Disorders of the brainstem and cerebellum

Abstract

The chapter begins with discussion of anatomy and functions of the brainstem (mesencephalon, pons, and medulla) and cerebellum. No other part of the central nervous system is packed with so many critical axon tracts and nuclei. Main brainstem functions are as follows: to provide transit and processing nuclei for ascending and descending pathways that convey signals to and from the cerebellum, cerebrum, and spinal cord; to integrate functions such as consciousness, muscle tone, posture, and normal autonomic functions; and to house cranial nerves 3-10. The cerebellum occupies only 10% of the brain volume but contains more neurons than the entire rest of the brain. Lesions in the brainstem often manifest as cerebellar, somatosensory and motor symptoms plus cranial nerve dysfunction. Damage to the cerebellum often results in errors in smooth motor movements. The chapter ends with a discussion of central pontine myelinolysis, lateral medullary syndrome or Wallenberg’s syndrome, and spinocerebellar atrophies with attention to their pathophysiology, major clinical features, major laboratory findings, and principles of management and prognosis.