Features of gait most responsive to tap test in normal pressure hydrocephalus

Abstract

Objective-To identify components of gait associated with a positive tap test (TT) in patients with idiopathic normal pressure hydrocephalus (iNPH).Patients and methods-Thirty-three patients with iNPH underwent clinical evaluation pre-and post-TT and were classified as responders (Rs) or non-responders (NRs). Elements of gait were assessed with a formal standardized Gait Scale and compared between groups.Results-Analysis of pre/post-TT group differences revealed an interaction for Total Gait Score and Walking Score, with improvements in responders only. Total Gait Scores improved by 29% in the Rs and 4.85% in the NRs. Rs showed significant post-TT improvements on a timed 10m walk, turning, and balance. Tandem walking, turning, truck balance and start stop hesitation showed trends toward improvement.Conclusions-The classic features of gait often used in determining diagnosis of NPH (wide based stride, reduced foot-floor clearance, and small steps) were not helpful in identifying responders to the TT. Walking speed, steps for turning, and tendency towards falling were most likely to improve post-TT. These straightforward measures can readily be adapted into clinical practice to assist in determination of shunt candidacy.

Lumbar Puncture Test in Normal Pressure Hydrocephalus: Does the Volume of CSF Removed Affect the Response to Tap?

“…As prior studies noted, gait disturbance is the symptom that shows the most dramatic improvement after an LTT and shunting. 19 The main conclusion of the current study is that within the 28 -50 mL range (values between the 5th and 95th percentile), there is no significant association between the volume of CSF removed and gait outcomes. Although high-volume spinal tap has been established as an accurate method to diagnose NPH and to identify patients who will likely benefit from shunt surgery, to our knowledge, there is no consensus on the amount of CSF required to be removed.…”

“…The current literature is ambiguous about defining what merits an effective response to an LTT, with no definitive guidelines followed by clinicians. 19,21,32 We defined our cutoffs to maximize the magnitude of improvement while maintaining a sufficient sample size to do meaningful statistical analyses.…”

“…Transient recovery in gait after the LTT has been considered a positive prognostic indicator for surgery, but no response after the LTT warrants further investigation. [18][19][20][21][22][23][24] A 2016 review by Mihalj et al 25 found the LTT to have an average published sensitivity of 58%, specificity of 75%, and accuracy of 62% in predicting positive response to shunt over 8 included studies. Complications that may compromise the effectiveness of high-volume LTT include headache and pain that may be pronounced enough to compromise gait testing.…”

Gait in normal pressure hydrocephalus: characteristics and effects of the CSF tap test

“…, Pedro André Kowacs 4 , Ricardo Ramina 5 Normal pressure hydrocephalus (NPH), described by Adams et al 1 in 1965, is characterized by a classic triad of symptoms, consisting of progressive gait apraxia, urinary incontinence, and dementia. They are associated with normal cerebrospinal fluid (CSF) pressure and ventricular dilation that cannot be attributed to cerebral atrophy 1 .…”

“…The TT is important for diagnosing NPH 3,4 as well as predicting clinical postoperative outcomes 3,4 . The volume of CSF removed can vary between 15 to 50 mL, according to different authors 5,6 . According to Japanese guidelines, the CSF-TT should be the first invasive test indicated 3 when NPH is suspected; it has a positive predictive value of between 72% and 100% and a low rate of complications 7 .…”