Left vocal cord paralysis
The axial fused PET/CT image at the level of the vocal
cords demonstrates asymmetric FDG uptake in the right vocal cord with no
significant uptake in the left vocal cord. The left vocal cord is mildly lax
with slight medial displacement. The fused PET/CT image of the chest
demonstrates a mass centered within the left aortopulmonary window with avid
FDG uptake. In addition, 2 pleural-based nodules are noted posteriorly within
the left hemithorax, which also demonstrate increased FDG uptake.
The recurrent laryngeal nerves (RLN) innervate the
laryngeal musculature and are essential to phonation, swallowing, breathing,
and coughing. The RLN arise from the vagus nerve (CNX) and injury to the RLN or
the vagus nerve may be secondary to neoplasm, trauma (including surgical),
radiation, or it may be idiopathic. The RLN arises from the nucleus ambiguous
in the medulla and exit the cranial vault with through the jugular foramina,
coursing inferiorly within the carotid sheath. The left RLN loops under the aortic
arch, while the right RLN loop under the brachiocephalic trunk. The RLN then
course superiorly along the tracheoesophageal grooves.
This case illustrates left vocal cord paralysis with
subsequent increased FDG uptake in the right vocal cord secondary to a
compensatory increased workload. The key finding in this case is the
hypermetabolic mass within the left aortopulmonary window, which may present
clinically with left recurrent laryngeal nerve palsy. The compensatory
asymmetric uptake in the right vocal cord is important for the radiologist to
distinguish from metastatic disease as it changes management significantly. Correlation
with a clinical history of dysphonia, hoarseness, or aspiration may be useful
to support the radiologic findings, but in some cases direct visualization with
laryngoscopy may be necessary.
In addition to the finding of asymmetric FDG uptake in
the contralateral vocal cord, additional CT findings of vocal cord paralysis
include paramedian positioning of the ipsilateral vocal cord, tilting of the
thyroid cartilage, dilation of the ipsilateral pyriform sinus, and displacement
of the arytenoid cartilage.
1. Komissarova M, Wong KK, Piert M, et al. Spectrum of 18F-FDG PET/CT
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Lee, M, Ramaswamy MR, Mohan R, Nathan CO. Unilateral vocal cord
paralysis causes contralateral false-positive positron emission
tomography scans of the larynx. Ann Otol Rhinol Laryngol. 2005;114:202-206.
Heller MT, Meltzer CC, Fukui MS, et al. Superphysiologic FDG uptake in
the non-paralyzed vocal cord. Resolution of false-positive PET result
with combined PET-CT imaging. Clin Positron Imaging. 2000;3:207-211.