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 - Acoustic (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 VI

Abducens

Eye moves side-to-side

Motor

CN V

Trigeminal

Sensation; clenched teeth

Both

CN VII

Facial

Facial expression, taste

Both

CN VIII

Acoustic

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.