Relationship between gait parameters and MR imaging in idiopathic normal pressure hydrocephalus patients after shunt surgery.

Background: A few previous studies have reported a change in gait motion in idiopathic normal pressure hydrocephalus (iNPH) patients after shunt surgery compared with before shunt surgery; however, there has been no detailed quantitative investigation of gait, including kinetic and kinematic parameters. Furthermore, the relationship between gait parameters and magnetic resonance (MR) imaging has not been confirmed.

Research Question: We investigated the gait motion in patients with iNPH, and evaluated the relationship between kinetic gait parameters and MR imaging before and after shunt surgery.

Methods: The subjects were 12 patients with iNPH who could walk 10 m without aids. A three-dimensional motion analysis system was used to obtain the spatiotemporal, kinetic, and kinematic parameters before and after surgery. Relationships between each gait parameter and MR imaging were assessed.

Results: The post-shunt walking speed and step length were increased compared with pre-shunt values. The post-shunt evaluation showed increased range of motion of the hip, knee, and ankle joints in the sagittal plane during the gait cycle. The peak flexion moment of the hip during the stance phase was greater after shunt surgery. The improvement rate of the Evans index was significantly correlated with the improvement rate of walking speed, and the total ranges of motion of the hip and ankle joints in the sagittal plane.

Significance: The propulsive force of the hip and ankle joints was regained after shunt surgery. Normalization of the Evans index could predict improvement in propulsive force after shunt surgery in iNPH.