bulba palsy

Five months ago my mother began to slur her speech. This happened instantly. She had a blood test, a scan and an electromyography. She has just learned that she needs to repeat the emg. On hearing this her speech has suddenly become a lot worse and her lower lip is tremulous, although she has absolutely no mobility problems. She has always suffered from extreme anxiety and insomnia. Could this cause bulba palsy like symptoms or are we dealing with mnd? She fears the latter, as her doctor has mentioned it, and is extremely worried and refusing further tests.   An honest opinion would be greatly appreciated.