Water Diffusivity Changes Along the Perivascular Space After Lumboperitoneal Shunt Surgery in Idiopathic Normal Pressure Hydrocephalus

Junko Kikuta; Koji Kamagata; Toshiaki Taoka; Kaito Takabayashi; Wataru Uchida; Yuya Saito; Christina Andica; Akihiko Wada; Kaito Kawamura; Chihiro Akiba; Madoka Nakajima; Masakazu Miyajima; Shinji Naganawa; Shigeki Aoki

doi:10.3389/fneur.2022.843883

Water Diffusivity Changes Along the Perivascular Space After Lumboperitoneal Shunt Surgery in Idiopathic Normal Pressure Hydrocephalus

Front Neurol. 2022 Feb 28:13:843883. doi: 10.3389/fneur.2022.843883. eCollection 2022.

Authors

Affiliations

¹ Department of Radiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Japan.
² Department of Innovative Biomedical Visualization, Graduate School of Medicine, Nagoya University, Nagoya, Japan.
³ Department of Neurosurgery, Juntendo University Faculty of Medicine, Bunkyo-ku, Japan.
⁴ Department of Neurosurgery, Juntendo Tokyo Koto Geriatric Medical Center, Koto-ku, Japan.
⁵ Department of Radiology, Nagoya University Graduate School of Medicine, Nagoya, Japan.

Abstract

Background: The aim of this study was to evaluate the water diffusivity changes along the perivascular space after lumboperitoneal shunt (LPS) surgery in idiopathic normal pressure hydrocephalus.

Methods: Nine patients diagnosed with idiopathic normal pressure hydrocephalus (iNPH; three men and six women, mean age ± SD = 75.22 ± 5.12 years) according to the guidelines for iNPH in Japan were included in the study. Post-LPS surgery, six patients with iNPH who exhibited improvement in symptoms were defined as responder subjects, while three patients with iNPH who did not were defined as non-responder subjects. We calculated the mean analysis along the perivascular space (ALPS) index of the left and right hemispheres and compared the differences between pre- and post-LPS surgery mean ALPS indices in iNPH patients. In the responder or non-responder subjects, the mean ALPS indices in the pre- and post-operative iNPH groups were compared using Wilcoxon signed-rank tests. Next, correlation analyses between pre- and post-operation changes in the mean ALPS index and clinical characteristics were conducted.

Results: The mean ALPS index of the post-operative iNPH group was significantly higher than that of the pre-operative iNPH group (p = 0.021). In responder subjects, the mean ALPS index of the post-operative iNPH group was significantly higher than that of the pre-operative iNPH group (p = 0.046). On the other hand, in the non-responder subjects, the mean ALPS index of the post-operative iNPH group was not significantly different compared to the pre-operative iNPH group (p = 0.285). The mean ALPS index change was not significantly correlated with changes in the Mini-Mental State Examination (MMSE) score (r = -0.218, p = 0.574), Frontal Assessment Battery (FAB) score (r = 0.185, p = 0.634), Trail Making Test A (TMTA) score (r = 0.250, p = 0.516), and Evans' index (r = 0.109, p = 0.780). In responder subjects, the mean ALPS index change was significantly correlated with Evans' index in pre-operative patients with iNPH (r = 0.841, p = 0.036).

Conclusion: This study demonstrates the improved water diffusivity along perivascular space in patients with iNPH after LPS surgery. This could be indicative of glymphatic function recovery following LPS surgery.

Keywords: ALPS index; cerebrospinal fluid; diffusion-weighted imaging; glymphatic system; idiopathic normal pressure hydrocephalus; interstitial fluid; lumboperitoneal shunt surgery.