34 / 412
Discussion
The role of CT in the evaluation of vocal fold paralysis is
well established. Its near routine use is justified by a high
diagnostic yield (35% to 62%)
6,7
and a high proportion of
cases due to underlying neoplasia (13% to 33%).
8,10
Its role
in paresis, however, is unclear, partly because the preva-
lence of a neoplastic etiology in published studies is a com-
paratively low (1.1% to 6%;
Table 6
)
1,4,12
and partly
because there is a paucity of studies examining the diagnos-
tic yield of CT paresis. A previous study found the diagnos-
tic yield of CT in IUVFP to be 1.7%.
12
The overall diagnostic yield of CT in the evaluation of
paresis in the current study was 2.9% (95% confidence
interval, 0.94% to 6.6%). Such values may justify the use of
routine CT evaluation. A similar percentage yield (1% to
4%) is seen by many authors as justification for the routine
use of magnetic resonance imaging in the evaluation of asym-
metric sensorineural hearing loss.
14
This argument for routine
CT in paresis might be strengthened from a qualitative
perspective, when one considers that 4 of 5 (80%) of our CT-
positive cases had a pathology that required operation,
which untreated may have led to serious morbidity.
Conversely, the study by Badia et al
12
described a final
yield of 0%, as the single CT-positive case was benign and
required no intervention.
The argument against the routine use of CT in the eva-
luation of IUVFP is strengthened when one considers the
discovery of incidental lesions and the potential morbidities
due to the performance of additional diagnostic tests and
interventions. This study identified an incidental yield of
27.6%. The majority of these patients with incidental ima-
ging findings (83.3%) underwent serial examination and
imaging alone (including serial thyroid ultrasound, CT of
the neck and chest, and magnetic resonance imaging of the
brain), thus exposing them to additional perhaps unneces-
sary radiation and expense. In all of these imaging-alone
cases, the incidental lesions did not evolve into clinically
significant pathologies over the mean laryngologic follow-
up period of 2.95 years (SD, 1.52). Five patients underwent
Table 6.
Etiology of Vocal Fold Paralysis vs Paresis (in Percentages).
Paralysis
Paresis
Etiology
MacGregor
10
(n = 1308)
Koufman
4
(n = 50)
Heman-Ackah
1
(n = 46)
Badia
12
(n = 176)
Present Study
(n = 237)
Total iatrogenic
22
20
4.3
39.2
3.4
Total neoplastic lesions
21.7
6
13
1.1
2.9
Total nonneoplastic benign disease
39.9
6
54.3
13.6
5.7
Idiopathic
a
16.4
68
28.3
46
88
a
Includes viral neuritis.
Table 5.
Proportion of Incidental Lesions by Anatomic Group.
Incidental Lesion Type
Proportion of All Incidental Lesions
Thyroid abnormalities
: nodules, cysts, enlargement
29
Pulmonary lesions
: nodules, granulomas, pleural plaques, hilar lymphadenopathy
40
Mediastinal lesions
: thoracic aortic aneurysms, mediastinal lymphadenopathy
15
Cervical abnormalities
: laryngocele, thyroglossal duct cyst, cervical lymphadenopathy
13
Miscellaneous
: vertebral lesions
4
Table 4.
Yield of CT in IUVFP.
Yield
Positive CT, n
Yield, % (95% CI)
Needed to Treat/Harm, n
Diagnostic
5
a
2.9 (0.94-6.6)
34
Incidental
48
b
27.6 (21.1-34.9)
4
Abbreviations: CI, confidence interval; CT, computed tomography; IUVFP, idiopathic unilateral vocal fold paresis.
a
Diagnostic of benign lesion, n = 4; diagnostic of a malignancy, n = 1.
b
Underwent clinical or imaging follow-up alone, n = 40; underwent fine-needle aspiration alone, n = 5; required operation, n = 3.
Paddle et al
14