MRI diffusion and perfusion alterations in the mesencephalon and pons as markers of disease and symptom reversibility in idiopathic normal pressure hydrocephalus

Abstract

Introduction Core symptomatology in idiopathic normal pressure hydrocephalus (iNPH) points at dysfunction in the mesencephalon and pons indicating pathological changes in these regions, but only a few studies have addressed the issue. The aim of this study was to investigate diffusion (ADC) and perfusion patterns pre-and postoperatively in these areas in iNPH. Methods Twenty iNPH patients and 15 healthy controls were included. Patients underwent a clinical examination and brain MRI pre-and 3-6 months postoperatively. The MRI-scan included diffusion and dynamic susceptibility contrast perfusion weighted sequences. Regions of interest in the mesencephalon and pons were drawn on a FLAIR sequence and co-registered to ADC maps and perfusion data. Results There were no significant differences in pre or postoperative ADC compared to the control group, however postoperative ADC increased by 10% (p = 0.026) in the mesencephalon and 6% (p = 0.016) in the pons in all patients and also in the subgroup of shunt responders by 11% (p = 0.021) and 4% (p = 0.020), respectively. Preoperative relative cerebral blood flow (rCBF) was similar in iNPH patients and controls. Postoperatively, rCBF increased in shunt responders by 6% (p = 0.02) in the mesencephalon and 11% (p = 0.004) in the pons. This increase correlated with the degree of clinical improvement (r s = 0.80, p = 0.031 and r s = 0.66, p = 0.021, respectively).

Radiological predictors of shunt response in the diagnosis and treatment of idiopathic normal pressure hydrocephalus: a systematic review and meta-analysis

“…1). Nine studies [8,14,14,23,26,27,31,41,59] cored a low risk of bias overall using the ROBINS-I [53] while 18 scored moderate [2][3][4][5]20,25,34,40,41,46,47,49,50, risk and 1 study was rated as serious risk [34] (Fig. 2, Supplementary Material: Table 4).…”

“…3). Twenty-five different radiological markers were investigated which are presented in Tables 2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20, and 21 and categorized anatomically and functionally according to the following: variables of the "Rad scale" [28], which is the most updated radiological scale to assess iNPH; DESH, that recently was given high attention in the updated Japanese guidelines [40]; measures of cerebral ventricle size; measures of altered CSF flow; other radiological measures.…”

Pathophysiological Mechanisms Underlying Idiopathic Normal Pressure Hydrocephalus: A Review of Recent Insights

“…Clinical improvements after CSF drainage have been associated with improvements in CBF in the lateral and frontal white matter regions (Virhammar et al, 2014 ), periventricular white matter (Ziegelitz et al, 2015 , 2016 ; Satow et al, 2017 ), periventricular thalamus (Ziegelitz et al, 2015 ), medial frontal region (Klinge et al, 2008 ), supplemental motor area (Lenfeldt et al, 2008 ), brainstem (Agerskov et al, 2020 ), and globally (Chang et al, 2009 ). Relating to prognostic variables prior to treatment, one study found decreased preoperative CBF in basal frontal lobes and anterior cingulate region in iNPH patients who responded to shunting compared to non-responders (Murakami et al, 2007 ).…”

Normal Pressure Hydrocephalus: Clinical Approach and Practical Considerations

“…Several clinical trials have suggested that acetazolamide, a carbonic anhydrase inhibitor, reduces CSF production. Therefore, this medication is recommended for patients deemed non-surgical candidates and those who decline surgery [19]. In addition, since shunt complications are common, acetazolamide can be an effective medical alternative [20].…”