"Injury" and "personal injury" shall mean only injury by accident arising out of and in the course of the employment and shall not include a disease in any form, except when it results naturally and unavoidably from the accident and except such diseases as are compensable under the provisions of Chapter 11 of this title. In construing this section an accident arising out of and in the course of employment shall include employment of an employee of a municipality outside the corporate limits of the municipality when the employment was ordered by a duly authorized employee of the municipality.

Stress arising out of and in the course of employment unaccompanied by physical injury and resulting in mental illness or injury is not a personal injury unless it is established that the stressful employment conditions causing the mental injury were extraordinary and unusual in comparison to the normal conditions of the employment.

Stress arising out of and in the course of employment unaccompanied by physical injury is not considered compensable if it results from any event or series of events which is incidental to normal employer/employee relations including, but not limited to, personnel actions by the employer such as disciplinary actions, work evaluations, transfers, promotions, demotions, salary reviews, or terminations, except when these actions are taken in an extraordinary and unusual manner.