Hi Thanks for posting on HCM Bell s palsy occurs when the seventh cranial nerve becomes swollen or compressed, resulting in facial weakness or paralysis. The exact cause of this damage is unknown, but believed to be triggered by a viral infection. Her condition may not be caused by chemo as chemo may not cause swelling or irritation in nerve that causes Bell s palsy. I will suggest you see your Neurologist for evaluation.The symptoms may go away after some time even without treatment.However, your Doctor may judge the need for corticosteroids, antiviral drugs and physiotherapy. Hope this will help Best regards