(a) For purposes of this section, "health care provider" means a physician, surgeon, dentist, occupational therapist, other health care professionals as defined in section 145.61 , hospital, or treatment facility.
(b) An action by a patient or former patient against a health care provider alleging malpractice, error, mistake, or failure to cure, whether based on a contract or tort, must be commenced within four years from the date the cause of action accrued.
(c) A counterclaim may be pleaded as a defense to any action for services brought by a health care provider after the limitations described in this section, notwithstanding it is barred by the provisions of this chapter, if the counterclaim belonged to the party pleading it at the time it became barred and was not barred at the time the claim sued on originated, but no judgment on the counterclaim except for costs can be rendered in favor of the party so pleading it.