5.2.5 If None of the Tables in the Guide Apply - AMA Guides
If the impairment under investigation is of a kind that cannot be assessed in accordance with the provisions of the Approved Guide, the Introduction to the Approved Guide authorises reference to the provisions of the current American Medical Association's Guides to the Evaluation of Permanent Impairment (the AMA Guides) in making the assessment. Note, however, that the AMA Guides are to be used only in very rare cases where it is not possible for a person's condition to be assessed under the Approved Guide.