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Neuro Dysfunction- Brain

Outline

A. Review of Anatomy and Physiology

    1. Four ventricles in brain
        a. 1st and 2nd (lateral ventricles), lie within cerebral hemispheres   

        b. 3rd ventricle- slit like cavity between thalami, joins to 4th ventricle
            by cerebral aqueduct (Aqueduct of Sylvius)

        c. 4th ventricle- located between medulla and pons anteriorly
            and cerebellum posteriorly, has openings into cranial
            subarachnoid space

        d. ventricles contain choroid plexus which produces CSF

    2. Flow of CSF

        a. Choroid plexus - ventricles- subarachnoid space- subarachnoid villi
            (absorb CSF)

B. Increased Intracranial Pressure (ICP)
    1. Three components in cranial cavity
        a. blood
        b. brain tissue
        c. CSF

    2. increase in volume in any of these three components raises
        ICP (ordinarily ICP = 4- 15 mm HG)

    3. Compensation for Increasing ICP- Four stages
        a. Stage I- vasoconstriction, CSF reduced through increased
            reabsorption

        b. Stage II-  systemic arterial vasoconstriction in attempt to
            increase BP to overcome increased ICP, hypoxia of brain tissue

        c. Stage III- severe hypoxia and acidosis    

        d. Stage IV- brain herniation

    4. Progression of symptoms with increasing ICP

        a. alertness- confusion- obtundation- stupor- coma

        b. widening of pulse pressure, changes in breathing patterns

        c. unilateral dilation of pupil is primary sign of impending
            herniation

C. Hydrocephalus (an abnormal increase in CSF)
    1. Communicating - when CSF not reabsorbed into arachnoid villi,
        due to too few functional villi either because
            a. destroyed by part meningococcal scarring

            b. obstruction by fragments of blood and infectious debris   

    2. Non- communicating-  when flow into subarachnoid space is
        obstructed, due to
            a. infection

            b. congenital malformation

            c. tumors

D. Head Injuries
    1. common sequelae- hemiparesis, aphasias, hemianopsia
        unconsciousness, (immediate or delayed), post traumatic
        epilepsy

    2. contrecoup injury

    3. penetration (open head injury) vs impact (closed head injury)

    4. Types of Injury
        a. mild head injury (concussion)- momentary loss of consciousness
        b. moderate head injury- longer loss of consciousness, mild
            neurological manifestations

        c. severe head injury (cerebral contusion)- tearing and shearing
            of brain structures

    5. Secondary Injuries
        a. Cerebral edema, due to
            1. vasogenic mechanisms (changes in capillary permeability)   

            2. cytotoxic mechanisms- failure of active transport system

            3. ischemic mechanisms- cellular death leading to changes
                in capillary permeability

        b. Diffuse Axonal Injury (DAI)

        c. Hemorrhage
            1. Epidural Hematoma
                usually due to tear in middle meningeal artery
                may have period of unconsciousness followed by lucid period

            2. Subdural hematoma
                classifies as acute, subacute, chronic

E. Meningitis and Encephalitis

    1. symptoms of meningitis (related to meningeal irritation)
            fever, headache, lethargy, nuchal rigidity, vomiting,
            progressing to photophobia, petecchiae, convulsions

    2. encephalitis, can be caused by rabies, Reye's syndrome,
        often due to infection with virus

F. Chronic Organic Brain Syndrome (COBS)

1. general symptoms
        a. loss of judgement
        b. change in affect
        c. loss of memory
        d. confusion
        e. loss of orientation
2. catastrophic reaction- when faced with task that seems overwhelming
        person may react by withdrawing or becoming extremely agitated

3. sundown syndrome -loss of familiar cues leads to agitation, confusion
and sometimes psychotic symptoms

4.. Alzheimer's Disease

1. presence of senile plaques, neurofibrillatory tangles

2. symptoms- progresses

    1. mild mental impairment

    2. confusion, agitation, irritability, extreme restlessness,
        incontinence of urine and stool

    3. totally unable to communicate, unable to perform self care

5. Creutzfeldt-Jakob Disease

a. caused by virus or prion
b. degeneration of pyramidal and extrapyramaidal systems
c. rapid progression once initiated

    6. Normal Pressure Hydrocephalus

a. due to obstruction of CSF with resulting dilation of
            ventricles

        b. gait disturbance is cardinal sign, followed by incontinence of
            bowel and bladder

    7. Wernicke  Korsakoff  Syndrome  

        a. due to chronic alcoholism

        b. symptoms of Wernike part of disease- nystagmus, ataxia
            confusion, signs of peripheral neuropathy, diplopia

        c. symptoms of Korsakoff's part of disease - confabulation

G. Cerebral Vascular Accident (CVA)
       1. risk factors-  atherosclerosis, obesity, cigarette smoking,
physical inactivity, family hx, diabetes, hypertension

2.due to deficit in blood supply to part of the brain

        3. types of stroke
            a. hemorrhagic- sudden, usually during activity

            b. embolic-     sudden, not related to activity

            c. thrombic- gradual, i.e. evolving over minutes or days

        4. localized effects by blood vessel effected

            a. anterior cerebral artery

            b. middle cerbral artery

            c. posterior cerbral artery

        5. aphasias

            1. expressive (motor, Broca's)

            2. Non expressive (sensory, receptive, Wernike's)