30 / 412
atrophy and irreversible muscle fibrosis and degenera-
tion of muscle endplates during long-term denervation
may hinder successful reinnervation.
28
Even after rein-
nervation, muscle fibers may fail to resume their normal
size, possibly because of the progressive exhaustion of
satellite cells whose activity and status may be the key
determinant of skeletal muscle regeneration potential.
Our previous work showed that the levels of myoD and
myogenin, which are markers for activated satellite
cells, were upregulated 6 to 12 months after denervation
and then downregulated over time, ultimately becoming
undetectable by 2 years after denervation. This indicates
a decreased myogenic ability after a 2-year denervation
duration,
22
which might explain the better surgical out-
come of laryngeal reinnervation on patients with a
denervation duration less than 2 years than on patients
with a denervation duration longer than 2 years. There-
fore, for UVFP patients with a denervation course of
more than 2 years, it may be better to combine reinner-
vation surgery with arytenoid adduction.
29,30
In addition, there are some other factors that may
also affect the surgical outcome of laryngeal reinnerva-
tion, such as the age of patients and the severity of nerve
injury.
31–33
Crumley recommended that patients’ age
should be less than 70 in order to ensure the effectiveness
of laryngeal reinnervation,
2
while Paniello et al. revealed
that patients under age 52 had significantly better voice
recovery than those over age 52.
34
Stratification analysis
on age in the present series of patients revealed that
laryngeal reinnervation is less effective when patients are
older than 60 years old. Details of further stratification
analysis on these two identified influential factors will be
presented in other reports (unpublished).
CONCLUSION
The data from this study indicate that surgical out-
come of laryngeal reinnervation is affected by denerva-
tion duration, the age of patients, and the severity of
nerve injury. Although delayed reinnervation is effective,
surgical outcome is better when the procedure is per-
formed within 2 years after nerve injury than when the
procedure is performed over 2 years.
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Laryngoscope 124: August 2014
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