Acute Nervous Disorders PDF

Pathophysiology (2) (MBS 214) Acute Neurologic Disorders Textbook ;Pathophysiology for the Health Professions, 4th edition, 2011 Chapter 22 (p.465-506)  Acute Neurologic Disorders Lecture outline:- Review of the Nervous System: General Effects of Neurologic...

Pathophysiology (2) (MBS 214) Acute Neurologic Disorders Textbook ;Pathophysiology for the Health Professions, 4th edition, 2011 Chapter 22 (p.465-506)  Acute Neurologic Disorders Lecture outline:- Review of the Nervous System: General Effects of Neurologic Dysfunction Acute Neurologic Problems Learning objectives: After studying this lecture ,the student is expected to describe pathophysiology of ; Brain tumors Vascular Disorders Infections Head injuries. Anatomy and Function of the Nervous System Functions: Control body functions through sensory input by sensory receptor neurons in PNS, and send signals that inform the CNS where information processing, and CNS sends motor output.  Function of the NS Basic functions: – Motor---skeletal muscle – Sensory----the senses – Autonomic ---the reflexes Higher functions: – Cognition ----thinking, planning, memory – Emotions ----feelings – Consciousness The important areas of the Human Brain  GENERAL EFFECTS OF NEUROLOGIC DYSFUNCTION 1-Level of consciousness; – The early change in case of acute brain disorders 2-Motor dysfunction; – Damage to the right side of the brain (motor or sensory cortex) affects the contralateral side of the body – Paresis(weakness) or paralysis – Muscle tone and reflexes (flaccid or spastic (hyperreflexia) – Nuchal rigidity, or a stiff, extended neck, due to meningeal and spinal nerve roots irritation – Ataxia: movement disorder related to damage of the cerebellum characterized by loss of coordination in voluntary movements 3-Sensory deficits; – General: may involve touch, pain, temperature, and position – Numbness a reduced, absent, or abnormal perception of sensation. (reduced or absent sensitivity to cutaneous stimulation). – Paresthesia; abnormal sensation of burning, prickling, itching, or tingling of the skin, with no obvious cause. – Special senses of: vision, hearing, taste, and smell. 4-Language disorders: – Aphasia; the inability to communicate, /Dysarthria, difficulty pronouncing words 5-Seizures or convulsions – caused by spontaneous excessive discharge of neurons in the brain. – manifested by involuntary repetitive movements or abnormal sensations 6-Increased intracranial pressure (ICP)  Aphasia Impairment of speech and language function Inability to comprehend or express language (speech) Wernicke’s area (where the temporal lobe and parietal lobe meet) and Broca’s area (at the back of the frontal lobe), which localized in the majority of people in left cerebral hemisphere are responsible for language function loss of the ability to produce language  HEMIANOPIA, loss of vision from the medial side of one eye and the lateral side of the other eye Effects of increased ICP  DIAGNOSTIC TESTS Computed tomographic (CT) scans, Magnetic resonance imaging (MRI), Cerebral angiography, Doppler ultrasound – for assessing patency of the carotid and intracerebral vessels, EEG : – provide useful information about electrical activity of the brain. Brain death is flat with no rhythms Lumbar puncture : – analyze the CSF for altered components. Clinical assessment routinely includes tools such as : – the assessment of normal reflexes ( uses tools such as a tuning fork, flashlight, reflex hammer, and a tool for examining the eye). – the Glasgow coma scale to assess the level of consciousness. – A neurological examination assesses motor and sensory skills, hearing and speech, vision, coordination, and balance. It may also test mental status, mood, and behavior.  ACUTE NEUROLOGIC PROBLEMS BRAIN TUMORS VASCULAR DISORDERS INFECTIONS BRAIN INJURIES  BRAIN TUMORS Definition: space-occupying lesions, result in pressure on the brain. Types :  Primary : Gliomas – form the largest category of primary malignant tumors – originating in neuroglial cells – astrocytoma are the most common tumor. Tumors may develop in the meninges (meningioma) Pituitary gland (adenoma)  Secondary brain tumors are quite common, – metastasizing from breast or lung tumors,  Signs and symptoms Focal effects Generalized effects; increased ICP (morning headache, vomiting ) Focal or generalized Seizures are often first sign, as the tumor irritates the surrounding  VASCULAR DISORDERS Interference with blood supply or blood flow leads to local damage and manifestations depending on cerebral artery involved. Types of Vascular Disorders: 1-Transient Ischemic Attacks (TIA); temporary partial reduction of blood flow in the brain in which symptoms occur rapidly but last only a short time (few minutes up to 2hrs). Sometimes called ministroke as it is similar to a stroke although it does not last as long. 2-Cerebrovascular Accidents (Stroke) total loss of blood flow to part of the brain that last at least 24 hours (diagnostic) leads to infarction of brain tissue. 3-Cerebral Aneurysms: a localized dilation in an artery due to weakness in the wall and is frequently asymptomatic and undiagnosed until it is very large or rupture occurs.  Ischemic stroke Hemorrhagic stroke often develop in the large arteries Q.Explain why the prognosis for a hemorrhagic type stroke is worse than for other types? Damage are more widespread, both hemispheres involved Increased ICP , Complicated by the secondary effects of bleeding, vasospasm, electrolyte imbalance and cerebral edema  Cerebrovascular Accidents CVA (Stroke) Risk factors for stroke include : – Uncontrolled diabetes – Severe or long-term hypertension and arteriosclerosis in the elderly – Elevated cholesterol levels, hyperlipidemia, atherosclerosis, – Family history of thrombotic stroke (TIAs) – Obstructive sleep apnea, heart disease, smoking and sedentary life – The combination of oral contraceptives and cigarette smoking. – Congenital malformations of cerebral vessel  Cerebrovascular Accidents WARNING SIGNS OF STROKE (CVA, or BRAIN ATTACK) 1. Sudden transient weakness, numbness, or tingling in the face, an arm or leg, or on one side of the body 2. Temporary loss of speech, failure to comprehend, or confusion 3. Sudden loss of vision 4. Sudden severe headache 5. Unusual dizziness or unsteadiness  Cerebrovascular Accidents Signs and symptoms; manifestations – depend on the location of the obstruction, the size of the artery involved, and The functional area affected – Motor deficits; weakness or paralysis of voluntary movement on opposite site of the body(contralateral) – Sensory deficits; contralateral paresthesia or numbness; possibly loss of vision – Speech deficits; aphasia when the left side of the brain is involved – Cognitive and emotional manifestations; confusion and personality changes – The National Institutes of Health (NIH) Stroke Scale: Designed to assist in rapid diagnosis in an emergency situation  INFECTIONS Meningitis Encephalitis Tetanus (lockjaw) Infection-Related Syndromes – Herpes Zoster (Shingles) – Guillain-Barré syndrome  Meningitis An inflammation of the meninges, the three layers of fibrous membrane that surround the CNS (pia mater, arachnoid, and dura mater). Caused by infections with bacteria or viruses Etiology: In children and young adults, – Neisseria meningitidis In neonates, – Escherichia coli most common causative organism In young children, – most often due to Haemophilus influenza In elderly persons and young children, – Streptococcus pneumonia -----a major cause  Meningitis Signs and symptoms: fever, chills, nausea, vomiting, photophobia (light sensitivity) severe headache. nuchal rigidity(a hyperextended, neck stiffness). changes in mental state (confusion, memory deficits, and other dementia-type symptoms). Hearing loss is a common result of meningitis. Progress to seizures ( common early indicators of increased ICP) Diagnostic tests – The primary test for meningitis is CSF examination obtained by lumbar puncture. – A needle inserted into the lumbar region of the spinal column through the dura mater and arachnoid membrane into the subarachnoid space.  Meningitis Encephalitis Causative agents Meningococci virus Escherichia coli Influenza pneumococci Predisposing Other infections, Insect bites sinusitis,otitis,measles Abscess tooth Head trauma Pathophysiology and -Increased ICP, edema Infection involve the Manifestations : of meninges, purulent brain tissue and may be exudate cover brain and the spinal cord in CSF Severe headache, & -Sudden onset of vomiting severe headache, back pain, Fever, photophobia Seizures Nuchal rigidity Decrease level of Vomiting, Fever, consciousness Irritability, Seizures Change in neurologic Leukocytosis functions Treatment antimicrobial antiviral  Other Infections Tetanus: The toxin produced by the tetanus bacteria (Clostridium tetani) , – anaerobe, a spore-forming bacillus. – The spores survive for years in soil – Wound infection Exotoxin enters the nervous system, causing – tonic muscle spasms, muscle fibers receive too many impulses, – Lockjaw (jaw stiffness) : the common name for tetanus, indicates one of the first symptoms, which is difficulty opening the mouth because of spasms of the masseter muscles – difficulty swallowing, – stiff neck  Infection-Related Syndromes Herpes Zoster (Shingles) Caused by varicella zoster virus (VZV) in adults Seen years after primary infection of varicella ( chickenpox, usually occurs in childhood). Usually affects one cranial nerve or one dermatome (cutaneous area innervated by a spinal nerve on one side of the body). Manifestation : A painful skin vesicular rash (blisters) in a localized area develop in a line, unilaterally. Vaccine is available for those 60 years or older  Guillain-Barré syndrome Known as post-infectious polyneuritis, acute idiopathic polyneuropathy Inflammatory disorder of the peripheral nerves (cranial & spinal) affect both sensory and motor function Changes cause impaired nerve conduction. The first sign is muscle weakness in legs and arms Unknown etiology  Head injury (traumatic brain injury) Any injury that results in trauma to the skull or brain. Causes: falls, sports injuries, cars or motorcycles accidents. Types of Head Injuries: 1- Concussion: – Resulting from a mild blow to the head, – Causes reversible interference with brain function – Recovery usually occurs within 24 hours without permanent damage. 2- Contusion: – bruising of brain tissue with rupture of small blood vessels and edema – Results from a blunt blow to the head. 3- Closed head injury: brain tissue injured, skull not fractured 4- Open head injuries: skull fracture, & penetration of brain; missiles 5- Skull fractures: Linear (simple fracture line), Comminuted (several fracture lines), Compound (brain tissue exposed to environment), Depressed (piece of bone below the level of skull), Basilar ( fracture base of the skull with leaking CSF through ears or nose).  Head Injuries Trauma to the brain tissue causes: Loss of function in the part of the body controlled by that specific area of the brain. Cell damage and bleeding – Hematoma is generally defined as a collection of blood outside of blood vessels – Hemorrhage is a large or heavy flow of blood from a damaged blood vessel – or a rapid loss of blood  Types of hematomas  Classified by their location in relation to the meninges, as follows: Epidural (extradural) hematoma – results from bleeding between dura and skull, – Signs usually arise within a few hours of injury Subdural hematoma – develops between dura and arachnoid – may be acute (signs present in about 24 hours) or subacute (over a week) or chronic subdural hematoma may occur in an elderly person, in whom brain atrophy allows more space for a hematoma to develop. Subarachnoid hemorrhage – occurs in the space between arachnoid and pia mater Intracerebral hematoma – Bleeding within the brain – may develop several days after injury  Describe the consequences and potential complications of a head injury? If unconscious for a prolonged period, immobility may results in pneumonia or decubitus ulcer.  Types of spinal cord injuries 1-Cervical spine injuries: result from hyperextension or hyperflexion of the neck 3-Compression fractures cause injury to the spinal cord when great force is applied to the top of the skull or to the feet 2-Dislocation of any vertebra may crush or compress the spinal cord and compromise the blood supply. 4-Penetrating injuries such as stab or bullet wounds  Acute spinal cord injury Signs & Symptoms depend on the level of the cord at which injury occurred, it may include: Muscle weakness or Loss of voluntary muscle movement in the chest, arms, or legs with breathing problems Loss of sensation (feeling) in the chest, arms, or legs Loss of autonomic function (Autonomic dysreflexia, esp. bowel and bladder ) Signs & Symptoms depend on the time that has elapsed since the injury (stages) – Stages of spinal cord injury Spinal shock: Immediately following injury, Post spinal shock; Following the period of spinal shock  May persist for days or weeks Above Cervical injury is particularly dangerous because of the risk of respiratory failure related to phrenic nerve dysfunction. below  Tetraplegia(quadriplegia) Paralysis of all four limbs Paraplegia paralysis of lower half of body Hemiplegia Paralysis of one side of body Ipsilateral (same side ) paralysis and contralateral loss of pain and temperature sensation  Autonomic dysreflexia following spinal cord damage  With injury of the cervical spine, stimulation of the sympathetic system may result in autonomic dysreflexia, a massive sympathetic reflex response that cannot be controlled from the brain  SPINAL CORD INJURY Complications are common after spinal cord injury due to immobility and autonomic dysreflexia : Contractures (muscle spasms) and pain Skin breakdown (decubitus ulcers) Respiratory and urinary infections Loss of function; Sexual function and reproductive capacity are affected.