Basic Principles Of Locatization

Question 1

What are the diff functions of diff lobes?

Answer 1

Frontal lobe = executive funcitoning

Parietal lobe = awareness of somatic sensation, processing somatic sensation, proprioception

Temporal lobe = auditory

Occipital lobe = visual cortex

Question 2

What is the pathway of the UMN?

Answer 2

Primary motor cortex (BA4) -> subcortical (corona radiata) & internal capsule & basal ganglia -> brainstem until spinal cord -> above the anterior horn cell

Question 3

What is the pathway of LMN?

Answer 3

Below anterior horn cell -> nerve root/peripheral nerves -> NM junction & muscles

Question 4

What aer the 2 ascending pathways seen in sensory exma?

Answer 4

Spinothalamic = light touch, temperature, and pain

DCT = joint position, vibratory & tactile discrimination

Question 5

What part of the brain is responsible for Gait & coordination?

Answer 5

Vestibulocerebellum
Spinocerebellum = station, walking, and tandem gait
Cerebrocerebellum = rapid alternatine movements, finger to nose, heel to shin, rebound check reflex, speech and nystagmus

Question 6

What are the basic principles of localization?

Answer 6

1. Accurately defining signs & sx
2. Pattern recognitiion
3. Levels of confidence
4. Longitudinal & transverse localization
5. Know ur decussations

Question 7

Where is the level of decussation in the CST & how does it present if lesions are below medulla and above medulla?

Answer 7

Point: pyramidal decussation in the medulla

Lesion above medulla = CL weakness
Lesion below medulla = IL weakness
*remember ascending path neto

Question 8

What is the point of decussation of the DC pathway and presenting signs of lesions above and below medulla?

Answer 8

Pt of decussation: ascends & crosses in the lower end of the medulla

Lesions below medulla: IL sensory loss
Lesions above medulla: CL sensory loss

Question 9

What is the pathway of spinothalamic tract ? lesions above and below spinal level will cause what?

Answer 9

Enters posterior spinal cord -> ascends to spinal nerve root segments -> crosses in ventral white commissue -> ascends to sensory cortex

Lesions at given spinal level: CL pain
Lesion below 1-2 spinal levels = temperature loss

Question 10

What aer the signs of LMN lesion?

Answer 10

Decreased tone (flaccid)
Decreased reflexes
- Babinski sign
+ Atrophy
+ Fasciculations

UMN lesion
+ Babinski sign
INC tone (spastic)
INC reflexes
No atrophy
No fasciculations

Question 11

What are the diff betw Central & Peripheral facial weaknessx?

Answer 11

Central facial palsy
- spares the forehead
- seen when a lesion interrupts the Corticobulbar fibers
- CL to the lesion

Peripheral facial palsy
- both forehead and lower face are weak
- lesions affect peripheral CN VII or its nucleus
- IL to the lesion

Question 12

What is the cause of tongue weakness?

Answer 12

CN XII nucleus => CL innervated

Tongue deviattes towards the side of the weakness

Question 13

What are the patterns of motor loss?

Answer 13

Cortex, Corona radiata, internal capsule = CL hemiparesis, Central faciall palsy

Brain stem = CL hemiparesis & IL CN deficits, Quadriparesis & bilateral CN deficits

Spinal cord = Quadriparesis or Parapersis

Anterior horn cell = localized or generalized

Nerve root = root distribution

Nerve plexus = >1 nerve root

Polyneuropathy = feet & legs, hands & arms

Mononeuropathy = single peripheral nerve

NMJ = fatigable pattern on weakness on repeated testing

Muscle = weakness involving proximal muscles > distal muscles

Question 14

What happens in the CN system at the spinal cord level?

Answer 14

Separation of modalities as it reaches the spinal cord
-> Posterior column ascends IL -> up to medulla
-> Spinothalamic ascends in the CL spinal cord -> decussates at the level of its entry

Question 15

What happens in the CN system at the CN V?

Answer 15

Central sensory nucleus of CN V -> extends within the brainstem from the pons to the spinal cord

Central lesions -> IL facial numbness

Question 16

What are the patterns of sensory loss?

Answer 16

Peripheral nerve

                                     Sensory loss Single nerves          =     Nerve distribution All PNS                     =.    Glove and stocking Spinal nerve roots =      Dermatomal Cauda equina.        =.     Both legs & perineum

Question 17

What is the presentation of complete transection, hemitransection, central cord distribution in diff lvels of the spinal cord?

Answer 17

Complete transection
- sensory loss occurs everything below the level of the lesion

Hemitransection
- Brown-Sequard syndrome: lesion on the spinal cord characterized by weakness or paralysis in one side of the body & loss of sensation in the opposite side

Central cord distrbution
- loss of pain/temp in band-like fashion over segments occupied by the lesion
- “cape-like” distribution
- commonly seen in Syringomyelia

Question 18

What are the sensory loss in complete transection, hemisection, central cord?

Answer 18

complete transection
-> all below the level of the lesion

Hemisection
-> IL: joint position, vibration, light touch
-> CL: temp & pain

Central cord
-> loss of pain/temp in band-like fashion over segments occupied by lesion

Question 19

What aer the diff patterns of sensory loss in the brain?

Answer 19

Brainstem
-> Loss of IL face of sensation
-> CL limb sensation

Thalamus
-> loss of all CL modalities, usually spares trunk

Parietal lobe
-> loss of CL modalities
-> numbness, agnosia, loss of 2-point discrimination, astereognosis, agraphestesia, hemisensory neglect

Question 20

What aer the diff patterns of sensory loss in teh visual system?

Answer 20

Prechiasmal = Monocular sensory loss
CHiasmal = Bitemporal hemiapnopsia
Optic tract/LGB/Optic radiation = CL homonymous hemianopsia

Temporal lobe = superior CL homonymous hemianopsia
Parietal lobe = Inferior CL homonympus hemianopsia
Occipital cortex = CL homonymous with macular sparing

Question 21

What are the 2 structures involved in horizontal gaze?

Answer 21

Frontal eye field (supratentorial)
Paramedian pontine reticular formation (pons)

Question 22

In preferential gaze, what does a cortical lesion & brainstem lesion look like?

Answer 22

Cortical lesion
-> preferential gaze towards teh lesions and away from the weakness

Brainstem lesion
-> preferential gaze away from the lesion & towards the weakness

Question 23

What is the term known to describe unequal pupils?

Answer 23

Anisocoria

Question 24

What are the 2 most common pupillary problems?

Answer 24

Anisocoria
Decreased pupil contriction to light

Question 25

How do u know in anisocoria if the large puil or small pupil is the abnormal one?

Answer 25

Small pupil = abnormal if anisocoria is greater in the dark than in the light

Larger pupil = abnormal if anisocoria > in light than in the dark

Question 26

What are the diff presentation of cerebellar symptoms?

Answer 26

Lateral lobes
->limb ataxia and hypotonia

Flocculonodula lobe
-> disturbed equilibrium: truncal ataxia,drunken gait, titubation of head and trunk

Anterior lobe
-> gait ataxia, inability ot do tandem walking

Question 27

What is the presentation of aphasia in cerebral cortex?

Answer 27

Frontal lobe = expressive dysphasia/aphasia (dominant)

Parietal lobe - receptive dysphasia/aphasia (dominant)

Temporal lobe = receptive dysphasia/aphasia (dominant)

Occipital lobe = CL homonymous hemianopia

Question 28

What are the steps on localization?

Answer 28

1. Get a good detailed history
2. Perform PE and Neuro exam
3. List down abn findings on neuro exam & correl each deficit with possible tracts or pathways involved
4. Find intersection
5. Localize