Functional effects of botulinum toxin in patients with HSP
hip abduction was measured using a goniometer. All outcomes
were averaged for both sides into a single score.
Functional tests. Functional balance was assessed barefooted
with the Berg Balance Scale (BBS, range 0–56) (18). The Timed
Up and Go (TUG test) (19) was performed with (adapted) shoes
and/or orthoses, but without other walking aids. Endurance was
assessed with the 6-min Walk Test (6MWT) (20) during which
all walking aids were allowed. Lastly, the Activities-specific
Balance Confidence (ABC) scale (21) was obtained as a sub-
jective measure of mobility and balance.
Procedure
All outcome measurements were performed on the day of
treatment prior to the injections (baseline; T0), 6 (± 1) weeks
after treatment (T1), and 16 (± 1) weeks after treatment (T2).
T1 was set at 6 weeks after treatment, because at this time-point
the physiological effects of BTX-A on spasticity were expected
to have reached a maximum (11). The effects of BTX-A were
expected to diminish progressively until approximately 16
weeks after the injections. Hence, T2 was set at 16 weeks post-
treatment to test the possible presence of a long-term effect of
the combined treatment. The instrumented assessments were
taken by the primary investigator. All other tests were assessed
by an independent physiotherapist.
Statistical analysis
All instrumented (parametric) outcome measures were tested
using repeated-measures analysis of variance (ANOVA). The
primary outcomes gait width and sidestep leg angle were tested
using time (T0 – T1 – T2) as within-subjects factor. For gait
width and gait speed, also gait condition (preferred – maximal)
was introduced as a within-subjects factor. Bonferroni corrected
post-hoc tests were applied in the case of a significant main effect
of time. All other (non-parametric) outcome measures (physical
and functional tests) were analysed with a Friedman’s test using
time (T0 – T1 – T2) as a within-subject factor. Wilcoxon’s tests
were used for post-hoc comparisons in the case of a significant
time effect. All statistical analyses were performed using IMB
SPSS Statistics Version 22 for Windows. The α-level was set at
0.05 for all analyses, with no adjustment for multiple outcomes.
RESULTS
Participants
From the total of 25 patients included in the study, 3
patients were lost between the first (T0) and second
measurements (T1): 1 patient experienced increasing
shoulder complaints that were already present before
the first visit. One patient was lost due to spontaneous
severe back pain, which had also repeatedly occurred
in the past. A third patient left the study due to perso-
nal circumstances. No other adverse events occurred
during the study.
Instrumented gait assessments
Table III summarizes the group results for all measu-
rements. There was a significant time effect on gait
width (F(2,42) = 6.143, p = 0.005). Gait width increased
by 12.6% from baseline to T1 (p = 0.021), and this im-
provement persisted at T2 (9.7%; p = 0.022) (see Fig.
2a). There was no effect of gait condition on gait width
(F(1,21) = 1.229, p = 0.280), nor was there a significant
time × gait condition interaction (F(2,42) = 1.081,
p = 0.349).
Table III. Outcomes measures
Friedman’s test
or repeated-
measures
ANOVA
Test Before intervention
(T0) After 6 weeks
(T1) After 16 weeks
(T2) GaitRite, mean (SD) [95% CI]
Gait width – preferred speed, cm
Gait width – maximal speed, cm 10.7 (5.8) [8.1–13.2]
10.0 (6.0) [7.4–12.7] 11.8 (6.0) [9.1–14.4]
11.5 (6.1) [8.8–14.2] 11.3 (5.7) [8.7–13.8]
11.2 (5.8) [8.7–13.8] F(2,42) = 6.143
0.96 (0.25) [0.85–1.07)
1.31 (0.41) [1.14–1.50] 1.04 (0.26) [0.93–1.16]
1.33 (0.35) [1.17–1.48] 1.07 (0.28) [0.94–1.20]
1.36 (0.41) [1.18–1.54] F(2,42) = 15.265
F(2,42) = 1.140
19.8 (3.8) [17.9–21.6]
19.3 (4.7) [16.5–22.2] 20.2 (4.1) [18.2–22,1]
19.4 (5.2) [16.3–22.6] F(2,32) = 8.568
F(2,24) = 0.107
Comfortable gait speed, m/s
Maximal gait speed, m/s
Radboud Falls Simulator
Leg angle – known dir, mean (SD) [95% CI] 18.7 (4.1) [16.7–20.7]
Leg angle – unknown dir, mean (SD) [95% CI] 19.1 (4.7) [16.3–22.0]
χ 2 (2, n = 21) = 12.559
Success rates – known dir, %, median [IQR] 70.0 [45.0] 90.0 [30.0] 90.0 [45.0] Success rates – unknown dir, %, median [IQR] 25.0 [55.0]
Clinical assessments 35.0 [72.5] 45.0 [70.0] χ 2 (2, n = 22) = 4.388
p-value
0.005 a
< 0.001 b
0.330
0.001 a
0.899
0.002 c
0.111
MAS – hip adductors, median [IQR] 2.5 [1.3] 1.0 [1.5] 1.8 [1.0] χ 2 (2, n = 22) = 33.890 < 0.001 d
MRC – hip adductors, median [IQR] 5.0 [0.0] 4.0 [1.0] 5.0 [0.3] χ 2 (2, n = 22) = 15.800 < 0.001 e
MRC – hip abductors, median [IQR] 5.0 [0.1] 5.0 [1.0] 5.0 [0.0] χ 2 (2, n = 22) = 4.957
50.7 (12.5) [45.2–56.2] 45.0 (10.8) [40.2–49.8] F(2,42) = 31.613
51.5 [9.0]
10.7 (4.2) [8.6–12.9]
376.0 (95.8) [327.0–425.2]
54.7 (22.8) [43.0–66.4] 51.0 [7.8]
10.5 (4.3) [8.3–12.7]
382.1 (95.2)[333.2–431.0]
51.5 (23.7) [39.3–63.6] χ 2 (2, n = 22) = 4.031
F(2,42) = 0.198
F(2,32) = 2.498
F(2,42) = 2.048
ROM – hip abduction, mean (SD) [95% CI] 38.8 (9.4) [34.6–42.9]
Other functional tests
BBS, median [IQR]
TUG, s, mean (SD) [95% CI]
6MWT, s, mean (SD) [95% CI]
ABC scale, %, mean (SD) [95% CI]
437
49.5 [10.0]
10.6 (3.8) [8.6–12.6]
367.5 (87.9) [322.3–412.7]
55.0 (21.85) [43.8–66.2]
0.084
< 0.001 f
0.133
0.821
0.098
0.142
a
T0T2>T1; e T0/2>T1, T0 = T2; f T0