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Neural Tube Defects
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=Associated w/ low FOLIC ACID intake during pregnancy
**Elevated alpha-fetoprotein in amniotic fluid + maternal serum = indicates possible NTD
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Spina Bifida Occulta
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=Failure of bony spinal canal to close but NO structural herniation
**Usually seen at lower vertebral levels
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Meningocele
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=meninges herniate through spinal canal defect
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Meningomyelocele
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=meninges + SC herniate through spinal canal defect
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BRAIN LESIONS
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**I will give you the AREA of the lesion
=you say the CONSEQUENCE
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Broca's Area
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=Motor (i.e. nonfluent/expressive) aphasia with GOOD comprehension
**i.e. speech is difficult to initiate, nonfluent, labored
=they know what they want to say but have trouble getting it out
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Wernicke's Area
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=Sensory (i.e. fluent/receptive) aphasia w/ POOR comprehension
**may vary from insertion of a few incorrect words to an outpouring of jargon
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How to remember Broca vs. Wernicke's?
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BROca's is BROken speech.
Wernicke's is Wordy but makes no sense.
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Arcuate fasciculus
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**Conduction aphasia
=poor repitition w/ good comprehension
=fluent speech
**i.e. the arcuate fasciculus runs between Broca's and Wernike's
=SO, the patient can understand what is being said BUT cannot repeat it/repeats it incorrectly
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Amygdala (=bilateral)
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**Kluver-Bucy Syndrome:
=hyperorality
=hypersexuality
=disinhibited behavior
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Frontal Lobe
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**Personality changes and deficits in concentration, orientation, and judgement.
**May have reemergencce of primitive reflexes.
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Right Parietal Lobe
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**Spatial Neglect Syndrome
=agnosia of the contralateral side of the world --> i.e. leads to neglect of the left side of the visual field
**SO, patient may only eat food on the right side of the plate or only draw the right side of the clock.
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Reticular Activating System
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COMA
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Mamillary Bodies (=bilateral)
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Wernicke-Korsakoff Syndrome
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Basal Ganglia
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**May result in a tremor at rest, chorea, or athetosis (i.e. slow writhing movements of hands or feet--seen in end stages of Huntington's).
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Cerebellar Hemisphere
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Intention tremor, limb ataxia
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Cerebellar Vermis
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Truncal ataxia, dysarthria
**Ok, so think:
=Cerebellar hemispheres are locating LATERALLY and so affect LATERAL LIMBS
=Vermis is located CENTRALLY and so affects the CENTRAL body
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Subthalamic Nucleus
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Contralateral hemiballismus (i.e. large amplitude flinging movements usually of arms/legs)
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Chorea
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**Chorea = dancing (Greek)
**Sudden, jerky purposeless movements
**Characteristic of BASAL GANGLIA lesion = i.e. Huntington's Disease
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Athetosis
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**Slow, writhing movements, especially of fingers.
**Characteristic of basal ganglia lesions
**Athetos = not fixed
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Hemiballismus
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**Sudden, wild flailing of 1 arm.
**Chacteristic of CONTRALATERAL SUBTHALAMIC NUCLEUS lesion.
=loss of inhibition of thalamus through globus pallidus
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Aphasia
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1) Broca's
2) Wernicke's
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Broca's Aphasia
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=Nonfluent aphasia w/ intact comprehension
**Broca's Area = inferior frontal gyrus
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Wernicke's Aphasia
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=Fluent aphasia w/ impaired comprehension
**Wernicke's Area = Superior Temporal Gyrus
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Involving the CEREBRAL CORTEX:
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1) Alzheimer's Disease
2) Pick's Disease
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Alzhemier's Disease
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**MOST COMMON CAUSE of dementia in the elderly
**Associated with:
1) Senile Plaques
=extracellular
=B-amyloid core
2) Neurofibrillary Tangles
=intracellular
=abnormally phosphorylated tau protein
**Don't forget that AD may cause amyloid angiopathy --> INTRACRANIAL HEMORRHAGE!
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Genetics of AD
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**Familial Form (10%) associated w/ genes on chromosomes 1, 14, 19 (ApoE4 allele) and 21 (p-App gene)
COLOR IMAGE 41
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What is the SECOND most common cause of dementia in the elderly?
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MULTI-INFARCT DEMENTIA
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Pick's Disease
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**Characterized by:
1) Dementia
2) Aphasia
3) Parkinsonian symptoms
**Associated with PICK BODIES:
=intracellular, aggregated TAU protein
**Specific for FRONTAL + TEMPORAL LOBES
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Diseases involving BASAL GANGLIA + BRAINSTEM:
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1) Huntington's Disease
2) Parkinson's Disease
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Huntington's Disease:
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**Autosomal dominant inheritance.
**Characterized by:
1) Chorea
2) Dementia
**Caused by atrophy of the CAUDATE NUCLEUS
=loss of GABAergic neurons--lose ACh + GABA
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Genetics of HD:
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**Caused by a trinucleotide repeat--CAG--on chromosome 4
=CAG --> "Caudate loses ACh + GABA"
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Parkinson's Disease
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**Associated w/ Lewy bodies (=eosinophilic intracytoplasmic inclusion found in the remaining dopaminergic neurons) + depigmentation of the substantia nigra pars compacta (=and thus loss of dopaminergic neurons)
**RARE cases have been linked to exposure to MPTP--a contaminant in illicit street drugs
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Symptoms of PD:
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TRAP
=Tremor (at rest)
=Rigidity (cogwheel)
=Akinesia/bradykinesia
=Postural instability
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Diseases involving SPINOCEREBELLAR region:
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1) Olivopontocerebellar Atrophy
2) Friedreich's ataxia
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Diseases involving the MOTOR NEURON:
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1) Amyotrophic Lateral Sclerosis ("Lou Gehrig's dz.)
2) Werdnig-Hoffmann Disease
3) Polio
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ALS
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=associated w/ BOTH UMN and LMN signs
=NO SENSORY deficit
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Werdnig-Hoffman Disease
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=Autosomal Recessive inheritance --> associated w/ degeneration of anterior horns
**Presents are BIRTH as a "FLOPPY BABY" + tongue fasciculations
**Median age of death = 7 months
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Polio
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=Follows infection w/ poliovirus
**Associated w/ degeneration of the anterior horns
=LMN signs
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What is Poliomyelitis?
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**Caused by POLIOVIRUS
=transmitted via the fecal-oral route
=replicates in the oropharynx and small intestine before spreading through the bloodstream to the CNS
=in the CNS --> leads to destruction of cells in the ANTERIOR HORN of the SC (=lower motor neuron destruction)
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Symptoms:
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=Malaise
=Headache
=Fever
=Nausea + abdominal pain
=Sore throat
+ Signs of LMN lesions:
=Muscle weakness + atrophy
=Fasciculations
=Fibrillation
=Hyporeflexia
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Findings:
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**CSF w/ lymphocytic pleocytosis (=i.e. increased white cell count) w/ slight elevation of protein
**Virus can be recovered from the stool OR throat.
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Demyelinating + Dysmyelinating Diseases
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1) MS
2) PML
3) Acute Disseminated (postinfectious) Encephalomyelitis
4) Metachromatic leukodystrophy
=a lysosomal storage disease
5) Guillian-Barre Syndrome
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Multiple Sclerosis: Epidemiology
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**Most often affects WOMEN in their 20's and 30's
=more common in WHITES
**Increased prevalence with INCREASED DISTANCE from the equator
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Histology:
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**Periventricular plaques (=areas of oligodendrocyte loss + reactive gliosis) w/ an intial SPARING of axons
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Presentation:
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**Most patients have a relapsing-remitting course
**Patients can present intitially w/:
=Optic Neuritis --> painful blind eye
=MLF Syndrome --> internuclear ophthalmoplegia
=Hemiparesis
=Hemisensory symptoms--numbness or weakness
=Bowel/bladder incontinence
COLOR IMAGE 47
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What is internuclear opthalmoplegia?
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=i.e. MLF Syndrome
**Occurs when you have demyelination of the medial longitudinal fasciculus --> causes binocular diplopia = double vision w/ both eyes open!
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The "CLASSIC" Triad of MS:
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MS is a SIN!
1) Scanning speech
=staccato-like speech where syllables of words are separated by pauses
2) Intention tremor
3) Nystagmus
**Patients will also have elevated protein (IgG) in their CSF.
COLOR IMAGE 47
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Treatment of MS:
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B-interferon OR immunosuppressant therapy
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Progressive Multifocal Leukoencephalopathy
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**Associated w/ the JC virus
**Seen in 2-4% of AIDS patients
=i.e. reactivation of latent viral infection
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