Effects of the Valsalva maneuver on pial artery pulsation and subarachnoid width in healthy adults.

AIM: The objective was to characterize the effects of Valsalva maneuver (VM) on the amplitude of cerebrovascular pulsation (CVP), and to explore the direct interactions between the cerebral vasculature and the cerebrospinal fluid compartment in VMIII. METHODS: Twenty-nine healthy volunteers between the ages of 25 and 40 (29.3 ± SE 4.0) were studied. Changes in the amplitude of CVP (cc-TQ) and width of subarachnoid space (SAS; sas-TQ) were recorded with NIR-T/BSS sensor. Changes in arterial blood pressure (ABP) and heart rate were measured using Finapres. Cerebral blood flow velocity (CBFV) in the left middle cerebral artery was recorded with transcranial doppler. RESULTS: sas-TQ remained unchanged, while cc-TQ increased in VMI (+40% vs. baseline). In VMIIa, sas-TQ increase (+3.4% vs. baseline) and deep decrease in cc-TQ (-81% vs. baseline) were observed. sas-TQ decrease started in VMIIb (-2.7% vs. baseline), with simultaneous slight increase in cc-TQ (-58% vs. baseline). In VMIII deep sas-TQ decrease (-6.2% vs. baseline) was associated with huge increase in cc-TQ (+110% vs. baseline; r=-0.56, p<0.01). During VMIV sas-TQ increased (-4.8% vs. baseline) while cc-TQ decreased (+38% vs. baseline). The drop of cc-TQ in VMIIa was significantly greater than corresponding changes in CBFV and ABP. Increase in cc-TQ in VMIII preceded CBFV and ABP changes in VMIV. CONCLUSION: The VM evokes significant changes in the amplitude of CVP. Changes in small vessel pulsation precede changes in CBFV. There are direct interactions between cc-TQ and sas-TQ in VMIII. NIR-T/BSS allows for continuous, non-invasive monitoring of the amplitude of CVP and width of the SAS.