Laryngeal nerve injury management and thyroid hormone replacement
THE CONTEXT
Thyroid surgery can affect voice through nerve injury or subtler changes, and the extent of resection influences the need for thyroxine.
Recurrent laryngeal nerve repair and voice rehabilitation
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If the transected ends of an injured recurrent laryngeal nerve are identified during surgery, they should be reanastomosed.
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When a segment has been excised, such as for malignant invasion, ansa cervicalis anastomosis may be considered.
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Ansa cervicalis anastomosis preserves neurological input without restoring vocal cord mobility. Avoiding denervation and muscle atrophy improves vocal quality.
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Permanent vocal cord paralysis should initially be managed conservatively with speech therapy. Medialisation procedures can be used if voice quality remains unacceptable.
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Nerve grafting has shown promise, but experience is limited.
Superior laryngeal nerve injury and counselling
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The external branch of the superior laryngeal nerve is vulnerable because it lies close to the superior thyroid artery. Injury reduces vocal cord tension, vocal power and range.
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Patients, especially professional voice users, should be advised that thyroid surgery changes the voice even without nerve trauma. For most patients, changes are subtle and demonstrable only on formal assessment.
Thyroid insufficiency
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Thyroxine replacement is required after total thyroidectomy. Around one in three patients need supplementation after lobectomy, with higher rates in those with thyroid autoantibodies.
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Subtotal thyroidectomy aimed to preserve enough tissue for thyroid function, but the required amount is difficult to judge.
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Recurrence of the original benign disease can necessitate difficult revision surgery. Subtotal thyroidectomy has therefore largely been abandoned except where exogenous thyroxine is unavailable.