Download Chronic Neurological Disorders - Lecture Slides | BIO 375 and more Study notes Pathophysiology in PDF only on Docsity!
Chronic Neurological Disorders
Bio 375
Pathophysiology
Chronic Neurologic Disorders
Hydrocephalus is a condition in which excess cerebrospinal fluid accumulates, compressing the brain tissue and blood vessels Because the cranial sutures have not closed the infants head enlarges CSF accumulates because more is produced than is absorbed back into the blood stream
There are two types of hydrocephalus: Noncommunicating or obstructive hydrocephalus occurs in babies when the flow of CSF through the ventricular system is blocked, usually at the aqueduct of Sylvius or foramen magnum; This is usually due to a developmental abnormality Communicating hydrocephalus results when the absorption of CSF through the arachnoid villi is impaired
Hydrocephalus
(Noncommunicating)
Spina bifida
This is a group of neural tube defects that are congenital anomalies of varying severity Neural tube develops during the fourth week of gestation, beginning at the cervical area and progressing to the lumbar area
The basic problem is failure of the posterior spinous processes on the vertebrae to fuse, allowing the meninges and spinal cord to herniate Lumbar area is the most common location Cervical area shown here->
Spina bifida
Spina bifida
Cerebral Palsy (CP)
CP is a group of disorders characterized by some degree of motor impairment It is caused by brain damage during the perinatal period; i.e. damage may occur before, during or shortly after birth and is nonprogressive Other areas of the brain may be damaged resulting in highly variable presentation 1 to 2 per 1,000 births
Pathophysiology of CP
Brain tissue is altered by: Malformation during development Mechanical trauma Hypoxia Hemorrhage Hypoglycemia Hyperbilirubinemia Any other factor causing necrosis
Etiology of CP
Hypoxia or ischemia is the major cause of brain damage; it can occur prenatally, perinatally or postnatally. Hypoxia may be caused by placental complications or a difficult delivery Hypoxia may occur in premature infant by: Vascular occlusion Hemorrhage Aspiration Respiratory impairment
Signs and Symptoms of CP
Effects may be apparent at birth but some cases show impaired motor development after several months
CP is classified either on the basis of the area affected or on the basis of motor disability
Three major groups have been identified
Classification of Seizures
Partial seizures (focal) Simple Motor (includes Jacksonian) Sensory (e.g. visual, auditory) Autonomic Psychic Complex (impaired consciousness) Temporal lobe or psychomotor Partial leading to generalized seizures
Classification of Seizures
Generalized (both hemispheres affected with loss of consciousness) Tonic-clonic (grand mal) Absence (petit mal) Myoclonic Infantile spasms Atonic (akinetic) Lennox-Gastaut syndrome (febrile seizures)
Seizures may be primary (idiopathic) or secondary (acquired) with an identified cause like post-traumatic syndrome Seizures can be caused by: Abnormality in the brain Systemic causes like hypoglycemia or withdrawal from drugs Seizures may be temporary like febrile seizures in infants Patient can have more than one type of seizure
Treatment for seizure disorders
Any primary cause should be treated and any specific triggers that precipitate seizures should be identified and avoided Anticonvulsant drugs are used to raise the threshold for neuronal stimulation If the area of brain excitability is small and accessible, surgery may help Combination of surgery and medication
Parkinson’s Disease
Parkinson’s Disease (Paralysis agitans) results from dysfunction in the extrapyramidal motor system from progressive degenerative changes in the basal nuclei, especially the substantia nigra. A decreased number of neurons secrete dopamine, an inhibitory neurotransmitter leading to an imbalance between excitation and inhibition in the basal nuclei
The excess stimulation affects movement and posture by increasing muscle tone and activity, leading to: Resting tremors Muscular rigidity Difficulty in initiating movement Postural instability Many patients also have a decreased number of cortical neurons which is characteristic of dementia
Types of Dementia
Alzheimer’s Disease
Alzheimer’s disease is characterized by a progressive loss of intellectual function that eventually interferes with work, relationships and personal hygiene. Typical changes with Alzheimer’s disease include: Progressive cortical atrophy which leads to dilated ventricles and widening of the sulci especially in the frontal lobes
Neurofibrillary tangles in the neurons and senile plaques are found in large numbers in the affected parts of the brain The plaques disrupt nerve transmissions They are composed of beta-amyloid precursor protein (βAPP) whose role in the brain is being intensely studied Some tangles are found in the brains of elderly persons whose cognitive functions are not impaired; it appears that the numbers and distribution of plaques are a significant factor in the disease
Pre-senile or early-onset Alzheimer’s disease is relatively rare and develops between the ages of 30-60 and is inherited; involves chromosomes 14, 19 and 21 Alzheimer’s disease (senile dementia) affects people over age 65 and appears to be multifactorial in origin
Senile dementia (AD) increases in incidence with age Genetic factors may play a role; links to at least four genes are known Other suspected factors include exposure to metals, e.g. aluminum Viruses; prions Mutated genes
