Chapter 16: Disorders of Brain Function

The presentation of consciousness exists along a continuum ranging from full alertness and orientation through progressive stages of reduced responsiveness including confusion, lethargy, stupor, and ultimately coma, a state characterized by absence of awareness and inability to respond to environmental stimuli. Central nervous system infections represent a critical category of brain disorders classified by anatomical location and affected structures: meningitis involves inflammation of the meningeal membranes surrounding the brain and spinal cord, encephalitis affects the brain tissue itself, and myelitis involves spinal cord inflammation. Each infection type presents distinct clinical presentations and requires specific diagnostic approaches and therapeutic interventions. The chapter addresses classification systems and clinical characteristics of primary and secondary brain tumors, including epidemiology, pathological features, and management considerations relevant to different patient populations. Congenital anomalies receive attention, particularly neural tube defects which represent the most prevalent developmental abnormality of the central nervous system, especially in pediatric patients. Seizure disorders are explored with emphasis on their diverse etiologies, noting that in childhood populations seizures frequently originate from extracranial sources and may be precipitated by systemic infections, elevated body temperature, toxic exposures, or metabolic disturbances rather than primary brain pathology. The chapter integrates pathophysiological mechanisms underlying these diverse conditions with clinical manifestations and contemporary assessment and management approaches, providing students with comprehensive understanding of how different disease processes disrupt normal neurological function.