The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fourth Edition, discusses rating cranial nerve and spinal cord impairments. Evaluation of impairment of the cranial nerves is based on clinical neurological assessment, and many cranial nerves also are addressed in other chapters of the AMA Guides (eg, the visual system or the ear, nose, and throat). With respect to cranial nerve I, an impairment estimate associated with anosmia or parosmia should be given only if this significantly interferes with daily activities. For cranial nerve II, the AMA Guides recommends ophthalmologic testing of visual fields and best correction. For cranial nerves III, IV, and VI, the reader is referred to section 8.3, and, for cranial nerve V, the AMA Guides provides a method of determining impairment associated with trigeminal neuralgia. A table provides data regarding impairment for conditions that affect the seventh cranial (facial) nerve; sensory loss related to the facial nerve does not interfere with activities of daily living. Auditory impairment (cranial nerve VIII) is rated according to criteria in the ear, nose, throat, and related structures chapter, including tinnitus. Cranial nerves IX, X, XI, and XII are involved in breathing, swallowing, speaking, and some visceral functions, and ratings criteria are presented. In terms of spinal cord impairments, the AMA Guides divides pathology into six categories: station and gait; use of the upper extremities; respiration; urinary bladder function; anorectal function; and sexual function.