Intercranial regulation

INTERCRANIAL REGULATION

Definition of Intracranial Regulation

  • Processes and mechanisms: Affect the normal functioning of the brain and other structures within the cranial vault.

  • Layman's terms: Refers to how the brain performs its necessary functions.

STRUCTURE AND PHYSIOLOGY OF THE CENTRAL NERVOUS SYSTEM

The Brain

  • Divisions: The brain is divided into three parts:   - Cerebrum: Largest part; manages conscious thoughts, actions, and sensory input.   - Cerebellum: Coordinates and regulates balance, movement, and posture.   - Brainstem: Responsible for basic life functions.

The Four Lobes of the Cerebrum

  1. Frontal Lobes:    - Functions: Motor movement, personality.

  2. Parietal Lobes:    - Functions: Sensation, perception.

  3. Temporal Lobes:    - Location: Beneath parietal lobes.    - Functions: Control of sound and language.

  4. Occipital Lobe:    - Functions: Vision.

Central Nervous System Composition

  • Components: Brain (and brainstem) and spinal cord.

  • **Spinal Cord Segments: **   - Cervical: C1-C7   - Thoracic: T1-T12   - Lumbar: L1-L5   - Sacral: S1-S5   - Coccygeal: Co1.

Functions of the Central Nervous System (CNS)

  • Responsibilities: Central nervous system controls body functions including:   - Physical functions.   - Emotional responses.   - Mental processes.

  • Key Structures and their Functions:   - Thalamus: Sensory processing, sleep, and wakefulness.   - Basal Ganglia: Motor control, decision-making, rewards, addictions, cognition, language, learning, and memory.   - Hypothalamus: Regulates body temperature, appetite, hormone release, and homeostasis.   - Limbic System: Manages emotion and memory, addressing sexual stimulation and learning.   - Reticular Formation: Controls sleep, wakefulness, cardiovascular functions, and endocrine responses.   - Medulla Oblongata: Connects the brain to the spinal cord.   - Pons: Involved in consciousness, pain, and cranial nerve functions.   - Midbrain: Responsible for motor movement and reflexes.

NERVOUS SYSTEM DIVISIONS

Central Nervous System vs. Peripheral Nervous System

  • Central Nervous System: Comprises the brain and spinal cord.

  • Peripheral Nervous System: Consists of:   - 12 pairs of cranial nerves.   - 31 pairs of spinal nerves.   - Autonomic nervous system (ANS).

AUTONOMIC NERVOUS SYSTEM

  • Division of the Peripheral Nervous System:   - Sympathetic: Prepares the body for 'fight or flight'; characterized by:     - Fast, focused, and fueled responses to perceived threats.   - Parasympathetic: Has a calming and relaxing effect; characterized by:     - Facilitating eating, urination, defecation, and reducing heart rate.

  • **Functions of Parasympathetic Division: **   - Constricts pupils.   - Stimulates saliva production.   - Constricts bronchi to slow heart rate.   - Stimulates digestive functions in the stomach, intestines, and pancreas.   - Promotes urination.   - Promotes genitalia erection.   

  • Functions of Sympathetic Division:   - Dilates pupils.   - Inhibits salivation.   - Dilates bronchi to increase heart rate.   - Stimulates adrenal gland to release epinephrine and norepinephrine.   - Inhibits digestive functions.   - Inhibits urination and promotes ejaculation and vaginal contractions.

PROTECTIVE MECHANISMS FOR THE BRAIN AND SPINAL CORD

  • Blood-Brain Barrier (BBB):   - A network of tightly packed cells forming blood vessels that prevent harmful substances from entering the brain.   - Examples of permeable substances:     - Water, carbon dioxide, oxygen, alcohol, anesthetics, antidepressants, antianxiety medications, anti-psychotics, seizure medications.

PHYSICAL ASSESSMENT OF NEUROLOGICAL FUNCTION

  • Components of Neurological Examination:   - Level of Consciousness (LOC): Assessed using the Glasgow Coma Scale.   - Cognitive Function: Assessed using the Mini Mental Status Exam.   - Cranial Nerve Assessment.   - Motor Assessment.   - Sensory Assessment: Involves testing vibration, pain sensitivity, etc.

Memory Assessment

  • Types of Memory:   - Long-term Memory: Ability to recall information from the past (e.g., childhood address or phone number).   - Short-term Memory: Ability to recall recent information (e.g., meals eaten earlier in the day).

GLASGOW COMA SCALE

  • Purpose: Used to objectively assess level of consciousness and track changes in neurological function.

Abnormal Motor Responses

  • Responses:   - Decorticate: Flexion in response to stimuli.   - Decerebrate: Extension in response to stimuli.

Reflexes

  • Definition: Involuntary and automatic responses to stimuli.   - Babinski Sign Test:     - Touch the sole of the foot.     - Positive Response: Toes flare upwards (indicative of neurological issues).     - Negative Response: Toes curl downward (normal response).

VITAL SIGNS IN NEUROLOGIC EVENTS

  • Observations:
      - Heart rate slows down. Blood flow may stop due to cardiac arrest.   - Blood pressure may show a disparity between systolic and diastolic values.   - Respiratory irregularities may necessitate vent support.   - Body temperature fluctuations due to damage to hypothalamus.

DIAGNOSTIC STUDIES

  • Types of Studies:   - Computed Tomography (CT): Check for iodine allergies prior to dye usage.   - Positron Emission Tomography (PET): Encourage fluid intake to flush out tracer.   - Magnetic Resonance Imaging (MRI): Check for metal implants.

LEVEL OF CONSCIOUSNESS (LOC)

  • Definition: Individuals must be aware of self, environment, and respond appropriately.   - Arousals:     1. Awake & Alert = Normal     2. Lethargic     3. Obtunded     4. Stuporous     5. Comatose

ORIENTATION ASSESSMENT

  • To Person: "Can you tell me your name?" (AO x 1).

  • To Place: "Can you tell me where you are?" (AO x 2).

  • To Time: "Do you know the date, day of the week, and next holiday?" (AO x 3).

  • To Situation: "Do you know why you are here?" (AO x 4).

  • Purpose: Assess cognition, response, and speech (AO x 3 or AO x 4).

CEREBRAL VASCULAR ACCIDENT (CVA)

  • Types of Stroke:   - Hemorrhagic (Bleed): Major stroke resulting from vessel rupture.   - Ischemic (Clot): Due to obstruction of blood flow.

  • Transient Ischemic Attack (TIA): Minor stroke that usually resolves.

  • Symptoms: Can develop gradually in unfolding CVA cases.   - Hemiparesis: Weakness on one side of the body.   - Hemiplegia: Inability to move one side of the body.

BRAIN DEATH

  • Definition: Legal death characterized by:   - Unresponsive to stimuli.   - No pupillary movement.   - Flat brain waves (no EEG activity).   - Absence of reflexes.

  • Professional Standards: Check Nurse Practice Act for authority to pronounce death.

CRANIAL NERVES (CN I-XII)

Cranial Nerve Overview

  1. CN I - Olfactory Nerve:    - Function: Sense of smell; typically not tested unless trauma causes issues.    - Implications: Loss of smell may indicate sinus disease or head injury.

  2. CN II - Optic Nerve:    - Function: Vision; tests include distance vision (Snellen chart), near vision (Rosenbaum), peripheral vision (Visual Field Test), and pupil function (PERRLA).    - Relation: Occipital lobe is responsible for vision; damage leads to vision loss.

  3. PERRLA:    - Assessment Method:      - Assess pupil response to light and accommodation.      - Use a penlight to test constriction and ensure consensual agreement in both pupils (PERRL).      - Observe pupil size changes during focus on nearby and distant objects for accommodation.

  4. CN III - Oculomotor Nerve:    - Function: Innervates extraocular muscles for upward eye movement and pupil constriction.    - Condition: Ptosis occurs if there's damage, causing droopy eyelid.

  5. CN IV - Trochlear Nerve:    - Function: Innervates extraocular muscles for downward eye movement.

  6. CN VI - Abducens Nerve:    - Function: Innervates muscles for lateral eye movement.    - Condition: Injuries can cause lack of eye movement and strabismus.

EOMs (Extraocular Muscles)

  • Definition: Surround each eye, controlling movement in various directions:   - Upward Movement: CN III.   - Downward Movement: CN IV.   - Side-to-Side Movement: CN VI.

  • Assessment: Combined assessment of CN III, IV, and VI allows identification of abnormalities like strabismus and ptosis.

  1. CN V - Trigeminal Nerve:    - Function: Sensory and motor functions; discriminates touch on facial areas, assessments for blink reflex, and motor evaluations in temporal and mandibular regions.    - Condition: Trigeminal neuralgia and issues with chewing.

  2. CN VII - Facial Nerve:    - Function: Sensory for taste (anterior 2/3 of tongue) and motor for facial expressions (eyebrow raising, cheek puffing).    - Condition: Bell's palsy can cause temporary paralysis on one side of the face.

Differentiating Facial Droop Causes

  • Scenario: Presence of right-sided facial droop may indicate CVA.

  • Differentiation Question: If you could ask only one question to distinguish between Bell's palsy and an acute stroke, what would it be?

  1. CN VIII - Vestibulocochlear Nerve:    - Function: Responsible for hearing and balance; transmission of auditory information from the inner ear to the brain.    - Conditions: Damage may lead to vertigo or hearing loss.

  2. CN IX - Glossopharyngeal Nerve:     - Function: Sensory for sour taste on posterior 1/3 of tongue; motor for soft palate and uvula movement.

  3. CN X - Vagus Nerve:     - Function: Motor for gag reflex, swallowing, and speech; longest cranial nerve affecting the heart and abdomen under parasympathetic control.

  4. CN XI - Spinal Accessory Nerve:     - Function: Motor for shoulder and neck movements; assessed through shoulder shrugging and turning neck against resistance.

  5. CN XII - Hypoglossal Nerve:     - Function: Motor for tongue movement; damage results in tongue deviation toward lesion site.

Summary Table of Cranial Nerves

Cranial Nerve

Name

Function

Type

CN I

Olfactory

Smell

Sensory

CN II

Optic

Vision

Sensory

CN III

Oculomotor

Eye moves upward

Motor

CN IV

Trochlear

Eye moves downward

Motor

CN V

Trigeminal

Sensation: clenched teeth

Both

CN VI

Abducens

Eye moves side to side

Motor

CN VII

Facial

Facial expression, taste

Both

CN VIII

Vestibulocochlear

Hearing

Sensory

CN IX

Glossopharyngeal

Raises uvula, sour taste

Both

CN X

Vagus

Gag reflex, swallowing

Motor

CN XI

Spinal Accessory

Shoulder, neck movement

Motor

CN XII

Hypoglossal

Tongue movement

Motor

CEREBELLUM ASSESSMENT

  • Function: Coordinates and regulates balance, movement, and posture.

  • Assessment Techniques:   - Finger to Nose Test: Assessing coordination.   - Heel to Shin Test: Heel runs down shin to assess leg coordination.   - Rapid Hand Movements: Tests speed and agility.   - Gait and Balance Assessment: Heel-to-toe walking test.

  • Balance Test (Romberg Test): Patient stands with feet flat, first with eyes open for 30 seconds and then closed. Safety concerns arise if the patient cannot maintain balance.

FACTORS AFFECTING INTRACRANIAL REGULATION

  • Potential Factors:   - Perfusion   - Neurotransmission   - Pathology/Injury   - Hypertension

Implications of Hypertension

  • Alters cerebral autoregulation resulting in higher perfusion pressure needs.

  • Neural Transmission Impairment Causes:   - Ischemia   - Damage to white matter   - Cognitive decline

Stroke Risks Associated with Conditions

  • Ischemic Stroke Risk Factors:   - Atherosclerosis   - Vessel wall damage

  • Hemorrhagic Stroke Risk Factors:   - Small vessel rupture   - Aneurysm formation.

OUTCOMES OF ALTERED INTRACRANIAL REGULATION

  • Potential Outcomes:   - Full Recovery   - Residual Damage   - Coma   - Persistent Vegetative State   - Brain Death

  • Examples of Residual Effects: Memory issues, speech difficulties, judgment impairments, mobility issues such as weakness or paralysis, seizures, total unconsciousness, and noticeable coma states.

  • Defining Brain Death: Complete cessation and irreversibility of all brain functions including brainstem activity.