Chapter 17 Cranial nerve reflexes: anatomical pathways, recording techniques and normative data

Abstract

Publisher Summary Recording of the brainstem reflexes enable to assess the functional integrity of these reflexes within the brainstem and their afferent and efferent connections. Many structural abnormalities, such as tumors or infarctions at the level of the brainstem may abolish reflexes. Recording of different brainstem reflexes may enable to exclude structural lesions or, on the other hand, to localize more accurately the lesion within the brainstem. In the latter case, a more tailored MR imaging examination of this region may be sufficient. Recording of the brainstem reflexes also plays an important role in the pre-selection of patients for additional MR imaging examination and in objectively assessing the functional abnormality of the cranial nerves by elucidating subtle changes in one or more variables of the reflex features in terms of amplitude or latency of the responses. The studies of different reflex responses also provide relevant information about the physiology and pathophysiology of segmental and suprasegmental control mechanisms upon the brain stem reflexes and help to differentiate between segmental or suprasegmental origin of an abnormality. This chapter describes the recording techniques, physiology, central pathways, and normative data of different brainstem reflexes. Only those neurophysiological tests that are believed to be relevant in the assessment of patients with movement disorders are discussed in this chapter.