What is NPH and how does it affect gait?

Normal Pressure Hydrocephalus (NPH) is a treatable disorder most commonly found in older adults. NPH is cause by a buildup of cerebrospinal fluid (CSF) putting pressure on the neurologic system, causing symptoms commonly seen in other neurological conditions. The most prevalent symptoms are dementia and ataxic gait, leading to NPH often being misdiagnosed as Alzheimer’s or Parkinson’s disease. This 2 minute video link from a 2019 Toronto TV station story titled “New clinic treats patients with reversible condition often mistaken for dementia” illustrates this point. While symptoms of NPH overlap with Alzheimer’s and Parkinson’s, the treatments are very different, making it essential to properly diagnose NPH. Unlike Alzheimer’s or Parkinson’s Disease, the symptoms of NPH can be quickly alleviated by draining CSF via spinal tap or shunt surgery.

Gait impairment is considered to be the earliest and strongest symptom of NPH. Ataxia and sensory and motor weakness lead to complaints of poor balance and unsteady gait. Falls, freezing of gait and difficulty with turns are common. Research over the last 20 years has pointed to quantitative measures of temporal spatial gait to be a key tool in identifying cases of NPH.

Where has NPH been linked to gait in the literature?

As far back as 2000, gait analysis was used to identify specific gait characteristics associated with NPH. Stolze et al. compared the gait of 10 patients and 12 age-matched healthy controls.  Spikes were placed on the bottom of shoes as the subject walked across draft paper and the comparison was able to identify decreased step length and increased stride width as key variables linked with NPH. [Read More Here]

In 2008, Williams et al. performed a study looking at 20 patients and 9 control subjects. Gait analysis was performed at baseline, after controlled CSF drainage and after shunt surgery. Shunt surgery was only performed on patients if there was an appropriate response to the controlled CSF drainage. In the group that that received shunt surgery, there was an improvement in velocity, double-support time, cadence, and stride length. These improvements existed after both CSF drainage and shunt surgery. The patients that did not receive shunt surgery showed no improvement in gait following controlled CSF drainage. [Read More Here]

In 2019, work out of the Barrow Neurological Institute by Song et al. looked to characterize NPH using clinical evaluation and gait analysis using the Zeno Walkway System. 28 subjects with no conflicting co-morbidities had assessments pre-lumbar puncture (pre-LP), post-lumbar puncture (post-LP), and 6-month post-shunt surgery. During the assessments, 15 common physical therapy tests and a gait analysis test were completed. Of the 15 common tests, 9 showed significant differences between pre-LP and either post-LP and post-shunt. Of the 10 variables analyzed from the gait data, 7 showed significant differences (Velocity, Step Length, Stride Length, Stance %, Swing %, Single Support %, and Ambulation Time). This study concluded identifying changes in certain gait metrics be a piece of information for a more conclusive NPH diagnosis. [Read More Here]

Is gait analysis useful for tracking treatment efficacy in NPH?

One of the most common clinical uses of temporal spatial gait analysis is to track patient function before and after treatment to quantify the gait changes associated with treatment. While research over the last 20 years has shown that temporal spatial gait metrics are tied to NPH, the 2008 study by Williams et al. and the 2019 study by Song et al. more specifically show the utility of using temporal spatial gait analysis to quantify changes in gait function pre and post treatment. In cases with suspected NPH, both of these studies were able to determine differences in gait metrics before and after controlled CSF drainage and shunt surgery. Williams et al. summarized their findings that “…objective improvement in gait variables in response to controlled CSF drainage is predictive of response to shunt surgery in patients with suspected NPH.” Song et al. state that “These [step length, stride length, single support %, velocity, Tinetti Gait, Tinetti Balance, Tinetti Total, Romberg eyes closed and standing base of support] characteristics could serve as indications of NPH following spinal tap procedures as well as prognostic features for future improvement after shunt placement.”

Temporal spatial gait analysis is an easy to administer test that can proved accurate data pre and post treatment. The papers presented here suggest that gait analysis could provide helpful information to clinicians who are treating patients with NPH. Additional research could be used to confirm and characterize the most important gait changes in patients with NPH pre and post CSF drainage.

Stolze H, Kuhtz-Buschbeck JP, Drücke H, Jöhnk K, Diercks C, Palmié S, Mehdorn HM, Illert M, Deuschl G. Gait analysis in idiopathic normal pressure hydrocephalus--which parameters respond to the CSF tap test? Clin Neurophysiol. 2000 Sep;111(9):1678-86. doi: 10.1016/s1388-2457(00)00362-x. PMID: 10964082.
Williams MA, Thomas G, de Lateur B, Imteyaz H, Rose JG, Shore WS, Kharkar S, Rigamonti D. Objective assessment of gait in normal-pressure hydrocephalus. Am J Phys Med Rehabil. 2008 Jan;87(1):39-45. doi: 10.1097/PHM.0b013e31815b6461. PMID: 17993991.
Song M, Lieberman A, Fife T, Nielsen M, Hayden S, Sabbagh M, Shi J. A prospective study on gait dominant normal pressure hydrocephalus. Acta Neurol Scand. 2019 Apr;139(4):389-394. doi: 10.1111/ane.13064. Epub 2019 Feb 19. PMID: 30676642.