- After thyroid surgery, the voice is affected temporarily in about one in ten patients and permanently in a little over two in a hundred, according to a review of 25,000 cases.
- After ablation, voice changes are reported in one in a hundred patients and permanent injury in fewer than two in a thousand, and a recent series of 620 nodules reported none.
- The two sets of figures come from different patients and are not a contest. What can be compared is what each technique does to protect the nerve.
The The nerve that moves the vocal cord on each side. It runs up the neck along the back of the thyroid. runs up the neck along the back of the thyroid, one on each side, and reaches the larynx, where it moves the vocal cord. If one stops working, the vocal cord on that side stops moving: the voice becomes hoarse and weak, it tires easily, and swallowing liquids is sometimes difficult. If the injury is temporary, the voice recovers in weeks or months. If it is permanent, there are treatments, but the voice does not fully return to what it was. That is why this nerve is the central concern of any physician treating the thyroid.
In surgery
To remove a lobe, the surgeon has to separate it from the nerve, which runs right alongside it. The surgeon identifies the nerve, follows it and protects it throughout the dissection. Today a A device that records the nerve's activity during surgery and warns with a signal if it is being irritated., which gives a signal when the nerve is being irritated, and magnifying loupes help with this. Even so, the nerve can become inflamed from handling, and in a small number of cases it can be injured. The figures depend a great deal on the extent of the surgery, on whether it is a first operation or a reoperation, and on the experience of the surgeon.
- 9.8%temporary vocal cord palsy after thyroid surgery, and 2.3% permanent, in a systematic review of 27 studies with 25,000 patients.Jeannon JP et al. Int J Clin Pract. 2009, 63(4): 624-629.
A nuance worth bearing in mind: those figures cover every type of surgery, including cancer operations with lymph node dissection and reoperations, which carry the most risk. In a lobectomy for a benign nodule, in experienced hands and with a neuromonitor, the permanent risk is clearly lower. It is worth asking your surgeon for their own figures, in addition to those in the literature.
In ablation
Ablation involves no incision, but heat spreads, and the nerve lies millimeters from the edge of the nodule. What protects it is the technique: the electrode enters through the center of the neck, pointing away from the nerve, the nodule is treated zone by zone with the electrode tip visible on screen at all times, a margin along the path of the nerve is left untreated and, if needed, fluid is injected to separate the nodule from nearby structures. And there is a reason the guidelines require local anesthesia: the patient speaks during the procedure, so any change in the voice is detected immediately and the procedure is stopped.
- 1.02%voice change after an ablation. Nerve paresis is usually transient and resolves in two to three months, and permanent injury is described in 0 to 0.17%.Chung SR, Suh CH, Baek JH et al. Int J Hyperthermia. 2017, 33(8): 920-930 · Issa PP et al. Gland Surg. 2024, 13(1): 77-86.
- 0permanent voice changes in 620 nodules treated at three North American centers, with an overall complication rate of 3.2%.Russell JO et al. Surgery. 2024, 175(1): 139-145.
How to read the two sets of figures
Surgery
- Temporary risk about one in ten, and permanent a little over two in a hundred
- The figures include cancer surgery, neck dissections and reoperations
- The nerve is seen, followed and monitored
- It is the usual path when there is cancer or a suspicion of cancer
Ablation
- Voice change in one in a hundred, and permanent in fewer than two in a thousand
- The figures are from benign nodules, without cancer or lymph nodes
- The nerve is not exposed: it is protected by the entry route, the safety margin and the patient's voice during the procedure
- For benign nodules and, in selected patients, a papillary cancer of one centimeter or less without lymph nodes. The comparison holds when both options are possible
The figures do not say one technique is better than the other: they say that, when both are possible for the same benign nodule, ablation exposes the nerve less. When only one is possible, the comparison no longer applies.
If the voice changes afterwards
In both cases, mild hoarseness in the first days is expected and resolves. What should be checked is a marked change that does not improve within the first week or that gets worse, or any difficulty swallowing liquids. The vocal cord is examined, almost always with a small camera passed through the nose, and then followed over time. Most Partial weakness of a nerve or muscle, in this case of the vocal cord. It is usually temporary. recover on their own in two to three months, and in the meantime, voice therapy helps.
- Jeannon JP, Orabi AA, Bruch GA, Abdalsalam HA, Simo R. Diagnosis of recurrent laryngeal nerve palsy after thyroidectomy: a systematic review. Int J Clin Pract. 2009, 63(4): 624-629.
- Chung SR, Suh CH, Baek JH et al. Safety of radiofrequency ablation of benign thyroid nodules and recurrent thyroid cancers: a systematic review and meta-analysis. Int J Hyperthermia. 2017, 33(8): 920-930.
- Issa PP et al. Gland Surg. 2024, 13(1): 77-86.
- Russell JO et al. Surgery. 2024, 175(1): 139-145.
- Kim JH et al. 2017 Thyroid Radiofrequency Ablation Guideline: Korean Society of Thyroid Radiology. Korean J Radiol. 2018, 19(4): 632-655.
