The first sign is often hoarseness of the voice - something noticeable in President Obama's voice in recent days.

BBC: How much stamina does it take to become US president?

Hoarseness, due to vocal cord paralysis after thyroid surgery, may be potentially related to injury to the recurrent laryngeal nerve.

FORBES: Move up http://i.forbesimg.com t Move down

Common symptoms include vocal fatigue, throat discomfort associated with speaking, hoarseness, as well as a chronic cough due to aspiration (food or liquids going down the trachea or windpipe).

FORBES: Move up http://i.forbesimg.com t Move down

The main side effect:hoarseness when the current begins.

FORBES: Rewiring the brain

On light throttle openings, the 330bhp 3.4 sounds, frankly, like it has a blowing exhaust, the familiar flat-six hoarseness akin to a dog coughing up an angora sweater, but on brief revels to three-quarters of the rev-range, the wail starts to build.

BBC: In search of the perfect road in Mallorca

Sorry for the hoarseness.

NPR: NATO Beats Taliban in Battle, Works to Win War