Chapter 14: Nervous System Disorders PPT Notes

Review of the Nervous System

The nervous system comprises three main components:
- Central Nervous System (CNS): Brain and spinal cord.
- Peripheral Nervous System (PNS): Cranial and spinal nerves, sensory neurons, and neuromuscular junctions.

Overview of the Nervous System

The CNS consists of the brain and spinal cord.
The PNS includes cranial nerves, spinal nerves, peripheral nerves, ganglia, sensory receptors in the skin, and enteric plexuses in the small intestine.

Brain

The brain serves as the communication and control center of the body.
It receives, processes, and evaluates inputs to decide on appropriate actions.
Initiates responses, including:
- Involuntary actions to maintain homeostasis, regulated by the autonomic nervous system (ANS).
- Voluntary actions.
- Reflex activities.

Protection of the Brain

Meninges: Three layers of membranes protecting the brain and spinal cord.
- Dura mater: The outer layer, closest to the bone.
- Subdural space: Located beneath the dura mater.
- Arachnoid: The middle layer.
- Subarachnoid space: Contains cerebrospinal fluid (CSF).
- Pia mater: Adheres to the surface of the brain.
Cerebrospinal fluid (CSF)
- Provides a cushion for the brain and spinal cord.
- Similar in appearance to plasma but with different electrolyte, glucose, and protein concentrations.
- Changes in CSF characteristics serve as a diagnostic tool.
- Constantly formed by the choroid plexuses of the ventricles.
- Flows through the ventricles into the subarachnoid space.
- Equal amounts of CSF need to be produced and reabsorbed to maintain intracranial pressure (ICP).
Normal CSF Characteristics
- Appearance: Clear and colorless
- Pressure: 9-14 mmHg or 150 mm H₂O
- Red blood cells: None
- White blood cells: Occasional
- Protein: 15-45 mg/dL
- Glucose: 45-75 mg/dL
- Sodium: 140 mEq/L
- Potassium: 3 mEq/L
- Specific gravity: 1.007
- pH: 7.32-7.35
- Volume in the system: 125-150 mL
- Volume formed in 24 hours: 500-800 mL
Blood-brain barrier
- Located at capillaries in the brain.
- Limits the passage of materials into the brain.
- Controls the balance of electrolytes, glucose, and proteins in the brain.
- Lipid-soluble substances can pass easily.
- Poorly developed in neonates.
Blood-CSF barrier
- Located at the choroid plexus.
- Controls constituents of CSF.

Functional Areas of the Brain

Cerebral Hemispheres
Diencephalon
Brain Stem
Cerebellum
Frontal lobe: Intellectual function and personality
- Prefrontal area (left cortex): Skilled movements
- Motor cortex: Voluntary movements
- Broca's area (left cortex): Speech (expression)
Parietal lobe:
- Somatosensory area: Sensation (e.g., touch, pain)
Occipital lobe: Visual cortex, vision
Temporal lobe:
- Auditory cortex: Hearing
- Olfactory cortex: Smell
- Wernicke's area (left cortex): Comprehension of speech
- Memory
Cerebellum: Body balance and position, coordinated movement
Medulla oblongata: Control and coordination centers for respiration and cardiovascular activity; swallow, vomiting, and cough reflex centers; nuclei of five cranial nerves
Hypothalamus: Autonomic nervous system link with the endocrine system; control of body temperature and fluid balance; centers for thirst and hunger
Thalamus: Sensory sorting and relay center
Basal nuclei: Coordination and control of body movement
Reticular activating system: Arousal or awareness
Limbic system: Emotional responses

Cerebral Hemispheres

Largest area of the brain, separated by the longitudinal fissure.
Cortex, or “gray matter,” consists of nerve cell bodies.
Corpus callosum, or “white matter,” comprises myelinated nerve bundles that connect the hemispheres.
Each hemisphere is divided into five major lobes: prefrontal, frontal, parietal, temporal, and occipital lobes.

Right and Left Hemispheres

Similar in structure but not necessarily in function.
The dominant hemisphere controls language (left hemisphere in most people).
Broca’s area: Motor or expressive speech area.
Wernicke’s area: Integration center for comprehending language.

Prefrontal Cortex

Coordinates complex cognitive behavior and components for expression of personality.
Basal nuclei
- Part of the extrapyramidal system (EPS).
- Controls and coordinates skeletal muscle activity.
Limbic System
- Consists of many nuclei and connecting fibers.
- Responsible for emotional reactions or feelings.

Diencephalon

Thalamus: Relay station for incoming sensory impulses.
Hypothalamus: Maintains homeostasis, controls the autonomic nervous system and endocrine system, regulates body temperature, fluid and food intake, sleep cycles, stress response, emotional responses, and sex drive.
Epithalamus

Brain Stem

Connects the brain and the spinal cord.
Consists of the midbrain, pons, and medulla oblongata.

Midbrain

Most superior portion of the brainstem.
Reticular formation and reticular-activating system (RAS)
- Network of nuclei and neurons throughout the brainstem.
- Connected to many parts of the brain.
- Determines the degree of awareness of the cerebral cortex.
- Drugs can affect the RAS, either increasing or decreasing input to the cerebral cortex and diencephalon.

Pons

Bundles of afferent and efferent fibers.
Bridge between the cerebellum and cerebrum.
Several nuclei of cranial nerves.

Medulla Oblongata

Control center for respiratory and cardiovascular function.
Coordination of cough reflex, swallowing, and vomiting.
Nuclei for several cranial nerves.

Cerebellum

Located dorsal to the pons and medulla.
Functions:
- Coordination of movements.
- Maintenance of posture.
- Maintenance of equilibrium.
- Input from the pyramidal system.
- Receives input from proprioceptors in muscles and joints, as well as visual and vestibular pathways.

Blood Supply to the Brain

Internal carotid and vertebral arteries supply blood.
Each internal carotid artery divides into anterior and middle cerebral arteries.
- Anterior cerebral artery
  - Supplies the frontal lobe.
- Middle cerebral artery
  - Supplies the lateral part of the cerebral hemispheres.
- Basilar artery
  - Formed by vertebral arteries.
  - Supplies branches to the brainstem and cerebellum.
  - Divides into right and left posterior cerebral arteries.
Circle of Willis
- Arrangement formed by anastomoses between the major arteries.
- Provided by:
  - Anterior communicating artery between the anterior cerebral arteries.
  - Posterior communicating arteries between the middle cerebral and posterior cerebral arteries.
Blood flow in cerebral arteries is relatively constant.
Autoregulation
- Increased carbon dioxide levels, decreased blood pH, and decreased blood pressure all result in immediate local vasodilation
- Baroreceptors and chemoreceptors
Venous blood from the brain collects in dural sinuses and drains into the right and left internal jugular veins.

Cranial Nerves

12 pairs originate from various parts of the brain.
Numbered from ventral to dorsal.
May contain:
- Motor fibers only
- Sensory fibers only
- Both motor and sensory fibers (mixed nerve)

Spinal Cord

Protected by the vertebral column, meninges, and CSF.
Continuous with the medulla oblongata.
Ends at the lower border of the first lumbar vertebra and extends as a bundle of nerve roots (cauda equina).
Consists of white matter and gray matter (core).
- Gray matter
  - Anterior horns: Cell bodies of motor neurons
  - Posterior horns: Interneurons (association neurons)
  - Lateral horns: Visceral motor neurons
- White matter
  - Afferent (sensory) and efferent (motor) fibers
  - Organized into tracts
  - Each tract has a unique position in the white matter.
  - Name of tract based on source and destination.
    - Ascending tracts: Spinal cord to the brain
    - Descending tracts: Brain to spinal cord

Spinal Nerves

31 pairs named by location in the vertebral column where they emerge.
Each nerve connects to the spinal cord by roots.
Ventral (anterior) root: Motor (efferent) fibers.
Dorsal (posterior) root: Sensory (afferent) fibers.

Reflexes

Automatic, rapid, involuntary responses to a stimulus.
Sensory stimulus
- From receptor—conducted along afferent fiber
Synapse
- In the spinal cord or, for cranial reflexes, in the brain
Efferent impulse to elicit the response
Connecting and interneurons
- Transmit sensory information to the brain

Neurons and Conduction of Impulses

Highly specialized, nonmitotic cells.
Conduct impulses throughout the central nervous system (CNS) and peripheral nervous system (PNS).
Require glucose and oxygen for metabolism.
Cell body and processes
- Axons: Conduct impulses away from the cell body.
- Dendrites: Receptor site, conducts impulses toward the cell body.
Nerve fibers may be covered by a myelin sheath.
- Insulates fiber and speeds up the rate of conduction.
- Formed by Schwann cells in the PNS and oligodendrocytes in the CNS.
- Gaps between the myelin sheath (nodes of Ranvier).
  Axon collaterals may emerge.

Glial Cells

Supportive cells in the CNS
- Astroglia: Contribute to the blood-brain barrier.
- Oligodendroglia: Provides myelin for axons in the CNS.
- Microglia: Phagocytotic.
- Ependymal cells: Line brain ventricles and neural tube cavity; form part of the choroid plexus.

Regeneration of Neurons

If the neuronal cell body is damaged, the neuron dies.
In the PNS, axons may be able to regenerate.
After damage to axon:
- Section distal to injury degenerates
- Schwann cell forms new tube at the end of remaining axon
- Cell body becomes larger to synthesize additional proteins for growth of the regenerating axon

Conduction of Impulses

Stimulus increases the permeability of the neuronal membrane.
- Depolarization caused by sodium influx.
- Generation of action potential.
- Repolarization caused by outward movement of potassium.
- Sodium-potassium pump moves ions into their normal position.
Myelinated fibers
- Saltatory conduction—rapid conduction

Synapses and Chemical Neurotransmitters

Synapse
- Presynaptic axon terminal
  - Vesicles contain neurotransmitter (synaptic vesicles).
- Synaptic cleft
- Postsynaptic receptor
Neurotransmitter
- Released into the synaptic cleft on stimulus.
- Inactivated by enzymes or reuptake into presynaptic axon
- Postsynaptic neuron dendrites or cell body depolarizes, depending on neurotransmitters present.

Examples of Neurotransmitters

Acetylcholine (excitatory):
- At neuromuscular junction
- In ANS and brain
Norepinephrine and epinephrine (excitatory):
- Brain
- Sympathetic nervous system (SNS)
Dopamine, serotonin (excitatory):
- Brain
Gamma-aminobutyric acid (GABA) (inhibitory):
- Brain
Glycine (inhibitory):
- Spinal cord

Autonomic Nervous System

Sympathetic and parasympathetic
- Motor and sensory innervation
- Involuntary
Antagonistic effects
- Maintains homeostasis; branches have antagonistic effects.
- Preganglionic fibers in the brain or spinal cord
- Postganglionic fibers outside the CNS

Sympathetic Nervous System

Fight-or-flight response increases the general level of activity in the body.
Preganglionic fibers arise from the thoracic and first two lumbar segments.
Ganglia located in chains or trunks.
Neurotransmitters
- Preganglionic—acetylcholine
- Postganglionic—norepinephrine
Receptors
- Alpha and beta receptors

Parasympathetic Nervous System

Originates in the brainstem and sacral spinal nerves.
Dominates the digestive system.
Aids recovery after sympathetic activity.
Ganglia are scattered and close to the target organ.
Neurotransmitter
- Acetylcholine—both presynaptic and postsynaptic
Receptors
- Nicotinic and muscarinic

General Effects of Neurologic Dysfunction

Local (Focal) Effects: Signs related to the specific area of the brain or spinal cord where the lesion is located
- Supratentorial and Infratentorial Lesions
- Left and Right Hemispheres
- Levels of Consciousness
- Motor Dysfunction
- Sensory Deficits
- Visual Loss
- Language Disorders
- Seizures
Increased Intracranial Pressure
Herniation
Diagnostic Tests

Local (Focal) Effects

Signs related to the specific area of the brain or spinal cord in which lesion is located
- Example—paresis or paralysis of the right arm results from damage to a section of the left frontal lobe
Expanding lesions
- Caused by growing tumor or hemorrhage
- Additional impairment is noted as adjacent areas become involved.

Supratentorial and Infratentorial Lesions

Supratentorial lesions
- Occur in the cerebral hemispheres above the tentorium cerebelli
  - Lead to specific dysfunction in a discrete area
Infratentorial lesions
- Located in the brainstem or below the tentorium
  - May affect many motor and sensory fibers
  - Result in widespread impairment
  - Respiratory and circulatory function may be impaired
  - Level of consciousness may be impaired

Left and Right Hemispheres

Damage to left hemisphere
- Loss of logical thinking ability, analytical skills, other intellectual abilities, communication skills
Damage to right hemisphere
- Impairs appreciation of music and art
- Causes behavioral problems
- Spatial orientation and recognition of relationships may be deficient
- Self-care deficits common

Level of Consciousness

Decreased level of consciousness or responsiveness
- Early changes with acute brain disorders
Levels of reduced consciousness may lead to:
- Confusion and disorientation
- Memory loss
- Unresponsiveness to verbal stimuli
- Difficulty in arousal
- Loss of consciousness or coma
Glasgow Coma Scale: Used in Assessment
- Criteria:
  - Eye opening
    - Spontaneous (4)
    - Response to speech (3)
    - Response to pain (2)
    - None (1)
  - Motor response
    - Obeys commands (6)
    - Localizes pain (5)
    - Normal flexion (to pain) (4)
    - Abnormal flexion (decorticate) (3)
    - Abnormal extension (decerebrate) (2)
    - None (flaccid) (1)
  - Verbal response
    - Oriented to time and place (5)
    - Confused (4)
    - Inappropriate words (3)
    - Incomprehensible (2)
    - None (1)

Vegetative State

Loss of awareness and mental capabilities
- Result of diffuse brain damage
- Brainstem function continues
- Appearance of a sleep-wake cycle
- Person is unresponsive to external stimuli
Locked-in syndrome
- Individual is aware and capable of thinking but is paralyzed and cannot communicate
Brain death criteria
- Cessation of brain function
  Includes function of the cortex and the brainstem
  Flat or inactive electroencephalogram (EEG)
- Absence of brainstem reflexes or responses
- Absence of spontaneous respirations when ventilator assistance is withdrawn
- Confirmation of irreversible brain damage and cause of dysfunction
- Evaluation twice by different physicians

Motor Dysfunction

Damage to upper motor neurons
- Interference with voluntary movements
- Weakness or paralysis on the contralateral side of the body
Damage to lower motor neurons
- Weakness or paralysis on the same side of the body
- At and below the level of spinal cord damage
Decorticate and decerebrate posturing: Indicates severe brain damage

Sensory Deficits

Somatosensory cortex in the parietal lobe receives and localizes basic sensory input
- Mapped by dermatomes - Assists in evaluation of spinal cord lesions
- Involves touch, pain, temperature, position
- Involves special senses of vision, hearing, taste, smell

Visual Loss: Hemianopia

Depends on site of damage in the visual pathway
- Optic chiasm damage
  - Vision lost in both eyes if chiasm is totally destroyed
  - Partial loss depends on particular fibers damaged
- Optic tract or occipital lobe damage
  - Loss of the visual field on side opposite to that of the damage

Language Disorders

Aphasia: Inability to comprehend or express language
- Receptive—damage to Wernicke’s area
- Expressive—damage to Broca’s area
- Mixed, global—damage to both areas or to the fibers and tracts between them
Dysarthria: Motor dysfunction affecting the muscles used in speech
Expressive, or motor aphasia Impaired ability to speak or write fluently or appropriately. Occurs when Broca’s area in dominant frontal lobe is damaged.
Receptive or sensory aphasia Inability to read or understand the spoken word. Source—inability to process information in the brain. Result of damage to Wernicke’s area in the left temporal lobe. Usually also affects expression.
Global aphasia Combination of expressive and receptive aphasia. Major brain damage, including Broca’s area, Wernicke’s area, and many communicating fibers.
- Fluent or nonfluent aphasia
  - Fluent aphasia Pace of speech relatively normal Includes made-up words Associated with damage to Wernicke’s area
  - Nonfluent aphasia Slow and labored, with short phrases Associated with damage to Broca’s area
Dysarthria Words cannot be articulated clearly. Motor dysfunction—usually results from cranial nerve damage or muscle impairment
Agraphia Impaired writing ability
Alexia Impaired reading ability
Agnosia Loss of recognition or association

Seizures

Seizures or convulsions are caused by spontaneous, excessive discharge of neurons in the brain.
Causes
- Inflammation
- Hypoxia
- Bleeding in the brain
Focal
- Related to the particular site of the irritation
- May become generalized
- Often manifested by involuntary repetitive movements or abnormal sensations (aura)
Generalized
- Absence seizures (petit mal)
- Tonic-clonic
- Myoclonic
Partial
- Simple partial
- Complex partial (psychomotor)
Continuous seizures (status epilepticus)
- Increased metabolism of glucose and oxygen
- May be life-threatening
- Increased ICP is common in many neurological problems.

Increased Intracranial Pressure

Increased ICP is common in many neurological problems.
- Brain hemorrhage, trauma, cerebral edema, infection, tumors, abnormal circulation of CSF
Early signs: If the cause is not removed
- Decreasing level of consciousness or decreased responsiveness (lethargy)
- Decreased pupillary responses
- Severe headache
  - From stretching of dura and walls of large blood vessels
- Vomiting: Often projectile, not associated with food intake. Result of pressure stimulating the emetic center in the medulla
- Papilledema: Increase of ICP causes swelling around the optic disc
Vital signs signs if increased intracranial pressure
- Development of cerebral ischemia Vasomotor centers respond in attempt to increase arterial blood supply to brain (Cushing reflex)
- Systemic vasoconstriction Increase of systemic blood pressure—more blood to brain to relieve ischemia
  - Baroreceptor response
    - In carotid arteries
    - Increased blood pressure by slowing heart rate
Continuation of vital signs
- Chemoreceptor response Respond to low carbon dioxide levels Reduction of respiratory rate Improved cerebral circulation Relieves ischemia Short time
- Increasing ICP causes ischemia to recur; cycle will repeat ICP continues to rise, blood pressures rises
- Increased pulse pressure is significant in people with ICP
The pressure on oculomotor nerve (cranial nerve [CN] III) is affected because of the size and response of pupils
- Pupil ipsilateral to lesion becomes fixed and dilated
  - As pressure increases, shift of contents across the midline both pupils become fixed and dilated Otorrhea or rhinorrhea Leaking of CSF from ear or nose
    Ptosis (droopy eyelid) may occur Effect of pressure on CN III
Changes in Cerebrospinal Fluid
Specimen produced by lumbar puncture Pressure of CSF is elevated when ICP is increased Composition of fluid may vary with cause CSF may be pinkish and contain erythrocytes Cloudy, yellowish fluid indicates WBCs Abnormal protein levels may indicate a neoplasm

Herniation

Transtentorial herniation Cerebral hemispheres, diencephalon, midbrain are displaced downward Resulting pressure affects flow of blood and CSF, RAS, and respiration
Uncal herniation Uncus of the temporal lobe is displaced downward Creates pressure on CN III, posterior cerebral artery, and RAS
Infratentorial (cerebellar, or tonsillar) herniation Cerebellar tonsils are pushed downward through the foramen magnum Compresses brainstem and vital centers infarction
Causes death

Diagnostic Tests

Computed tomography (CT) scans
Magnetic resonance imaging (MRI)
Cerebral angiography
Doppler ultrasound
Electroencephalography
Radionuclide may be used to track perfusion in CNS
Lumbar puncture used to check pressure and analyze CSF

Acute Neurologic Problems

Brain Tumors
Vascular Disorders
Infections
Brain Injuries
Spinal Cord Injuries

Brain Tumors

Space-occupying lesions that cause increased ICP
- Benign and malignant tumors can be life-threatening unless accessible and removable
- Gliomas form the largest category of primary malignant tumors They are classified according to cell derivation and the location of the tumor.
Tumors in the meninges or pituitary gland cause similar neurological effects.
- Primary malignant tumors rarely metastasize outside the CNS.
- Secondary brain tumors Metastasize from breast or lung tumors Cause effects similar to those of primary brain tumors Pathophysiology

Vascular Disorders

May be hemorrhagic or ischemic
Interference with blood supply to a specific area

Transient Ischemic Attacks (TIAs)

May occur singly or in a series
Result from temporary localized reduction of blood flow in the brain

Signs and Symptoms of TIAs

Directly related to the location of ischemia
Intermittent short episodes of impaired function
- e.g., muscle weakness in arm or leg
Visual disturbances
Numbness and paresthesia in the face
Transient aphasia or confusion may develop
Repeated attacks may be a warning sign for obstruction related to atherosclerosis

Cerebrovascular Accidents (CVAs)

A CVA (stroke) is an infarction of brain tissue that results from lack of blood caused due to occlusion of a cerebral blood vessel or rupture of a cerebral vessel.
5 minutes of ischemia causes irreversible nerve cell damage. Central area of necrosis develops All function lost
Surrounded by an area of inflammation- this zone will regain function following healing.

Types of CVAs

Occlusion of an artery by an atheroma Often develop in large arteries
Sudden obstruction caused by an embolus caused due to lodging in a cerebral artery
Intracerebral hemorrhage Caused by rupture of a cerebral artery in patient with severe hypertension- Effects are evident in both hemispheres Complicated by secondary effects of bleeding
Treatment Clot-busting agents Surgical intervention Glucocorticoids Supportive treatment Occupational and physical therapists; speech language pathologists

Causes of CVAs

MRI can determine cause of the stroke
- Risk factors: Diabetes, hypertension, systemic lupus erythematosus, atherosclerosis, history of TIAs, increasing age, obstructive sleep apnea, heart disease, smoking, sedentary lifestyle Combination of oral contraceptives and cigarette smoking Congenital malformation of blood vessels
Increasing age increased risk of stroke.

Cerebral Aneurysms Signs and Symptoms

Loss of visual field or visual disturbances: Headache and photophobia is seen along with intermittent periods of dysfunction.
Nuchal rigidity caused by meningeal irritation, vomiting, seizures, loss of consciousness in case of massive rupture along with rapidly followed by death of the individual.

Infections

Different age groups are susceptible to infection by different causative organisms; the infect may be secondary to other infections Children and young adults
- Neisseria meningitidis or meningococci
  - Classic meningitis pathogen
    Frequently carried in the nasopharynx of asymptomatic carriers Spread by respiratory droplets Occurs more frequently in late winter and early spring
Treatment Aggressive antimicrobial therapy Specific treatment measures for ICP and seizures Glucocorticoids Reduction of cerebral inflammation and edema Vaccines are available for some types of meningitis
Brain Abscess: Localized infection Frequently in frontal or temporal lobes; Usually necrosis of brain tissue and surrounding area of edema; May spread from organisms in ear, throat, lung, sinuses. Surgical drainage and antimicrobial therapy

Pathophysiology & Etiology of Meningitis

Microorganism reach the brain via Blood Nearby tissue Direct access Infections spread rapidly through the meninges Inflammatory response leads to increased ICP Exudate present in the CSF Blood vessels on brain surface appear dilated Slide preparation of CSF showing many neutrophils with bacterial meningitis A from Stevens ML: Fundamentals of Clinical Hematology, Philadelphia, 1997, Saunders; B and C from Mahon CR, Manuselis G: Textbook of Diagnostic Microbiology, ed 2, Philadelphia, 2000, Saunders; D from Cooke RA, Stewart B: Colour Atlas of Anatomical Pathology, ed 3, Sydney, 2004, Churchill Livingstone. Copyright © 2023, Elsevier Inc. All Rights Reserved.
Etiology - Neonates Escherichia coli most common causative organism Usually in conjunction with a neural tube defect, premature rupture of the amniotic membranes, difficult delivery. In young children Haemophilus influenzae Most often in the autumn or winter Children and young adults Neisseria meningitides or meningococcus Older adults Streptococcus pneumoniae major cause

Other Infections

Rabies Viral transmitted by Bite of rabid animal Transplantation of contaminated tissues Virus travels along peripheral nerves to CNS Headache and fever, nervous hyperirritability, sensitivity to touch, seizures Virus also travels to salivary glands; Difficulty swallowing Fear of fluids Respiratory failure, death
Tetanus Caused by Clostridium tetani Spores can survive in soil (years) Wound: Exotoxin enters nervous system results in tonic muscle spasms, jaw stiffness Difficulty swallowing; stiff neck Headache and skeletal muscle spasm Respiratory failure
Poliomyelitis (infantile paralysis) Polio virus Immunization available Attacks motor neurons of spinal cord and medulla Fever, headache, vomiting, stiff neck, pain, flaccid paralysis

Infection-Related Syndromes

*(1 of 5) Herpes zoster (shingles) Caused by varicella-zoster virus in adults Can occur years after primary infection of varicella (chickenpox) Usually affects cranial nerve or one dermatome Pain, paresthesia, vesicular rash
If antiviral drugs started within 48 hours of onset, pain is significantly reduced Lesions and pain persist for several weeks Postherpetic pain may persist for months to years in some cases Vaccine available for those 60 years or older

(2 of 5) Post-polio syndrome (PPS) Occurs 10 to 40 years after recovery from original infection Progressive and debilitating fatigue, weakness, pain, muscle atrophy The more severe the original infection, the more severe are the effects of PPS
(3 of 5) Reye’s syndrome Cause not fully determined Linked to viral infection in children treated with aspirin. Leads Pathological changes in brain and liver Brain Function severely impaired by cerebral edema Liver Enlarged, fatty changes develop in tissue Can result in acute failure Manifestations vary in severity No immediate cure
(4 of 5) Guillain-Barre syndrome Postinfection polyneuritis, acute idiopathic polyneuropathy, acute infectious polyradiculoneuritis Inflammatory condition of the PNS Exact cause unknown: Local inflammation with accumulated lymphocytes, demyelination, axon destruction Changes cause impaired nerve conduction treatment is primarily supportive but is life-threatening.

Meningitis Signs and Sumptoms

Sudden onset is common Severe headache; Back pain
Photophobia; Nuchal rigidity; Kernig sign Brudzinski sign Vomiting, irritability, lethargy, fever, chills with leukocytosis Progression to stupor or seizures
Diagnostic Tests Examination of CSF (obtained by lumbar puncture Identification of causative organism

Types of Head Injuries

Concussion (minimal brain trauma) Reversible interference with brain function. Causes sudden excessive movement of the brain; Result of mild blow to the head or whiplash-type injury Amnesia and headaches may follow Recovery usually within 24 hours, without permanent damage Contusion Bruising of brain tissue, rupture of small blood vessels, and edema Blunt blow to the head, possible residual damage Closed head injury Skull is not fractured in injury; Brain tissue is injured and blood vessels may be ruptured Extensive damage may occur when head is rotated
Open head injuries Involve fractures or penetration of the brain Depressed skull fractures Involve displacement of a piece of bone below the level of the skull Compression of brain tissue Blood supply to the area often impaired pressure to brain; Basilar fractures Occur at the base of the skull Possible leakage of CSF through ears or nose May occur when forehead hits the windshield
Contrecoup injury Area of the brain contralateral to the site of direct damage is injured brain bounces off of the skull Secondary to acceleration or deceleration injuries Primary brain injuries Direct injuries Laceration or compression of brain tissue Rupture or compression of cerebral blood vessels Damage because of rough or irregular inner surface of the skull Movement of lobes against each other
Treatment and Pathophysiology Glucocorticoid agents Decrease edema Antibiotics Reduce risk of infection Surgery may be necessary Reduction in ICP Blood products and oxygen Used to protect remaining brain tissue;
The types of Hematomas results in bleeding between dura and skull Subdural hematoma Develops between dura and arachnoid Hematoma may be acute or subacute Tear in arachnoid may allow CSF to leak into subdural space Creates additional pressure Hematoma disintegrates about 7 days postinjury Hemolysis increases osmotic pressure ICP Subarachnoid hemorrhage Occurs in space between arachnoid and pia Associated with traumatic bleeding from the blood vessels at the base of the brain Blood mixes with CSF no localized hematoma formation Intracerebral hematoma Results from contusions or shearing injuries May develop several days after injury Treatment and Pathophysiology Glucocorticoid agents Decrease edema Antibiotics Reduce risk of infection Surgery may be necessary Reduction in ICP Blood products and oxygen Used to protect remaining brain tissue

Spinal Cord Injuries

Classification Simple Single line break Compression Crushed or shattered bone in multiple fragments Wedge Displaced angular section of bone Dislocation Vertebra forced out of its normal position; Laceration of nerve tissue by bone fragments Usually permanent loss of conduction in affected tracts Complete transsection or crushing of cord Irreversible loss of all sensory and motor function at and below the level of injury; Partial transection or crushing; May allow recovery of some function Bruising Reversible damage Prolonged ischemia and necrosis;
Autonomic Dysreflexia; Massive sympathetic reflex response that cannot be controlled from the brain Often initiated by infection, genital stimulation, or other stimuli Leads to: Increased blood pressure Vasoconstriction below the injury Vasodilation above the injury Tachycardia

Congenital Neurologic Disorders

The types of Congenital Neurologic Disorders classified with Hydrocephalus Excess CSF accumulates within the skull. Two types: Noncommunicating or obstructive Occurs in babies Flow of CSF through ventricular system is blocked Communicating Impaired absorption of CSF; Communicating Hydrocephalus Absorption of CSF through subarachnoid villi is impaired Neonates Skull can expand to a certain degree to relieve pressure. If not treated, brain tissue is