A novel prognostic role of proton MR spectroscopy in shunted idiopathic normal pressure hydrocephalus

Abstract

Objective: To assess the prognostic potential of preoperative proton MRS in predicting postoperative outcomes for patients with INPH undergoing VPS.

Methods: Preoperative MRS data were obtained and analyzed from 15 patients with INPH who underwent VPS. The concentrations of key metabolites-Cho, Cr, NAA, and Lac-were quantified in the Tha, BG, PV, and MF regions. Metabolite ratios were calculated, and clinical response to shunting was assessed using the Hellström INPH scale. Prognostic accuracy was determined via ROC analysis.

Results: • Cho: Elevated levels in the left MF region were associated with favorable neuropsychological outcomes. Conversely, lower levels in the left Tha correlated with improved gait, cognitive, continence, and overall outcomes. • Cr: Decreased levels in the right Tha and BG were predictive of improved continence. • NAA: Higher levels in the right MF region and lower levels in bilateral frontal PV areas were linked to better neuropsychological response. • Lac: Elevated levels in the left BG were associated with improved balance. Threshold values predictive of a favorable total shunt response included left and average Tha Cho ≤ 6 and ≤ 5.4, respectively, and average Tha and BG NAA ≤ 9 and ≤ 7.35, respectively.

Conclusion: Proton MRS demonstrates promising utility as a non-invasive tool for predicting postoperative outcomes in INPH patients. In particular, regional levels of Cho, Cr, and NAA provide critical insights for optimizing patient selection and surgical planning. These findings could also deepen our understanding of the intricate pathophysiological mechanisms underlying INPH.

Keywords: Choline; Creatine; Idiopathic normal pressure hydrocephalus (INPH); Lactate; N-acetylaspartate; Proton magnetic resonance spectroscopy (MRS); Ventriculoperitoneal shunt (VPS).