Increased prefrontal cortical activation during challenging walking conditions in persons with lower limb amputation – an fNIRS observational study

Figures & data

Figure 1. Illustrates the location of the optode sources and detectors on the scalp. The labels starting with S (S1, S2 … S8)(light gray color) represent the sources. The labels starting with D (D1, D2, …, D8)(dark gray color) represent the detectors. The 20 source-detector pairs called channels are illustrated with bars.

Table 1. Participant demographics and characteristics

	Able-bodied controls (N = 33)	Persons with LLA (N = 39)	p-value
Sex (female/male), n	14/19	17/22	0.92
Age, years	53.6 (12.4)	51.7 (12.3)	0.51
Weight, kg	82.9 (15.7)	84.2 (19.7)	0.76
Height, m	1.76 (0.1)	1.76 (0.1)	0.89
MoCA	27.5 (1.7)	27.1 (1.9)	0.60
TMT-A, s	29.9 (7.8)	34.0 (12.0)	0.09
TMT-B, s	70.9 (24.8)	81.0 (31.4)	0.13
Time since amputation, years	N/A	22 (18)
Amputation etiology
Cancer, n	N/A	6
Trauma, n	N/A	24
Infection (non-diabetic), n	N/A	1
Congenital, n	N/A	6
Other (non-diabetic), n	N/A	2
PLUS-M	N/A	58.4 (7.6)
AMP	N/A	42.9 (2.2)

Values are means (SD) except for sex and amputation etiology which is the number of observations (n). MoCA = The Montreal Cognitive Assessment (Scale range 0–30; higher scores indicate greater cognitive function). TMT-A = Trail Making Test A. TMT-B = Trail Making Test B. PLUS-M = Prosthetic Limb Users Survey of Mobility (T-score ranging between 21.8 and 71.4, higher score indicates greater mobility). AMP = Amputee Mobility Predictor (Scale 0–47, higher scores indicate better mobility). N/A = not applicable. Clinical data were compared using Student’s t-test. Sex was compared using the chi-square test.

Figure 2. a, b, c. Bar charts of the mean PFC activation (Arbitrary Unit) with 95% confidence intervals (shown as light gray lines) for each of the 20 channels in condition.

UW (Usual walking with self-selected walking speed), WCT (walking and carrying a tray with two cups filled with water) and WUT (walking on uneven terrain), respectively, for both groups.

Table 2. Figure-of-eight Walk test (F8W) parameters for the participants

Walking condition	Variable	Persons with LLA (N = 39)	Able-bodied controls (N = 33)	Mean difference	95% CI of the difference	Between-groups p-values (Bonferroni adjusted)	Effect size Cohen’s d
UW	Time, s.	9.0 (2.0)	8.0 (1.9)	.9	−.03–1.86	0.177	0.51
	Steps, n.	13.8 (2.5)	12.6 (2.0)	1.2	.12–2.36	0.090	0.68
WCT	Time, s.	10.6 (2.2)	9.4 (2.0)	1.2	.28–2.17	0.033	0.77
	Steps, n.	15.8 (2.9)	14.3 (1.9)	1.5	.41–2.66	0.021	0.61
WUT	Time, s.	10.1 (2.4)	8.6 (1.9)	1.4	.50–2.39	0.009	0.69
	Steps, n.	15.0 (3.0)	13.1 (1.9)	1.9	.81–3.05	0.003	0.76

Values are means (SD). s. = seconds. n. = number. UW = Usual walking with self-selected walking speed. WCT = Walking and carrying a tray with two cups filled with water. WUT = Walking on uneven terrain. Figure-of-eight Walk test (F8 W) parameters were compared and mean difference estimated using linear mixed effects models. Bold numbers are significant values after Bonferroni adjustment for multiple tests. CI = confidence interval.