Table 4. Causes of Thyroidectomy-related Dysphonia
Neural Functional Consequence
Impact on Voice
Character
RLN injury (complete
or partial, transient or
permanent)
• Immobile and laterally
displaced vocal fold (VF)
• Inadequate closure of
VFs with phonation and
swallowing
• Loss of VF bulk and tone
• Bowing of VF
• Breathy voice
• Vocal fatigue
• Hoarseness
External Branch of the
Superior Laryngeal Nerve
(EBSLN) injury (complete
or partial, transient or
permanent)
Physical findings are not
good predictors but, if
present, may include:
• Posterior laryngeal
rotation toward the
paretic side, or shift of the
petiole
• Bowing of the VF on the
weak side
• Inferior displacement of
the affected VF
• Vocal fatigue
• Decreased ability to raise
pitch
• Inability to project voice
• Decreased pitch flexibility
and range
Non-Neural
Direct cricothyroid muscle
injury— transient myositis
or direct injury
As for EBSLN As for ESBLN
Regional so tissue injury
(in the presence of intact
neurological function)
• Laryngotracheal regional
scar with fixation
• Strap muscles denervation
or trauma
• Local hematoma and/or
edema
• Voice fatigue
• Decrease in vocal range
• Speech becomes more
monotone
• Vocal pitch can be lower
Intubation-related injuries
• General: 6%-13%
• VF paresis: 0.04%
• VF trauma (ie, edema,
hematoma, laceration)
• VF granuloma
• Arytenoid dislocation
• Hoarseness
• Odynophagia
Voice change from unrelated
concurrent upper respiratory
tract infection
Typically viral-related
laryngitis unrelated to
surgery, rarely associated
with VF paresis
• Hoarseness
• Breathy voice if VF
paresis/paralysis exists
