Search

Objective: Diffusion tensor imaging (DTI) along the perivascular space (ALPS) (DTI-ALPS)-by calculating the ALPS index, a ratio accentuating water diffusion in the perivascular space-has been proposed as a noninvasive, indirect MRI method for assessing glymphatic function. The main aim of this study was to investigate whether DTI-ALPS would reveal glymphatic dysfunction in idiopathic normal pressure hydrocephalus (iNPH) and whether the ALPS index was associated with disease severity., Methods: Thirty iNPH patients (13 men; median age 77 years) and 27 healthy controls (10 men; median age 73 years) underwent MRI and clinical assessment with the Timed Up and Go test (TUG) and Mini-Mental State Examination (MMSE); only the patients were evaluated with the Hellström iNPH scale. MRI data were analyzed with the DTI-ALPS method and Radscale screening tool., Results: iNPH patients showed significantly lower mean ALPS index scores compared with healthy controls (median [interquartile range] 1.09 [1.00-1.15] vs 1.49 [1.36-1.59], p < 0.001). Female healthy controls showed significantly higher ALPS index scores than males in both hemispheres (e.g., right hemisphere 1.62 [1.47-1.67] vs 1.33 [1.14-1.41], p = 0.001). This sex difference was not seen in iNPH patients. The authors found a moderate exponential correlation between mean ALPS index score and motor function as measured with time required to complete TUG (r = -0.644, p < 0.001), number of steps to complete TUG (r = -0.571, p < 0.001), 10-m walk time (r = -0.637, p < 0.001), and 10-m walk steps (r = -0.588, p < 0.001). The authors also found a positive linear correlation between mean ALPS index score and MMSE score (r = 0.416, p = 0.001). Simple linear regression showed a significant effect of diagnosis (B = -0.39, p < 0.001, R2 = 0.459), female sex (B = 0.232, p = 0.002, R2 = 0.157), and Evans index (B = -4.151, p < 0.001, R2 = 0.559) on ALPS index. Multiple linear regression, including diagnosis, sex, and Evans index score, showed a higher predictive value (R2 = 0.626) than analysis of each of these factors alone., Conclusions: The ALPS index, which was significantly decreased in iNPH patients, could serve as a marker of disease severity, both clinically and in terms of neuroimaging. However, it is important to consider the significant influence of biological sex and ventriculomegaly on the ALPS index, which raises the question of whether the ALPS index solely reflects glymphatic function or if it also encompasses other types of injury. Future studies are needed to address potential confounding factors and further validate the ALPS method.

Background: Symptomatic Chiari I malformation is treated with suboccipital decompression and C1 laminectomy. However, whether the dura should be opened (durotomy) or enlarged with a graft (duraplasty) remains unclear., Objective: To compare outcomes in adult Chiari I malformation patients treated with duraplasty, durotomy, or without dural opening ("mini-decompression")., Methods: A retrospective, multicenter, population-based cohort study was performed of all adult patients surgically treated for a Chiari I malformation at 3 regional neurosurgical centers between 2005 and 2017. Three different dura management strategies were favored by the participating hospitals, with data stratified accordingly. The primary outcome was measured using the Chicago Chiari Outcome Scale (CCOS), dichotomized into favorable (CCOS ≥13) or unfavorable (CCOS ≤12). Propensity score matching was used to adjust for potential confounders in outcome comparisons., Results: In total, 318 patients were included, of whom 52% were treated with duraplasty, 37% with durotomy, and 11% with mini-decompression. In total, 285 (90%) showed a favorable surgical outcome (CCOS ≥13). Duraplasty was associated with more favorable CCOS and shorter hospital stay compared with durotomy, both in unadjusted (93% vs 84%. P = .018 and 6.0 vs 8.0 days, P < .001) and adjusted analyses (92% vs 84%, P = .044 and 6.0 vs 8.0 days, P < .001). Mini-decompression was excluded from the adjusted analyses because of its small sample size., Conclusion: In this study of adult Chiari I malformation, posterior fossa decompression with duraplasty was associated with more favorable postoperative outcome, as determined by the CCOS, compared with posterior fossa decompression with durotomy alone., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)