Cranial nerves are discussed elsewhere in this text. This chapter identifies some other commonly seen syndromes involving the brainstem and cranial nerves. Lesions affecting one cranial nerve solely or predominantly are discussed under the respective nerve; brainstem lesions producing cranial…
Neuromuscular Transmission Defects Neuromuscular transmission defects present with weakness and fatigability. The tendency to fatigue early and the absence of sensory symptoms are clues to these disorders. These defects are due to impaired synaptic transmission, either from impaired acetylcholine (ACh)…
Approach to Diagnosis Neuromuscular disorders have specific clinical findings, as discussed here, but part of the task of neuromuscular localization is ruling out a lesion of the spinal cord or brain. Central disorders producing peripheral manifestations usually affect systems other…
Spinal Cord Anatomy and Localization Localizing a lesion to a specific location within the cord is key to diagnosis. The differential diagnosis is narrowed by deciding exactly how the cord is affected through the following signs: ■ Corticospinal tract deficits…
Brainstem Dysfunction Midbrain Isolated cranial nerve (CN) III or CN IV palsy is rarely due to a midbrain lesion, despite the location of the nuclei. Midbrain lesions can produce partial or complete palsies of these cranial nerves plus hemiparesis from…
Diagnosis of Cerebellar Lesions The first important distinction in clinical practice is among lesions that primarily affect the vermis, that primarily affect the cerebellar hemispheres, or that diffusely affect the cerebellum. The second important distinction is between lesions that affect…
Basal Ganglia Lesions of the basal ganglia typically produce movement disorders, with the predominant results being abnormalities of tone and involuntary movement. For clinical purposes, the important classification is into the following two categories: ■ Akinetic rigid syndromes (too little…
The uniqueness of the human brain derives from the higher mental functions, such as reasoning, memory, language, speech, calculations, praxis, recognition of objects (gnosis), and the asymmetrical organization of these functions in the cerebral hemispheres. Cerebral dominance, or the specialization…
Anatomy of the Peripheral Neuromuscular System The essential features of the peripheral neuromuscular system are motor nerves, sensory nerves, autonomic nerves, the neuromuscular junction (NMJ), and muscle fibers. Motor neurons originate in the spinal cord and brainstem and innervate skeletal…
Spinal Cord Organization The spinal cord serves as a conduit for information relayed between the brainstem and peripheral nervous system. In addition to this purely conductive function, there is substantial neural processing at segmental levels of the spinal cord. This…