Chronic Nervous Disorders PDF

Pathophysiology (2) (MBS 214) Chronic Neurologic Disorders Textbook; Pathophysiology for the Health Professions, 4th edition, 2011 Chapter 23 (p.509-528)  Chronic Neurologic Disorders Lecture outline:- Congenital Neurologic Disorders Seizure Disorders...

Pathophysiology (2) (MBS 214) Chronic Neurologic Disorders Textbook; Pathophysiology for the Health Professions, 4th edition, 2011 Chapter 23 (p.509-528)  Chronic Neurologic Disorders Lecture outline:- Congenital Neurologic Disorders Seizure Disorders Chronic Degenerative Disorders Dementia Spinal Cord Problem Learning objectives: After studying this lecture ,the student is expected to: Describe the pathophysiology of : congenital neurologic disorders,hydrocephalus,spina bifida and cerebral palsy Differentiate the types of seizures Describe the pathophysiology of chronic degenerative disorders,; multiple sclerosis, Parkinson's disease, myasthenia gravis and Huntington’s disease Describe the changes in the brain as Alzheimer’s disease develops and the effects on function Describe the pathophysiology of herniated intervertebral disc. CONGENITAL NEUROLOGIC DISORDERS HYDROCEPHALUS SPINA BIFIDA CEREBRAL PALSY  Hydrocephalus “water on the brain” Excessive accumulation of cerebrospinal fluid following an abnormal secretion, circulation and absorption, within the skull. – compressing the brain tissue and blood vessels – Result in increased ICP  Types of hydrocephalus 1- Noncommunicating or obstructive hydrocephalus – Where the ventricles cannot communicate due to obstruction of cerebral aqueduct between 3rd and 4th ventricles---increase size of 3rd and lateral ventricles mainly due to tumor in 4th ventricle (ependymoma) – Occurs in babies 2- Communicating hydrocephalus, – The ventricles are normally connected but the cause is impaired absorption of CSF through arachnoids villi with the result of enlargement of all ventricles – The common cause is meningitis – Associated with dilatation of all ventricles  Hydrocephalus Signs and symptoms. In the neonate: The head can enlarge and the fontanels bulge Dilated scalp veins Recording head size is a standard procedure after birth Infant ; – Eyes show the “sunset sign,” in which the white sclera is visible above the colored pupil – Lethargic, irritable and difficult to feed with high-pitched cry when moved or picked up In older children and adults, manifestations include classic signs of increased intracranial pressure as fontanels are closed. The condition must be diagnosed and treated as soon as possible to minimize brain damage.  Hydrocephalus Diagnostic tests A computed tomography (CT) or magnetic resonance imaging (MRI – locate the obstruction or abnormal flow – determine the size of the ventricles. Treatment Surgery – to remove an obstruction provide a shunt for CSF from the ventricle into the peritoneal cavity or other extracranial site, – A shunt must be replaced as the child grows. (vulnerable to blockage or infection )  Spina bifida Common developmental defect. Neural tube defect: Caused when the neural tube does not completely close due to failure of the vertebral posterior spinous processes to fuse. The result is the emergence of meninges and neural tissue through the vertebral column. Most common location is lumbar area  Types of Spina bifida hidden spina bifida visible as a protruding sac/cyst over the spine. A B C 1-The mildest because the 1- The same bony defect, Most serious form vertebral bones do not fully 2- Herniation or protrude 1- Herniation of the spinal surround the spinal cord, of the meninges occurs cord and nerves along 2- No herniation of the 3- A cyst—a fluid-filled sac with the meninges and CSF spinal cord and meninges of meninges and CSF cover occurs, 3-Defect may not be spinal cord on the surface 2- Resulting in visible, a tuft of hair is considerable present on the skin over the neurologic impairment site  Spina bifida Diagnostic tests; Elevation of Alpha-fetoprotein (AFP) in maternal blood – AFP is a substance made in the liver of fetus. – The amount of AFP in the blood of a pregnant woman can help see whether the baby may have problems as spina bifida and anencephaly. – diagnosed prenatally by ultrasound or AFP in amniotic fluid by amniocentesis – specimen obtained at 16 to 18 weeks’ gestation  Spina bifida Signs and symptoms Meningocele and myelomeningocele are visible as a protruding sac over the spine. – Extent of neurologic deficit depends on the level of the defect and the status of the nerve tissue; – Impaired sensory and motor function at and below the level of the herniation. – Muscle weakness or paralysis – Fecal and urinary incontinence, depending on the level of damage Treatment Surgical repair After repair, ongoing assistance and occupational and physical therapy  Cerebral Palsy (CP) Motor function disorder that affect a person’s ability to move and maintain balance and posture Appears during infancy or early childhood Resulting from permanent damage to the brain which may occur before, during, or shortly after birth that affects a child’s ability to control his or her muscles. Hypoxia or ischemia is the major cause Cerebral palsy (CP) is usually diagnosed ischemia during the first or second year after birth. There is no cure for cerebral palsy, but treatment can improve the lives of those who have the condition.  Types of Cerebral Palsy Doctors classify CP according to ; The main type of movement disorder involved and areas of the brain are affected, – Stiff muscles (spasticity) --- cortex – Uncontrollable movements (dyskinesia)---basal ganglia – Poor balance and coordination (ataxia)---cerebellum  Classification of the motor disability that occurs in CP involuntary The main sign that a child might have cerebral palsy is a delay reaching motor or movement milestones (such as rolling over, sitting, standing, or walking). Cerebral palsy may be accompanied by other dysfunction or manifestations ; Intellectual function; varies from normal intelligence to severely cognitively impaired in small percentage-mental retardation Communication and speech; difficult because of motor disability Seizures and Visual problems Changes in the spine (such as scoliosis); or joint problems (contracture) Spastic palsy described by what limb (s)of the body are affected:  Extrapyramidal cerebral palsy a neurological disorder Athetosis:a condition in which characterized by jerky involuntary abnormal muscle contractions cause movements affecting especially the involuntary writhing movements. It shoulders, hips, and face affects some people with cerebral palsy, impairing speech and use of the hands. This image gives a nice pictorial overview of the problems experienced by children with Cerebral Palsy.  CEREBRAL PALSY Treatment: Individualized and immediate therapy is necessary. Early stimulation programs for motor skills Speech and language pathology assessment Physical therapy and regular exercise therapy Devices that can improve mobility and reduce deformities. Occupational therapy, works with the child to maximize hand function, teach the use of adaptive devices  SEIZURE DISORDERS A seizure is an uncontrolled electrical discharge from brain cells that causes mental and physical symptoms (hyper excitable neuron) Occur when there is abnormal surge of electrical activity in the brain (a burst of electrochemical activity in the brain) results in: – uncontrolled, excessive discharge (firing) of neurons in the brain  SEIZURE DISORDERS Each seizure lasts for a few seconds or minutes Seizure disorders are characterized by recurrence. – Epilepsy is the old term for recurrent seizures, Seizure disorders are classified by – their location in the brain – their clinical features, (an alteration in sensation, behavior, and consciousness – EEG patterns during and between seizures  SEIZURE DISORDERS Seizures may be: – primary (idiopathic) or – secondary (acquired, have identified cause )- posttraumatic syndrome. Seizures may result from; – an abnormality in the brain or – from systemic causes Seizures may be : – a temporary problem, such as febrile seizures in an infant, or – chronic and frequent. An individual can have more than one type of seizure.  SEIZURE DISORDERS Etiology; Familial incidence is more evident in young children Four genes have been identified Acquired seizures ; congenital disorders head injury tumor, infection, or hemorrhage in the brain, high fever in an infant or young child (febrile seizure). Systemic disorders, such as renal failure or hypoglycemia, Precipitating factors, Sensory stimuli, such as loud noises or bright or flashing lights, Physiological or biochemical stimuli, – stress, – excessive premenstrual fluid retention, – hypoglycemia, – hyperventilation (alkalosis). Change in medication,  Classification of Seizures (types) I. Partial seizures (focal): have a single or focal origin, – often in the cerebral cortex, may or may not involve altered consciousness a. Simple : patient retains awareness 1. Motor 2. Sensory (e.g., visual, auditory) 3. Autonomic 4. Psychic b. Complex (impaired consciousness) 1. Temporal lobe or psychomotor 2. Partial leading to generalized seizures II. Generalized: produced by electrical impulses involve the whole brain (have multiple foci or origins) – both hemispheres affected, loss of consciousness a. Tonic-clonic (grand mal) b. Absence (petit mal) c. Myoclonic d. Infantile spasms e. Atonic (akinetic) f. Lennox-Gastaut syndrome (febrile seizures) III. Unclassified; IV. Status epilepticus; Recurrent or continuous tonic – clonic seizures without recovery of consciousness  Manifestations of Seizures Disorders Absence (petit mal) seizures – generalized seizures – more common in children than adults – lasts for 5 to 10 seconds – brief loss of awareness and sometimes transient facial movements – No memory of the episode is retained. Tonic-clonic (grand mal) seizures – The most common type of generalized seizures – The patient lose consciousness and usually collapses – His body stiffens for 30 to 60 sec (Tonic phase) – Then jerks for 30 to 60 sec.(clonic phase) – After which he goes into deep sleep  Pattern of Tonic-clonic seizures Tonic stage : Prodromal signs: nausea, irritability, depression, or muscle twitching some hours before the onset of a seizure An aura:visual or auditory sensation, immediately precedes the loss of consciousness in many persons. Loss of consciousness: Loss of postural reflexes and falls to the floor. Strong tonic muscle contraction: Brief flexion, followed by extension of the limbs and rigidity in the trunk (ictal phase). A cry: escapes as the abdominal and thoracic muscles contract, forcing air out of the lungs. The jaws are clenched tightly, and respiration ceases.  Pattern of Tonic-clonic seizures The clonic stage – the muscles alternately contract and relax, resulting in a series of forceful jerky movements that involve the entire body. Increased salivation (foaming at the mouth) and bowel and bladder incontinence may occur. Subside of Contractions – the body is laxity and consciousness slowly returns. Post-ictal period – The person is confused and fatigued, with aching muscles, and falls into a deep sleep  Seizures disorders Complications of a seizures: – hypoxia, – airway obstruction, – Acidosis – status epilepsy; Recurrent or continuous tonic – clonic seizures without recovery of consciousness Injuries may occur ,arise from generalized tonic clonic (grand mal) seizures  Seizures disorders Diagnostic tests EEG: determine the type and location of the seizure. MRI: detect any structural abnormality in the brain. Treatment Any primary cause should be treated, Specific factors that precipitate seizures should be identified and avoided. Anticonvulsant drugs  Chronic Degenerative Disorders Neurodegenerative disorders: are characterized by progressive and irreversible loss of neurons from specific regions of the brain. 1. Multiple Sclerosis (MS) 2. Parkinson’s Disease (Paralysis Agitans) 3. Amyotrophic Lateral Sclerosis (ALS), 4. Myasthenia Gravis 5. Huntington disease (HD), or Huntington’s chorea  Motor neuron pathway Upper Motor Neuron: First neuron in the motor command pathway with its cell body in the cerebral cortex that synapses on the lower motor neuron in the spinal cord Transmit information from brain to spinal cord and brain stem Lower Motor Neuron: Second neuron in the motor command pathway that is directly connected to the skeletal muscle Transmit information from spinal cord or brain stem to skeletal muscles  MULTIPLE SCLEROSIS (MS) A progressive demyelinating disease Normal nerve It involves deterioration or damage of the myelin sheath of neurons in the central nervous system and some cranial nerves (optic) Pathophysiology Loss of myelin interferes with the conduction of impulses in the affected fibers. – May affects motor, sensory, and autonomic fibers Multiple sclerosis is characterized only by remissions and exacerbations (recurrence), causes additional areas of the central Nerve affected by MS nervous system (CNS) to be affected, and neural degeneration becomes irreversible.  MULTIPLE SCLEROSIS (MS) Etiology The onset usually occurs in individuals between ages 20 and 40, More common in women by a 2 : 1 ratio. Cause is unknown, – May be an autoimmune disorder, that may be triggered by a virus or bacterial infection.The autoantibodies destroy the oligodendrocytes, the myelin-producing neuroglia of the central nervous system, which results in the formation of scleroses, or plaques of scar tissue, that do not provide electrical insulation or protect the axon – May be nutritional deficit – May change in blood flow to neurons May have genetic, immunologic, and environmental components. – Increased risk for close relatives of affected individuals.  MULTIPLE SCLEROSIS (MS) The earliest lesion; – an inflammatory response – loss of myelin in the white matter of the brain or spinal cord. Multiple Sclerosis Plaques are the characteristic lesions of MS – Refers to larger areas of inflammation and demyelination – Develop later, become visible, – Frequently beside the lateral ventricles in the brain, in the brain stem, and in the optic nerves. The gross hallmark of MS is the – Each plaque varies in size multiple sclerosis plaque This coronal section of cerebrum Several may coalesce into a single shows a classic periventricular, patch. symmetric locations of plaques by the lateral ventricles (arrows).  Multiple sclerosis— distribution of lesions.  MULTIPLE SCLEROSIS (MS) Signs and symptoms: depend on area affected. Eye : Blurred vision is a common early sign, diplopia (double vision), scotoma (a spot in the visual field) Muscle : Weakness or paralysis start in the legs , progressive weakness and paralysis extending to the upper limbs dysarthria (poor articulation) may occur. Sensation : Paresthesia, areas of numbness, burning, or tingling (sensory nerve fibers damaged). Spinal reflexes : Loss of coordination, and bladder, bowel, and sexual dysfunction occur. Chronic fatigue is common. Later in the course of the disease, – Depression or euphoria may develop. – Complications related to immobility, such as respiratory infection, decubitus ulcers, and contractures  MULTIPLE SCLEROSIS (MS) Diagnostic tests No definitive test Multiplicity of effects and recurrences based on patient history and physical examination MRI studies are best for – diagnosis and monitoring – detect multiple CNS lesions. Treatment There is still no cure for MS, but therapies include suppression of the immune response, and interferon, which seems to prolong remissions in some patients. The possibility of stimulating remyelination of neurons is also being investigated. A, Typical white matter Therapy includes physical therapy and exercise to changes around the maintain mobility. Occupational therapy is essential ventricles shown on MRI in in assessing the need for and provision of adaptive multiple sclerosis. devices to simplify work and reduce fatigue B, Change in the spinal cord in multiple sclerosis.  PARKINSON’S DISEASE A progressive degenerative disorder of the basal ganglia – Where neurons produce the inhibitory neurotransmitter dopamine begin to degenerate and die, and the deficiency of dopamine causes specific kinds of muscular symptoms.(motor dysfunction) Etiology Primary usually develops after age 60 Secondary Parkinsonism – encephalitis, – trauma, – vascular disease. – Drug-induced Parkinson’s ;phenothiazines tranquilizers  PARKINSON’S DISEASE – Tremor, or involuntary shaking, of the hands is probably the most common symptom. – The accessory movements regulated by the basal ganglia gradually diminish, and the affected person walks slowly without swinging the arms. – A mask-like face is characteristic of this disease, as the facial muscles become rigid. – Eventually all voluntary movements become slower and much more difficult, and balance is seriously impaired. – non-motor symptoms (NMS) (constipation, gastrointestinal disturbances, sleep disturbances and sensory alterations, among others) Treatment Dopamine replacement therapy Physical therapy & exercise  AMYOTROPHIC LATERAL SCLEROSIS (ALS) Myotrophic means “muscle wasting” and sclerosis refers to the degenerative “hardening” of the lateral corticospinal tracts. Also called Lou Gehrig’s disease, Cause has not been identified – genes on various chromosomes have been linked to the disease. Primarily affects individuals between the ages of 40 and 60, particularly men  AMYOTROPHIC LATERAL SCLEROSIS (ALS) Pathophysiology; ALS is a progressive degenerative disease affecting both upper motor neurons in the cerebral cortex and lower motor neurons in the brain stem and spinal cord. Leads to loss of neurons in cerebral cortex and spinal cord in diffuse asymmetrical pattern  AMYOTROPHIC LATERAL SCLEROSIS (ALS) Leads to loss of neurons in cerebral cortex and spinal cord in diffuse asymmetrical pattern Progressive muscle weakness and loss of fine motor coordination Usually begins in hands &forearms Death due to respiratory failure in 2-5 years Sensory neurons, cognitive function, and cranial nerves III, IV, and VI to the eye muscles are not affected.  AMYOTROPHIC LATERAL SCLEROSIS (ALS) Treatment No specific treatment is available Stem cell therapy is under investigation. A new drug, Rilutek (riluzole) has been developed to slow further damage to neurons moderate exercise and rest is helpful. Electronic communication devices are recommended for use relatively early in the course of the disease. Respiratory therapist, nutritionist, speech pathologist, occupational therapist, physical therapist, psychologist, and social worker. In most cases respiratory failure occurs in 2 to 5 years, although some individuals survive for a longer period.  MYASTHENIA GRAVIS An autoimmune disorder impairs the receptors for acetylcholine (ACh) at the neuromuscular junction Pathophysiology autoantibodies to Ach receptors form, – destroying the receptor site, preventing any further stimulation of the muscle. – skeletal muscle weakness – facial and ocular muscles are usually affected initially, – Note: dysphagia and aspiration are significant problems  MYASTHENIA GRAVIS Diagnostic tests; electromyography, to test for muscle fatigue, Serum antibodies test. Signs and symptoms: Muscle weakness in the face and eyes, Impaired vision, and a nasal monotone speech Chewing and swallowing become difficult head droops and arms become weaker Upper respiratory infections common Treatment Anticholinesterase agents Glucocorticoids Plasmapheresis, – removes antibodies from the blood Thymectomy  Huntington disease (HD), or Huntington’s chorea A hereditary disorder of the basal ganglia that leads to progressive loss of motor coordination, – an autosomal-dominant trait carried on chromosome 4  does not manifest until midlife (25-35 up to 40 years)  Pathophysiology – Progressive atrophy of the brain particularly in the basal ganglia and the frontal cortex depletion of (GABA),in the basal nuclei Levels of ACh in the brain also appear to be reduced.  Huntington disease (HD), or Huntington’s chorea Signs and symptoms – The earliest symptoms are mood swings and personality changes – As the disease advances ,restlessness and choreiform (rapid, jerky, uncoordinated) movements in the arms and face. Diagnostic tests – DNA analysis. Treatment No therapy to slow the progress of the disease. Symptomatic therapy only, such as physiotherapy  Chronic Degenerative Disorders 1. MULTIPLE SCLEROSIS(MS)---demyelination 2. PARKINSON’S DISEASE(PARALYSIS AGITANS)---no dopamine 3. AMYOTROPHIC LATERAL SCLEROSIS(ALS),---motor tracts go bad 4. MYASTHENIA GRAVIS—autoimmune, Ach receptor 5. Huntington disease (HD), or Huntington’s chorea---- inherited, autosomal dominant genetic defect ,in brain and basal ganglia ,Ach and GABA deficiency  DEMENTIA A progressive, incurable form of mental deterioration, affects approximately 5 million people and is the cause of 100,000 deaths each year. – loss of hippocampal and cortical neurons of memory and cognitive ability The first symptoms, which usually begin after age 65, are memory lapses and slight personality changes. As the disease progresses, there is total loss of memory, reasoning ability, and personality, and those with advanced disease are unable to perform even the simplest tasks or self-care There are many causes of dementia, including Vascular disease (e.g., arteriosclerosis), infections, toxins, genetic disorders.  ALZHEIMER’S DISEASE Structural changes in the brains of Alzheimer’s patients may be seen at autopsy. Neurofibrillary tangles are abnormal fibrous proteins found in cells of the cerebral cortex in areas important for memory and reasoning. Also present are plaques made of another protein called beta-amyloid that are damaging to neurons. A deficit of the neurotransmitter ACh also occurs in the affected brain. No definitive diagnostic tests available – Exclusion of other disorders – Careful medical and psychological history Etiology A mature plaque with central The specific cause is unknown amyloid core (white arrow) next – At least four defective genes located on to a neurofibrillary tangle (black different chromosomes have been associated arrow). with AD  ALZHEIMER’S DISEASE Signs and symptoms Extend over 10 to 20 years Behavioral changes, – irritability, and mood swings Gradual loss of memory and lack of concentration. Impaired learning and poor judgment Decline of Cognitive function, memory, and language skills Managing the activities of daily living becomes difficult, affecting meal preparation, dressing, and personal hygiene. In the late stage, inability to recognize family, lacks of environmental awareness, incontinent, and inability to function Treatment no specific treatment, occupational therapy ,psychologists and speech therapy Anticholinesterase drugs led to some temporary improvement  OTHER FORMS OF DEMENTIA Vascular Dementia; senile dementia Caused by cerebrovascular disease Often a result of multiple small brain infarctions. common in persons older than age 70, – particularly those with hypertension. Onset insidious, – memory loss, apathy, and inability to manage daily routines. Progression may be in stages Other neurologic impairment is common  OTHER FORMS OF DEMENTIA AIDS Dementia common in the later stages of AIDS Virus invades brain tissue May be exacerbated by other infections, and by tumors Gradual loss of memory and cognitive ability impaired motor function Children with congenital HIV infection, – the brain is frequently affected, – delayed motor development SPINAL CORD PROBLEM Herniated intervertebral disc.  Herniated intervertebral disc. Pathophysiology Herniation involves protrusion into the extradural space, of the nucleus pulposus, – the inner gelatinous component of the intervertebral disc, through a tear in the annulus fibrosus, the tough outer covering of the disc. Sensory, motor, or autonomic function can be impaired. Most common location is the lumbosacral discs, at L4 to L5 or L5 to S1 Some herniations involve cervical discs between C5 and C7 Complications ;If pressure is prolonged ,severe, permanent damage to the nerve may result.  Herniated intervertebral disc. Etiology predisposed to herniation – degenerative changes in the intervertebral disc resulting from age , metabolic changes ,obesity – herniation usually is caused by trauma (50%)or poor body mechanics Signs depend on the location and extent of the protrusion – Most effects are unilateral – large protrusions may cause bilateral effects. Manifestations: lumbosacral herniation Lower back pain – Radiating down one or both legs – Exacerbated by coughing Numbness, as well as muscle weakness, if compression is severe  Herniated intervertebral disc. Diagnostic Tests Myelography with contrast dye, CT scans, and MRI confirm the herniation. Treatment Bed rest; Application of heat, ice, or traction; Drugs, such as analgesics, anti-inflammatory agents, and skeletal muscle relaxants, are the initial approach. It is important to note that the pressure on the disks is highest in the sitting position. Physiotherapy and an appropriate program of exercise An occupational therapist can recommend appropriate modifications to daily life Surgery in severe cases includes laminectomy or discectomy and spinal fusion