The main issue with thyroid surgery as it pertains to the voice is that the nerve that controls vocal cord movement goes right thru the thyroid gland. With thyroid surgery, the risk is injury to this nerve which would than affect the voice. Worst case, the nerve could get accidentally cut resulting in permanent vocal cord paralysis.
This study looked at 27 professional singers who underwent thyroid surgery, 60% due to cancer. What they found was return to performance rate was 100%, mean time to performance after surgery was 2.26 months (± 1.61). All three vocal instrument mean scores, pre-op vs. post-op, were unchanged:
• Voice Handicap Index (VHI): 4.15 (± 5.22) vs 4.04 (± 3.85), p = 0.9301
• Singing Voice Handicap Index (SVHI): 11.26 (± 14.41) vs 12.07 (± 13.09), p = 0.8297
• Evaluation of Ability to Sing Easily (EASE): 6.19 (± 9.19) vs 6.00 (± 7.72), p = 0.9348
The vocal parameters most affected from surgery until first performances were vocal fatigue (89%), high range (89%), pitch control and modulation (74%) and strength (81%). Final mean intraoperative EMG amplitude was within normal limits for intraoperative stimulation and had no relationship with time to first professional performance (p = 0.7199).
Overall, the study concluded that
"neural monitored thyroidectomy, including for thyroid malignancy, in professional voice users is safe without any changes in three different voice/ singing instruments, with 100% return to performance." [link]This information is extremely helpful when counseling professional singers and its possible impact on their voice afterwards.
Thyroidectomy in the Professional Singer-Neural Monitored Surgical Outcomes. Thyroid. 2015 Mar 19. [Epub ahead of print]