Term
| What are the nervous system fundamentals? |
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Definition
- Brain has highly specialized functional units.
- CNS is seperated by the BBB
- CNS is protected by the bones of the skull and vertebrae.
- CNS is surrounded by CSF.
- Neurons are NON-DIVIDING, PERMANENT cells. |
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Term
| What are the signs and symptoms of neurologic disorders? |
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Definition
- headache
- cerebral edema
- hydrocephalus
- Increased intracranial pressure and herniation
- seizures
-decreasing levels of consciousness |
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Term
| Explain PRIMARY VS. SECONDARY HEADACHES |
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Definition
- HEADACHES = #1 REASON FOR SEEKING HEALTH CARE IN THE US.
- PRIMARY headache types:
> Migraine headache
> Tension headaches: caused by pericranial muscle spasm
>> treatment: exercise, stress management, posture
> Chronic daily headaches (CDH)
>> 4 hrs/day, 25 days, mo.
>>> Could be related to decreased serotonin levels
- Secondary headache: Associated with an identifiable underlying cause. |
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Term
| Explain MIGRAINE headaches |
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Definition
- 70-80% of headache cases
- Clear familial tendency, most common in women ages 20-45, average onset: LATE TEENS
- Causes:
> Initial VASOCONSTRICTION followed by VASODILATION
> Decreased SEROTONIN levels appear to be important in the pathogenesis.
> Muscle problems (especially neck muscles)
- "MENSTRUAL migraine" - Cycles in estrogen withdrawal contributes to changes in SEROTONIN.
- may be triggered by some FOODS in people
- Other triggers: stress/release of stress, sunlight (esp. flickering), jet lag, etc. |
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Term
| What are the clinical signs and treatment for migraines? |
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Definition
- Extremely intensive headaches (throbbing)
- Nausea/vomitting
- Photophobia and Phonophobia
- Aggrevated by physical activity
- Often unilateral
- * Often preceded by an AURA (* REVERSIBLE focal numbness and visual blurring that PRECEDES migraines.
- Treatments: Prescription meds and preventative meds |
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Term
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Definition
- = Abnormal fluid accumulation in the brain tissue
- An increase in the fluid content of the brain tissue
- Flattened gyri and narrowed Sulci
- Leads to INCREASED INTRACRANIAL PRESSURE and may cause HERNIATION if severe. |
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Term
| Explain Increased Intracranial Pressure (ICP) |
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Definition
- Poorly tolerated due to the rigid nature of the skull
- * Normal Intracranial components (3 tissue "compartments")
> 80% brain tissue ( brain tumor, cerebral edema, etc.)
> 10% Blood supply: (hematoma, hemorrhage, etc.)
> 10% CSF ( XS production, obstruction, etc.)
- * Compensation for Increased ICP
> 1st: Decrease CSF
> 2nd: Decrease blood supply
> 3rd: herniation |
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Term
| Explain Cerebral Perfusion Pressure |
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Definition
- The pressure required to get blood to the brain tissue.
- Formula = MAP - ICP
- * If the ICP becomes close to or greater than the MAP, then the tissue perfusion will DECREASE (due to pressure gradient, the pressure in the skull will be too high and blood won't go up there)
- The result is hypoxia and cell injury and/or cell death. |
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Term
| Explain ICP symptoms, etc. |
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Definition
- It's a LIFE-THREATENING condition
- Symptoms depend on HOW FAST it develops
> Sudden, explosive increase: sudden death
> Rapid, but more gradual increase: severe headache, blurred vision, vomiting
> Chronic elevation: headaches, dementia, personality changes
- If severe could lead to HERNIATION
- Death due to increased ICP is due to the compression of the vital centers in the brain stem. |
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Term
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Definition
- The displacement of brain tissue.
- Increased intracranial pressure isn't always evenly distributed.
- Brain tissue shifts from an ANATOMICAL COMPARTMENT of High pressure to an area of lower pressure.
- * Results in:
> Compression of blood vessels in the herniated tissue.
> Increased pressure on the parts of the brain that were normally located there. |
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Term
| Explain Herniations involving medulla oblongata |
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Definition
- Eventually the increased pressure will lead to DOWNWARD DISPLACEMENT of the brain.
- Hernation of the medulla oblongata of the FORAMEN MAGNUM may result.
- Immediate death will occur since this is where the CARDIO-RESPIRATORY center is. |
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Term
How much CSF is in the body at one time?
How much produced per day? |
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Definition
- At one time there is 150 ml of CSF.
- Body produces 500 ml/day however. |
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Term
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Definition
- An abnormal increase in the CSF volume in any part or all parts of the ventricular system.
- * Causes:
> Congenital abnormalities
> obstruction by tumor encroachment
> inflammation
> post-infection scarring blocks villi
> villi obstructed with debris or blood
- * Hydrocephalus ex vacuo
> secondary to brain atrophy |
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Term
| Explain CONGENITAL HYDROCEPHALUS |
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Definition
- Cranial sutures separate leading to bulging of the fontanels.
- ICP may remain near normal.
- surgical shunting procedures
- risk of developmental disorders |
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Term
| Explain the ALTERED STATES OF CONSCIOUSNESS |
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Definition
- *Normal consciousness has two distinct components:
> AROUSAL: the state of WAKEFULNESS
> CONTENT OF THOUGHT: The state of AWARENESS
- Unconsciousness: the state of being insensible, or without conscious experience
> Sleep: phsiologic unconsciousness
> various intermediate states
> Coma: profound unconsciousness |
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Term
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Definition
- A rapid, high frequency electrical discharge of cerebral neurons.
- Seizures are a symptom, not a disease.
- "Seizure threshold" is genetically variable.
- CONVULSION: jerky, rapid, contract-release movement often seen with seizures.
- * Phases of seizures:
> Aura (Pre-Ictal): Short
> Ictal: Actual seizure
> Post-Ictal: Aftermath of seizure |
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Term
| * Explain the different types of Seizures |
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Definition
- GENERALIZED seizures: Involves neurons located bilaterally, consciousness is always lost
- PARTIAL seizures: Involves neurons located unilaterally
- SECONDARY GENERALIZED seizures: Starts off as a partial and then moves onto a generalized seizure.
- CLUSTER seizures: A subsequent onset of multiple seizures, where one starts before the previous one even finishes
- STATUS EPILEPTICUS seizures: Patient remains in a constant seizure until treatment is done, fatal w/o treatment |
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Term
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Definition
- Epilepsy: term for a primary condition that causes seizures.
> Some examples that cause epilepsy: metabolic defects, genetic predisposition, congenital malformation |
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Term
| * 1/3 of seizures are caused by a secondary cause: |
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Definition
- Cerebral lesion: brain tumor, anoxia, vascular disease, infarctions, infections, etc.
- Metabolic disorder: hypoglycemia, hypocalcemia
- Cerebral trauma: head trauma, perinatal trauma, postnatal trauma, etc. |
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Term
| * What are the different mechanisms of head trauma? |
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Definition
- Primary injury: Caused DIRECTLY by the insult. (baseball bat, trauma, etc.)
- Secondary injury: other problems seen IN THE HEAD INDIRECTLY due to insult, includes cerebral edema, hemorrhage, increased ICP, and hypoxia from cerebral ischemia
- Tertiary injury: Seen in OTHER PARTS OF THE BODY as a result of a primary injury. (apnea, decreased pulmonary resistance, changes in the ECG, hypotension) |
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Term
| Expand on Primary Injuries more |
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Definition
- Primary Injuries can be caused by blunt or open trauma and can include:
> Concussion: Functional disturbance
> Contusion: bruising
> Hematoma and hemorrhage: epidural or subdural
> Skull fractures: simple, depressed, basilar |
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Term
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Definition
- Functional disturbance w/o significant macroscopic changes
- Patients recover w/o permanent sequelae
> old belief is now requestioned
- "Post-concussion syndrome"
> insomnia, headache, irritability, poor memory and concentration
- Grading scale:
- Mild concussions (grades I-III)
- diffuse brain injury
- Confusion and disorientation with brief amnesia but NEVER was unconscious
- "Classic" Concussion ( grade IV)
> Immediate loss of CONSCIOUSNESS with amnesia |
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Term
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Definition
- Bruise to the cortical surface of the brain
- focal injury due to blunt trauma
- high fatality rate
- can lead to hematomas
- * Coup Lesion: Bruising located at the site of impact
- * Countercoup lesion: located at opposite side of impact due to brain hitting the opposite side of the skull
- High mortality, those who survive usually have considerable neurological problems |
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Term
| Explain Intracranial Hemorrhages / Hematoma's |
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Definition
- IntraCRANIAL (in the SKULL, not brain)
- Compresses the underlying brain tissue
- May be caused by:
- Rupture of an aneurysm
- rupture of a congenitally abnormal blood vessel
- Rupture of a blood vessel due to hypertension
- trauma
- bleeding disorders
- * Location / Cause
> epidural or subdural space -> trauma
> intracerebral hemorrhages --> cerebrovascular disease
> subarachnoid hemorrhages --> cerebrovascular disease |
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Term
| Explain a Epidural Hematoma / Hemorrhage |
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Definition
- Most common site is the rupture of the MIDDLE MENINGEAL ARTERY as it passes along the temporal bone from a SKULL FRACTURE.
- If not drained immediately it can cause herniation and death.
- Many patients are lucid at first but progressively lose consciousness
- Bleeding is arterial so it expands rapidly |
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Term
| Explain a Subdural Hematoma / Hemorrhage |
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Definition
| - Disruption of the BRIDGING VEINS that extend from the surface of the brain to the dural sinuses. |
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Term
| * Explain a Acute Subdural Hematoma |
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Definition
- Caused by a rapid change in head velocity (whiplash, shaking a baby)
- Ranges from small to massive, unilateral or bilateral
- Compression on the brain --> Increased ICP --> Possible Hernation
- May evolve into chronic subdural Hematoma |
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Term
| Explain * Chronic Subdural Hematoma / Hemorrhage |
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Definition
- Develops over a period of weeks to months
- Often associated with BRAIN ATROPHY
- Composed of a YELLOW TINGED FLUID separated from the surface of the brain and the dura mater by a NEOMEMBRANE composed of collagen and granulation tissue.
- Because symptoms are slowly evolving this is often confused with DEMENTIA. |
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Term
| Explain Cerebrovascular disorders |
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Definition
- 3rd leading cause of death in the US.
- Brain makes up 2% of the body weight, but consumes 20% of the oxygen.
- * Cerebrovascular disorder's include:
> Subarachnoid Hematoma / Hemorrhage
> Intracerebral Hematoma / Hemorrhage
> Cerebrovascular Accident (CVA) / Stroke
> Arteriovenous Malformation (AVM)
>Aneurysm
> Headache |
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Term
| Explain a Subarachnoid Hemorrhage/Hematoma |
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Definition
- Blood escapes from a defect into the subarachnoid space --> Bloody CSF tap
- Results from:
> IntraCRANIAL aneurysm
> AVM
> hypertension |
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Term
| Explain Intracerebral Hemorrhage / Hematoma |
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Definition
- In the BRAIN
- NOT the same as INTRACRANIAL
- Most COMMON underlying cause is HYPERTENSION.
- Neoplasm
- Aneurysm
- Open heart surgery
- Coagulation disorders
- Vascular Malformation |
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Term
| Explain what can be expected to see in a Cerebrovascular Accident of the Middle Cerebral Artery |
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Definition
- Contralateral hemiparesis and spasticity
- Loss of sensation on the side of the body OPPOSITE of the side the infarct occurred.
- visual field abnormalities
- speech abnormalities |
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Term
| Explain what happens in extreme cases and most cases with a cerebrovascular accident with the Internal Carotid Artery |
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Definition
- Extreme cases: Ipsilateral cerebral hemisphere infarction with monocular blindness.
- Most cases: Collateral flow from the circle of willis supplies the internal carotid area, so deficits are diminished. |
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Term
| Explain the clinical significance in a Cerebrovascular Accident in the Vertebrobasilar Arteries |
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Definition
- Variance in clinical significance
> Large, rapidly fatal infarcts involving the brain stem.
> Small, clinically silent infarcts |
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Term
| Explain Transient Ischemic Attacks (TIA's) |
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Definition
- "Mini-stroke"
- It is ischemia WITHOUT the infarction
- Often precedes cerebrovascular accidents
- Comparable to angina
- last several MINUTES to several HOURS
- Self limiting episodes of obstruction by emboli or platelet aggregates
- 1/3 of patients with TIA's will have a significant infarct within 5 years. |
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Term
| Explain Cerebral Aneurysms |
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Definition
- * The most common cause of spontaneous SUBARACHNOID HEMORRHAGE is rupture of a SACCULAR ANEURYSM.
- Types of Cerebral Aneurysms:
> saccular aneurysms: present in 1% of the general population
- fusiform dilations: atherosclerosis
> infectious "mycotic" Aneurysms (bacterial)
> dissecting aneurysm |
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Term
| Explain the Sites of Saccular Aneuysm |
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Definition
- * Most (80%) of saccular aneurysms arise at BIFURCATIONS.
- Thought to arise from congenital defects (1% of population)
- At a greatest risk of rupture when the diameter of the aneurysm is between * 4-7mm. |
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Term
| Explain the clinical features of Saccular Aneurysms |
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Definition
- space-occupying lesions, INCREASED ICP
- abrupt onset associated with severe headache, vomiting, and loss of consciousness (if rupture)
- 50% of these patients die within several days
- Other complications *
> Cerebral Infarcts (usually within 4-9 days)
> Acute Hydrocephalus
> Herniation
> Chronic Hydrocephalus (may develop in survivors) |
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Term
| Explain Arteriovenous Malformations |
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Definition
- * CONGENITAL
- Abnormalities in the angiogenesis, producing a mass of tortuous blood vessels
- Range from small incidental lesions to large ones associated with variable neurologic deficits and massive hemorrhage.
- * Lack a capillary bed
- Small arteries have a deficient in the TUNIC MEDIA
- blood is shunted from high pressures to low pressures without the normal "buffering" from the capillary system
- Predisposed to rupture and hemorrhaging |
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Term
| Explain Nervous system Diseases and Infections |
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Definition
- The CNS may be affected by diseases that affect specific organs, or brain specific diseases.
- * Multi-systemic diseases:
> Liver disease (Hepatic Encephalopathy)
> Atherosclerosis
- * Brain-specific diseases:
> Prions = Infectious proteins
> Polio = a neurotropic virus
> Rabies = racoons, foxes, bats, skunks |
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Term
| Explain Infections of the Nervous System |
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Definition
- The CNS may be directly attacked by bacteria, viruses, fungi, protozoans, rickettsiae.
- Results in a pyogenic (NOT PYROGENIC) Infection, some may be toxic
- * Common Nervous System Infection:
> Meningitis: Infection of the meninges
> Abscess: Localized collection of pus
> Encephalitis: acute illness, usually viral |
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Term
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Definition
- Meningitis may be caused by bacteria, viruses, fungi, parasites, or other toxins
- * Acute Purulent Meningitis: Bacterial; fatal without treatment (Neutrophils)
- * Acute Lymphocytic Meningitis: Viral, cases are often self-limiting (Lymphocytes)
- * Spinal Meningitis: Implications;
> Increased ICP
> Increased pressure on spinal cord |
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Term
| Explain Bacterial Meningitis |
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Definition
- Infection of the CSF in the subarachnoid space, and ventricular system
- Organisms from the blood stream, ear or sinuses, or opening cause the infection
- Fever, headache, vomiting, stiff neck, seizures, blurred vision, numbness
- Complication: * Secondary Hydrocephalus
- Treatment: * Penicillin |
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Term
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Definition
- Focal defect filled with pus (liquefactive necrosis)
- May be caused by a variety of different BACTERIA
- Sources of bacteria include: Endocarditis, Lung Abscess
- Clinical Features include: Fever, Increased ICP, variable neurologic deficits |
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Term
| Explain Viral Encephalitis |
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Definition
- * Most common causes are:
> Herpes Simplex
> Arthropod-borne viruses: occur in epidemics, varying seasonally and geographically
> Starts off in birds ("natural reservoir") then mosquitoes act as the transport units and gives the virus to humans ("accidental host")
- Can result in widespread nerve cell degeneration, edema, and area's of necrosis +/- hemorrhage.
- May range from a mild infectious disease to a life threatening disorder.
- Symptoms: Fever, delirium, unconsciousness, seizures, paralysis, abnormal reflexes, etc. |
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Term
| Explain Degenerative Diseases |
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Definition
- Disorders characterized by spontaneous, progressive degeneration of neurons
> May or may not be familial (hereditary)
- * Common degenerative disorders of the CNS:
> Alzheimer's - most common cause of dementia
> Parkinson's - disturbance in motor function
> Multiple Sclerosis - autoimmune demyelination |
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Term
| Explain Alzheimer's Disease |
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Definition
- One of the MOST COMMON causes of SEVERE cognitive dysfunction in older persons.
- Progressive increase in incidence with increasing age.
- Symptoms:
- Subtle at first and often confused with depression
- Progressive impairment in memory (especially recent events) and other cognitive functions.
- Patient becomes disorientated and confused
- Results in complete disorientation and loss of language and other higher cortical functions. |
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Term
| Explain the possible causes of Alzheimer's |
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Definition
- unknown cause; possible theories include:
- GENETIC FACTORS play a role in some cases
- ** Implication of abnormalities on chromosomes 21, 19, and 14
> Down syndrome patients over 40 years old
> * most familial cases have a mutation on chromosome 14
> no single genetic defect responsible for all cases
- Deposition of AMYLOID is a consistent feature
- LOSS OF NEUROTRANSMITTER STIMULATION |
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Term
| Explain Parkinson's Disease |
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Definition
- * Disturbance in motor functions: characterized by rigidity, stooped posture, gait disturbances, slowing of voluntary movements, and a characteristic tremor
- ** Parkinson's is not a single disease: But a disturbance in the dopamine-secreting neurons in a particular part of the brain
- Can be due to: trauma, toxic agents, vascular diseases, encephalitis, etc. |
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Term
| Explain Multiple Sclerosis |
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Definition
- An AUTOIMMUNE DEMYELINATING disease that affects the CNS.
> * T cells are reactive to a component of the myelin.
> Hereditary and environmental factors MAY play a role in the development of the autoimmunity.
- Young adults (age 18-40 years)
- Acute or Insidious onset, followed my multiple exacerbations and remissions (ex... = disease gets worse, remissions = disease gets better) |
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Term
| Explain the Clinical features of Multiple Sclerosis |
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Definition
- Course:
> Some patients die within weeks to months
> some have a normal lifespan
- Common manifestations include:
> Visual and speech disturbances
> paresthesia (abnormal sensations)
> spasticity of one or more extremities
> gait abnormalities
> Intellectual Function is TYPICALLY preserved |
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