Are we supererestimating gait assessments of patients with idiopathic normal-pressure hydrocephalus?

Improvement in gait velocity variability after cerebrospinal fluid elimination and its relationship to clinical symptoms in patients with idiopathic normal pressure hydrocephalus

AIM

This study aimed to investigate the improvement in gait velocity variability after cerebrospinal fluid (CSF) elimination, and the association between gait velocity variability and gait and cognitive impairment in patients with idiopathic normal pressure hydrocephalus.

METHODS

The gait velocity of 44 patients with idiopathic normal pressure hydrocephalus was measured using the Timed Up and Go Test (TUG) for a total of 10 times over 3 days each before and after CSF elimination. The coefficient of variation (CV) in the time required for the sequence of actions in TUG (TUG-CV) was calculated using 10 TUG data, and used for measuring intraindividual gait velocity variability. Gait quality was evaluated with the Gait Status Scale Revised (GSSR), and cognitive function was evaluated with the Mini-Mental State Examination and the Frontal Assessment Battery.

RESULTS

The TUG, TUG-CV, GSSR and Frontal Assessment Battery results improved significantly after CSF elimination. The analyses using pre-CSF elimination results showed that the TUG-CV significantly and positively correlated with the TUG and GSSR results, and negatively with Mini-Mental State Examination results, but not with age and the Frontal Assessment Battery results. The stepwise multiple regression analysis indicates that the TUG, GSSR and Mini-Mental State Examination results were significant predictors of the TUG-CV. The analysis using data of change after CSF elimination showed that ΔTUG and ΔGSSR were significant predictors of ΔTUG-CV.

CONCLUSIONS

Gait velocity variability improved after CSF elimination, and gait velocity variability was associated with gait disturbances and cognitive impairment in patients with idiopathic normal pressure hydrocephalus. Geriatr Gerontol Int 2024; 24: 693-699.

Gait Analysis in Idiopathic Normal Pressure Hydrocephalus: A Meta-Analysis

Background

Gait analysis objectively quantifies gait impairment in idiopathic normal pressure hydrocephalus (iNPH), may improve diagnosis and evaluation for surgical candidacy.

Objectives

This meta-analysis aims to understand which objective gait parameters improve after tap-test (TT) and CSF shunt surgery (CSS), also comparing responders (R) with non-responders (NR) and to assess if gait restores within the range of healthy controls after procedures.

Methods

Studies enrolling iNPH with at least one instrumented gait measure were selected. Three time points of gait assessment were defined: PRE, POST-TT, and POST-CSS. Gait velocity, cadence, step length, stride length, and double limb support time were evaluated. Patients were categorized based on responsiveness to CSF diversion procedures.

Results

Seventeen studies including 527 patients were selected. iNPH improved significantly in almost all gait parameters POST-TT, and to a greater extent POST-CSS. Gait parameters consistently discriminated iNPH from healthy controls. Despite the aforementioned improvements, iNPH's gait did not completely normalize after CSF diversion procedures. Meta-regression analysis also revealed that TT's effect on gait velocity plateaus after 24-48 hr and returns to baseline in 90-100 hr.

Conclusions

Gait analysis is a reliable quantitative instrument to assess gait impairment in iNPH, demarking a net differentiation from healthy controls, according to the notion that the iNPH CSF dynamic alteration also leads to an irreversible damage. Specific gait parameters improve among TT-R, providing an opportunity to select patients that will respond to CSS. Future studies validating a standardized reporting method including criteria of responsiveness, specific gait parameters, and timeframe of assessment are needed.

Gait Apraxia and Hakim's Disease: A Historical Review

In 1965, Prof. Salomón Hakim described, for the first time, a condition characterized by normal pressure hydrocephalus and gait alterations. During the following decades, definitions such as "Frontal Gait", "Bruns' Ataxia" and "Gait Apraxia" have been frequently used in pertinent literature in the attempt to best define this peculiar motor disturbance. More recently, gait analysis has further shed light on the typical spatiotemporal gait alterations that characterize this neurological condition, but a clear and shared definition of this motor condition is still lacking. In this historical review, we described the origins of the terms "Gait Apraxia", "Frontal Gait" and "Bruns' Ataxia", starting with the first works of Carl Maria Finkelburg, Fritsch and Hitzig and Steinthal during the second half of the 19th century and ending with Hakim's studies and his formal definition of idiopathic normal pressure hydrocephalus (iNPH). In the second part of the review, we analyze how and why these definitions of gait have been associated with Hakim's disease in the literature from 1965 to the present day. The definition of "Gait and Postural Transition Apraxia" is then proposed, but fundamental questions about the nature and mechanisms underlying this condition remain unanswered.

Gait apraxia evaluation in normal pressure hydrocephalus using inertial sensors. Clinical correlates, ventriculoperitoneal shunt outcomes, and tap-test predictive capacity

BACKGROUND

Idiopathic normal pressure hydrocephalus (iNPH) is a neurological condition with gait apraxia signs from its early manifestation. Ventriculoperitoneal shunt (VPS) is a surgical procedure available for treatment. The Cerebrospinal fluid Tap Test (CSF-TT) is a quick test used as selection criterion for VPS treatment. Its predictive capacity for VPS outcomes is still sub judice. This study is aimed to test the hypothesis that wearable motion sensors provide valid measures to manage iNPH patients with gait apraxia.

METHODS

Forty-two participants of the Bologna PRO-Hydro observational cohort study were included in the analyses. The participants performed the Timed Up and Go (TUG) and the 18 m walking test (18mW) with inertial sensors at baseline, three days after the CSF-TT, and six months after VPS. 21 instrumental variables described gait and postural transitions from TUG and 18mW recordings. Furthermore, participants were clinically assessed with scales (clinical variables). We tested the hypothesis by analysing the concurrent validity of instrumental and clinical variables, their individual- and group-level responsiveness to VPS, and their predictive validity for VPS outcomes after CSF-TT.

RESULTS

The instrumental variables showed moderate to high correlation with the clinical variables. After VPS, most clinical and instrumental variables showed statistically significant improvements that reflect a reduction of apraxic features of gait. Most instrumental variables, but only one clinical variable (i.e., Tinetti POMA), had predictive value for VPS outcomes (significant adjusted R² in the range 0.12-0.70).

CONCLUSIONS

These results confirm that wearable inertial sensors may represent a valid tool to complement clinical evaluation for iNPH assessment and prognosis.