A tough year for the Oakland Athletics on the field got even more difficult Monday. Starting shortstop Cliff Pennington had to leave Monday night's game against the Mariners in the sixth inning because of facial paralysis.

The San Francisco Chronicle reports Pennington was diagnosed with a case of Bell's Palsy, normally a temporary illness, in which a nerve causes facial paralysis. The condition normally goes away in a few days.

WebMD reports the cause of Bell's palsy is not known. "Many health problems can cause weakness or paralysis of the face," the site says. "If a specific reason cannot be found for the weakness, the condition is called Bell's palsy." However, Bell's palsy is not a sign of a stroke.

Symptoms of Bell's palsy include:

• Sudden weakness or paralysis on one side of your face that causes it to droop.

• Drooling.

• Eye problems, such as excessive tearing or a dry eye.

• Loss of ability to taste.

• Pain in or behind your ear.

• Numbness in the affected side of your face.

• Increased sensitivity to sound.

The Athletics doctors put Pennington on medication immediately. He compared the injury to a bad dentist visit.

"It feels like I went to the dentist and the whole left side of my face is numb," he said.

Pennington promised to return to the A's lineup as soon as he can blink again.

The shortstop is hitting .264 with 5 homers and 32 RBI's for a 49-62 Oakland team that sits 12 games behind the Texas Rangers in the American League West.

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