Introduction

Idiopathic intracranial hypertension (IIH) and idiopathic normal pressure hydrocephalus (iNPH) both are the functional brain diseases with unclear pathogenesis. The disorders of hemodynamics and CSF flow are a significant role in these syndromes. Nevertheless, the exact mechanisms of its dysfunction are not clearly defined. The purpose of this study was to reveal the most important aspects of the hemo- and cerebrospinal fluid dynamics in patients with idiopathic intracranial hypertension and idiopathic normal pressure hydrocephalus.

Materials and Methods

The two groups of volunteers were formed: the patient group consisted of 9 patients with clinical/radiological signs of either IIH or iNPH without any organic lesions of the brain and the control group that consisted of 12 persons without any functional and organic neurological disorders. This study was performed on Philips "Ingenia" 3.0T scanner using the phase-contrast MR-angiography for the quantitative evaluation of the hemo- and cerebrospinal fluid dynamics. A number of parameters were analyzed including Pulsatility Index (PI), Arterio-Venous Delay (AVD), Stroke Volumes (SV) and Intracranial Complaince (ICC). Data were analyzed with the Mann-Whitney test.

Results and Discussion

ICC decreased by 58% (p<0.01) and the total venous outflow was 52% higher (p<0.05) in all patients compared with the control group. In the patients with IIH the AVD is 37% lower (p<0.05) and PI on the great occipital foramen and cervical area is 15% lower (p<0.05) than the same parameters in the control group. In the patients with iNPH PI on the aqueductal area increased nearly by 2.3 times (p<0.05) as compared with the healthy people. In the iNPH patients the PI on the straight sinus increased by 40% (p<0.05) as compared with the control group.

Conclusion

Decreasing of ICC is the most common feature of functional disturbances of the cerebrospinal fluid dynamics. These patients have a congestion of fluid inside the intracranial volume that has to be compensated by increasing the venous outflow. In the IIH patients the excess fluid accumulates in the brain interstitial space, while in the iNPH patients the excess fluid accumulates mostly in the lateral ventricles and primarily the straight sinus compensates this congestion.

Acknowledgements

The work was supported by Russian Science Foundation (the project #19-75-20093).

References

No reference found.