What causes adult laryngeal nerve palsy?

Depends. There are many causes of laryngeal nerve paresis (palsy). The most common cause is after surgery. Thyroid surgery, neck surgery or cardiac surgery. It could be caused by a tumor or mass affecting the nerve. It may also be idiopathic... No known cause - likely viral. If you suspect laryngeal nerve palsy, you should be seen by an ent.
Laryngeal nerve pals. Laryngeal nerve palsy can have many causes the differential is long. The nerve can get stretched in surgery or cut. It could get invaded by tumor either directly by the thyroid gland mass or down in the chest by a lung tumor or mass. Benign tumors can put pressure on the nerve. A stroke could cause the nerve to be out inflammation around the nerve from systemic diseases can cause the nerve to go.