Lesions and Disorders Flashcards
Cerebellar lesions produce…
Dysmetria (movements that are inaccurate in space and disjointed in time)
Think that this is because the cerebellum’s major function is to enable smooth, coordinated movement (sort of like Tai Chi).
Tetanus toxin
Fill in, from spinal cord chapter
Lower motor nerve lesions
With few exceptions, these result in flaccid paralysis ipsilateral to and at the level of the lesions.
Other symptoms include hyporeflexia, hypotonicity, fasciculations, atropy (wasting) of the affected motor units, and fibrillations.
Poliomyelitis
Fill in
UMN lesion
Result in spastic (i.e. hypertonic,stiff) paresis (wakness) that may be ipsilateral, or contralateral, to the lesion, and below the level of the lesion.
Will result in hyperreflexia.
Horner’s Syndrome
Results in the following signs ipsilateral to the lesion:
Meiosis
Ptosis
Anhydrosis
Also results in orthostatic/postural hypotension
Is due to a lesion that interferes with autonomic axons in the hypothalamic tract and/or the sympathetic chain.
Uncal Herniation
In the event of increased intracranial pressure, uncal herniation can cause descending contralateral motor problems via compression of the cerebral peduncle.
CN III may also be compressed (signs include CN III palsy, ptosis, and dilated/”blown” pupil)
CN III Palsy
Results in loss of function all the muscles that control the eye except for the SO and LR muscles -> this leads to a “down-and-out” eye (external strabismus).
Knocks out the levator palpabrae superioris -> drooping eyelid (ptosis)
Loss of the autonomic innervation of the pupil constrictor muscle, the sphincter pupillae -> blown/constitutively dilated pupil (myadrasis)
CN VI Palsy
This results in internal strabismus (inwardly deviated eye)
Patients present with diplopia
Hemiparesis
Fill in
Bell’s Palsy
Idiopathic unilateral facial paralysis
Loss of the function of muscles of facial expression on the side ipsilateral to lesion due to a cranial nerve VII lesion (Facial nerve lesion)
What is the difference between a central and a peripheral Bell’s Palsy?
The forehead muscles receive mixed innervation from both facial nerves.
Therefore, of the lesion to the facial nerve occurs above the level of the isolated facial nerve, it is a central facial palsy, where the paralysis is only below the level of the forehead).
Peripheral facial palsy results in paralysis of the entire side of the lesion that is ipsilateral to the lesion.
Upper (superior) homonomous quadrantanopsia
“Pie in the sky” scotoma.
Results from lesions to (contralateral?) Meyer’s loop.
Which region of the brain is pathologic in Parkinson’s disease?
Destruction of the dopaminergic neurons in the substantia nigra pars compacta,(SNc) leads to dopamine depletion and consequent strong inhibition of the thalamus and movement.
Which region of the brain is pathologic in Huntington’s disease?
The striatum
Movement disorders
Conditions characterized by abnormal voluntary movements or by the presence of excessive involuntary movements.
Can have hyper- or hypo-kinetic features.
What types of dysfunctions do movement disorders reflect?
Dysfunction:
- among basal ganglial structures
- between the basal ganglia, cerebellum, and other CNS areas.
What are the four major symptoms of parkinsonism?
- Bradykinesis (hypokinesis)
- rest tremor
- postural instability
- rigidity
(TBP R) -> tau beta pi recruitment
(tremor, bradykinesis, postural instability, rigidity)
Hypokinetic movement disorders
Too few, too small, too slow
All have a core of “parkinsonism,” i.e. bradykinesis/akinesia and rigidity.
PD and other causes of parkinsonism (multiple systems atrophy, progressive supranuclear palsy).
Hyperkinetic movement disorders
Too much, too big, too fast
May be jerky (myoclonus, chorea, ballism, tics), or not-jerky (dystonia, athetosis, tremor)
Grestmann’s Syndrome
Left parietal lesion of the “angular gyrus”.
Results in “body schema disturbance” (Autopagnosia), although the four following signs are typical:
- agraphia
- finger agnosia
- acalculia
- R/L confusion
Balint’s Syndrome
Disorder of reaching and looking.
Due to bilateral parietal lesions.
Can arise from the tau-opathies, prion disease, etc.