Because a hypothesis is different from the research question, research is usually required before you make a hypothesis. A hypothesis is a prediction of the test that is about to incur. Without the research the people doing the test would not know what to be looking for or how to setup the test. Because of the reason;
I assume the answer is, after generating an idea from an observation.
In Bell's palsy, the facial nerve that is injured and inflamed causes symptoms like twitching, weakness, or paralysis on one side of the face, sometimes both; drooling; a drooping eyelid or one corner of the mouth droops.
