Speed matters: fast pace 10-metre walking test is superior to normal pace in predicting gait recovery following ventriculoperitoneal shunt insertion in normal pressure hydrocephalus

Purpose Idiopathic normal pressure hydrocephalus (iNPH) is characterised by Hakim’s tetrade comprising gait, balance, cognitive and urinary disturbance. As gait deteriorates early, 10-m walking tests (10MWT) before and after lumbar tap or extended lumbar drainage tests have been used to identify patients who may benefit from permanent cerebrospinal fluid diversion in the form of a ventriculoperitoneal (VP) shunt. Whether 10MWT should be performed at fast or normal pace to best predict benefit from shunting has been unclear so far. Methods We included 125 iNPH patients into a retrospective, longitudinal, single-centre cohort study and performed 10MWT before and after 72-h lumbar drainage, immediately after VP shunt insertion and at the 6-month, 1-year, 2-year, 3-year, 5-year and 8-year marks postoperatively. Results We found that time and step count improvements of normal and fast 10MWT before and after lumbar drainage were maintained in the first two to three years postoperatively. Furthermore, fast pace 10MWT time and step count better predicted postoperative gait improvement than normal pace 10MWT. Early responders of fast gait measures (walking pace improved by ≥ 0.1 m/s or step count improvement > 10% after lumbar drainage) were 3.91 (pace) and 6.29 (steps) times more likely to benefit from surgery as opposed to 2.64 (pace) and 1.93 (steps) times for normal walking pace. Conclusions Our study suggests that the 10MWT should be performed at fast pace (maximum speed), and when normal and fast pace results are contradictory, the fast pace outcome should take priority.