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Neuro Shelf > Neuroanatomy/Spinal Cord > Flashcards

Neuroanatomy/Spinal Cord Flashcards

1
Q

66 yo p/w gait difficulty x2 yrs

  • hypertonic legs, brisk reflexes, b/l upgoing toes, impaired joint position sense
  • recently become paranoid

Dx

A

Dx = B12 deficiency: causes combined damage of corticospinal tract and dorsal columns in the spinal cord

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2
Q

Which CN are responsible for the corneal reflex

A

Afferent limb = CN V (trigeminal)

Efferent limb = CN VII (facial)

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3
Q

Define Chiari malformation

A

Congenital d/o of downward herniation of the cerebellar tonsils into the foramen magnum

  • one of the leading causes of a syrinx
  • often manifests w/ headaches and cerebellar symptoms
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4
Q

Which will cause a ‘pupil spearing third’ nerve palsy- microvascular disease (diabetes) or compressive lesion

A

Parasympathetic fibers run on the periphery of the EOM motor fibers => compression lesion will cause enlarged pupil

While pathology in the nerve itself will cause EOM weakness w/o pupillary dilation = ‘pupil sparing third’

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5
Q

Oxcarbazepine and OCPs- why shouldn’t you combine these?

A

Carbamazepine/tegretol (AED) increases metabolism of OCPs => makes OCPs less efficacious

So oxcarbazepine will decrease the efficacy of the OCPs

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6
Q

If pt loses temp/pain/fine touch/vibration on the same side of the body, localize the lesion

A

Above the inferior medulla (where the dorsal column tract decussates) b/c underneath that they are running contralaterally

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7
Q

What is pure word deafness?

(a) Locate the lesion

A

Pure word deafness = pts can hear, speak, and write, but cannot recognize spoken language
-often think ppl are speaking in another language

(a) Lesion of b/l primary auditory cortex
- needs to be b/l b/c hearing has b/l representation in the CNS => pts cannot become deaf from unilateral CNS lesion

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8
Q

Dorsal columns

(a) Fxn
(b) Location of synapses
(c) Location of decussation
(d) Final destination

A

Dorsal columns

(a) Vibration/fine touch, proprioception
(b) Synapses
- dorsal root nuclei of the lower medulla
- again at the VPL of the thalamus

(c) Decussates
- decussates in the lower medulla forming flattening called the medial lemniscus

(d) Primary somatosensory cortex (postcentral gyrus)

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9
Q

Pt presents w/ diplopia after being hit in the eye w/ a softball a few months ago
-notice head is tilted towards the right shoulder at rest

Localize the lesion

A

Lesion localizes to the left trochlea nerve (CN IV)

CN IV controls the superior oblique (SO4) that depresses and intorts the eye => get vertical diplopia when it’s out, so pt compensates by tilting head towards the unaffected side
-can’t downward intort the left eye, so tilt right head down to equilibrate

-often injury is 2/2 trauma

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10
Q

Which sensory modalities go thru the thalamus?

A

All except olfaction

Olfaction (smell thru olfactory bulbs CNI) is the only sensory modality which bypasses the thalamus

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11
Q

Which (if any) of the CNs decussate?

(a) Resulting innervation

A

CN IV (trochlear) is the only one that decussates

(a) Right CNIV innervates the left superior oblique
- while left trochlear innervates the right superior oblique (SO4)

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12
Q

Manifestations of posterior cord syndrome

A

2/2 occlusion of the two posterior spinal arteries => knocking out both dorsal column pathways = loss of proprioception

-often pts experience intense pain and burning sensations in their limbs

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13
Q

56 yo F w/ h/o EtOH abuse p/w gait difficulties x2 yrs

  • wide based gait, positive Romberg’s
  • mildly ataxic on finger to nose, strength is intact

Likely MRI finding

A

Atrophy of the cerebellar vermis

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14
Q

Damage to left frontal lobe (left frontal eye fields) would cause gaze preference to which direction?

A

Frontal eye fields deviate the eyes to the opposite direction, so left frontal eye fields deviate eyes to the right

Damage to left frontal lobe = eyes can’t deviate to the right = gaze preference to the left
-so gaze preference is to the same side of the lesion

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15
Q

What is glossopharyngeal neuralgia?

A

Similar to trigeminal neuralgia (episodes of electrical shock sensation), pain in the posterior tongue and pharynx

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16
Q

Spinothalamic tract

(a) Fxn
(b) Location of synapses
(c) Location of decussation
(d) Final destination

A

Spinothalamic tract

(a) Pain/temp sensation

(b) Synapses twice
- dorsal root ganglion
- VPL of the thalamus

(c) Decussates once at the anterior commissure 1-2 levels above entering the spinal cord
(d) Primary somatosensory cortex = Postcentral gyrus

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17
Q

What is the conus medullaris?

A

Termination of the spinal cord at L1/L2

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18
Q

Physical exam finding indicating APD (afferent pupillary defect)

A

APD: when you do swinging light test and you don’t get direct and consensual pupil response b/l

  • APD = affected eye paradoxically dilates light swung from unaffected to affected eye
  • -both pupils constrict when light held in front of unaffected eye

Indicates lesion of the optic nerve

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19
Q

Tx for Bell’s palsy

A

Oral steroids and acyclovir
-acyclovir beneficial if started early in the course of the illness

Just in case the Bell’s palsy is 2/2 herpes zoster infxn of CN VII: presents w/ painful rash in the ear canal and dysfunction of CN VII (and sometimes VIII)

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20
Q

Where does the sympathetic nervous system originate?

A

Nucleus in the intermodeiolateral cell column of vertebral levels T1-L2

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21
Q

Hallmark eye finding of PSP

(a) Localize lesion

A

Restricted upgaze = upgaze palsy

(a) Lesion localizes to pineal gland
- pinealoma similarly presents w/ upgaze palsy

22
Q

Origin of motor fibers for CN IX and X

A

Nucleus ambiguus = group of motor neurons in the medulla

23
Q

Origin of the parasymp fibers of the oculomotor nerve

A

Parasympathetic fibers of CN III originate in the Edinger-Westphal nucleus of the brainstem

24
Q

Tremor seen in cerebellar injury

A

Intention tremor

  • increases during purposeful movement
  • oscillation increases as the target is reach
25
Q

Where would pain/temp sensation be lost due to lesion of the left spinothalamic tract at T10

A

Spinothalamic tract enters dorsal horn, then ascends 1-2 levels as it decussates across the anterior grey commissure

=> lesion at T10 causes loss of pain/temp on contralateral dermatome 1-2 below, so loss of pain/temp of the right T11/T12 dermatome

26
Q

ALS

(a) What degenerates?
(b) Findings on EMG

A

(a) Degeneration of motor neurons of the brain, CN nuclei, and spinal cord (anterior horn cells)
- basically all motor neurons

(b) EMG findings:
fasciculations, fibrillations, sharp waves

27
Q

24 yo F dx w/ optic neuritis

To help speed up recovery what do you give?

A

Solumedrol (IV steroids) then oral taper

28
Q

Corticospinal tract

(a) Fxn
(b) Location of synapses
(c) Location of decussation
(d) Final destination

A

Corticospinal tract

(a) Motor signals: down from precentral gyrus or supplemental motor areas thru the internal capsule
(b) Synapses at the ventral/anterior horn of the level of exit in the spinal cord

(c) Decussates at the levels of the medullary pyramids in the lower medulla
(d) Nmj

29
Q

Two etiologies to think of before diagnosing idiopathic Bell’s palsy

A
  1. If b/l- think Lyme disease

2. Sarcoidosis often presents w/ Bell’s palsy

30
Q

Two etiologies of anterior cord syndrome

A

Anterior cord syndrome is due to occlusion of the anterior spinal artery
-seen in pts who become hypotensive, or have surgery on their abdominal aorta

31
Q

Unilateral CN V injury

(a) Describe the impact on the muscles of mastication/
(b) Which brainstem reflex will be affected?

A

(a) Muscles of mastication have bilateral cortical innervation => unilateral CN V damage doesn’t cause weakness of jaw movements

(b) Corneal reflex (eye blinks if irritated), trigeminal nerve carries the afferent limb
- while facial nerve carries efferent limb

32
Q

Describe manifestations of Bell’s palsy

A
  1. Weakness of facial muscles
    - CN VII innervates orbicularis oculi, zygomaticus, levator labii superioris, depressor labii inferioris, buccinator, nasalis

Possible symptom of hyperacusis since CN VII innervates the stapedius muscle which dampers sound

  1. Dry eyes/dry mouth
    - b/c CN VII innervates submandibular and sublingual glands
  2. Decreased sensation of taste
    - CN VII receives taste from the anterior 2/3 of the tongue
33
Q

Clinical presentation of B12 deficiency

A

UMN signs and proprioceptive difficulties due to ‘combined damage’ of both the corticospinal tract and the dorsal column

34
Q

Trigeminal nerve

(a) Sensory distribution
(b) Motor fxn

A

Trigeminal nerve = CN V

(a) Sensation of skin on the face
- V1,2,3
(b) Innervates the muscles of mastication
- only V3 has motor

35
Q

Pt dragging right leg
-MRI shows intramedullary lesion on the right side of the spinal cord

Name another expected sensory finding

A

Decreased pain/temp sensation on the left

-spinal cord lesion: spinothalamic tract decussates at the anterior grey commissure 1-2 levels above entry in thru dorsal horn

36
Q

Clinical presentation of optic neuritis

A

Blurry vision, pain w/ EOM

Specific sign: pt can p/w loss of color vision, especially the color red

37
Q

Trigeminal neuralgia may be the presenting feature of what disease?

A

MS

38
Q

Differentiate cauda equina and conus medullaris syndrome

A

Cauda equina

  • gradual and unilateral
  • bowel/bladder retention is a later finding
  • decreased knee reflexes
  • LE weakness often asymmetrical

Conus medullaris

  • sudden and b/l
  • bowel/bladder incontinence develop early
  • knee reflexes are preserved
  • weakness is symmetrical
39
Q

Expected diagnosis in a pt w/ internuclear opthalmoplegia

A

Internuclear opthalmoplegia = lesion in the MLF (medial longitudinal fasciculus) connecting CNIII and CNVI
-problem w/ conjugate gaze: when right eye looks one way the left eye doesnt follow

Most commonly seen in MS

40
Q

75 yo M p/w gait instability

  • legs crossed in front of each other
  • hyperreflexia, b/l Babinski

Dx

A

Dx = cervical spondylosis (spinal osteoarthritis)

-‘scissoring gait’ associated w/ UMN lesion: seen in spinal cord tumor, trauma, compression (cervical spondylosis)

41
Q

Name some ototoxic drugs

A
  • aspirin can cause tinnitus (ringing in ears)

- aminoglycoside abxs (-‘mycin’)

42
Q

45 yo F wakes up w/ left facial droop

  • trouble closing left eye, cannot wrinkle left face
  • noises sound louder on the left, dull pain behind left ear

Dx?

A

Dx = Bell’s palsy = facial nerve palsy

-innervates muscles of facial expression = orbicularis oculi, smile muscle, also stapedius muscle (dampens sounds)

43
Q

Which symptom bothers MS pts the most

A

Fatigue :-(

-lots of Adderall given to MS pts

44
Q

Pt w/ NMO p/w intractable hiccups and nausea/vomiting

Locate the lesion

A

Lesion = area postrema

45
Q

Left eye ptosis, dilated left pupil, eye deviated down and out

Localize the lesion

A

Lesion localizes to oculomotor nerve (CNIII)

CN III palsy

  • ptosis due to loss of innervation to levator palpebrae superioris
  • dilated pupil 2/2 loss of parasympathetics (which come from the Edinger-Westphal nucleus)
  • down and out b/c loss of innervation to many EOM (all except superior oblique and lateral rectus)
46
Q

What illegal substance interferes w/ B12 metabolism

A

Nitrous oxide (laughing gas)

47
Q

What is the only FDA approved medication to slow the course of ALS

(a) Mechanism

A

Riluzole

(a) Extends survival by preventing stimulation of glutamate receptors

48
Q

45 yo M w/ progressive weakness for months starting in right leg, progressing to left arm

  • muscles have been ‘jumping’ recently
  • weak in RLE and RUE
  • muscle wasting of intrinsic hand muscles
  • reflexes absent in right leg, brisk elsewhere w/ upgoing toe on left

Dx

A

ALS

-b/c both UMN and LMN findings

49
Q

Define anisocoria

A

Anisocoria = difference in size of the pupils

Tell which pupil is pathologic by using light!

Constricted pupil in bright room is normal, while abnormal in dark room

50
Q

In a pt w/ a unilateral spinal cord lesion, where would you expect the pain/temp abnormalities to begin on the body

A

Contralateral dermatomes 1-2 vertebrae below

-second-order neurons of the spinothalamic system ascend 1-2 levels as they cross in the anterior gray commissure

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