Chapter 13: Diseases and Disorders of the Nervous Syste.System

Human Diseases a Systemic Approach

Central Nervous System (CNS)

Comprised of the brain & spinal chord.

Peripheral Nervous System (PNS)

Nerves outside of the CNS. 12 pairs of cranial & 31 pairs of spinal nerves.

Neuron

nerve cell

Dendrites

Filamentous extensions on neurons that carry information towards the cell body

Interneuron

Carries impulses between neurons

Meninges

Three layered tissue protecting the brain & spinal chord

Pia mater

Innermost part of the meninges

Arachnoid

Middle layer of the meninges

Dura mater

outermost layer of the meninges. Toughest layer.

Subdural space

Between the dura mater & arachnoid

Subarachnoid space

Between the arachnoid & pia mater. CSF circulates through it

Basal ganglia

Controls muscle coordination & steady movement

Somatic system

part of the PNS. controls voluntary muscle action, receives input from sensory receptors & organs. 12 pairs of cranial nerves & 12 pairs of spinal nerves

Autonomic nervous system (ANS)

Part of the PNS. Controls glands & involuntary muscles.

Sympathetic nervous system

Part of the ANS. comprised of nerves arising from the thoracic & lumbar area of the spine. Controls fight or flight actions.

Parasympathetic Nervous System

Part of the ANS. Includes nerves arising from cranial & sacral regions. Regulate body’s resting functions.

Enteric Nervous System

Part of PNS. Network of nerves in the abdomen controlling GI organs

Electroencephalography (EEG)

Records the brain’s electrical activity

Lumbar puncture (Spinal tap)

Used to study CSF.

Myelography

Radiopaque dye injected in the subarachnoid space to visualize spinal chord structure.

Traumatic Brain Injury

Damage to the brain from external physical forces. Falls & motor vehicles are the leading causes.

Concussion

Common type of mild brain injury. May cause short loss of consciousness, headache, nausea, vomiting, photosensitivity, dizziness, cognitive impairment, and mood changes.

Severe brain injury signs & symptoms

Brain function impairments, loss of consciousness, amnesia, muscle weakness, incoordination, personality & mood changes. involved in 1/3 of injury-related deaths

Mild coma on Glasgow scale

15-13

Moderate coma on Glasgow scale

9-12

Severe coma on Glasgow scale

3-8

Vegetative coma on Glasgow scale

3>

Prevention of brain & spinal chord injury

Always wear helmet on motorcycle, bicycle, or snow/skateboard. Never dive into shallow water or water of unknown depth, remove tripping hazards, use ladders as instructed with someone to support.

Spinal chord injury

includes compression, bruising, fractures, or swelling. May result from severe osteoarthritis, cancer, or herniated discs. Motor sensory & internal organ function may be lost.

Epilespy

CNS disorder characterized by abnormal electrical activity in the brain. Induces seizures, loss of consciousness, and motor/sensory disturbances.

Stroke

Sudden interruption of blood flow to part of the brain from a blood clot or burst blood vessel in the brain. Lack of oxygen causes brain cells to die.

Signs & symptoms of stroke

Sudden numbness, loss of vision, or muscle weakness on one side of the face/body, confusion, difficulty walking, speaking, and understanding.

Simple focal seizure

No loss of consciousness, minor sensory & motor disturbance, tingling & flashing lights, involuntary movement

Dyscognitive focal seizure

Loss of awareness or consciousness. Staring & purposeless movements

Absence seizure (Petit mal seizures)

Staring into space (day dreaming)

Tonic seizure

Stiffening of the muscles

Clonic seizures

Repeated jerking on both sides of the body

Myoclonic seizure

Jerking or twitching of the upper body, arms, or legs

Atonic seizure

Loss of normal muscle tone. Body goes limp.

Tonic- clonic seizure (Grand mal seizure)

Combination of all seizure symptoms.

Transient Ischemic attack (TIA)

Mini stroke. Temporary interruption of blood flow to the brain. May be a precursor to stroke.

Trigeminal Neuralgia (Tic douloureux)

Severe chronic pain resulting from dysfunction of the fifth cranial nerve. Induces sudden stabbing pain resembling electric shock in the lips, gums, or chin. (Described as the most painful medical condition ever reported.)

Trigeminal nerve

5th cranial nerve. Transmits information from the face & jaw.

Bell’s Palsy

Paralysis of facial muscles caused by inflammation of facial nerves. (Usually affects one side of the face causing inability to salivate, form tears, blink, or move facial muscles resulting in drooping eyelid, lips, and expressionless face.)

Meningitis

Acute inflammation of the pia mater & arachnoid mater. Induces severe headache, stiff neck, high fever, chills, vomiting, confusion, and photosensitivity.

Meningococcal meningitis

Causes skin rash and other meningitis symptoms

Meningitis symtoms in infants

Bulging fontanel, irritability, poor reflexes.

Encephalitis

Inflammation of the brain most often caused by viral infection (arboviruses, enteroviruses, HSV, chickenpox, shingles, west nile virus). Induces headache, fever, muscle and joint aches, weakness, and seizures in severe cases.

Poliomyelitis (Polio)

Crippling potentially fatal viral infection transmitted orally affecting motor neurons.

Nonparalytic polio signs & symptoms

Fever, sore throat, headache, weakness, vomiting, stiff neck, and back ache.

Postpolio syndrome (PPS)

Recurrence of symptoms after many years of polio infection

Rabies

Viral infection of the brain in wild mammals with signs and symptoms occurring late in its course before death. (Induces fever, headache, agitation, confusion, hallucination, difficulty swallowing, excess salivation, hydrophobia, insomnia, partial paralysis then death.)

Shingles (Herpes Zoster)

Latent reactivation of chicken pox causing bands of red, painful watery blisters along the dermatomes not crossing the midline

Postherpetic neuralgia

Pain continuing after shingles rash clears.

Tetanus (Clostridium tetani)

Condition of acute muscle rigidity & paralysis from bacterial nerve toxin. Lockjaw.

Trismus

Rigid flexed jaw associated with tetanus

Botulism (Clostridium botulinum)

Condition of muscle weakness caused by bacterial nerve toxin which binds to motor neurons preventing them from sending contraction signals

Reye Syndrome (RS)

Uncommon potentially fatal or disabling neurological illness occurring in children after viral infection causing liver & brain inflammation. (Linked to aspirin)

Alzheimer’s Disease (AD)

Most common form of dementia where connections between neurons die and dense protein plaques & neurofibrillary tangles develop.

Multiple Sclerosis (MS)

Chronic, progressive degenerative autoimmune CNS disorder where the immune system attacks myelin sheaths

Amyotrophic Lateral Sclerosis (ALS) (Lou Gehrig’s Disease)

Serious terminal disease of progressive loss of motor function from destruction causing twitching, weakness, and slurred speech.

Parkinson’s Disease (PD)

Degenerative disease characterized by progressive loss of control over muscle coordination and movement. Caused by reduced levels of dopamine & norepinephrine from death of neurons in the substantia nigra.

Essential tremor

Disorder characterized by shaking of the hands & head especially during voluntary movement.

Huntington’s Disease (Huntington’s chorea) (HD)

Autosomal dominant disorder on chromosome 4; progressive degenerative brain disease. Causes involuntary jerky movements, loss of judgement and impulse control.

Hydrocephalus

Buildup of CSF around the brain. One of the most common birth defects. 70-90% of children with spina bifida also have it.

Cerebral Palsy (CF)

Congenital disorder characterized by impaired muscle movement, tone, and posture. Breech birth is a risk factor.

Brain tumor signs & symptoms

More frequent & severe headaches, vision loss, diplopia, confusion, dizziness, vomiting, speech & hearing problems, and loss of coordination.