The book Johnny Got His Gun kind of answers this question. In the book, a WWI soldier gets blown up by an artillery shell and wakes up in a hospital missing most of his body. He has lost his arms, legs, nose, mouth, eyes, and ears.

In the end he learns he can communicate with a nurse by tapping his head in Morse code. So it would seem as long as you could move you head with your neck, you can still communicate with others.