Extended lumbar drain trials for diagnostic evaluation of idiopathic normal pressure hydrocephalus with the Berg Balance Scale.

OBJECTIVE

Idiopathic normal pressure hydrocephalus (iNPH) is characterized by impaired gait, cognitive impairment, and urinary incontinence. Idiopathic NPH is treated with insertion of a ventriculoperitoneal shunt (VPS), but response to VPS placement varies. Extended lumbar drain (ELD) trials over a 3-day period can predict VPS success. Patients undergoing ELD trials are evaluated for gait improvement after lumbar drain (LD) placement using the Berg Balance Scale (BBS). This study examines changes in BBS scores in iNPH patients undergoing an ELD trial to determine the optimal trial length.

METHODS

This single-center, retrospective analysis included iNPH patients from 2007 to 2023 who underwent an ELD trial. Daily BBS scores were compared along with frequency of achieving the minimal detectable change (MDC), the threshold for clinical improvement, which varies between 4 and 7 points depending on the baseline score. Billing data were used to calculate the average daily charges of admission for ELD trials, excluding the LD procedure cost.

RESULTS

Eighty iNPH patients were included. The mean BBS score difference from baseline improved by 3.7 points on day 1, 7.19 points on day 2, and 8.38 points on day 3. MDC thresholds were met by 31% of patients on day 1, 77% on day 2, and 82% on day 3. The increase in MDC achievement from day 1 to day 2 was significant (p < 0.0001), while the change from day 2 to day 3 was not (p = 0.3428). The average total admission charge was $31,168.14 (standard error of the mean $994.61), with a per diem charge of $9756.05 after subtracting the LD procedure charge ($1900).

CONCLUSIONS

While daily improvements in BBS score are seen during the ELD trial, achievement of MDC thresholds primarily happens by day 2. These data suggest that for patients who meet the MDC, limiting the ELD trial to 2 days could reduce costs without compromising the diagnostic utility of the ELD.