MA-201 Book Notes Ch. 22 The Nervous System

Introduction to the Nervous System

  • Divisions of the Nervous System:

    • Central Nervous System (CNS): Comprises the brain and spinal cord. Its primary role is to process information and coordinate body activities.

    • Peripheral Nervous System (PNS): Includes all nerves outside the CNS, connecting it to the rest of the body.

  • Functions of the Nervous System:

    • Controls and coordinates all body activities.

    • Transmits signals between different parts of the body.

    • Crucial for correlating external and internal factors for survival.

    • Gathers, stores, and analyzes information to decide on appropriate responses.

    • Detects and interprets sensory information.

    • Makes decisions based on sensory information.

    • Carries out motor functions based on decisions.

  • Structural Units: Neurons are the basic structural units, responsible for transmitting nerve impulses.

  • Developmental Changes: The nervous system undergoes significant changes from childhood to older adulthood, impacting its function and efficiency.

  • Nerve Impulse Transmission: Impulses are transmitted via electrical and chemical signals.

  • Subsystems: Consists of various subsystems, some capable of independent function.

Medical Terminology

  • Neurology: The field specializing in the nervous system.

  • Neurologists: Specialists who treat nervous system disorders.

  • Key Medical Terminology (Prefixes/Suffixes):- -algia, -dynia: pain

    • arachn/o-: spider

    • -ase, -lysis: to break down

    • astr/o: star

    • dur/o: hard

    • -ethesia: feeling

    • micr/o: small

    • mot/o: movement

    • neur/o: nerve

    • olig/o: scant

    • myel/o: spinal cord or bone marrow

Sections and Functions in Detail

  • Central Nervous System (CNS):

    • Consists of the brain and spinal cord.

    • Functions: Processes information and coordinates activities.

  • Peripheral Nervous System (PNS):

    • Connects the CNS to other body parts.

    • Subdivisions:

      • Somatic Nervous System (SNS): Controls voluntary movements and transmits sensory information to the CNS.

      • Autonomic Nervous System (ANS): Controls involuntary functions.

        • Sympathetic Nervous System: Prepares the body for stress-related activities ("fight or flight").

        • Parasympathetic Nervous System: Conserves energy and restores the body to a restful state ("rest and digest").

  • Gray Matter vs. White Matter:

    • Gray Matter: Composed of nerve cell bodies and unsheathed true dendrites; appears gray.

    • White Matter: Consists of myelinated nerve fibers; appears white.

  • Components of a Nerve (Bundled Unit Outside CNS):

    • Nerve cell bodies

    • Nerve fibers

    • Ganglion

    • Axons

    • Blood vessels

    • Connective tissue

Structural Units of the Nervous System

  • Composed of specialized tissues, nerve cells (neurons), fibers, and tracts.

  • Neurons: Basic functional units responsible for transmitting nerve impulses.

  • Neuroglia (Glia): Support cells for neurons.

    • Astrocytes: Star-shaped cells that attach blood vessels to nerve cells.

    • Microglia: Act as phagocytes, engulfing invaders.

    • Oligodendrocytes: Produce the myelin sheath in the CNS.

  • Types of Neurons:

    • Motor Neurons (Efferent Nerves):

      • Transmit impulses away from the CNS to control body functions (muscle contraction, gland secretion, and organ function).

      • Have an axon (sends info) and dendrites (receive info).

      • Axons are covered with a myelin sheath and can be several feet long.

      • Dendrites are unsheathed and branch-like.

    • Sensory Neurons (Afferent Nerves):

      • Transmit impulses toward the CNS, attaching to sensory receptors.

      • Lack true dendrites, are sheathed, and resemble axons.

    • Interneurons:

      • Located entirely within the CNS.

      • Act as a liaison, mediating impulses between sensory and motor neurons.

Nerve Fibers, Nerves, and Tracts

  • Nerve Fibers: Single elongated processes, typically axons of motor neurons or peripheral processes of sensory neurons.

    • Sheaths (Protective membranes in PNS):

      • Myelinated Sheaths: Contain an inner myelin sheath and an outer neurilemma (Schwann cells), which aid in nerve fiber regeneration.

      • Unmyelinated Sheaths: Wrapped only in the neurilemma, lacking myelin.

    • CNS vs. PNS Nerve Fiber Regeneration:

      • CNS nerve fibers lack Schwann cells, making damage permanent.

      • PNS nerve fibers can regenerate due to Schwann cells.

  • Nerves: Bundled units of nerve fibers found outside the CNS.

    • Afferent Nerves: Conduct impulses to the CNS.

    • Efferent Nerves: Conduct impulses from the CNS to muscles, organs, and glands.

    • Mixed Nerves: Contain both afferent and efferent fibers.

  • Tracts: A group of nerve fibers within the CNS with the same origin, function, and termination.

    • Spinal Cord Tracts: Contains sensory (afferent) tracts ascending to the brain and motor (efferent) tracts descending from the brain.

    • Corpus Callosum: The largest nerve tract, connecting the right and left cerebral hemispheres.

Life Span Considerations

  • Embryonic Development: The child's nervous system begins developing around 6 weeks of embryonic age.

  • Birth: Brain waves can be measured at birth.

  • Childhood Neurological Testing: Assesses reflexes, mental status, motor functions, balance, and sensory system during well-child visits.

  • Older Adults (without neurological disease): Intellectual performance is generally maintained until at least age 80.

    • Tasks may take longer due to slower central processing.

    • Verbal skills are typically maintained until age 70, followed by a gradual reduction in vocabulary, semantic errors, and abnormal pronunciation.

    • Normal Aging Changes: Decrease in nerve cells in the brain.

      • Brain weight declines by about 10% from age 20 or 30 to age 90.

      • Increase in the area of the cerebral ventricles.

      • Changes in neurotransmitter levels can impact mood and cognitive function.

      • Reaction times may slow, affecting physical performance and reflexes.

Nerve Impulses and Synapses

  • Initiation: A nerve impulse begins with stimulation at a sensory receptor (e.g., pain receptors, retinal receptors).

  • Sensory Receptors: Specialized to respond to specific stimuli (heat, cold, light, pressure, and pain).

  • All-or-None Principle: A receptor must receive sufficient stimulation (reach its specific threshold) to send an impulse; otherwise, no impulse is transmitted.

  • Transmission Pathway:

    1. The receptor reacts, initiating an impulse.

    2. Impulse travels from the receptor nerve to other nerves.

    3. Axons transmit impulses; dendrites receive them.

    4. Synapse: The site where an impulse is transmitted from the axon of one nerve to the dendrite of another.

    5. Synaptic Space: A small gap across which the impulse travels (no direct contact).

    6. Neurotransmitters: An impulse reaches a synaptic knob at the end of the axon, causing vesicles to release neurotransmitters into the synaptic space.

    7. Neurotransmitters cross the synaptic space and bind to receptors on the dendrite of the next neuron.

    8. This domino effect continues until the impulse reaches its target, taking a fraction of a second.

Central Nervous System (CNS) Detailed

  • Components: Brain and spinal cord.

  • Function: Process and respond to impulses (conscious or unconscious).

  • Gray Matter: Composed of unsheathed cell bodies and true dendrites; appears gray.

  • White Matter: Composed of myelinated nerve fibers; appears white.

  • Distribution in CNS:

    • Spinal Cord: Gray matter forms the core (H-shaped), surrounded by white matter.

    • Brain: The white matter forms the core, surrounded by the gray matter (cortex).

The Brain

  • Largest Mass of Nervous Tissue: Weighs about 3 pounds in males, slightly less in females.

  • Protection (Meninges - three layers): - Pia Mater: The innermost, delicate layer holding blood vessels to the brain and spinal cord.

    • Arachnoid Mater: The middle, web-like layer.

    • Dura Mater: Outermost, toughest layer.

  • Major Brain Divisions: Cerebrum, Diencephalon, Brainstem (Midbrain, Pons, and Medulla Oblongata), and Cerebellum.

  • Cerebrum: The Largest part, composed of gray and white matter.

    • Governs sensory and motor activities, emotions, consciousness, memory, and voluntary movements.

    • The cerebrum is divided into two hemispheres, which are connected by the corpus callosum.

    • The surface is marked by gyri (ridges) and sulci (grooves), with deep grooves called fissures.

  • Cerebral Cortex: Outer covering of the cerebrum, housing 75% of all neurons.

    • Interprets sensory information, initiates movements, stores memories, and creates emotions.

  • Lobes of the Cerebral Cortex: Frontal Lobe: Reasoning, personality, emotions, problem-solving, speech, and movement.

    • Parietal Lobe: Touch, pain, temperature, pressure, size, shape, and color recognition.

    • Temporal Lobe: Hearing, memory, organization, sequencing.

    • Occipital Lobe: Vision, recognition of printed words.

  • Diencephalon: Composed of the thalamus and hypothalamus.

    • Thalamus: Relay center for all sensory impulses (except smell).

    • Hypothalamus: Regulates autonomic activities, behavior, emotions, thirst, hunger, body temperature, and metabolic functions.

  • Brainstem: Contains the midbrain, pons, and medulla oblongata.

    • Relays visual, auditory, and sensory information to the cerebrum.

    • Midbrain: Below the cerebrum and above the pons; associated with visual reflexes and eye movements.

    • Pons: Between midbrain and medulla oblongata; contains fiber tracts linking cerebellum and medulla to higher cortical areas; involved in motor control.

    • Medulla Oblongata: Connects pons and brain to spinal cord; controls vital functions (heartbeat, blood pressure, breathing, swallowing, coughing, sneezing, vomiting).

  • Cerebellum: The second-largest brain portion, located above the brainstem and below the cerebrum.

    • Coordinates voluntary movements, muscle tone, and equilibrium.

    • Maintains posture and balance.

Spinal Cord

  • Dimensions: Approximately 17 to 18 inches (43 to 45 centimeters) in adults.

  • Extension: From the base of the medulla oblongata to the junction between the first and second lumbar vertebrae (L1 and L2).

  • Functions (primarily in white matter): Conducts sensory impulses from the body to the brain.

    • It also transmits motor impulses from the brain to the body.

    • It serves as a reflex center for nerve impulses that do not require brain involvement.

Cerebrospinal Fluid (CSF)

  • Description: Colorless, often referred to as the "blood" of the nervous system.

  • Production: Produced by the choroid plexus in the brain's ventricles.

  • Movement: Moves from the ventricles into the connecting canals, then through the spinal canal and subarachnoid space around the brain.

  • Functions:

    • Cushions and protects the brain and spinal cord, allowing them to float.

    • Nourishes the brain and spinal cord with oxygen and glucose.

    • Acts as a vehicle to carry neurotransmitters (e.g., monoamines, acetylcholine, and neuropeptides).

Peripheral Nervous System (PNS) Detailed

  • Main Subdivisions: Somatic Nervous System (SNS) and Autonomic Nervous System (ANS).

  • Nerve Connections: PNS nerves link the CNS to sensory organs (eyes, ears), other body organs, muscles, blood vessels, and glands.

Cranial Nerves

  • Number: 12 pairs, originating in the brain, identified by Roman numerals.

  • Naming: Named based on function or area served.

  • Functions of Specific Cranial Nerves:

    • Olfactory (I): Sense of smell.

    • Optic (II): Vision.

    • Oculomotor (III): Motor impulses to four eye muscles and the eyelid muscle.

    • Trochlear (IV): Motor impulses to the superior oblique muscle of the eyeball.

    • Trigeminal (V): Sensory input from the face, nose, mouth, forehead, and top of the head; motor fibers to the jaw muscles.

    • Abducens (VI): Motor impulses to the lateral rectus muscle of the eyeball.

    • Facial (VII): Controls facial/scalp muscles, lacrimal gglands, andsalivary glands; taste input from tongue.

    • Vestibulocochlear (VIII): Hearing and equilibrium.

    • Glossopharyngeal (IX): Taste, swallowing, saliva secretion.

    • Vagus (X): Controls pharynx, larynx, and thoracic/abdominal organs; swallowing, voice production, heart rate, and digestive movement.

    • Accessory (XI): Controls trapezius and sternocleidomastoid muscles (head/shoulder movement).

    • Hypoglossal (XII): Tongue movements.

Spinal Nerves

  • Number: 31 pairs, connected to the spinal cord.

  • Naming: Named for the region of the vertebral column.

  • Distribution: 8 cervical spinal nerves

    • 12 thoracic spinal nerves

    • 5 lumbar spinal nerves

    • 5 sacral spinal nerves

    • 1 coccygeal spinal nerve

  • Plexuses: Cervical, brachial, and lumbosacral plexuses are formed by spinal nerve distributions.

Somatic Nervous System (SNS)

  • Function: Controls skeletal muscles, sensory organs, and skin.

  • Nature: "Voluntary" nervous system, responsible for voluntary muscle movements.

  • Sensory Processing: Processes sensory information from the eyes, ears, nose, and touch.

Autonomic Nervous System (ANS)

  • Function: Controls involuntary bodily functions (heart rate, smooth muscle control, glandular secretion, sweating, and blood pressure).

  • Homeostasis: Sympathetic and parasympathetic divisions work together to maintain homeostasis.

  • Sympathetic Division:

    • Location: Thoracic and lumbar spine.

    • Ganglia: Sympathetic ganglia are nerve cell bodies where spinal nerve axons enter.

    • Response: Widespread stimulation, preparing the body for "fight or flight." 

    • Physiological Changes: Increased alertness, metabolic rate, heart rate, respiration, and blood pressure; release of epinephrine (adrenaline) from the adrenal gland.

    • Example: Responding to a fire alarm.

  • Parasympathetic Division:

    • Location: Formed by cranial nerves (III, VII, IX, X) and sacral nerves (II, III, IV).

    • Nerve Distribution: Cranial fibers serve internal organs (thoracic, abdominal, and pelvic); sacral fibers serve the lower colon, rectum, bladder, and reproductive organs.

    • Response: Calming effect, promoting "rest and digest."

    • Physiological Changes: Conserves energy by decreasing heart rate and metabolism; stimulates the digestive system.

Common Pathologies Associated with the Nervous System

  • Nervous system disorders range from simple headaches to complex conditions like Alzheimer’s disease.

  • Timely recognition and reporting are crucial to prevent long-lasting disability.

Diagnostic Tests and Procedures

  • Babinski’s Sign: Reflex test; positive if the great toe extends when the lateral sole is stroked (indicates nervous system lesions).

  • Brain Scan: Uses radioactive isotopes to assess brain function and abnormalities.

  • Carotid Endarterectomy: Surgical removal of carotid artery obstructions to prevent strokes (useful for severe stenosis with TIA).

  • Cerebral Angiogram: X-ray of the brain's blood vessels after radiopaque contrast injection.

  • Cerebrospinal Fluid Shunts: Surgical creation of an opening to drain excess CSF (for hydrocephalus).

  • Cordectomy: Removal of part of the spinal cord.

  • Craniotomy: Surgical incision into the brain through the skull.

  • Cryosurgery: Uses extreme cold to destroy brain tissue, control bleeding, and treat tumors.

  • Echoencephalogram: Ultrasonic recording of brain echoes to detect abnormal brain shifts.

  • Electroencephalogram (EEG): Detects electrical abnormalities in the brain to evaluate disorders.

  • Electromyogram (EMG): Records muscle contractions from electrical stimulation.

  • Laminectomy: Removal of a posterior vertebral arch.

  • Lumbar Puncture (Spinal Tap): Needle puncture in the lumbar area to withdraw CSF for examination or inject anesthesia.

  • Nerve Block: A regional anesthetic to stop sensory stimulation along a nerve path (for extreme pain).

  • Positron Emission Tomography (PET): Uses positive radionucleotides to reconstruct brain sections and measure oxygen/glucose uptake, blood flow, and volume.

  • Romberg’s Sign: Test for neurological function; positive if the patient sways with eyes closed and feet together.

  • Spinal Puncture: Same as Lumbar Puncture.

  • Sympathectomy: Excision of part of the sympathetic nervous system (nerve or ganglion).

  • Transcutaneous Electrical Nerve Stimulation (TENS): Mild electrical stimulation to skin electrodes over painful areas to interfere with pain transmission.

  • Trephination: Cutting out a piece of skull bone to relieve brain pressure.

  • Vagotomy: Surgical incision into the vagus nerve (sometimes for medication administration to inhibit its function).

Specific Neurological Diseases and Disorders

  • Alzheimer’s Disease:

    • Description: Progressive, degenerative disease affecting the brain and cognitive function.

    • Prevalence: Over 5.1 million affected; ~200,000 under 65; nearly two-thirds are women.

    • Etiology: Not definitively known; believed to involve genetic predispositions, lifestyle choices (activity level), and overall environment.

    • Symptoms: Initial: Inability to remember recent events.

    • Progression: Inability to rationalize thoughts, difficult speech (interrupted thought processes), decline in reading/writing skills, personality changes (irritability, aggression, agitation, depression, violence).

    • Advanced: Inability to self-care, eat, or speak.

    • Treatment: Medications can slow progression in early stages (continuous lifelong use); an active lifestyle and mentally stimulating activities may reduce risk.

  • Amyotrophic Lateral Sclerosis (ALS) / Lou Gehrig’s Disease:

    • Description: A condition that breaks down motor neurons.

    • Etiology: The cause is unknown; however, heredity and environmental factors are believed to play a role.

    • Symptoms: Degeneration/death of motor neurons leads to loss of control over voluntary muscle movements (arms, legs, trunk, diaphragm); muscle weakness, atrophy, slurred speech, muscle stiffness, and difficulty chewing/swallowing. Some forms may involve dementia or sensory symptoms.

    • Treatment: No cure. Medications and therapies (speech, physical, and respiratory) can slow progression and maintain independence/quality of life. Advanced stages often require full ventilatory support.

  • Bell’s Palsy (Facial Palsy):

    • Description: Sudden onset of weakness or paralysis of muscles on one side of the face.

    • Etiology: Damage to a facial nerve (running beneath each ear).

    • Symptoms: Unilateral facial paralysis, facial drooping, lack of expression on the affected side, possible headaches, changes in taste, excessive drooling or tearing.

    • Treatment: Corticosteroids (early on to reduce swelling) and medications for specific symptoms. Eye care is crucial if blinking is affected (drops, ointments, patches). Often resolves on its own within weeks/months.

  • Disk Disorders (Degenerative Disk Disorder - DDD):

    • Description: Affects at least one vertebral disk; common in 40% of people aged 40+.

    • Etiology: Deterioration of intervertebral disks causing pain and reduced stature.

    • Symptoms: Severe pain, decreased mobility, pain spreading from the affected disk, neck/back/leg pain, leg/muscle weakness, and incontinence.

    • Treatment Options: Bed rest, heat/cold, anti-inflammatory drugs, muscle relaxers, analgesics, physical therapy (for ruptured/slipped disks), alternative therapies (massage, acupuncture, biofeedback), and surgery in severe cases.

  • Encephalitis:

    • Description: Inflammation of the brain, primarily affecting infants and older adults in the U.S.

    • Causes: Often viral infections (measles, mumps, West Nile virus - transmitted by mosquitoes/ticks).

    • Symptoms: Common: Headache, sudden fever, vomiting, sensitivity to light, stiff neck/back, confusion, drowsiness, clumsiness, irritability.

    • Emergency: Loss of consciousness, decreased responsiveness, seizures, muscle weakness, impaired judgment.

    • Treatment includes hospitalization, antibiotics, antiviral medications, anticonvulsants, steroids to reduce inflammation, and sedatives for irritability or agitation.

  • Epilepsy and Seizures:

  • Seizures: Caused by abnormal, intense bursts of electrical activity in the brain.

    • Epilepsy is characterized by recurring seizures; it affects ~2.2 million people.

    • Incidence: About 48 out of every 100,000 people develop epilepsy each year.

    • Causes: Genetic predisposition, brain trauma, strokes, brain tumors, infectious diseases, prenatal injury. In more than 50% of cases, the cause remains unknown.

    • Symptoms: Can interfere with muscle control, movement, speech, vision, or awareness. Range from single lifetime occurrences to repeated episodes.

    • Treatment: Medication (often lifelong) to reduce the frequency/severity; surgery is considered in severe cases.

    • Triggers: Sensitivity to light, stress, disrupted sleep patterns, and hormonal fluctuations. Minimizing exposure helps management.

  • Headaches:

    • Prevalence: Over 10 million physician visits annually.

      • Etiology/Susceptibility: Not well understood; specific type and treatment are often challenging for doctors.

      • IHS Criteria (1988): Used to differentiate headache types based on attacks per month, duration, pain characteristics, and accompanying symptoms

    • Types of Headaches:

      • Migraine:

        • Description: Debilitating, more common in women.

        • Etiology: Hormones (higher prevalence in women), triggers.

        • Triggers: Sensory stimulation (noise, bright lights), stress.

        • Symptoms: Intense pain (typically on one side, often behind the eye), sensitivity to light/noise, nausea, vomiting, and sometimes aura (tunnel vision, visual disturbances, and odor sensitivity).

        • Treatment options include over-the-counter medications such as acetaminophen, ibuprofen, and naproxen sodium, as well as prescription medications if the over-the-counter options are ineffective. Headache journals help identify/avoid triggers.

      • Tension Headaches:

        • Etiology: Often unknown, possibly linked to stress or fatigue.

        • Symptoms: Pressing or squeezing pain on both sides of the head, neck, or face. Sensitivity to light/sound.

        • Treatment: Similar to migraine (OTC/prescription pain relievers), stress reduction (yoga, meditation, biofeedback), and possible antidepressants/antianxiety medications.

      • Cluster Headaches:

        • Etiology: Unknown, possibly related to hypothalamus disruption.

        • Symptoms: Intense, penetrating pain behind the eyes or temples. The patient may experience symptoms such as a runny nose, tearing eyes, or droopy eyelids on the affected side. Attacks last 15 minutes to 3 hours, often at night/early morning, with multiple episodes daily.

        • Treatment: Conventional analgesics, prescription medications, and 100% pure oxygen masks. For severe cases or intolerance, surgical options are available.

      • Posttraumatic Headaches:

        • Etiology: Follow traumatic brain injury; caused by brain swelling/shrinkage or chemical release.

        • Symptoms: Similar to migraine/tension. The symptoms include decreased concentration and memory, sensitivity to noise and light, increased fatigue, dizziness, and personality changes. Develops 24-48 hours post-injury, but can appear later.

        • Treatment: Pain relievers for immediate symptoms. Antidepressants, antiseizure medications, and blood pressure pills are used to reduce its occurrence. Nonmedication therapies: nerve stimulation, physical therapy, relaxation techniques, and psychological support/behavior therapy.

      • Huntington’s Chorea (Huntington’s Disease - HD):

        • Description: Progressive degenerative disorder of the basal ganglia causing uncontrolled bodily movements.

        • Etiology: Inherited genetic mutation.

        • Onset: Typically mid-to-late 30s, can be juvenile.

        • Initial Symptoms: Uncontrolled movements of hands, feet, and trunk; changes in physical and emotional patterns (irritability, mood swings, depression, anger).

        • Common Signs/Symptoms: Involuntary movement, rigidity, balance/coordination problems, difficulty swallowing, slurred speech.

        • Treatment: Focuses on controlling emotional problems and muscle movements (antidepressants, mood stabilizers, and antipsychotic drugs). Tetrabenazine specifically reduces jerking/movements. No cure; most patients die within 15 years of diagnosis.

  • Hydrocephalus:

    • Description: Excessive CSF in the brain's ventricles, causing pressure on the brain/skull.

    • Etiology: No specific cause identified. Potential causes: defects in fluid drainage, complications from premature birth, genetic abnormalities, developmental disorders, and head injuries.

    • Symptoms:

      • Infants: Enlarged head, irritability, sleepiness, vomiting, seizures.

      • Older Children/Adults: Balance problems, coordination/gait disturbance, nausea/vomiting, visual disturbance, drowsiness, personality changes, memory loss, irritability.

    • Treatment: Surgical insertion of a shunt into a ventricle to drain CSF, allowing it to be absorbed by the body.

  • Meningitis:

    • Description: Infection of the meninges (protective membranes of the brain/spinal cord).

    • Etiology: Viral or bacterial infection.

    • Signs/Symptoms: Neck stiffness, headache, vomiting, high fever, chills. Additional: photosensitivity, increased fatigue, decreased appetite, difficulty concentrating.

    • Treatment: Immediate medical treatment is crucial. Treatment options include antibiotics for bacterial infections, anti-inflammatory medications to reduce brain swelling, general analgesics, and anticonvulsants.

    • Prevention: Isolation may be needed. Vaccinations are available for Neisseria meningitidis (meningococcus), Streptococcus pneumoniae (pneumococcus), and Haemophilus influenzae type b (Hib). Hib vaccine administered at 2 months; meningococcal vaccine for 11+ years.

  • Multiple Sclerosis (MS):

    • Description: Chronic, potentially debilitating autoimmune disease affecting the brain and spinal cord; no known cure.

    • Etiology: Autoimmune attack on myelin (protective sheath around CNS nerves), causing demyelination and formation of dense, scar-like tissue (sclerosis), impeding nerve impulse transmission.

    • Signs/Symptoms (varied):

      • Neurologic: Emotional lability, euphoria/depression, forgetfulness, apathy, scanning speech, impaired judgment, irritability.

      • Sensory: Visual issues (blurred vision, diplopia, nystagmus, visual field defects, eye pain), auditory issues (vertigo, nausea), and tactile issues (numbness, paresthesias, diminished temperature sense, pain with spasms, and loss of proprioception).

      • Musculoskeletal: Fatigue, limb weakness, ataxic movements, intention tremors, spasticity, muscular atrophy, dragging of foot/foot drop, dysarthria with slurred speech.

      • Urinary: Hesitancy, frequency, retention, reflex bladder emptying.

      • Reproductive: Impotence (males), loss of genital sensation.

    • Potential Complications: Convulsive seizures, dementia, blindness, diminished cough reflex, respiratory infections, difficulty chewing, dysphagia, decreased/absent sphincter control, bowel incontinence, constipation, recurring UTIs.

    • Treatment: Depends on type/severity. Drug therapy aims to minimize symptoms, delay progression, and improve quality of life.

  • Neuralgia:

    • Description: General term for nerve pain (e.g., trigeminal, sciatic).

    • Etiology: Chemical irritation, trauma (including surgery), inflammation, and infections. Diabetes is a common cause.

    • Signs/Symptoms: Pain is usually brief but severe, often described as shooting pain along the affected nerve.

    • Treatment: Varies by cause, location, and severity. Rest, stretching, and heat. OTC analgesics (aspirin, acetaminophen, ibuprofen), anticonvulsants (Lyrica, Neurontin), narcotic painkillers, and nerve blocks/anesthetic injections. Surgical procedures to decrease nerve sensitivity.

  • Parkinson’s Disease:

    • Description: Progressive disorder caused by degeneration of nerve cells in brain areas controlling movement, leading to dopamine shortage.

    • Etiology: Unknown; linked to genetic factors, aging, and environmental influences.

    • Signs/Symptoms: Tremor of a limb (especially at rest, often starting in one hand), slow movement (bradykinesia) or inability to move (akinesia), rigid limbs, shuffling gait, stooped posture, reduced facial expression (mask-like face), soft voice. Additional: depression, personality changes, dementia, sleep disturbances, speech impairment, sexual difficulties.

    • Treatment: Levodopa (dopamine-based medication) is common but may have side effects with increasing dosages. Surgical interventions for involuntary motions (few patients qualify).

  • Sciatica:

    • Description: Pain along the sciatic nerve (the longest nerve, from the lower spine to the foot sole).

    • Etiology: Often inflammation from a pinched nerve root or excessive pressure on the sciatic nerve (typically unilateral).

    • Signs/Symptoms: Sharp pain from the lower back down the back of the thigh. May worsen with activity, at night, or with weather changes. Numbness and tingling sensations.

    • Treatment: Analgesics, anti-inflammatories, and steroids. Cold/heat therapy. Restricting pain-causing activities. Gentle stretching (prescribed). Surgical intervention in extreme cases (e.g., slipped disk).

  • Spinal Cord Injuries:

    • Description: Causes paralysis, affecting mobility and sensation below the injury site.

    • Types of Paralysis:

      • Quadriplegia: Paralysis from the shoulders down.

      • Paraplegia: Paralysis from the waist down.

      • Hemiplegia: Paralysis affecting one side of the body.

    • Causes: Trauma, damage, lesions, or breaks in the spinal cord.

    • Signs/Symptoms: Complete immobility and loss of sensation below the injury site. Complications: pressure sores, blood clots, muscle atrophy, UTIs, and pneumonia.

    • Treatment: Focuses on reducing complications through effective patient care. Physical therapy is beneficial (especially for hemiplegic patients due to stroke).

  • Stroke (Cerebrovascular Accident - CVA):

    • Leading Cause of Death: Third leading cause in the United States.

    • Causes/Types:

      • Ischemic Stroke: Caused by a clot impairing the blood supply to the brain.

      • Hemorrhagic Stroke: Caused by a hemorrhage in the brain.

    • Symptoms: Sudden numbness/weakness on one side of the body. Confusion or trouble speaking. Vision disturbances in one or both eyes. Dizziness, loss of balance/coordination. Severe headache with no known cause (often the "worst headache" of life).

    • Treatment: Emergency intervention is crucial. Stabilization: mechanically removing the clot, dissolving blood clots, and stopping hemorrhage. Surgery may be necessary. Medications to control brain swelling and blood pressure. Post-incident treatments to reduce recurrence.

  • Transient Ischemic Attack (TIA) / "Ministrokes":

    • Description: Can last seconds to hours, typically resolve without treatment, but are precursors to true strokes.

    • Etiology: Clot or blockage hindering blood supply to the brain, often due to plaque (fatty deposits, cholesterol) buildup in blood vessels.

    • Signs/Symptoms: Temporary sudden weakness, numbness, changes in consciousness. Symptoms vary depending on the affected brain area.

    • Treatment: Immediate medical attention is crucial even if symptoms resolve. Preventive measures: anticoagulants, aspirin therapy. Lifestyle changes: quit smoking, healthy weight, reduced alcohol, lower blood pressure, and diabetes control.

  • Traumatic Brain Injuries (TBI):

    • Types:

      • Concussion: Blow to the head, potential loss of consciousness.

      • Contusion: More serious bruising of the brain.

      • Depressed Skull Fractures: Skull pieces pushed inward, causing brain injury.

    • Hematomas (localized swelling with clotted blood):

      • Epidural Hematoma: Develops outside the dura mater (between the dura mater and skull).

      • Subdural Hematoma: Develops beneath the dura mater (between the dura mater and arachnoid mater); can cause pressure requiring surgery.

    • Signs/Symptoms (vary): Loss of consciousness, headache, confusion, dizziness, nausea/vomiting, blurred vision, pupillary changes, ringing in ears, and behavioral/mood/sleep pattern changes.

    • Treatment: Depends on trauma. Medications/procedures to reduce swelling/pressure. Pain relievers (caution with ibuprofen/aspirin due to bleeding risk). Rehabilitation exercises. Seizure suppression (benzodiazepines, barbiturates). In the most severe cases, surgery may be necessary.

Professionalism in Neurological Care

  • Medical Assistant's Role: Be courteous, professional, and understanding with neurological patients. Know the routine for determining necessary care/treatment before the patient arrives.

  • Driving and Neurological Disorders (Legal/Ethical Considerations):

    • Many states require seizure-free periods for individuals with epilepsy before driving.

    • Physicians may have an ethical or legal duty to report patients whose driving could be impaired by epilepsy.

    • Medical assistants should be aware of local laws and support the physician's guidance.