Vasomotor reactivity comparison in multiple sclerosis patients with white matter lesions and nonmultiple sclerosis subjects with white matter lesions in brain magnetic resonance imaging

Cerebrovascular Reactivity and Neurovascular Coupling in Multiple Sclerosis-A Systematic Review

The inflammatory processes observed in the central nervous system in multiple sclerosis (MS) could damage the endothelium of the cerebral vessels and lead to a dysfunctional regulation of vessel tonus and recruitment, potentially impairing cerebrovascular reactivity (CVR) and neurovascular coupling (NVC). Impaired CVR or NVC correlates with declining brain health and potentially plays a causal role in the development of neurodegenerative disease. Therefore, we examined studies on CVR or NVC in MS patients to evaluate the evidence for impaired cerebrovascular function as a contributing disease mechanism in MS. Twenty-three studies were included (12 examined CVR and 11 examined NVC). Six studies found no difference in CVR response between MS patients and healthy controls. Five studies observed reduced CVR in patients. This discrepancy can be because CVR is mainly affected after a long disease duration and therefore is not observed in all patients. All studies used CO₂ as a vasodilating stimulus. The studies on NVC demonstrated diverse results; hence a conclusion that describes all the published observations is difficult to find. Future studies using quantitative techniques and larger study samples are needed to elucidate the discrepancies in the reported results.

Effects of low oxygen dead space ventilation and breath-holding test in evaluating cerebrovascular reactivity: A comparative observation

OBJECTIVE

This study aims to explore the application prospect of low oxygen dead space ventilation (LODSV) in evaluating vasomotor reactivity (VMR) by comparison between LODSV and breath-holding test (BHT).

METHODS

Outpatient or inpatient patients who underwent transcranial Doppler sonography (TCD) were enrolled into this study. These patients successively underwent BHT and LODSV. The cooperation degree, tolerance conditions and adverse reactions in patients were recorded, and VMR was calculated, compared and analyzed.

RESULTS

Patients had poor cooperation during BHT. Except for compensatory tachypnea after BHT, patients basically had no adverse reaction. The main manifestations of patients undergoing LODSV were deepened breathing and accelerated frequency in the end of the ventilation, and increased heart rate and a slight decline in pulse oxygen that rapidly recovered after ventilation. The increase rate of blood flow velocity in patients undergoing LODSV was significantly higher than in BHT (P<0.001), and its calculated VMR value was approximately 15% higher than BHT (P<0.001). BHT revealed a monophasic curve that slightly descends and rapidly increases, and LODSV revealed a curve that descends for a short time and slowly increases with a platform.

CONCLUSION

LODSV can effectively eliminate the affect of poor cooperation in patients, and avoid intolerance caused by hypoxia. Hence, VMR value is more accurate than that determined by BHT; and this can reflect the maximum reaction ability of the blood vessels. Therefore, this method has higher clinical application value.