Canadian Medical Guide > Diseases > Nervous System Diseases > Central Nervous System Diseases > Brain Diseases Terms and Definitions




Brain Diseases

Medical Definition: Pathologic conditions affecting the BRAIN, which is composed of the intracranial components of the CENTRAL NERVOUS SYSTEM. This includes (but is not limited to) the CEREBRAL CORTEX; intracranial white matter; BASAL GANGLIA; THALAMUS; HYPOTHALAMUS; BRAIN STEM; and CEREBELLUM.
Also Called: Pathology, Brain
Brain Diseases Categories.
Canadian Medical Guide Definition Akinetic Mutism - A syndrome characterized by a silent and inert state without voluntary motor activity despite preserved sensorimotor pathways and vigilance. Bilateral FRONTAL LOBE dysfunction involving the anterior cingulate gyrus and related brain injuries are associated with this condition. This may result in impaired abilities to communicate and initiate motor activities. (From Adams et al., Principles of Neurology, 6th ed, p348; Fortschr Neurol Psychiatr 1995 Feb;63(2):59-67)
Canadian Medical Guide Definition Amblyopia - A nonspecific term referring to impaired vision. Major subcategories include stimulus deprivation-induced amblyopia and toxic amblyopia. Stimulus deprivation-induced amblopia is a developmental disorder of the visual cortex. A discrepancy between visual information received by the visual cortex from each eye results in abnormal cortical development. STRABISMUS and REFRACTIVE ERRORS may cause this condition. Toxic amblyopia is a disorder of the OPTIC NERVE which is associated with ALCOHOLISM, tobacco SMOKING, and other toxins and as an adverse effect of the use of some medications.
Canadian Medical Guide Definition Amnesia, Transient Global - A syndrome characterized by a transient loss of the ability to form new memories. It primarily occurs in middle aged or elderly individuals, and episodes may last from minutes to hours. During the period of amnesia, immediate and recent memory abilities are impaired, but the level of consciousness and ability to perform other intellectual tasks are preserved. The condition is related to bilateral dysfunction of the medial portions of each TEMPORAL LOBE. Complete recovery normally occurs, and recurrences are unusual. (From Adams et al., Principles of Neurology, 6th ed, pp429-30)
Canadian Medical Guide Definition Basal Ganglia Diseases - Diseases of the BASAL GANGLIA including the PUTAMEN; GLOBUS PALLIDUS; claustrum; AMYGDALA; and CAUDATE NUCLEUS. DYSKINESIAS (most notably involuntary movements and alterations of the rate of movement) represent the primary clinical manifestations of these disorders. Common etiologies include CEREBROVASCULAR DISEASE; NEURODEGENERATIVE DISEASES; and CRANIOCEREBRAL TRAUMA.
Canadian Medical Guide Definition Brain Damage, Chronic - A condition characterized by long-standing brain dysfunction or damage, usually of three months duration or longer. Potential etiologies include BRAIN INFARCTION; certain NEURODEGENERATIVE DISORDERS; CRANIOCEREBRAL TRAUMA; ANOXIA, BRAIN; ENCEPHALITIS; certain NEUROTOXICITY disorders; metabolic disorders (see BRAIN DISEASES, METABOLIC); and other conditions.
Canadian Medical Guide Definition Brain Death - A state of prolonged irreversible cessation of all brain activity, including lower brain stem function with the complete absence of voluntary movements, responses to stimuli, brain stem reflexes, and spontaneous respirations. Reversible conditions which mimic this clinical state (e.g., sedative overdose, hypothermia, etc.) are excluded prior to making the determination of brain death. (From Adams et al., Principles of Neurology, 6th ed, pp348-9)
Canadian Medical Guide Definition Brain Diseases, Metabolic - Acquired or inborn metabolic diseases that produce brain dysfunction or damage. These include primary (i.e., disorders intrinsic to the brain) and secondary (i.e., extracranial) metabolic conditions that adversely affect cerebral function.
Canadian Medical Guide Definition Brain Edema - Increased intracellular or extracellular fluid in brain tissue. Cytotoxic brain edema (swelling due to increased intracellular fluid) is indicative of a disturbance in cell metabolism, and is commonly associated with hypoxic or ischemic injuries (see HYPOXIA, BRAIN). An increase in extracellular fluid may be caused by increased brain capillary permeability (vasogenic edema), an osmotic gradient, local blockages in interstitial fluid pathways, or by obstruction of CSF flow (e.g., obstructive HYDROCEPHALUS). (From Childs Nerv Syst 1992 Sep; 8(6):301-6)
Canadian Medical Guide Definition Brain Injuries - Acute and chronic (see also BRAIN INJURIES, CHRONIC) injuries to the brain, including the cerebral hemispheres, CEREBELLUM, and BRAIN STEM. Clinical manifestations depend on the nature of injury. Diffuse trauma to the brain is frequently associated with DIFFUSE AXONAL INJURY or COMA, POST-TRAUMATIC. Localized injuries may be associated with NEUROBEHAVIORAL MANIFESTATIONS; HEMIPARESIS, or other focal neurologic deficits.
Canadian Medical Guide Definition Cerebellar Diseases - Diseases that affect the structure or function of the cerebellum. Cardinal manifestations of cerebellar dysfunction include dysmetria, GAIT ATAXIA, and MUSCLE HYPOTONIA.
Canadian Medical Guide Definition Cerebrovascular Disorders - A broad category of disorders characterized by impairment of blood flow in the arteries and veins which supply the brain. These include CEREBRAL INFARCTION; BRAIN ISCHEMIA; HYPOXIA, BRAIN; INTRACRANIAL EMBOLISM AND THROMBOSIS; INTRACRANIAL ARTERIOVENOUS MALFORMATIONS; and VASCULITIS, CENTRAL NERVOUS SYSTEM. In common usage, the term cerebrovascular disorders is not limited to conditions that affect the cerebrum, but refers to vascular disorders of the entire brain including the DIENCEPHALON; BRAIN STEM; and CEREBELLUM.
Canadian Medical Guide Definition Dementia - An acquired organic mental disorder with loss of intellectual abilities of sufficient severity to interfere with social or occupational functioning. The dysfunction is multifaceted and involves memory, behavior, personality, judgment, attention, spatial relations, language, abstract thought, and other executive functions. The intellectual decline is usually progressive, and initially spares the level of consciousness.
Canadian Medical Guide Definition Encephalomalacia - Softening or loss of brain tissue following CEREBRAL INFARCTION; cerebral ischemia (see BRAIN ISCHEMIA), infection, CRANIOCEREBRAL TRAUMA, or other injury. The term is often used during gross pathologic inspection to describe blurred cortical margins and decreased consistency of brain tissue following infarction. Multicystic encephalomalacia refers to the formation of multiple cystic cavities of various sizes in the cerebral cortex of neonates and infants following injury, most notably perinatal hypoxia-ischemic events. (From Davis et al., Textbook of Neuropathology, 2nd ed, p665; J Neuropathol Exp Neurol, 1995 Mar;54(2):268-75)
Canadian Medical Guide Definition Epilepsy - A disorder characterized by recurrent episodes of paroxysmal brain dysfunction due to a sudden, disorderly, and excessive neuronal discharge. Epilepsy classification systems are generally based upon: (1) clinical features of the seizure episodes (e.g., motor seizure), (2) etiology (e.g., post-traumatic), (3) anatomic site of seizure origin (e.g., frontal lobe seizure), (4) tendency to spread to other structures in the brain, and (5) temporal patterns (e.g., nocturnal epilepsy). (From Adams et al., Principles of Neurology, 6th ed, p313)
Canadian Medical Guide Definition Headache Disorders - Common conditions characterized by persistent or recurrent headaches (see HEADACHE). Headache syndrome classification systems may be based on etiology (e.g., VASCULAR HEADACHE, post-traumatic headaches, etc.), temporal pattern (e.g., CLUSTER HEADACHE, paroxysmal hemicrania, etc.), and precipitating factors (e.g., cough headache).
Canadian Medical Guide Definition Hydrocephalus - Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, INTRACRANIAL HYPERTENSION; HEADACHE; lethargy; URINARY INCONTINENCE; and ATAXIA (and in infants macrocephaly). This condition may be caused by obstruction of cerebrospinal fluid pathways due to neurologic abnormalities, INTRACRANIAL HEMORRHAGES; CENTRAL NERVOUS SYSTEM INFECTIONS; BRAIN NEOPLASMS; CRANIOCEREBRAL TRAUMA; and other conditions. Impaired resorption of cerebrospinal fluid from the arachnoid villi results in a communicating form of hydrocephalus. Hydrocephalus ex-vacuo refers to ventricular dilation that occurs as a result of brain substance loss from CEREBRAL INFARCTION and other conditions.
Canadian Medical Guide Definition Hypothalamic Diseases - Neoplastic, inflammatory, infectious, and other diseases of the hypothalamus. Clinical manifestations include appetite disorders; AUTONOMIC NERVOUS SYSTEM DISEASES; SLEEP DISORDERS; behavioral symptoms related to dysfunction of the LIMBIC SYSTEM; and neuroendocrine disorders.
Canadian Medical Guide Definition Intracranial Hypertension - Increased pressure within the cranial vault. This may result from several conditions, including HYDROCEPHALUS; BRAIN EDEMA; intracranial masses; severe systemic HYPERTENSION; PSEUDOTUMOR CEREBRI; and other disorders.
Canadian Medical Guide Definition Intracranial Hypotension - Reduction of CEREBROSPINAL FLUID pressure characterized clinically by HEADACHE which is maximal in an upright posture and occasionally by an abducens nerve palsy (see ABDUCENS NERVE DISEASES), neck stiffness, hearing loss (see DEAFNESS), NAUSEA, and other symptoms. This condition may be spontaneous or secondary to SPINAL PUNCTURE; NEUROSURGICAL PROCEDURES; DEHYDRATION; UREMIA; trauma (see also CRANIOCEREBRAL TRAUMA); and other processes. Chronic hypotension may be associated with subdural hematomas (see HEMATOMA, SUBDURAL) or hygromas. (From Semin Neurol 1996 Mar;16(1):5-10; Adams et al., Principles of Neurology, 6th ed, pp637-8)
Canadian Medical Guide Definition Neuroaxonal Dystrophies - A nonspecific term referring both to the pathologic finding of swelling of distal portions of axons in the brain and to disorders which feature this finding. Neuroaxonal dystrophy is seen in various genetic diseases, vitamin deficiencies, and aging. Infantile neuroaxonal dystrophy is an autosomal recessive disease characterized by arrested psychomotor development at 6 months to 2 years of age, ataxia, brain stem dysfunction, and quadriparesis. Juvenile and adult forms also occur. Pathologic findings include brain atrophy and widespread accumulation of axonal spheroids throughout the neuroaxis, peripheral nerves, and dental pulp. (From Davis & Robertson, Textbook of Neuropathology, 2nd ed, p927)
Canadian Medical Guide Definition Subdural Effusion - Leakage and accumulation of CEREBROSPINAL FLUID in the subdural space which may be associated with an infectious process; CRANIOCEREBRAL TRAUMA; BRAIN NEOPLASMS; INTRACRANIAL HYPOTENSION; and other conditions.
Canadian Medical Guide Definition Thalamic Diseases - Disorders of the centrally located thalamus, which integrates a wide range of cortical and subcortical information. Manifestations include sensory loss, MOVEMENT DISORDERS; ATAXIA, pain syndromes, visual disorders, a variety of neuropsychological conditions, and COMA. Relatively common etiologies include CEREBROVASCULAR DISORDERS; CRANIOCEREBRAL TRAUMA; BRAIN NEOPLASMS; BRAIN HYPOXIA; INTRACRANIAL HEMORRHAGES; and infectious processes.

Brain Diseases Medical Definitions and Terms

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