Influence of an irregular surface & low light on the step variability of PN pati

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Gait Posture. 2005 Aug;22(1):40-5.

Influence of an irregular surface and low light on the step

variability of patients with peripheral neuropathy during level gait.

Thies SB, JK, Demott T, Ashton- JA.

Biomechanics Research Laboratory, Biomedical Engineering, University

of Michigan, 3204 G.G. Brown, 2350 Hayward Street, Ann Arbor, MI

48109-2125, USA.

Patients with peripheral neuropathy (PN) report greater difficulty

walking on irregular surfaces with low light (IL) than on flat

surfaces with regular lighting (FR).

We tested the primary hypothesis that older PN patients would

demonstrate greater step width and step width variability under IL

conditions than under FR conditions.

Forty-two subjects (22 male, 20 female: mean +/- S.D.: 64.7 +/- 9.8

years) with PN underwent history, physical examination, and

electrodiagnostic testing.

Subjects were asked to walk 10m at a comfortable speed while

kinematic and force data were measured at 100Hz using optoelectronic

markers and foot switches. Ten trials were conducted under both IL

and FR conditions. Step width, time, length, and speed were

calculated with a MATLAB(®) algorithm, with the standard deviation

serving as the measure of variability.

The results showed that under IL, as compared to FR, conditions

subjects demonstrated greater step width (197.1 +/- 40.8mm versus

180.5 +/- 32.4mm; P < 0.001) and step width variability (40.4 +/-

9.0mm versus 34.5 +/- 8.4mm; P < 0.001), step time and its

variability (P < 0.001 and P = 0.003, respectively), and step length

variability (P < 0.001).

Average step length and gait speed decreased under IL conditions (P <

0.001 for both). Step width variability and step time variability

correlated best under IL conditions with a clinical measure of PN

severity and fall history, respectively.

We conclude that IL conditions cause PN patients to increase the

variability of their step width and other gait parameters.