Comprehensive Neurovascular System and Degenerative Disorders Study Guide

Brain Anatomy and Physiology

  • The Cerebrum

    • Hemispheric Specialization:

      • Right Hemisphere: Responsible for controlling the left side of the body.

      • Left Hemisphere: Responsible for controlling the right side of the body.

    • Frontal Lobe:

      • Characteristics: The largest lobe of the brain.

      • Functions: Intellectual thought processes, concentration, cognition, memory, judgment, and personality.

      • Executive Function: Defines the individual's unique character.

      • Affect: The ability to express feelings outwardly.

      • Inhibition: Relates to self-awareness.

      • Broca’s Area: Located in the left hemisphere. It manages the motor control of speech.

      • Damage Implications: Expressive aphasia. The patient cannot express speech (speech is impaired), but comprehension of language remains intact.

    • Temporal Lobe:

      • Functions: Serves as the auditory receptive area.

      • Sound Memory: Stores memories of music and lyrics.

      • Wernicke’s Area: Located in the left hemisphere. It is responsible for the understanding/comprehending of language.

      • Damage Implications: Receptive aphasia. The patient cannot receive or comprehend language, but they can express verbal sounds (often without meaning).

    • Parietal Lobe:

      • Functions: Primarily sensory and motor integration.

      • Spatial Awareness: Awareness of where objects are in space.

      • Orientation: Differentiation between left and right.

    • Occipital Lobe:

      • Functions: The visual center of the brain; it analyzes visual stimuli.

  • The Cerebellum

    • Location: Situated inferior to the cerebrum.

    • Fine Movement: Controls precision activities such as writing and cutting with scissors.

    • Balance and Posture: Maintains bodily equilibrium.

    • Proprioception: The awareness of the position of extremities without the need for visual confirmation.

  • The Brain Stem

    • Midbrain: Acts as the motor relay system.

    • Pons: Termed the "vice president of respiration." It controls the depth of breathing (deep versus shallow).

    • Medulla Oblongata: The primary cardiac and respiratory center. It regulates heart rate (HRHR) and respiratory rate (RRRR).

System Classifications and Spinal Nerves

  • Central Nervous System (CNS): Comprised of the Brain and the Spinal Cord.

    • Nuclei: Clusters of neuron cell bodies located inside the CNS.

  • Peripheral Nervous System (PNS): Connects the CNS to the rest of the body via cranial and spinal nerves.

    • Ganglia: Clusters of neuron cell bodies located outside the CNS.

  • Spinal Cord and Nerves (31 Pairs Total)

    • Cervical (8 pairs): Mnemonic: "Breakfast at 8."

    • Thoracic (12 pairs): Mnemonic: "Lunch at 12."

    • Lumbar (5 pairs): Mnemonic: "Dinner at 5."

    • Sacral (5 pairs) + Coccygeal (1 pair): Mnemonic: "Midnight Snack."

    • Critical Innervation Levels:

      • C3−C5C3-C5: Diaphragm management.

      • T1−T6T1-T6: Chest.

      • T7−T12T7-T12: Abdomen.

      • L1−L5L1-L5: Legs.

      • S2−S4S2-S4: Bowel, bladder, and sexual function.

  • Nerve Fiber Types

    • Afferent (Sensory): Transmits signals to the CNS (e.g., perceiving pain/"aray").

    • Efferent (Motor): Transmits signals from the CNS (e.g., responding to pain by moving/"edi tanggalin").

  • Motor Divisions

    • Somatic: Governing voluntary movements.

    • Autonomic: Governing involuntary movements.

Autonomic Nervous System (ANS) Comparison

  • Sympathetic Nervous System (SNS)

    • Nickname: "Fight or Flight."

    • Neurotransmitters: Catecholamines (Epinephrine, Norepinephrine).

    • Hormone Source: Adrenal Medulla.

    • General Effect: Increases body activities, excluding the gastrointestinal tract (GITGIT) and genitourinary tract (GUTGUT).

    • Receptor Type: Adrenergic (Anti-cholinergic).

    • Pupils: Dilate (Mydriasis).

    • Cardiovascular: Increased HR and Blood Pressure.

    • Respiratory: Increased RR; Bronchodilation to maximize oxygen.

    • Mouth: Dry mouth.

    • GI/GU: Constipation and urinary retention; associated with fluid volume excess.

  • Parasympathetic Nervous System (PNS)

    • Nickname: "Rest and Digest."

    • Neurotransmitter: Acetylcholine.

    • Source: Vagal stimulation.

    • General Effect: Decreases body activities, excluding the GITGIT and GUTGUT.

    • Receptor Type: Cholinergic (Vagal).

    • Pupils: Constrict (Miosis).

    • Cardiovascular: Decreased HR and Blood Pressure.

    • Respiratory: Decreased RR; Bronchoconstriction.

    • Mouth: Increased salivation.

    • GI/GU: Diarrhea and urinary frequency; associated with fluid volume deficit.

The 12 Cranial Nerves

  • I. Olfactory (Sensory): Sense of smell. Deficit: Anosmia (loss of smell).

  • II. Optic (Sensory): Vision. Deficit: Blurring, blindness, or anisocoria.

  • III. Oculomotor (Motor): Upward eye movement and pupil constriction. Deficit: Diplopia (double vision), ptosis (eyelid drooping), and pupil dilation.

  • IV. Trochlear (Motor): Downward eye movement. Deficit: Diplopia and difficulty looking down.

  • V. Trigeminal (Both): Facial sensation and mastication (chewing). Deficit: Tic douloureux or severe facial pain.

  • VI. Abducens (Motor): Lateral eye movement. Deficit: Diplopia and inability to move eyes laterally.

  • VII. Facial (Both): Facial expression and taste on the anterior 2/32/3 of the tongue. Deficit: Bell’s palsy, facial drooping, and lacrimation changes.

  • VIII. Vestibulocochlear (Sensory): Hearing and balance. Deficit: Hearing loss, tinnitus, and vertigo.

  • IX. Glossopharyngeal (Both): Swallowing and taste on the posterior 1/31/3 of the tongue. Deficit: Dysphagia (difficulty swallowing) and abnormal gag reflex.

  • X. Vagus (Both): Muscle movement of the pharynx and larynx. Deficit: Dysphagia and hoarseness.

  • XI. Accessory (Motor): Neck and shoulder movement. Deficit: Inability to move the neck or shrug shoulders.

  • XII. Hypoglossal (Motor): Tongue movement. Deficit: Dysarthria (speech difficulty) and tongue deviation.

Neurologic Assessment Scales and Formulas

  • Glasgow Coma Scale (GCS)

    • Eye Opening (E): Spontaneous (4), To speech (3), To pain (2), No response (1).

    • Verbal Response (V): Oriented (5), Confused (4), Inappropriate words (3), Incomprehensible sounds (2), No response (1).

    • Motor Response (M): Obeys command (6), Localizes pain (5), Flexion/Withdrawal from pain (4), Abnormal flexion/decorticate (3), Abnormal extension/decerebrate (2), No response (1).

    • Total GCS Scores:

      • 13−1513-15: Mild brain injury.

      • 9−129-12: Moderate brain injury.

      • 3−83-8: Severe brain injury (Coma).

  • AVPU Scale (Rapid Check)

    • A: Alert.

    • V: Responds to Voice.

    • P: Responds to Pain.

    • U: Unresponsive.

  • Cerebral Perfusion Pressure (CPP) Calculations

    • Mean Arterial Pressure (MAP) Formula:

    • MAP=SBP+2(DBP)3MAP = \frac{SBP + 2(DBP)}{3}

    • CPP Calculation Formula:

    • CPP=MAP−ICPCPP = MAP - ICP

    • Normal Values:

      • CPP Normal: 60−100 mmHg60-100\,mmHg

      • MAP Normal: 70−100 mmHg70-100\,mmHg

    • Example Case: BP of 150/70 and ICP of 25.

    • MAP=150+2×703=96.67 mmHgMAP = \frac{150 + 2 \times 70}{3} = 96.67\,mmHg

    • CPP=96.67−25=71.67 mmHgCPP = 96.67 - 25 = 71.67\,mmHg (Rounded to 72).

Increased Intracranial Pressure (ICP)

  • Dynamics of ICP

    • Normal ICP Range: 0−15 mmHg0-15\,mmHg.

    • Components of the Cranial Vault: 1. Brain tissue, 2. Blood, 3. Cerebrospinal Fluid (CSF).

    • Monro-Kellie Hypothesis: Because the cranium is a rigid, inexpansible vault, an increase in any one of the three components must be offset by a decrease in another. If not, ICP rises.

  • Signs and Symptoms

    • Earliest Sign: Changes in Level of Consciousness (LOC). Progression includes restlessness, confusion, disorientation, lethargy, obtunded state, stupor, and finally coma.

    • Late Sign: Cushing’s Triad

      1. Hypertension (specifically with a wide pulse pressure).

      2. Bradycardia.

      3. Bradypnea.

      • Note: Pulse Pressure = SBP−DBPSBP - DBP (Normal is 30−40 mmHg30-40\,mmHg).

    • Other Signs: Anisocoria (pupillary changes due to CN III compression) and projectile vomiting (due to stimulation of the Chemoreceptor Trigger Zone/CTZ).

  • Nursing and Medical Management

    • Diagnostics: CT Scan (first-line, fast, ~15 mins), MRI (detailed, detects early changes, takes ~1 hour).

    • Positioning: Neutral/midline head position to promote venous return; Head of Bed (HOB) at 30−45∘30-45^{\circ} (Semi-Fowler’s).

    • Preventive Care: Give stool softeners and high-fiber diet to prevent straining.

    • Patient Instruction: Exhale during movement to avoid the Valsalva maneuver.

    • Contraindications:

      • Avoid Lumbar Puncture: Risks brain herniation through the foramen magnum due to pressure drops.

      • Avoid: Extreme hip flexion, coughing, sneezing, laughing, vomiting, and sudden bed movements.

Seizure Disorders

  • Classification

    • Partial Seizure: Originates in a specific part of the brain.

      • Jacksonian Seizure: Starts in one distal area and spreads to adjacent regions.

    • Generalized Seizure: Affects the whole brain.

      • Tonic-Clonic (Grand Mal): Tonic (rigidity) phase followed by Clonic (jerking) phase; involves loss of consciousness.

      • Absence (Petit Mal): Brief blank stare, similar to daydreaming, with no memory of the event.

  • Precautions and Environmental Control

    • Safety: Padded side rails (raised), bed in lowest position, loose clothing, oxygen and suction available at bedside.

    • Environment: Quiet, private room, dim lighting, limited visitors, away from noise and the nurse's station.

  • Acute and Post-Seizure Management

    • During Seizure: Priorities are Airway and Safety. Time the seizure. Do not restrain. Ease to the floor and protect the head. In bed: remove pillows, keep bed flat, protect the neck. Side-lying position is preferred to prevent aspiration. Never force the mouth open or insert an oral airway.

    • After Seizure: Maintain airway, keep in side-lying position, reorient the patient upon awakening, and monitor until full consciousness returns.

  • Pharmacology

    • Rescue Meds (Active Seizure): Benzodiazepines (e.g., Midazolam, Lorazepam, Diazepam IV bolus).

    • Maintenance Meds (Prevention): Phenytoin (Dilantin). Therapeutic level: 10−20 mcg/mL10-20\,mcg/mL. Side effect: Gingival hyperplasia. Nursing: Regular dental checks, soft toothbrush. Avoid antacids as they decrease effectiveness.

Cerebrovascular Disorders (Stroke)

  • Stroke Types

    • Ischemic Stroke: Reduced perfusion due to atherosclerosis, thrombus, or embolism (often from Atrial Fibrillation). Includes Transient Ischemic Attacks (TIA) which involve no necrosis.

    • Hemorrhagic Stroke: Bleeding into brain tissue. Primary cause: Rupture of small vessels due to uncontrolled Hypertension (HPN). Secondary causes: Aneurysm, neoplasm, or anticoagulants.

  • Assessment and Diagnostics

    • BE FAST Mnemonic: Balance loss, Eyes (vision changes), Facial droop, Arm drift, Speech (slurred), Time (act fast).

    • Diagnostics:

      • CT Scan: Ischemic appears as a dark area (penumbra); Hemorrhagic appears as a white area (RBC presence).

      • 12-lead ECG: Check for Atrial Fibrillation.

  • Medical Management

    • Ischemic: Thrombolytic therapy (tPA/Alteplase) within 3−4.53-4.5 hours of onset. Anticoagulants (Warfarin) or Antiplatelets (Aspirin/Clopidogrel).

    • Hemorrhagic: Antihypertensives, Vitamin K with Fresh Frozen Plasma (to aid clotting), and Phenytoin (seizure prevention).

  • Clinical Manifestations and Nursing Care

    • Motor Loss: Hemiplegia (paralysis), Hemiparesis (weakness), Ataxia (unsteady gait), Dysphagia. Nursing: Range of Motion (ROM) exercises, approach on the unaffected side, aspiration precautions (upright, chin tuck, thick liquids, test gag reflex).

    • Verbal Deficits:

      • Expressive Aphasia: Use writing/magic slate.

      • Receptive Aphasia: Use gestures, pictures, and actions.

      • General: Do not finish sentences; allow ample time for response.

    • Visual Deficits: Homonymous Hemianopsia (loss of half visual field). Nursing: Place objects on the unaffected side and encourage scanning towards the affected side by turning the head.

Neurological Trauma

  • Skull Fractures

    • Types: Simple linear, Comminuted (splintered), Depressed (displaced inward), and Basilar (skull base).

    • Basilar Symptoms: Raccoon’s Eyes (periorbital edema), Battle Sign (mastoid bruising), Rhinorrhea (nasal CSF leak), and Otorrhea (ear CSF leak).

    • Halo Test: Fluid on 4x4 gauze showing a yellowish ring indicates CSF (due to glucose content).

  • Brain Injury

    • Concussion: Jarring of the brain.

    • Contusion: Bruising or damage to brain tissue.

    • Coup-Contrecoup: Injury occurring in two opposite directions due to brain movement within the skull.

  • Intracranial Hemorrhage

    • Epidural Hematoma: Between skull and dura. Arterial origin. Rapid development. Mnemonic: EAR (Epidural, Arterial, Rapid).

    • Subdural Hematoma: Between dura and arachnoid. Venous origin. Slow development. Mnemonic: SVS (Subdural, Venous, Slow).

  • Spinal Cord Injury (SCI)

    • Cervical: Affects diaphragm (respiratory paralysis risk) and leads to Quadriplegia.

    • Thoracic: Affects abdominal muscles/bowel; leads to paralytic ileus.

    • Lumbar: Affects bladder and legs; leads to Paraplegia.

    • SCI Management: Immobilize on a flat, firm spine board. Maintain neutral, extended head/neck. Move patient as a single unit (log-roll) to prevent twisting.

Infectious and Degenerative Diseases

  • Meningitis (Inflammation of the Meninges)

    • Causative Agents: Streptococcus pneumoniae and Neisseria meningitidis.

    • Signs of Meningeal Irritation:

      • Nuchal Rigidity: Stiff neck.

      • Photophobia: Light sensitivity.

      • Kernig’s Sign: Pain in lower back when extending the knee with the hip flexed.

      • Brudzinski’s Sign: Hips and knees flex automatically when the neck is flexed (highly sensitive).

    • Management: Lumbar puncture for CSF assessment. Antibiotics (Penicillin G, Ceftriaxone) given within 30 minutes of arrival. Dexamethasone given 15−2015-20 minutes before antibiotics to reduce inflammation.

  • Parkinson’s Disease (Dopamine Deficiency)

    • Pathophysiology: Destruction of substantia nigra leading to decreased dopamine.

    • Cardinal Manifestations (TRAP):

      1. Tremors (at rest, e.g., pill-rolling).

      2. Rigidity.

      3. Akinesia/Bradykinesia.

      4. Postural instability.

    • Gait/Signs: Shuffling gait, festinating gait (rapid steps), microphagia (small writing), mask-like facies.

    • Treatment: Levodopa + Carbidopa (Sinemet). Carbidopa prevents the peripheral breakdown of Levodopa.

  • Alzheimer’s Disease

    • Causes: β\beta-amyloid plaques, neurofibrillary tangles, and decreased Acetylcholine.

    • The 5 A’s: Amnesia (memory), Anomia (naming), Agnosia (recognition), Apraxia (purposeful tasks), Aphasia (communication).

    • Medication: Donepezil (Aricept) to increase Acetylcholine.

Autoimmune Neurological Disorders

  • Multiple Sclerosis (MS): Irreversible CNS demyelination by sensitized T cells. Signs: Charcot’s Triad (Scanning speech, Intention tremors, Nystagmus).

  • Guillain-Barré Syndrome (GBS): Reversible PNS demyelination. Ascending paralysis ("Ground to Brain"). Priority: Breathing/Diaphragm. Often follows a viral infection. Use plasmapheresis.

  • Myasthenia Gravis (MG): Neuromuscular junction disorder at receptor sites. Descending weakness ("Mind to Ground"). Sign: Ptosis and Diplopia.

    • Tensilon Test (Edrophonium): Temporary relief (30 sec−5 mins30\,sec - 5\,mins) confirms MG. Antidote: Atropine.

    • Crisis Management:

      • Myasthenic Crisis: Underdose; Tensilon improves symptoms.

      • Cholinergic Crisis: Overdose; Tensilon worsens symptoms; give Atropine.