NS Clinical relevance and summary Flashcards

1
Q

why do the body areas affected by shingles correspond to dermatomes?

A

virus within dorsal root ganglia, and usually restricted to 1 or 2 dorsal root ganglia so body areas reflect dermatomal distribution of those roots.

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2
Q

what are the contents of the spinal epidural space, and which is the most medically important and why?

A

blood vessels and AT
most important= vertebral venous plexus
plexus is valveless and communicates freely with veins of pelvic, abdom, thoracic and cranial cavities. So can provide route for spread of infections and cancer cells from viscera to brain.
* batson venous plexus receives drainage from prostatic veins, and plexus connects with vertebral venous plexus, allowing prostate cancer to metastasise to the VC, and so may present with back pain.

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3
Q

what will be the outcome of a lesion of the cuneate tract unilaterally at any level of the SC?

A

loss of tactile, pressure, vibration, light touch and conscious proprioception sensations in dermatomes of upper limb of ipsilateral side below level of lesion as tract ascends to brain without crossing (decussation in medulla.)
gracile tract= lower limb

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4
Q

Patient has sensory ataxia and +ve Romberg sign,what vitamin deficiency might this highlight and why are these symptoms important to pick up on for this disease?

A

Vit B12, causing degenerative changes in dorsal column
NS signs will be first to appear rather than those of anaemia- pernicious anaemia- megaloblastic, pallor, fatigue.
If signs detected early, can completely cure symptoms with vit B12 IM injections.

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5
Q

what tract damage is almost invariably associated with Babinski sign?

A

corticospinal tract
stroking of lateral aspect of sole of foot with hard, blunt instrument causes dorsiflexion/extension of large toe and fanning of other toes. Normal response= flexion of all toes- flexion plantar response.

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6
Q

signs and causes of cerebellar dysfunction?

A
Together= DANISH PASTRIES
DANISH= signs= dysdiadochokinesis, dysmetria (past pointing)
ataxia- broad-based gait
nystagmus
intention tremor
scanning speech
hypotonia- +ve heel to shin test- coordination lack, ataxia?
PASTRIES=causes
paraneoplastic syndromes
Freidreich's ataxia
stroke
trauma
raised intracranial pressure
infection
ethanol
MS
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7
Q

What is it about the blood brain barrier in infants that allows kernicterus to occur?

A

the capillary endothelium is immature and fenestrated, allowing bilirubin to enter.

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8
Q

How can cerebral oedema occur with disruption of BB barrier?

A

e.g. with trauma or tumours- astrocytic foot processes of BB barrier disrupted, and as these requlate quantity of Na+ and H20 that can cross, disruption causes fluid leakage into the brain.

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9
Q

describe what is meant by the sacral sparing phenomenon

A

this is due to the somatotopic localisation in the long ascending and descending pathways. the more rostral spinal nerves (e.g. cervical and thoracic are represented internal to the more caudal, so with bilateral damage of the central part of the spinal cord, there is loss of sensations and voluntary motor control in area of peripheral distribution of the more rostral SC segments below the lesiom, but not the more caudal. **

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10
Q

what symptoms would a hemisection of the SC cause?

A

would damage lateral corticospinal tract, causing spastic paralysis ipsilaterally, and dorsal column, causing loss of tactile, vibration and proprioception senses ipsilaterally, and spinothalamic tract, causing loss of pain and temp senses contralaterally as decussation of these fibres at segmental level of SC, in anterior (ventral) white comissure.
=brown-sequard syndrome

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11
Q

what visceral afferent fibres supply the urinary bladder?

A

pain and temperature impulses from fundus travel with SNS nerves and reach SC via dorsal roots of T12 and L1
from mucosa at neck of bladder, pain and temp impulses travel with the sacral PNS nerve to S2, 3 and 4.
The spinothalamic tract then transmits impulses of both to higher centres.

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12
Q

how is fullness of bladder detected?

A

mechanoreceptors in bladder wall- send impulses to SC via sacral PNS route (S2-S4)
sensation that micturition is imminent arises from mechanoreceptors in trigone, impulses travel with sacral PNS nerves to S2-S4, and ascend in DC medial-lemniscal tract.

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13
Q

what is the uninhibited reflex bladder?

A

occurs with bilateral lesions of micturition centres in frontal lobe, so no conscious decision to void?
bladder is therefore incontinent but empties fully as reflex control of pontine micturition centres intact

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14
Q

what is the automatic reflex bladder?

A

results from bilateral SC lesions above sacral levels e.g. SC transection
bladder incontinent as cut ascending sensory and descending autonomic pathways creating UMN type lesion producing spastic reflex bladder, where patient insensitve to bladder filling. Stretching will activate intact spinal reflex producing incontinence, but bladder emptying will be incomplete due to interruption of spinal reflex pathways that trigger pontine micturition centres.

=urge urinary incontinence

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15
Q

what is the flaccid non reflex bladder?

A

results from bilateral lesions of sacral SC or spinal nerve roots in cauda equina. causes severe urinary retention and incontinence as PNS fibres lost necessary for detrusor contraction, so overflow incontinence results.

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16
Q

what syndrome does syringomyelia result in?

A

commissural syndrome= bilateral loss of pain and temp sensations in dermatomes at levels of the lesion.
lesion= pathologic cavitation of SC, cavity opens up around canal of SC.

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17
Q

what remains intact in anterior spinal artery syndrome?

A

the dorsal column, as this receives blood from the posterior spinal artery
therefore fine touch and conscious proprioception remain intact.

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18
Q

name given to condition in which syphilis (treponema pallidum) causes degeneration of dorsal columns?

A

tabes dorsalis

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19
Q

through what structure do fibres of the spinothalamic tracts conveying pain and temperature sensations decussate?

A

ventral (anterior) white commissure

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20
Q

why do fasciculations occur with lesions of lower motor neurones?

A

increased sensitivity of ACh receptors to circulating ACh, so only a very small amount of ACh will stimulate nerve APs to cause muscle contractions.

May be seen when patient asked to protrude their tongue in a cranial nerve examination.

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21
Q

what are upper motor neurones?

A

descending tracts of brain and SC, with cell bodies located in cerebral cortex or the brainstem, axons remain in CNS.

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22
Q

what are lower motor neurones?**

A

cell body located in SC (lamine IX) or cranial nerve motor nuclei.

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23
Q

what do lesions of the hypoglossal nucleus result in?

A

paralysis and atrophy of ipsilateral tongue muscles

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24
Q

what is the corticobulbar tract?

A

descends from cerebral cortex, through internal capsule, to brainstem cranial nerve motor nuclei (CL?), and control muscles of facial expression, extra-ocular muscles and neck muscles.

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25
Q

function of reticulospinal tracts?

A
automatic movements (locomotion)
2 neurone groups= pontine and medullary reticular neurones
pontine= facilitate extensor movements, and inhibit flexor
medullary do the opposite
pontine extensor excitatory area is under inhibtory control from higher centres, whereas medullary areas is facilitated by higher centres.

so if brainstem impairment below level of red nucleus in midbrain, get decerebrate posturing= extension of U and LLs, as impair inhibition from cerebral cortex normally exerted on reticular formation (on pontine fibres.) to inhibit extensor reflexes mediated by reticular formation.

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26
Q

what is decorticate posturing and how does it occur?

A

impairment of brainstem activity above level of red nucleus, so red nucleus can cause flexion in upper limbs, so patients LLs extend but ULs flex.

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27
Q

example of a disease where no voluntary movement can be achieved?

A

amyotrophic lateral sclerosis/Lou Gehrig disease

28
Q

describe how corticobulbar tracts are associated with cranial nerve motor nuclei in the brainstem?

A

all the nonocular brainstem lower motor neurones are supplied bilaterally by the motor area except the lower motor neurones of the lower facial muscles, which are supplied solely by the CL motor area.
so after a unilateral lesion of the corticobulbar tract above the pons (and so above the level of the lower motor neurones of the facial nerve emerging from the pons) only the CL lower facial muscles are paralysed, and so frontal sparing will occur due to bilateral innervation of facial nerve.

29
Q

what is Huntington’s chorea, and what chromosome is affected?

A

progressive disorder caused by inheriting a dominant gene.
degeneration of striatal neurones occurs, altering the balance of activity in direct and indirect pathways, causing loss of inhibition of undesired movements, so may get jerking of head, smacking of lips and tongue, jerking movements in distal parts of upper and lower limbs.
chromosome 4

30
Q

most likely cause of bilateral lower limb weakness (paraparesis)?

A

SC lesion

if brain affected, would have to be both sides which is less likely

31
Q

what do paraparesis, hemiparesis, monoparesis and quadriparesis mean?

A
para= both sides affected, so both upper limbs or both lower limbs have weakness
hemi= 1 side of body has wekaness
monoparesis= 1 limb has weakness
quadriparesis= all 4 limbs have weakness
32
Q

the anterior spinal artery is a relatively small artery supplying blood to the anterior 2/3 of the SC. How is it capable of supplying sufficient blood to the SC?

A

there are numerous anastomoses- lots of vessels feed into it e.g. neck arteries and the artery of adamkiewicz= from a branch of aorta, very prone to damage in surgery e.g. surgery for aortic aneurysms and thoracic surgery e.g. lower lobectomies. Artery comes off branch of aorta near lower level of ribs.

33
Q

where would there be damage to cause a dermatomal loss of sensation?

A

SC or nerve roots

34
Q

why does peripheral neuropathy in diabetes commonly affect the feet 1st , and then the hands?

A

glove and stocking distribution

length dependent neuropathy, longest nerves go to the feet.

35
Q

how can sensory ataxia be distinguished from cerebellar ataxia?

A

sensory= don’t know where joints are= loss of conscious proprioception= dorsal column disease. Become unsteady when close their eyes and stood on a narrow base- sway= +ve romberg’s test, as lost conscious proprioception, and closing their eyes then means they lose vision, so they lose balance.
with cerebellar ataxia= ptnt will already be swaying before doing romberg’s test, not lost proprioception, already swaying with eyes open.

36
Q

what 3 things are needed for balance?

A

balance organ in inner ear- vestibular systrem
proprioception
vision

can balance with 2 of the 3

37
Q

how is the SC supplied with arterial blood?

A

single anterior spinal artery- supplies A. 2/3
paired posterior spinal arteries- posterior 1/3= dorsal columns

95% of SC infarcts are anterior.

38
Q

most common cause of SA haemorrhage?

A

rupture of berry aneurysms in arteral circle of Willis

also arteriovenous malformations= collection of arteries and veins with a developmental origin.

39
Q

presentation of SA hamorrhage?

A

sudden onset, severe headache, typically occipital area, thunderclap, may say felt like someone hit them on back of head
nausea and vomiting, possibly coma
meningism- also neck stiffness and photophobia

40
Q

what does a SD haematoma commonly follow?

A

a head injury e.g. fall- but often minor

41
Q

what symptoms and signs may a patient subsequnetly experience if suffered a pterion fracture with initial LOC, and then lucid interval of recovery?

A

Progressive hemiparesis and stupor
Rapid tentorial or tonsillar herniation
Ipsilateral pupil dilation
Coma, respiratory arrest, and death

=due to secondary brain injury

42
Q

cell most commonly associated with CNS tumours?

A

astrocyte

43
Q

haemorrhage of an artery on surface of brain will result in blood leakage into which space?

A

SA space

44
Q

what is agnosia?

A

inability to process sensory info

45
Q

why are lumbar punctures done at L3/L4 or L4/L5 levels in adults?

A

to avoid damage to SC which usually ends at caudal border of L1 or cranial border of L2 in adults, but may end up to middle of L3 vertebra.

46
Q

how are different levels of SC distinguished between in transverse SC sections?

A

cervical: thin posterior horn, large anterior horn with lateral extension
thoracic: thin posterior and anterior horns
lumbar: massive posterior horn and massive anterior horn with medial extension
sacral: massive posterior horn, and massive anterior horn with lateral extension.

47
Q

2 areas of brain which often show damage in huntington’s chorea?

A

striatum

subthalamic nuclei

48
Q

which other area of the brain do the basal ganglia work with?

A

cerebellum

49
Q

describe the clinical sign that is seen with meningism

A

kernig’s sign
= positive when the thigh is bent at the hip and knee at 90 degree angles, and subsequent extension in the knee is painful (leading to resistance). This may indicate subarachnoid hemorrhage or meningitis.

50
Q

3 features of meningism?

A

headache
photophobia
neck stiffness

51
Q

what might make resting tremor of parkinson’s disease ptnt worse?

A

stress

but often improves during voluntary movement

52
Q

what does a festinating gait mean in parkinson’s?

A

small steps taken by patient, shuffling

53
Q

would a ptnt fall towards or away from side of a cerebellar lesion?

A

towards
as vestibulospinal tracts descent ipsilaterally and receive input from vestibular system and from cerebellum to affect postural muscles. damage will result in postural loss on same side as lesion.

54
Q

how does polio gain access into body?

A

via GI tract

55
Q

how do ptnts present with polio?

A

lower motorneurone paralysis of affected segments ( polio invades alpha motorneurone cell bodies) but without any sensory loss.

56
Q

functions of different types of peripheral nerve fibres?

A

A-alpha: myelinated, large diameter, proprioception, fast conduction velocity:alpha-motoneurons, muscle spindle primary endings, Golgi tendon organs, touch
A-beta: touch, kinesthesia, muscle spindle secondary endings
A-gamma: touch, pressure, gamma-motoneurons
A-delta: fast pain, crude touch, pressure, temperature (cold)
B: preganglionic autonomic
C: slow pain, touch, pressure, temperature (warmth), postganglionic autonomic

57
Q

what can cause referred pain to L shoulder?

* due to convergence of visceral pain fibres and cutaneous fibres in dorsal horn of SC on 2nd order afferent.

A

MI
ectopic pregnancy- paracolic gutters of infracolic compartment to subphrenic space, causing diaphragmatic irritation
ruptured spleen
perforated peptic ulcer

58
Q

differences between CT and MRI?

A
CT= use of ionising radiation as X-rays used to produce cross-sectional images.
MRI= depends on magnetic properties of protons and is imaging method of choice for most brain and SC disorders as doesn't use radiation.
59
Q

which imaging technique is best for viewing anatomy of brain?

A

MRI
has greater resolution than CT, can be used in any body plane, and is free from artefacts from bone/blood vessels unlike CT.

60
Q

why are fractures of skull vault easily seen on plain X-ray?

A

not masked by denser bony structures

61
Q

why are fractures petrous temporal bone, which the middle and inner ear sits within, not easily seen on skull X-ray?

A

bone is very dense, and cannot be positioned to be free of overlying structures

62
Q

why can extent of fracture of petrous temporal bone be seen with CT?

A

can set the thickness of the image slices and the interval

between them. By studying the sequence of slices the extent and direction of the fracture can be followed

63
Q

what can PET scans help to show in terms of CNS functioning?

A

hypometabolic areas as likely site of origin of seizures
in differential diagnosis of dementia
distinguish between clinically similar movement disorders

64
Q

when are EEG abnormalities seen?

A

epilepsy
encephalitis
dementia
some metabolic states affecting brain

65
Q

what is a delay with a visual evoked response suggestive of?

A

optic neuropathy

66
Q

when might somatic evoked potentials be used?

A

detect and localise lesion in CNS in MS
in Vit B12 deficiency disturbing dorsal columns
monitor integrity of neural structures in neurosurgery to minimise or prevent damage
assessment of NS trauma

67
Q

how can presence of peripheral nerve damage be confirmed?

A

nerve conduction studies- motor and sensory