion and extension may create a pumping effect that enhances CSF fluctuation. In a study involving seventy-one human subjects, Byrne et al demonstrated that oscillatory head tilt significantly increased the amplitude of THM variance, and the changes were apparently moderated by increased parasympathetic tone.73 Yogic practices that induce what some sources refer to as kriyas (involuntary oscillations of the spine and or extremities) may enhance CSF flow as well. (In Sanskrit the word “kriya” denotes action or a process that can produce a desired effect.) The somatopsychic wave phenomenon reported in recipients of Network Care may have a similar effect.36"