While the present condition of Senator McCain prompts this question I am looking for a general answer under similar circumstance for any senator, not necessarily "just McCain".
Is there a mechanism for the Senate or the State (of Arizona in this case) to remove a sitting senator for medical cause against his will. The 25th Amendment, section 4, essentially provides that others may declare a president unable to discharge his duties and may be displaced from office. Are there similar provisions pertaining to a senator?
edit: The answers present thus far refer to expulsion, and note that it is "disciplinary"... which is actually what I was trying to avoid. While certainly the senate could go on without the voice of any single senator, their state is entitled to representation. In the past (when the Senate was more "collegial") I know there were times when opposing Senators 'skipped voting' so as to preserve the balance that would have occurred had their ill member been present. In today's environment I doubt this would happen.