245 / 412
reported. In a recent review by Misono and Merati,
24
the
risk of vocal fold paralysis in thyroidectomy was between
0.8% and 2.3%; anterior cervical spine injury, less than 1%;
cardiac/aortic surgery, 2%; mediastinoscopy, 0.2% to 6%;
esophagectomy, 11%; and carotid endarterectomy, 4%.
Idiopathic UVFP was the etiology in 124 (13.2%) patients.
Some older studies reported idiopathic etiologies to be the
most common cause of UVFP,
2,6-10
but a recent review of
the literature reported a rate of idiopathic UVFP of 24%
6
10%.
21
The decrease in idiopathic UVFP is likely due to
better imaging capabilities to find small lesions along the
nerve, as well as the shift toward surgery-related UVFP,
which increases the proportion of cases with a clear etiology.
The data in this study by comparison to earlier studies of
UVFP etiologies show the trend toward increasing surgical
rather than malignant or idiopathic causes. This trend may
be due to several factors. Since this study was conducted at
a large tertiary referral center, as were the other recent stud-
ies by Rosenthal et al
15
and Takano et al,
16
a greater
amount of surgery, as well as more complicated surgery,
was likely being performed. An increased number of com-
plicated surgeries both increase the risk of injury to the
recurrent laryngeal nerve, as well as the relative numbers of
UVFP due to surgical causes. In addition, as diagnostic ima-
ging capabilities continue to improve, UVFP due to malig-
nant or idiopathic causes will continue to decrease, as
tumors are identified before causing UVFP and the course
of the vagus and recurrent nerve can be imaged to deter-
mine the etiology of cases formerly diagnosed as idiopathic.
In analysis of laterality, 621 (66.2%) patients had left-
sided UVFP, consistent with previous studies showing
left-sided UVFP ranging from 59% to 81%.
1,2,7,8,11,15,16
Intrathoracic etiologies had the expected left-sided predomi-
nance, due to the anatomic course of the left recurrent laryn-
geal nerve. The statistically significant left-sidedness of
some other etiologies may be a little harder to explain:
Table 2.
Unilateral Vocal Fold Paralysis Laterality.
a
Etiology
n
Right
Left
Skew
P
-value
b
Thyroid surgery
140
64
76
–0.04
.31
Lung surgery
73
15
58
–0.29
<.01
Lateral neck surgery
61
25
36
–0.09
.16
Cardiac surgery
58
9
49
–0.34
<.01
Cervical spine surgery
48
27
21
0.06
.39
Esophageal surgery
37
6
31
–0.34
<.01
Carotid surgery
22
6
16
–0.23
.03
Skull base surgery
18
12
6
0.17
.16
Parathyroid surgery
18
9
9
0
1.00
Mediastinal surgery
17
10
7
0.09
.47
Idiopathic
124
39
85
–0.19
<.01
Lung cancer
73
6
67
–0.42
<.01
Intubation
58
17
41
–0.21
<.01
Trauma
30
14
16
–0.03
.72
Metastatic cancer
24
10
14
–0.08
.41
Laryngeal cancer
20
7
13
–0.15
.18
Skull base tumor
18
4
14
–0.28
.02
CVA
18
7
11
–0.11
.35
Thyroid cancer—direct invasion
14
6
8
–0.07
.59
Esophageal cancer
11
4
7
–0.14
.37
Abbreviation: CVA, cerebral vascular accident.
a
Etiologies with less than 10 patients not shown.
b
P
values based on
x
2
comparison with 50-50 L-R split with same N. Bold,
P
\
.05.
Figure 1.
Left-right skew by etiology. Solid circles, statistically signif-
icantly skewed; open circles, not significant. Skew = (# cases on right
/ total cases for etiology) – 0.5. If left = right, skew = 0 (as seen for
18 parathyroid cases); if all cases occurred on left, skew = –0.5.
Grouped are the intrathoracic causes of unilateral vocal fold paraly-
sis (lung malignancy, thoracic, cardiac, and esophageal surgery).
Spataro et al
20