Diagnostic Value of FDG-PET/CT in Laryngeal Nerve Palsy

Aim Paresis of the recurrent laryngeal nerves may be a symptom of malignancy due
to the anatomical course of the nerves in the neck and mediastinum. Therefore,
FDG-PET/CT may be useful as an ancillary examination for diagnosing malignancy.
The Aim was to investigate the frequency of malignant findings and the diagnostic
yield of FDG-PET/CT in patients presenting with recurrent laryngeal nerve palsy.
Materials and Methods We retrospectively included all patients referred for FDGPET/
CT scans with recurrent laryngeal nerve palsy from the Department of ENT
Head and Neck Surgery at our hospital from January 2011 until March 2013. Scan
results were compared to clinical workup including biopsy and pathology results. A
scan was considered true positive if PET/CT was suggestive of malignancy along the
pathway of the recurrent laryngeal nerves, and this finding was confirmed by
biopsy and false positive if not confirmed by biopsy and/or follow-up. A true
negative scan was one without abnormal FDG-uptake and a follow-up
demonstrating non-malignancy, whereas a false negative scan was present if
follow-up was consistent with malignancy in a patient in whom PET/CT failed to
detect a malignancy suspicious lesion. Results The study comprised 48 patients, 23
females and 25 males with a mean age of 66 years (range 37-89). Nine of these had
a history of radically treated cancer. Twenty-one (44 %) were diagnosed with
cancer during follow-up, most frequently of the lung, breast and oesophagus. The
palsy was right-sided in 13 patients, left-sided in 32 and bilateral in 3. Mean followup
was 6 months (range 1-24). PET/CT was suggestive of malignancy in 27 patients
(21 true positive, 6 false positive) and showed no malignancy in 21 (21 true
negative, 0 false negative). Thus, the sensitivity, specificity, accuracy, positive and
negative predictive values were 100% [85%-100%], 78% [59%-89%], 88% [75-94%],
78% [59%-89%], and 100% [85%-100%], respectively (Wilson score based 95%
confidence intervals in brackets). Conclusion In this retrospective survey, biopsy
proven malignancy (whether newly diagnosed or relapsed) was the cause of
recurrent laryngeal nerve palsy in almost half of the patients. FDG-PET/CT was
excellent in finding (sensitivity 100%) and ruling out malignancy (negative
predictive value 100%).