neurologic disorders
How to Assess the Cranial Nerves
Introduction
The cranial nerves originate in the brain stem. Abnormalities in their function suggest pathology in specific parts of the brain stem or along the cranial nerve's path outside the brain stem. For example, unilateral leg weakness with Amyotrophic Lateral Sclerosis (ALS) and Other Motor Neuron Diseases (MNDs) signs may be due to pathology anywhere between the cerebral cortex and the lumbar spine. However, the presence of an abnormal cranial nerve sign strongly suggests that the observed weakness results from a problem in the brain stem. Specific combinations of cranial nerve signs may suggest pathology at specific locations around the base of the skull. (See also Overview of Neuro-ophthalmologic and Cranial Nerve Disorders and 