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regression analysis. In further stratification analysis,
there was a significant difference between group A and
C and group B and C (P
<
0.05), but not between group
A and B (P
>
0.05).
Electromyographic Findings
All patients received laryngeal electromyographic
examinations preoperatively. However, postoperative
EMG results were available in only 148, 97, and 41
patients in group A, B, and C, respectively. The electri-
cal activity in the TA muscles of the affected vocal folds
during EMG in the present study was divided into two
types: spontaneous activity and VMUR. Spontaneous
activity, which included positive waves, fibrillations, and
complex repetitive discharges, could not be recorded;
and VMUR were improved in each group postoperatively
(
P
<
0.05). Denervation duration was identified as a sig-
nificant variable with regard to the parameter postoper-
ative VMUR in multivariable logistic regression
analysis. In further stratification analysis, there was a
significant difference between group A and C and group
B and C (
P
<
0.05), but not between group A and B
(
P
>
0.05).
DISCUSSION
Laryngeal reinnervation with ansa cervicalis to
RLN anastomosis was reintroduced by Crumley
2
and fol-
lowed by many other investigators,
4–6
and it has been
presented as a good procedure to achieve a normal voice
quality. Previous studies in animal models
7,10,11
and in
humans
12
have shown that reinnervation can potentially
restore laryngeal function when it is performed immedi-
ately after RLN injury. In the clinical setting, most
UVFP patients suffer from hoarseness and aspiration for
several months or even years before they seek medical
help. Even in UVFP patients who are diagnosed early,
TABLE III.
Stratification Analysis on Denervation Duration.
Parameters
Groups
Changes Between Preoperative and Postoperative
Values
P
Values of Preopera-
tive and Postoperative
Comparison
P
Values of Intergroups
Comparison
Preoperative Median
(QL, QU)
Postoperative Median
(QL, QU)
Overall Grade
A
2.2 (2.0–2.4)
0.0 (0.0–0.4)
<
0.001
P
total
<
0.01
B
2.2 (2.0–2.4)
0.0 (0.0–0.6)
<
0.001
P
ab
>
0.05;
P
bc
<
0.01
C
2.2 (2.0–2.4)
0.4 (0.2–0.7)
<
0.001
P
ac
<
0.01
Overall sample
2.2 (2.0–2.4)
0.2 (0.0–0.6)
<
0.001
Jitter
A
1.87 (1.44–2.66)
0.26 (0.21–0.35)
<
0.001
P
total
<
0.001
B
1.75 (1.33–2.34)
0.24 (0.15–0.30)
<
0.001
P
ab
>
0.05
C
1.85 (1.48–2.05)
0.49 (0.39–0.83)
<
0.001
P
ac
<
0.05;
P
bc
<
0.05
Overall sample 1.82 (1.40–2.47)
0.27 (0.22–0.42)
<
0.001
Shimmer
A
9.47 (8.49–10.90)
2.86 (2.44–3.61)
<
0.001
P
total
<
0.001
B
9.55 (8.55–11.12)
3.12 (2.34–3.72)
<
0.001
P
ab
>
0.05;
P
bc
<
0.05
C
9.37 (8.37–10.87)
4.82 (4.04–5.54)
<
0.001
P
ac
<
0.05
Overall sample 9.49 (8.49–10.90)
3.22 (2.52–4.29)
<
0.001
NHR
A
0.18 (0.14–0.29)
0.02 (0.01–0.02)
<
0.001
P
total
<
0.001
B
0.17 (0.14–0.25)
0.02 (0.01–0.02)
<
0.001
P
ab
>
0.05;
P
ac
<
0.05
C
0.20 (0.13–0.23)
0.04 (0.03–0.07)
<
0.001
P
bc
<
0.05
Overall sample 0.18 (0.14–0.25)
0.02 (0.01–0.03)
<
0.001
MPT
A
6.02 (4.68–6.79)
17.17 (14.97–21.46)
<
0.001
P
total
<
0.001
B
5.59 (4.46–6.89)
17.37 (14.93–20.75)
<
0.001
P
ab
>
0.05;
P
ac
<
0.05
C
5.45 (4.54–6.69)
14.75 (11.10–17.22)
<
0.001
P
bc
<
0.05
Overall sample 5.73 (4.60–6.79)
16.56 (14.42–20.33)
<
0.001
Post-VMUR
A
2.0 (1.0–2.0)
0.0 (0.0–0.0)
<
0.001
P
total
<
0.01
B
2.0 (1.0–2.0)
0.0 (0.0–0.0)
<
0.001
P
ab
>
0.05;
P
bc
<
0.01
C
2.0 (1.0–2.0)
0.0 (0.0–2.0)
<
0.001
P
ac
<
0.001
Overall sample
2.0 (1.0–2.0)
0.0 (0.0–1.0)
<
0.001
Glottal closure
A
3.0 (3.0–3.0)
0.0 (0.0–0.0)
<
0.001
P
total
>
0.05
B
3.0 (3.0–3.0)
0.0 (0.0–0.0)
<
0.001
P
ab
>
0.05
C
3.0 (3.0–3.0)
0.0 (0.0–0.0)
<
0.001
P
bc
>
0.05;
P
ac
>
0.05
Overall sample
3.0 (3.0–3.0)
0.0 (0.0–0.0)
<
0.001
MPT
5
maximum phonation time; NHR
5
noise-to-harmonics ratio; QL= low quartile; QU= upper quartile; VMUR
5
voluntary motor-unit recruitment.
P
<
0.05 is deemed as statistically significant.
Laryngoscope 124: August 2014
Li et al.: Denervated Duration on Reinnervation for UVFP
8