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Flashcards in Nervous System Deck (42):
1

Describe the functions of the four major lobes of the brain.

Frontal motor functions, behavior, emotions, higher intellect.

Parietal sensory functions.

Occipital visual center. 

Temporal hearing and smelling.

2

Compare the functions of the midbrain, pons, and medulla oblongata with that of the cerebellum. 

midbrain, pons, MO = myelinated nerve bundles connecting brain to SC
visual and auditory reflex, cardiac, vasomotor, respiratory centers

 

cerebellum = sensory input from SC and inner ear to cortex

balance, muscle tone, mvmt coordination

3

Describe the function of the spinal cord.

anterior horn >> peripheral nerves

- extensions of cortical and subcortical brain neurons

- carry motor impulses 

posterior horn >> spinal ganglia

- carry sensory input

4

Describe the circulation of the cerebral spinal fluid.

Produced by choroid plexus in 3rd ventricles.  Flows at low pressure lateral ventricles >> 3rd V >> 4th V >> lateral openings + median opening >> central canal of SC

5

List the main cells of the nervous system. 

Glial cells (support) = astrocytes, oligodendroglia, microlia, ependymal

Neurons

6

What are the most important diseases of the nervous system.

  • Developmental and genetic diseases
  • Diseases caused by trauma
  • Circulatory disorders
  • Infectious diseases
  • Autoimmune diseases
  • Metabolic and nutritional diseases
  • Neurodegenerative diseases
  • Brain tumors

7

What are the sites of brain herniation caused by intracranial hypertension?

Subfalcine herniation: cingulate gyrus protrudes beneath the falx cerebri

Transtentorial herniation: uncus protrudes tentorium cerebelli

Tonsillar hernation: cerebellar tonsils protruding into the foramen magnum

8

List the main dysraphic disorders of the CNS and describe their pathogenesis.

Incomplete fusion of the neural tube >> dysraphic disorders

anencephaly calvaria not formed

meningocele meninges protrude through defect

myelomeningocele protrusion of meninges + SC

spina bifida absence of vertebral arches

9

List the most important intracranial hemorrhages and describe their causes

Epidural hematoma usually from fracture, rupture of middle meningeal artery, lethal

Subdural hematoma tearing of thin-walled veins, accumulation over lateral hemispheres

Subarachnoid hemorrhages ruptured aneurysms, typically at the base of the brain, may be preceded by HTN

Intracerebral head trauma, stroke, hematologic disease

10

What is stroke?

Ischemic (85%)

or hemorrhagic (15%)

 

11

What is global cerebral ischemia, and what are its consequences?

Widespread atherosclerotic narrowing over entire cerebrovascular system

small lacunar infarcts >> multi-infarct dementia

 

12

What is the pathogenesis of "watershed infarcts" and laminar necrosis of the brain?

Watershed infarcts: hypoperfusion of the marginal zones between arteries (carotid and basilar)

Laminar necrosis: hypoperfusion of deeper zones of gray matter that receive blood from penetrating arteries

13

Describe the pathology of cerebral infarcts.

Thrombotic occlusion >> infarct

ischmic brain = liquefactive necrosis = encephalomalacia

- pale or hemorrhagic (more common with arterial thrombi)

infarct becomes pseudocyst

 

14

Correlate the pathology of intracerebral hemorrhage with the clinical features of the disease.

Most common site: basal ganglia

infarct >> pseudocysts with wall of  hemosider laden macrophages

Basal ganglia: hemiplegia, hemiparesis

Cerebellar: nausea, vomiting, loss of balance, HA

Pontine: death

15

What are the main pathologic findings after brain injury?

Concussion: transient LOC, NO significant brain changes

Contusion: bruise, hemorrhagic coup and contercoup lesion

Laceration: open trauma, neurologic deficit

16

Compare hyperextension and hyperflexion injuries of the cervical spine.

hyperextension - rupture of anterior spinal ligaments, compression of posterior SC

hyperflexion - compression of anterior SC

17

Compare bacterial and viral infections of the CNS

Bacterial

Spread: sepsis, bacteremia, septic emboli, open wounds, sinus infection, inner ear infection
*Strep pneumoniae causes most cases of bacterial meningitis in adults

Viral
Spread: hematogenous spread

*herpes = most common viral cause of localized encephalitis in the US

18

What are prions?

Prions = small infectious particles composed of proteins

*do not contain dna/rna

19

List the most important protozoal and fungal causes of opportunistic diseases of the CNS.

Protozoal: toxoplasmosis (neonates, AIDs)

 

Fungal: candida, aspergillus, cryptococcus (AIDs)

20

Compare the pathology of encephalitis and meningitis.

encephalitis = localized or diffuse inflammation of brain parenchyma

usually virus invades neural or glial cells

meningitis = inflammation of the meninges

21

Describe the features of neurosyphilis.

- usually presents as chronic meningitis

- meninges: infiltrated with lymphocytes and plasma cells (small BV)

- perivascular inflammation >> cortical ischemia

- tabes dorsalis = atrophy of dorsal (sensory columns)

22

What are the most important AIDS-related CNS lesions?

HIV infects macrophages and T lymphocytes, and these cells "import" the virus to the CNS

 

toxoplasma, cryptococcus

23

What is MS?

An autoimmune demyelinating disease

W > M, 20-45 y/o

24

Correlate the pathologic features of MS with the clinical signs and symptoms of this disease.

Presence of IgG oligoclonal bands >> responding to antigen?

- Typically involves white matter >> both sensory and motor abnormalities

- Periventricular plaques (lateral hemispheres)

- early lesions = lymphocytes and foamy macrophages

- late lesions = demyelinated axons and reactive astrocytes (gliosis)

25

How do inborn errors of metabolism affect the CNS?

Tay-Sachs = deficiency of hexosaminidase A >> accumulation of gangliosides

Neimann-Pick = deficiency of sphingomyelinase >> accumulation of sphingomyelin >> atrophy

26

What is the cause and what are the signs of Wernicke-Korsakoff syndrome?

Thiamine deficiency!

Wernicke's = ocular, gait, mental

Korsakoff's = amnesia, confabulation

hypothalamus, periaqueductal region (midbrain), mamillary bodies

27

How does alcohol affect the brain?

  • Dementia (atrophy of gyri)
  • Dilated ventricle
  • Wernicke-Korsakoff syndrome
  • Pontine myelinolysis (r/t vigorous Na correction)
  • Myelopathy
  • Neuropathy
  • Myopathy
  • Subdural hematoma
  • Cerebellar atrophy

28

What are the most important neurodegenerative diseases?

Alzheimers >> frontal/occipital cortex

Huntingtons >> frontal cortex and basal ganglia

Parkinsons >> substantia nigra

ALS >> motor neurons in anterior horn of SC, brainstem, frontal cortex

29

What is Alzheimer's disease, and how is it diagnosed?

Clinical diagnosis based on demonstration of progressive dementia (excluding other causes)

30

Describe the macroscopic and microscopic pathologic findings in Alzheimer's disease.

Chromosome's 21 &19 >> APOE4 (19) mutation >> beta amyloid= extracellular

hyperphosphorylation of tau protein >> axonal microtubule binding = intracellular

Brain is atrophic, neuritic plaques, neurofibrillary tangles, deposition of amyloid (see with silver impregnation and congo red stain)

31

What is Parkinson's disease?

A subcortical neurodegenerative disorder characterizd by movement disorder and changes of EPS nuclei

*decreased number of dopaminergic neurons in substantia nigra

32

Correlate the pathology of Parkinson's disease with the clinical features of the disease.

depigmented substantia nigra, due to loss of dopaminergic neurons, decreased amount of dopamine in striatum

loss of neurotransmitters correlates with the clinical appearance of movement disorders

loss of melanin-rich neurons, remaining neurons contain round eosinophilic inclusions = lewy bodies (beta synuclein)

33

What is ALS?

Possibly caused mutation of copper-zinc superoxide dismutase (SOD1) on chromosome 21

motor weakness and progressive muscle wasting

34

Correlate the pathology of ALS to the clinical features.

Loss of motor neurons in SC, midbrain, cerebral cortex

(most prominent lateral cerebrospinal pathways)

weakness and wasting of small hand muscles >> fasciculation >> slurred speech >> paralysis of respiratory muscles

35

Classify brain tumors.

50% are metastases

75% glial

15% meningeal

5% cranial/spinal nerves

2% neural cell precursors

 

36

List the most common brain tumors and their predominant location.

  • medulloblastoma >> cerebellum
  • astrocytoma >> cerebrum (children = cerebellum)
  • meningioma >> falx cerebri
  • glioblastoma multiforme >> cerebrum
  • oligodendroglioma
  • ependymoma >> 4th ventricle
  • schwannoma

37

Compare glioblastoma with other gliomas.

glioblastoma = most common

- butterfly-like appearance (crosses hemispheres)

- highly anaplastic astrocytic cells (fetal appearance, small blue nuclei, no cytoplasm) 

or multinucleated, bizarre

38

Which brain tumors occur most often in children?

Medulloblastoma!

Ependymoma

Pilocytic astrocytoma

39

Why do medulloblastomas metastasize?

They can enter CSF and be carried by CSF

40

What are meningiomas?

Most are benign, impinge from outside the cerebral hemispheres

10x more common in Women

surgically curable, good prognosis

41

Which tumors originate from the peripheral nerves?

schwanomma

neuroma

42