This study aims to characterize dynamic stability disorders in two conditions mainly affecting the elderly and with similar walking deficits: hydrocephalus at normal pressure and Parkinson's disease, to provide the most relevant monitoring criteria in usual care.

Walking disorders in normal pressure hydrocephalus are manifested by slowing and ataxic gait, similar to disorders in Parkinson's disease. No studies in the literature have focused on advanced measures of dynamic stability in hydrocephalus at normal pressure, compared to Parkinson's disease, on large samples. The Laboratory of Analysis and Restoration of Movement, located in a Neurorehabilitation Department, provides quantitative data on gait and in particular dynamic stability as part of additional assessments to help patients follow up. Since 2010, people with normal pressure hydrocephalus or Parkinson's disease regularly benefit from these assessments. Retrospective analysis of all these data would help to better characterize motor disorders in hydrocephalus at normal pressure, by discriminating them from those associated with Parkinson's disease. It would lead to the definition of relevant indices to be used for patient follow-up.

Inclusion Criteria:

• Age >18 years
• Patient who performed a walking test in the Laboratory Analysis and Restoration of Movement
• Diagnosis of normal pressure hydrocephalus or Parkinson's disease

Exclusion Criteria:

• Levodopa drugs administrated during a delay of 12 hours before walking test
• Presence of an other neurologic disease or of any disease associated with motor disorders in lower limb.

Patients with normal pressure hydrocephalus or Parkinson's disease.