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Neuroanatomy III > 27 - Lesions III > Flashcards

27 - Lesions III Flashcards

1
Q

Basal ganglia function

A

Inhibition and facilitation

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2
Q

Describe inhibition of the basal ganglia

A

Inhibiting involuntary movement at rest

Stopping volitional movements upon completion

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3
Q

Describe facilitation of the basal ganglia

A

Releasing or disinhibiting voluntary movements

Accelerating voluntary movements

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4
Q

Chorea

A

dance-like, involuntary, rapid movements. Can be associated with Huntington disease, rheumatic fever, systemic lupus erythematosus, and other conditions

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5
Q

Athetosis

A

slow, twisting, writhing movements, with larger amplitude than chorea, commonly involving the hands

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6
Q

Hemiballism

A

jerking and twitching movements of one side of the body (involuntary violent flinging or jerking of a limb or limbs in an uncoordinated manner caused by a lesion of the contralateral subthalamus)

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7
Q

Dystonia

A

impaired or disordered tonicity, especially muscle tone (involuntary muscle spasms)

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8
Q

What area of the brain is Parkinson’s disease associated with?

A

Basal ganglia

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9
Q

What causes Parkinson’s disease?

A

Death of dopaminergic cells in the pars compacta of the substantia nigra

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10
Q

How do you treat Parkinson’s disease?

A

L-dopa metabolized to dopamine by dopaminergic cells

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11
Q

What are the key symptoms of Parkinson’s disease?

A
  • Rigidity
  • Slowness of movement (bradykinesia)
  • Slumped posture
  • Resting tremor
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12
Q

What is the cause of the rigidity, slowness of movement and slumped posture?

A

It is a basal ganglia problem

Excessive inhibition with a lack of facilitation

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13
Q

What is the cause of the resting tremor?

A

It is a basal ganglia problem

Lack of suppression of involuntary movement

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14
Q

What is the striatum in relation to the basal ganglia?

A

The striatum is the “input gate” to the basal ganglia

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15
Q

How is the striatum affected by Parkinson’s disease? How is it affected by Huntington’s disease?

A

Parkinson’s disease results in loss of dopaminergic innervation to the striatum (and other basal ganglia) and a cascade of subsequent consequences.

Atrophy of the striatum is also involved in Huntington’s disease, choreas, choreoathetosis, and dyskinesias.

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16
Q

What is Tourette’s syndrome?

A

An inherited neuropsychiatric disorder with onset in childhood, characterized by multiple physical (motor) tics and at least one vocal (phonic) tic. These tics characteristically wax and wane, can be suppressed temporarily, and are preceded by a premonitory urge.

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17
Q

What two signs must be present to define Tourette’s?

A

Motor and vocal tics

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18
Q

What one sign, in particular, makes Tourette’s unique among all extrapyramidal syndromes?

A

Vocal tics

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19
Q

What is the cerebellum responsible for?

A

Precision

Movements are precise, on time and on target

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20
Q

In more detail, what is the function of the cerebellum?

A
  • Integration of equilibrium and locomotion
  • Integration of head and eye movements
  • Coordinating voluntary movements
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21
Q

What does coordination of voluntary movements entail?

A
  • Comparing cortical input with motor output
  • Providing feedback for ongoing movements
  • Making adjustments to ongoing movements
  • Ensuring accurate targeting
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22
Q

Ataxia

A

impaired ability to coordinate muscular movement usually associated with staggering gait and postural imbalance

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23
Q

Nystagmus

A

Involuntary eye movements

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24
Q

Dysmetria

A

Refers to a lack of coordination of movement typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye. It is a type of ataxia. It is sometimes described as an inability to judge distance or scale

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25
Q

Dysdiadochokinesia

A

Inability to quickly substitute antagonistic motor impulses to produce antagonistic muscular movements

Inability to perform rapid alternating movements (e.g., pronation/supination of hands)

Indicates cerebellar dysfunction

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26
Q

What is the midline cerebellum responsible for (vermal area)?

A

spinocerebellum- muscle tone and adjusting movements of axial trunk and proximal limbs

Think spine like a spine right down the middle

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27
Q

What is the lateral cerebellum (hemispheric area) responsible for?

A

cerebrocerebellum- precise control of executed movements (timing, duration, force, velocity and trajectory of movements, of extremities, especially hands and fingers

Think cerebro like the two sides of the brain - on the lateral sides

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28
Q

Where would you see movement problems that result from a lesion in the vermal area of the cerebellum

A

Midline cerebellum lesion

Symptoms will be present in the axial trunk and proximal portions of the limbs

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29
Q

Where would you see movement problems that result from a lesion in the hemispheric area of the cerebellum

A

Lateral cerebellum lesion

Symptoms will be present in the distal extremities, especially the hands and fingers

There will be a loss of precise control of detailed finger movements like typing or playing the piano

30
Q

Describe why cerebellar arterial syndromes typically manifest a mix of cerebellar and brainstem signs and symptoms

A

???

31
Q

What is SCA syndrome?

A

Superior cerebellar artery syndrome

32
Q

Describe SCA syndrome

A

SCA syndrome is due to thrombosis of the superior cerebellar artery that supplies the spinothalamic tract and the superior cerebellar peduncle - It’s a STROKE/INFARCT

There is incoordination in performing skilled movements, with loss of pain and temperature senses on the side of the face and body opposite to that of the lesion.

33
Q

What are the specific symptoms of SCA syndrome?

A
  • Ipsilateral dysmetria and limb ataxia
  • Contralateral pain and temperature loss
  • Contralateral superior oblique paralysis (SO4)
  • Ipsilateral Horner’s syndrome
34
Q

Horner’s syndrome

A
  • Drooping of upper eyelid (partial ptosis)
  • Constricted pupil
  • Flushed, dry face
35
Q

Describe the main functions of the limbic system

A

Hippocampus - “memory”

Amygdala - “fear”

36
Q

Describe the hippocampus function

A
  • Short term memory

- Consolidation into long term memory

37
Q

Describe the amygdala function

A
  • Basic drives (fear, rage, sexual arousal)

- Organizing behavior appropriate to drives

38
Q

What part of the brain is responsible for “working memory”? Give an example

A

Frontal cortex

Declarative memory examples
Episodic (experience) = Putting the milk on the shelf instead of the refrigerator and not remembering you did it

Semantic (factual) = Adding up a set of numbers with no intent to memorize

39
Q

What part of the brain is responsible for short-term memory? Give an example

A

Hippocampus

Declarative memory examples
Episodic (experience) = Meeting someone for the first time and learning their name, which you intend to remember

Semantic (factual) = studying neuroanatomy and trying to remember the function of the hippocampus

40
Q

What part of the brain is responsible for long-term memory? Give an example

A

Association area of the cortex

Declarative memory examples
Episodic (experience) = Remembering walking down the aisle on your wedding day

Semantic (factual) = Remembering you childhood phone number

41
Q

What are symptoms of Alzheimer’s disease?

A

Alzheimer’s disease is a degenerative disorder of the brain - most common form of dementia in elderly

Individuals with this disease are unable to form new memories

With progression of the disease, confusion and deficits in executive function occur

42
Q

What causes Alzheimer’s disease?

A

This disease is caused by pathologic alterations including neurofibrillary tangles, neuritic plaques and neuronal degeneration

43
Q

Where do these pathologic alterations occur?

A

First they appear in the entorhinal cortex (memory and navigation) of the medial temporal lobe

From there, degeneration spreads to the hippocampus

As the disease progresses, it progresses to deeper layers of the entorhinal cortex

44
Q

What is the effect of this degeneration?

A

The neuronal degeneration hinders the normal flow of information through the hippocampal formation

45
Q

What will occur as the disease progresses? Why?

A

Confusion deficits in executive function will occur following further spread of neurofibrillary tangles to the temporal pole and prefrontal cortex

Subicular pathology (degeneration in the subiculum of the hippocampus (lowest region)) occurs roughly at the same time that neurofibrillary tangles invade the temporal neocortex

46
Q

Describe the symptoms of temporal lobe epilepsy

A

In temporal lobe epilepsy, patients sometimes display bizarre behaviors or have psychological disturbances, even between seizures

47
Q

How are these symptoms associated with lesions?

A

These symptoms can be present in patients with very clear temporal lobe lesions (i.e. tumors) or even in patients without lesions

This leads to the hypothesis that the temporal lobe, specifically the medial portion of the temporal lobe, may be structurally or physiologically abnormal even if no lesion is detected there

48
Q

What can very fine resolution MRI imaging of the temporal lobe reveal?

A

Using coronal imaging, often times temporal sclerosis is found in patients with temporal lobe epilepsy

This shows up as subtle scarring and lose of volume of the parahippocampal gyri

There is a loss of volume and loss of neurons in this region and the surrounding structures

49
Q

What is a syndrome that is caused by thiamine deficiency from the diet?

A

Korsakoff’s syndrome or amnestic cofabulatory syndrome

50
Q

In what cases do we typically see Korsakoff’s syndrome?

A

It is a disorder most often resulting from a thiamine (B1) nutritional deficiency in chronic alcoholism

51
Q

Describe the symptoms and patient presentation of thiamine deficiency (Korsakoff’s syndrome)

A

Affected individuals have loss of recent memory and in order to compensate (cover) for this memory loss, they make up fictitious information or events to “fill in the gaps”

52
Q

What morphological changes occur with individuals with thiamine deficiency?

A

Changes occur in the…

  • Hippocampal formation
  • Columns of the fornix
  • Mamillary bodies of the hypothalamus
  • Medial dorsal nucleus of the thalamus
53
Q

Which area exhibits the MOST drastic modification and is considered unique to thiamine deficiency?

A

Drastic modification in the medial dorsal nucleus of the thalamus

54
Q

More about the cerebellum…

A

Just an FYI

This is from lectures slides, not the handout

55
Q

What are three goals of the cerebellum?

A

1 - Integration of equilibrium and locomotion
2 - Integration of head and eye movements
3 - Coordinating voluntary movements

56
Q

How does the cerebellum integrate head and eye movements?

A

Via the MLF

Note that when there is a deficit in the ability to coordinate head and eye movements, there is likely an implication with the medial longitudinal fasciculus (MLF)

57
Q

What four ways does the cerebellum coordinate voluntary movemetns?

A

1 - Comparing cortical input with motor output
2 - Providing feedback for ongoing movements
3 - Making adjustmetns to ongoing movements
4 - Ensuring accurate targeting

58
Q

How does the cerebelllum accomplish the task of comparing cortical input with motor output?

A

Corticopontocerebellar pathway

Brings a copy of the motor plan down to the cerebellum

59
Q

How does the cerebellum accomplish the task of providing feedback for ongoign movements?

A

Cerebellum cortex and dentorubrothalamic tract

60
Q

How does the cerebellum accomplish the task of making adjustments to ongoing movements?

A

Vestibulospinal tract
Reticulospinal tract
Rubrospinal tract

61
Q

Describe the role of the cerebellum ensuring accurate targeting

A

PRECISION – this is the importance of the cerebellum

62
Q

How can you determine whether a tremor is caused by a lesion in the basal ganglia or the cerebellum?

A

If you have a tremor while resting, think BASAL GANGLIA***

If you have a tremor while doing something active like reaching, think CEREBELLUM***

63
Q

For the vermis region, paravermal region and lateral region, what body regions do they contribute to?

A

In the vermis region –> control of AXIAL muscles
In the paravermal region –> control of INTERMEDIATE muscles or PROXIMAL muscles
In the lateral region –> control of EXTREMITY muscles

64
Q

How can the results of tandem walking tell you which side of the cerebellum the lesion is on?

A

Tandem walking – get patient to walk heel-to-toe –> if the lesion is in the midline of the cerebellum, the patient has an equal chance of falling to the right or left – will fall to both sides

If you have a RIGHT hemispheric lesion, patient will fall to the right

If you have a LEFT hemispheric lesion, patient will fall to the left

65
Q

What are some other cerebellar tests?

A

Finger to nose test and finger-nose-finger test –> cerebellar test

66
Q

What is interesting about cerebellar arteries?

A

The arteries are circumferential from the ventral side

They have to make a path around to the back of the brainstem to the cerebellar region

They “drop off” some branches on the way

67
Q

AICA path and branches

A

When dealing with the cerebellum we have the AICA – anterior inferior surface of cerebellum
In order to get there, you need to go around something (part of the PONS)
The external anatomy is then very important to us
Why not drop off a few arteries and supply that region? It does that – supplies the lateral aspect of the pons at the ponto-medullary junction

68
Q

PICA path and branches

A

If you were to look at the PICA
In order to make the way there, need to run around the medulla of the brain stem
Might as well drop off some branches so it does
Have this image in mind

69
Q

SCA path and branches

A

Now look at SCA
Gets to the superior part of cerebellum
Has to cross over the lateral surface of the midbrain, so it decides to drop some branches there
In lecture we called these the quadrigeminal arteries and supply the quadrigeminal area (some variation is present)

70
Q

Which CNs “cross over”?

A

There are only two CNs that cross over
CN III has a partial
Trochlear (CN IV) has a full decussation

Trochlear emerges from the DORSAL aspect of the brainstem –> Will see CONTRALATERAL symptoms

Think of Spocter’s “naughty significant other” example… Strange but it works.

71
Q

How does the alzheimer’s brain change?

A

Age-matched normal brain-note some
widening of sulci (gyri shrinkage)

Alzheimer’s- note widening of ventricles
And shrinkage of hippocampal structures

Neuroanatomy III (9 decks)

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