Neural Function PDF

Chapter 11 Neural Function  Introduction The nervous system manages: Muscles, glands, and organs Heart rate Blood flow Breathing Digestion Urination Defecation  Anatomy and Physiology Intricate network of specialized cells and tissues Recei...

Chapter 11 Neural Function  Introduction The nervous system manages: Muscles, glands, and organs Heart rate Blood flow Breathing Digestion Urination Defecation  Anatomy and Physiology Intricate network of specialized cells and tissues Receive and react to stimuli on physiologic and cognitive levels Main components Central nervous system Peripheral nervous system  Central Nervous System (1 of 2) Brain and spinal cord Encased by three meninges Cerebrospinal fluid (CSF) Neural tissue Neuroglia and neurons Neurons and impulse transmission Electrical impulses of the neural system  Central Nervous System (2 of 2) Brain regions Cerebrum Diencephalon Brain stem Cerebellum Components of the spinal cord Spinal reflex arcs  Peripheral Nervous System Consist of the spinal nerves and cranial nerves 31 spinal nerve pairs Sensory and motor types of spinal nerves Cervical, brachial, lumbar, and sacral plexuses 12 pairs of cranial nerves  Autonomic Nervous System (ANS) Controls smooth muscles Responsible for fight-or-flight response Divisions Sympathetic Parasympathetic Neurotransmitters and receptors Motor portion of ANS Preganglionic, myelinated neurons Postganglionic, unmyelinated neurons  Blood Supply to the CNS Brain Mostly from internal carotid arteries, anterior circulation Spinal cord Vertebral arteries, posterior circulation Blood-brain barrier (BBB) Prevents exposure to potentially harmful substances  Hydrocephalus Excess CSF within ventricles and subarachnoid spaces Dilation of ventricles and compression of brain and blood vessels Obstructive or communicating Incidence and prevalence Risk factors  Hydrocephalus: Clinical Manifestations Infants with unfused cranial sutures Unusually large head, bulging fontanelle, vomiting, dilated scalp veins, lethargy, etc. Older children and adults Headache followed by vomiting, nausea, blurred vision or diplopia, and balance, coordination, or gait problems, etc. Adults with normal pressure hydrocephalus Gait dysfunction, cognitive impairment, and urinary incontinence  Spina Bifida Second most common birth defect in United States Neural tube defect varying in severity Incidence, risk factors, and complications Forms Spina bifida occulta Meningocele Myelomeningocele Treatment Surgery (meningocele, myelomeningocele)  Cerebral Palsy (CP) Nonprogressive disorders appearing in infancy or early childhood Permanently affects motor movement and muscle coordination Results from brain abnormalities or damage to cerebellum Risk factors (partial list) Prematurity, LBW, breech births, multiple fetuses, hypoxia, hypoglycemia  CP: Clinical Manifestations Classified according to movement disorder involved Neurobehavioral signs Developmental reflexes Motor tone and posture Spastic subtype Dyskinetic subtype Ataxic subtype Complications  Meningitis Inflammation of the meninges, usually from infection Transmission modes Risk factors and complications Clinical manifestations mimic influenza infection Diagnosis Throat cultures, lumbar puncture, PCR test Head CT Treatment Antibiotics, antivirals, hydration, and fever management  Encephalitis Brain inflammation, usually from infection Primary or secondary Manifests as flulike symptoms Diagnosis includes: History and physical exam Head CT and MRI, EEG Lumbar puncture Treatment: supportive Prevention strategies  Zika Virus Disease Flavivirus transmitted primarily by mosquitoes Manifests as flulike symptoms Diagnosis History and physical exam Body fluid examination Treatment: supportive Importance of prevention  Brain Injuries Caused by: Sudden and violent blow or jolt Penetrating head wound Disruption of normal brain function Main causes of TBIs Complications Closed vs. open injuries  TBIs: Clinical Manifestations Vague and slow or sudden and severe development Glasgow Coma Scale Limitations Neurobehavioral changes Consciousness Coma Vegetative state Minimally conscious state  Increased Intracranial Pressure Increased volume (fluid or tissue) in cranial cavity Monro-Kellie hypothesis Explains pressure-volume relationship among: ICP Volume of CSF, blood, and brain tissue Cerebral perfusion Compensation mechanisms Herniation complication  ICP: Clinical Manifestations Vary depending on age Decreasing level of consciousness, vomiting, increasing BP, bradycardia, papilledema, fixed and dilated pupils, posturing Infants Separate sutures and bulging fontanelle Children and adults Behavior changes, severe headache, lethargy, neurologic deficits, seizures  Hematomas Collection of blood in tissue from ruptured blood vessels Classified by location Epidural, subdural, intracerebral, and subarachnoid Formation of hematomas and effects Diagnosis History, physical, head CT and MRI, cerebral angiogram, and intracranial pressure monitor Treatment: surgical removal of blood  Spinal Cord Injuries Result from: Direct injury to the spinal cord Indirectly from damage to bones, tissue, or blood vessels Causes of injury Primary and secondary injury Edema and hemorrhagic necrosis Spinal shock  SCIs: Clinical Manifestations (1 of 2) Significant loss of neurologic functioning Spinal shock Flaccid paralysis, lack of sensation, loss of reflex activity Poor temperature control Neurogenic shock Loss of sympathetic tone in vascular smooth muscle Massive vasodilation  SCIs: Clinical Manifestations (2 of 2) Autonomic dysreflexia Loss of coordinated heart rate and vascular response SCI dysfunction Dependent on level, location, and severity of injury American Spinal Injury Association (ASIA) classification (A-D classes)  Cerebral Vascular Accident (1 of 2) Interruption of cerebral blood supply Ischemic or hemorrhagic types Incidence and prevalence Ischemic strokes Thrombotic and embolic subtypes Penumbra Cascade of events for brain ischemia Cytotoxic edema and vasogenic edema Transient ischemic attacks (TIAs)  Cerebral Vascular Accident (2 of 2) Clinical manifestations Sudden loss of focal brain function in ischemic strokes Manifestation based on effect on anterior or posterior circulation Diagnosis History and physical exam Head CT and MRI, cerebral angiography, EKG, and lab tests Crucial to determine ischemic or hemorrhagic origin  CVA: Treatment Importance of early treatment Ischemic strokes Thrombolytic agents, angioplasty, or carotid endarterectomy, statin agent Hemorrhagic strokes Surgical repair of aneurysms or arteriovenous malformations, blood removal TIA treatment strategies  Cerebral Aneurysm Localized outpouching of a cerebral artery Causes and risk factors Asymptomatic until compression or rupture Risk of rupture Diagnosis Head CT or MRI EEG Cerebral arteriography Treatment: surgical repair  Arteriovenous Malformations Arteries and veins connected in tangled mess Causes and incidence Presentations of intracranial hemorrhage, seizure, and headaches Diagnosis Head CT or MRI Treatment Excision, focused radiation therapy, or endovascular embolization  Migraine Headaches Severe headaches Often associated with systematic complaints Types Migraine with or without aura Results from wave of self-propagating neuronal and glial depolarization Spreads across the cerebral cortex Neurogenic inflammation leads to neuronal sensitization  Migraine: Clinical Manifestations Experience of a prodrome Irritability, euphoria, depression yawning, food craving, constipation Visual, sensory, language, and motor auras Throbbing or pulsatile pain, nausea and vomiting Photophobia and phonophobia Triggers  Tension-Type Headaches Result from hypersensitivity of nerve fibers Episodic or chronic Generally mild to moderate manifestations Dull, full, or tight feelings Diagnosis History and physical exam Treatment Pharmacotherapeutic agents NSAIDs, acetaminophen, aspirin, etc. Preventive measures  Cluster Headaches Short bursts of unilateral orbital pain Key features Trigeminal distribution of the pain Unilateral and same side autonomic features Manifests with severe throbbing or stabbing pain, lacrimation, ptosis, sweating, etc. Diagnosis: history and physical exam Treatment Oxygen and triptans to abort acute attack Preventive therapy (e.g., verapamil)  Seizure Disorders Transient physical or behavioral alteration resulting from abnormal electrical brain activity Potential causational mechanisms Definitions of epilepsy Incidence and prevalence Febrile seizures in children  Seizure Disorders: Clinical Manifestations Focal and generalized seizure categories Simple or complex focal seizures Types of generalized seizures Absence, tonic, clonic, myoclonic, atonic, and tonic-clonic Unknown type category  Multiple Sclerosis Debilitating inflammatory, immune-mediated condition Demyelination and axonal degeneration of brain, spinal cord, and optic nerve Progressive and irreversible Genetic susceptibility for MS development Theoretical explanation for demyelination Immune involvement  MS: Clinical Manifestations Characterized by remissions and exacerbations Sensory symptoms in limbs or face Visual issues, motor spasticity, cognitive changes Bladder, bowel, and sexual dysfunction Sleep issues, brainstem symptoms, fatigue, pain Experience of transverse myelitis  Parkinson’s Disease Neuron loss in substantia nigra and depletion of dopamine Results in impairment in smooth, coordinated muscle movement Structures of the basal ganglia Causes and cascade of cellular level abnormalities  Parkinson’s Disease: Clinical Manifestations Key manifestations Tremor, akinesia, rigidity, postural instability Other motor dysfunction manifestations Masked facial expression, slowing or stopping of automatic movements, micrographia, speech impediments Nonmotor manifestations Mood changes, cognitive dysfunction, and dementia  Amyotrophic Lateral Sclerosis Damage to motor neurons of cerebral cortex, brain stem, and spinal cord Investigation of etiology Early manifestations Footdrop, lower-extremity weakness, hand weakness, dysarthria or dysphagia, etc. Diagnosis: no definitive test or cure Treatment Drugs to slow progression Supportive and palliative care  Myasthenia Gravis Autoimmune condition Acetylcholine receptors impaired or destroyed by IgG autoantibodies Manifests as muscle weakness and fatigue Ocular dysfunction, affected bulbar muscles, limb involvement, etc. Diagnosis History, physical exam, and serum testing Treatment Symptom management  Huntington’s Disease Genetically programmed degeneration of neurons in the brain Autosomal dominant disorder with defect on chromosome 4 in HTT gene Clinical manifestations Choreiform movements, psychiatric problems, and dementia Treatment: Focused on slowing progression and managing symptoms Tetrabenazine, tranquilizers, antipsychotics, coping strategies, etc.  Alzheimer’s Disease Most common form of dementia among older adults Degeneration/atrophy of healthy brain tissue Decline in memory and mental abilities Increasing incidence Pathologic characteristics Amyloid plaques Neurofibrillary tangles Loss of connections among neurons  AD: Clinical Manifestations Begins with mild memory loss and confusion Subtypes of memory Explicit memory Semantic and episodic Implicit memory Procedural, priming and perceptual learning, associative and nonassociative learning Specific pattern of memory loss Impairment of problem solving, judgment, and executive functioning  Vascular Dementia Progressive syndrome resulting from any disorder impairing cerebral blood flow Often coexists with dementia Common cause and finding Cerebral small vessel disease Manifestations dependent on coexisting disorders  Dementia with Lewy Bodies Formation of Lewy bodies Made of proteins ubiquitin and synuclein Essential manifestation of progressive dementia Early impairment of attention, executive and visuospatial functioning Clinical criteria for diagnosis Pharmacologic and nonpharmacologic treatment strategies  Frontotemporal Dementia Disorder spectrum leading to focal degeneration of frontal and/or temporal lobes Three forms of clinical manifestations Behavioral variant FTD Nonfluent and semantic primary progressive aphasia Treatment Nonpharmacologic treatment Behavior modification techniques Caregiver support  Creutzfeldt-Jakob Disease Rare, rapidly progressive form of dementia Caused by an infectious prion Long incubation period Fatal within 1 year of onset Manifests as ataxia, lack of coordination, muscle twitching, myoclonic jerks, spasticity Treatment Interleukins and immunomodulator agents Custodial care, medications for symptoms, family counseling  AIDS Dementia Complex Dementia common in later stages of AIDS Clinical manifestations Encephalitis, behavioral changes, gradual decline in cognitive functioning Progressive slowing of motor function Staging system (0 to 4) Aggressive antiretroviral therapy as cornerstone of treatment  Brain Tumors Life-threatening whether malignant or benign Cause increase in ICP, difficult to access Primary vs. secondary tumors Manifests as headaches, nausea, vomiting, seizures, neurocognitive dysfunction, etc. Diagnosis History, physical exam, brain MRI, and biopsy Treatment Surgical removal, if possible Radiation, chemotherapy, targeted drug therapy, and rehabilitation  Depressive Disorders Mood disorder commonly featuring persistent sad, empty, or irritable mood Cognitive changes and somatic manifestations Incidence and prevalence Complex and multifactorial development Genetic factors, alterations in neuroendocrine system, abnormal neurotransmitter functioning Neural network model  Depressive Disorders: Clinical Manifestations Major depressive disorder (MDD) Depressed mood, anhedonia Changes in weight, sleep, and activity Feelings of worthlessness or excessive guilt Diminished ability to concentrate or indecisiveness Impaired functioning Persistent depressive disorder Premenstrual dysphoric disorder Depressive Disorders: Diagnosis and Treatment Diagnosis History and physical exam DSM-V criteria Treatment Psychotherapy and pharmacotherapy SSRIs and herbal supplements Other therapies Relaxation and lifestyle management For severe depression Brain stimulation  Bipolar Disorders (1 of 2) Episodes of mania, hypomania, and major depression Complex, multifactorial, and poorly understood pathogenesis Connection with schizophrenia development Genetic influence Manifestations of mania Inflated self-esteem, decreased need for sleep, talkative, flight of ideas, distractibility, etc.  Bipolar Disorders (2 of 2) Manifestations of depressive episodes Same as in MDD Bipolar I and II as subtypes Hypomanic episode 4 day duration of manic symptoms Cyclothymic disorder Pharmacotherapeutics as mainstay of treatment  Schizophrenia (1 of 2) Chronic, recurrent psychotic disorder Characterized by: Alterations in perception of reality, Disorganized thinking or abnormal behavior Disruptions in normal emotional states and expressions Likely resulting from genetic, epigenetic, and environmental factors  Schizophrenia (2 of 2) Clinical manifestation categories Positive, negative, and cognitive symptoms Criteria for diagnosis Related disorders Schizoaffective disorder, schizotypal personality disorder, delusional disorder Treatment Pharmacotherapeutics Psychosocial interventions  Anxiety Disorders (1 of 2) Group of disorders characterized by fear and anxiety Incidence and prevalence Types of anxiety disorders Unknown biological basis Genetic links  Anxiety Disorders (2 of 2) Manifestations by type of anxiety disorder Panic disorder Generalized anxiety disorder Social anxiety disorder Diagnosis History and physical exam DSM-V criteria Treatment Pharmacotherapy with psychotherapy Behavioral techniques Obsessive Compulsive Disorders Chronic, repetitive, intrusive thoughts or urges Repetitive mental or behavioral acts Obsessions and compulsions as manifestations Themes Treatment Psychotherapy, family therapy, and psychoeducation Pharmacotherapeutics, brain stimulation, and surgical techniques