Neurology

Skull Openings:

  • Transtentorial Shelf/Notch: A small opening.
  • Foramen Magnum: A larger opening.

Broca’s Area:

  • Responsible for speech production.
  • Located in the left hemisphere.
  • Associated with speech and language disorders, such as expressive or receptive aphasia.

Neurological Posturing:

  • Decorticate: Arms flexed; indicates hemispheric dysfunction.
  • Decerebrate: Arms extended; suggests dysfunction in the midbrain or pons, with a worse prognosis.

Reflexes:

  • Doll’s Eyes Reflex: Eyes move in the opposite direction of head movement (positive reflex indicates good brainstem function).
  • Cold Caloric Test: Ice water injected into the ear canal causes eyes to move toward the side of the injection (positive response indicates proper brainstem function).

Visual and Neurological Signs:

  • Homonymous Hemianopia: Loss of vision in half of each eye’s field; associated with damage to the optic nerve (CN II) and occurs on the side opposite the injury.
  • Babinski’s Reflex: Toes fan outward when the foot’s sole is stroked; a positive Babinski on the opposite side of the issue indicates a problem.
  • Eye Deviation: Eyes turn toward the side of the lesion.
  • Motor Changes: Occur on the side opposite the injury.
  • Altered Mental Status (AMS): Changes in consciousness are the first signs of neurological issues.
  • Pupil Changes: The first sign in cases of epidural hematoma.

Medication Reversal:

  • Romazicon: Used to reverse the effects of benzodiazepines.

Brain Regions and Functions:

Cerebrum:

  • Divided into right and left hemispheres.
  • Handles sensory perception, judgment, reasoning, and emotions.

Brainstem:

  • Includes the midbrain, pons, and medulla.
  • Controls breathing, heart function, and involuntary movements like coughing, gagging, and corneal reflexes.

Cerebellum:

  • Located at the back of the brain.
  • Maintains balance, posture, and equilibrium.

Frontal Lobe:

  • Governs personality, abstract thinking, and long-term memory.

Temporal Lobe:

  • Responsible for short-term memory, speech, and sense of smell.

Parietal Lobe:

  • Recognizes objects, interprets spatial relationships, and processes pain and touch sensations.

Occipital Lobe:

  • Plays a role in vision.

Cranial Nerves:

  • Olfactory: Controls the sense of smell.
  • Optic: Responsible for vision.
  • Oculomotor: Manages pupillary function.
  • Vestibulocochlear (VIII): Involved in hearing and balance.
  • Note: All cranial nerves except I and II originate from the brainstem.

Glasgow Coma Scale (GCS)

  • Based on best observed response.
  • Highest score: 15 (indicates normal function).
  • Score below 8: Associated with a poor outcome.
  • Obtunded state: Patient can still speak but may mumble.
  • Stuporous state: Patient is unable to speak, only moans or grimaces.

Traumatic Brain Injury (TBI) Classification

  • Determined by GCS score:
    • Severe: 3-8
    • Moderate: 9-12
    • Mild: 13-15

Types of Skull Fractures

Linear Skull Fracture

  • No surgical intervention needed.

Depressed Skull Fracture

  • Surgery required if depression exceeds 5mm.

Basilar Skull Fracture

  • Surgery considered if persistent cerebrospinal fluid (CSF) leakage occurs.
  • Involves a meningeal tear, increasing the risk of meningitis.
  • Signs and Symptoms:
    • Raccoon Eyes: Bruising around the eyes (periorbital discoloration).
    • Battle’s Sign: Bruising behind the ear.
    • Otorrhea: Fluid leaking from the ear.
    • Rhinorrhea: Fluid leaking from the nose.
    • Loss of Smell: Due to damage to the olfactory nerve (CN I).

Management and Precautions

  • CSF Identification:
    • Check for glucose in fluid.
    • CSF creates a halo sign (yellow ring surrounding a central blood clot) when placed on gauze.
  • Precautions:
    • Use dry, sterile gauze to cover the nose or ear; do not pack the area.
    • Avoid inserting an NG tube—opt for an orogastric (OG) tube instead.
    • Do not allow the patient to blow their nose to prevent increased pressure and further leakage.

Neurological Emergencies & Disorders

Cushing’s Response

  • Indicators of brainstem pressure:
    • Increased systolic blood pressure (SBP)
    • Decreased heart rate (HR)
    • Decreased respiratory rate (RR)
  • Suggests impending brain herniation.

Types of Brain Herniation

Central Herniation

  • Symmetrical swelling on both sides of the brain causing downward pressure.
  • Develops gradually.
  • First sign: Altered level of consciousness (LOC).
  • Babinski reflex present on both sides.

Uncal Herniation

  • One-sided brain swelling, shifting brain tissue laterally.
  • Rapid progression.
  • First sign: Pupil changes, followed by altered LOC.
  • Babinski reflex on the opposite side of the brain injury.

Stroke (Cerebrovascular Accident – CVA)

Effects Based on Affected Hemisphere

  • Right-sided stroke: Emotional instability.
  • Left-sided stroke: Difficulty with speech (aphasia).

Types & Duration of Ischemic Stroke

  • Transient Ischemic Attack (TIA): Lasts less than 12 hours.
  • Reversible Ischemic Neurologic Deficit (RIND): Lasts 1-2 months.
  • Cerebral infarction: Permanent damage.

Treatment Priorities

  1. Rule out low blood sugar (hypoglycemia) first.
  2. Obtain a CT scan within 25 minutes of arrival.
  3. Do not lower blood pressure unless it exceeds 220/120 mmHg, as this can reduce cerebral perfusion.

TPA (Tissue Plasminogen Activator) Treatment Criteria

  • Symptoms began within 4.5 hours.
  • No hemorrhage on CT scan.
  • No contraindications present.
  • Blood pressure target for the first 24 hours: Keep below 180/105 mmHg.
  • Preferred medication for BP control: Labetalol.
  • Most serious complication: Intracerebral hemorrhage (watch for worsening LOC).

Subarachnoid Hemorrhage (SAH)

  • Caused by a ruptured aneurysm (commonly from the middle cerebral artery).
  • Classic symptom triad:
    • Sudden, severe headache (“thunderclap headache”).
    • Loss of consciousness.
    • Neck stiffness (nuchal rigidity).

Complications

  • Rebleeding: Prevented with Aminocaproic acid (Amicar).
  • Vasospasm: Can be reduced with Nimodipine, while avoiding low blood pressure.
  • ICP wave monitoring:
    • Type “A” waves are the worst (indicate severe ICP elevation).

Arteriovenous Malformation (AVM)

  • Congenital abnormal connection between arteries and veins (bypasses capillaries).
  • Signs & Symptoms:
    • Brain hemorrhage.
    • Headache.
    • Seizures.
  • Treatment:
    • Embolization to reduce bleeding.
    • Heparin to prevent clot formation.
    • Surgical removal or radiation therapy for smaller malformations.

Increased Intracranial Pressure (ICP)

  • Normal ICP: 0-10 mmHg.
  • Moderately elevated ICP: 10-20 mmHg.
  • High ICP: Above 20 mmHg.
  • First symptom of increased ICP: Altered LOC.

ICP Management

  • Hypotension is dangerous (reduces brain perfusion).
  • Symptoms of worsening ICP:
    • Altered LOC → Pupil changes → Cushing’s response.
    • Restlessness, nausea, vomiting, and seizures.
  • Monitoring: Keep transducer level with the external auditory meatus.
  • ICP waveforms:
    • Type “A” waves = most severe.
    • Type “B” waves = concerning.
    • Type “C” waves = common.

How to Reduce ICP

  • Lower blood volume in the brain using:
    • Mannitol (osmotic diuretic).
    • Hypertonic saline (3%).
    • Furosemide (Lasix).
  • Position the patient upright to improve drainage.

Avoid Worsening ICP

  • No hypotonic fluids (can worsen swelling).
  • No physical restraints (increases agitation).
  • No excessive pain or agitation (use Propofol for sedation).
  • No acidosis (prevents cerebral vessel dilation).

Intracranial Hematomas

Epidural Hematoma

  • Rapid onset, typically from an arterial bleed (meningeal artery).
  • First sign: Pupil changes, followed by LOC changes.
  • Symptoms: Headache, confusion, irritability.
  • Treatment: Emergency burr hole procedure; monitor ICP.

Subdural Hematoma

  • Slower progression, typically from a venous bleed.
  • First sign: Altered LOC, followed by pupil changes.
  • Treatment: Surgical drainage and ICP management.

Intracerebral Hematoma

  • Caused by stroke, skull fracture, or gunshot wounds.
  • Symptoms: May or may not show increased ICP signs.
  • Treatment: Surgery if the hematoma is large or neurological function declines.

Seizures & Status Epilepticus

Prevention Medications

  • Phenytoin (Dilantin).
  • Phenobarbital.

Emergency Treatment

  • Lorazepam (Ativan) or Diazepam (Valium) to stop active seizures.

Status Epilepticus

  • Seizures lasting ≥5 minutes or multiple seizures without regaining consciousness.
  • Brain oxygen supply cannot meet demand.
  • Unresponsive to usual medications.
  • Can cause:
    • Cardiac arrhythmias.
    • Rhabdomyolysis.
    • Hypoglycemia.
    • Electrolyte imbalances (hyperkalemia).
  • Fatal if not treated due to excessive brain metabolic demand.

Brain Tumors

  • Seizures are an early warning sign.
  • High fatality rate, even for benign tumors due to brain compression.
  • Steroid therapy helps manage swelling but does not cure the tumor.

Encephalopathy

  • Brain dysfunction caused by multiple factors (metabolic, hypoxic, infectious, toxic).
  • Can cause increased ICP.
  • Signs & Symptoms:
    • Cognitive decline.
    • Personality changes.
    • Memory impairment.
    • Agitation and seizures.
    • Coma or even brain death in severe cases.

Treatment Priorities

  • Identify and treat the underlying cause.
  • Prevent increased ICP.
  • Ensure patient safety:
    • Avoid restraints (can worsen agitation).
    • Keep head of bed elevated (do not lay flat).
    • Avoid hypotonic fluids (can worsen brain swelling).

Neurological Disorders & Conditions

Cerebrospinal Fluid (CSF) Normal Ranges

  • Glucose: 60% of blood glucose level
  • Protein: 20-45 mg/dL
  • Lumbar Puncture (LP) Pressure: 80-180 mmHg

Meningitis

Bacterial Meningitis

  • CSF Findings:
    • Decreased glucose (<60%)
    • Elevated protein (>45 mg/dL)
    • Increased LP pressure (>180 mmHg)
    • Elevated white blood cells (WBCs)
    • Cloudy or purulent appearance
  • Treatment: Antibiotics

Viral Meningitis

  • CSF Findings:
    • Glucose remains normal (≈60%)
    • Slight increase in protein
    • Normal LP pressure (80-180 mmHg)
    • Mildly elevated WBCs
    • Clear appearance

Common Symptoms of Meningitis

Both bacterial and viral meningitis cause meningeal irritation, leading to:

  • Headache
  • Neck stiffness (nuchal rigidity)
  • Positive Brudzinski’s sign (flexing the neck causes involuntary hip and knee flexion)
  • Positive Kernig’s sign (hip flexion at 90° causes neck pain due to tight hamstrings)

Guillain-Barré Syndrome (GBS)

  • Triggered by viral infection, causing progressive weakness starting in the lower body and moving upwards.
  • Does not affect consciousness.
  • Severe cases may impair diaphragm function, leading to respiratory failure.
  • Monitoring priorities:
    • Breathing difficulties (respiratory failure risk)
    • Urine retention (loss of bladder control)
  • Treatment:
    • Steroids
    • Plasmapheresis (plasma exchange)
    • Intravenous immunoglobulin (IVIG) therapy

Myasthenia Gravis (MG)

  • Autoimmune disorder leading to worsening muscle weakness and paralysis.
  • Early signs: Fatigue
  • Later stages: Muscle paralysis

Treatment Approaches

  • Steroids
  • Plasmapheresis
  • IVIG therapy
  • Pyridostigmine (cholinesterase inhibitor to enhance muscle function)
  • Thymectomy (removal of thymus gland if indicated)

Crisis Management via Tensilon Test

  • Myasthenic Crisis (caused by too little acetylcholine):
    • Tensilon injection improves symptoms.
  • Cholinergic Crisis (caused by excessive acetylcholine):
    • Tensilon worsens symptoms (muscle weakness, excessive tears/saliva, GI distress).

Muscular Dystrophy (MD)

  • A group of inherited disorders that weaken muscles due to genetic mutations.
  • Progression pattern: Starts near the core of the body, extending outward to the limbs (legs affected before arms).

Key Terminology

  • Myopathy: Ongoing muscle weakening.
  • Atrophy: Gradual loss of muscle mass.

Types of Muscular Dystrophy

  • Duchenne MD:
    • Begins in early childhood.
    • Life expectancy: Late teens to early 20s due to respiratory failure or heart complications.
  • Becker MD:
    • Later onset than Duchenne.
    • Life expectancy: 40s, usually due to heart failure.

Management & Prevention

  • Steroid therapy
  • Use of CPAP for breathing support
  • Annual flu vaccination
  • Baseline lung function tests
  • Heart monitoring (ACE inhibitors/ARBs for cardiomyopathy prevention)
  • Avoidance of certain anesthesia due to malignant hyperthermia risk

Brain Death

  • Complete and irreversible loss of brain function, including the cerebrum, cerebellum, and brainstem.
  • Before diagnosing brain death, the following must be ruled out:
    • Cause of coma must be known and irreversible.
    • Brain imaging should explain the coma.
    • Effects of sedatives or other CNS depressants must be absent.
    • Paralytic agents should not be in the patient’s system.
    • Severe electrolyte imbalances or acid-base disorders must be excluded.
    • Body temperature should be normal or at most mildly low.
    • Systolic blood pressure (SBP) should be ≥100 mmHg.
    • The patient must not have any spontaneous breathing efforts.

Clinical Examination for Brain Death

  • Pupils do not react to light.
  • No corneal reflex present.
  • No gag or cough reflex.
  • No response to painful stimuli in all four limbs.

Bedside Confirmation Tests

  • Apnea Test: Absence of spontaneous breathing when disconnected from the ventilator.

Diagnostic Testing for Brain Death

  • Cerebral angiography (checks for blood flow to the brain).
  • Electroencephalogram (EEG) (detects brain activity).
  • Transcranial ultrasound (assesses cerebral circulation).

Reflex Testing

  • Absent Doll’s Eye Reflex: Eyes remain fixed in place instead of moving when the head is turned.
  • Absent Cold Caloric Test Response: No eye movement when ice water is introduced into the ear canal.

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