Single- and dual-task gait assessment before and after cerebrospinal fluid drainage in suspected idiopathic normal pressure hydrocephalus: Dual-task walking identifies additional responders.

BACKGROUND

Gait change after cerebrospinal fluid drainage (CSFD) in idiopathic normal pressure hydrocephalus (iNPH) is usually assessed during single-task walking. Dual-task gait assessment may provide additional diagnostic value, as both gait and cognition are commonly impaired in iNPH.

METHODS

We analyzed GAITRite gait data from 122 patients with suspected iNPH before and after CSFD and from 146 cognitively healthy controls assessed once. Normal walking, working memory dual-task walking, semantic memory dual-task walking, and fast walking were examined. Eight parameters were analyzed across single- and dual-task conditions; fast walking was used to derive gait speed reserve. Exploratory responder analyses defined response per parameter as improvement ≥ 75th percentile of within-sample change and an absolute change ≥ 10% of the baseline group mean. Two sensitivity analyses applied combinations of lower and higher thresholds.

RESULTS

Compared with controls, patients showed gait impairment across most parameters and walking conditions. After CSFD, most parameters improved, and gait velocity showed the largest within-condition standardized effect size. Pre-post effects were generally largest during normal walking. Under the primary responder model, 84 patients responded during normal walking, 85 during the working memory dual-task, and 72 during the semantic memory dual-task; 43 responded in all three conditions and 9 in none. Importantly, 25.7% of responders were identified only through dual-task conditions, while under the stricter model, 45.3% of responders would have been missed by normal walking alone.

CONCLUSION

Normal walking captured the largest average gait changes after CSFD, but dual-task assessment added individual-level diagnostic information by identifying responders missed by normal walking.