47 / 412
represent paresis or paralysis in large part) in 346 (83%)
patients. Sataloff et al.
14
reviewed 751 patients who
underwent LEMG for all causes over a 4-year period.
This series contained 689 suspected cases of paresis/
paralysis by videostrobscopy, with LEMG confirming the
diagnosis in 661 patients (95.9%). The variation among
these three series reveals substantial differences among
practitioners regarding diagnosis and testing.
Respondents indicated that they principally relied
on laryngoscopy, usually under stroboscopic light, to
make the diagnosis of VFP. Although LEMG is the only
way to definitively diagnose laryngeal neuropathy objec-
tively in vivo, the vast majority of respondents evidently
felt that laryngoscopic criteria were sufficiently reliable
to support the diagnosis alone. Only one respondent rou-
tinely relied on LEMG for diagnosis, and only the minor-
ity of patients ever had LEMG at all. Many reasons may
prevent the use of LEMG, lack of availability and exper-
tise prominent among them, but respondents felt that
the sensitivity of LEMG was not high. There is little
doubt that LEMG is highly specific for neuropathy. Find-
ings of fibrillations, positive sharp waves, or polyphasic
motor unit action potentials are unambiguous signs of
neurologic impairment. Unfortunately in paresis, such
clearly abnormal findings may be absent or obscured.
Decreased recruitment of otherwise normal-appearing
motor unit action potentials may be the only abnormality
present. Because this relative change may be small and
mimicked by incomplete muscle activation or suboptimal
needle placement, there remains a role for physician
judgment and inevitably error. Moreover, the maximal
interference pattern in striated muscle is typically pres-
ent at only 30% of maximum isometric contraction, which
creates the possibility that even substantial paresis may
be obscured during testing. Thus, although LEMG can
provide important information that laryngoscopy cannot,
it is not clear that it is a more accurate diagnostic tool
than laryngoscopy in the diagnosis of VFP.
Reliance on laryngoscopy begs the question of which
findings are considered important. To say that one may
find signs of paresis in virtually every larynx is only a
mild exaggeration. Unlike systems such as the extraocu-
lar muscles, mild discoordination in the larynx probably
carries little functional and evolutionary disadvantage
as long as glottic closure for airway protection is brisk
and effective. Thus, much asymmetry in vocal fold
TABLE II.
Practice Related to VFP
New patients with voice-related
complaint/month
49
6
3.2,
r
5
25
VFP diagnosis/month
8.5
6
1.6,
r
5
12
Diagnosis of VFP Rests Principally On:
History
1 (1.7%)
Laryngoscopy (continuous light)
10 (17%)
Strobovideolaryngoscopy
42 (72%)
LEMG
1 (1.7%)
% Patients diagnosed with VFP
who had videostroboscopy
96
6
1.6%,
r
5
12
% patients diagnosed with VFP
who had LEMG
26
6
4.0%,
r
5
31
LEMG
5
laryngeal electromyography; VFP
5
vocal fold paresis.
Fig. 4. Positive predictive value of
laryngoscopic signs for vocal fold
paresis.
MW
5
mucosal
wave;
VF
5
vocal fold.
Laryngoscope 125: April 2015
Wu and Sulica: Paresis Survey
27