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Neurology > Peripheral Neuropathies > Flashcards

Peripheral Neuropathies Flashcards

1
Q

Name 5 mechanisms that can cause nerve malfunction?

Give an example of each!

A

Demyelination: MS

Axonal degeneration: due to a toxin

Compression: disc prolapse

Infarction: stroke

Infiltration by inflammatory cells: sarcoidosis

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2
Q

What is an axon?

A

The long, slender projection of the neuron (nerve cell)

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3
Q

What is mononeuropathy?

A

When there is a problem with one single nerve

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4
Q

What is multiple mononeuropathy?

A

Only a few nerves are affected, often in different parts of the body

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5
Q

What is polyneuropathy?

A

Many nerves are affected in about the same areas on each side of the body

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6
Q

What usually causes mononeuropathies?

A

Acute compression on the nerve(s)

  • in anatomically exposed nerves
  • in nerves that pass through tight cavities (entrapment)

Trauma or surgery

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7
Q

Give two examples of when mononeuropathy occurs in an anatomically exposed nerve?

A

The common peroneal nerve is exposed at the head of the fibula

The radial nerve is exposed to pressure from the humerus

The ulnar nerve is exposed to pressure at the elbow: cubital tunnel

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8
Q

Where is the fibula?

A

In the leg

It is the more lateral leg bone, next to the tibia

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9
Q

Give an example of when mononeuropathy occurs in a nerve that passes through a tight cavity?

A

The median nerve passing through the carpal tunnel

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10
Q

What is a nerve entrapment?

A

When a nerve that travels through a tight cavity gets compressed

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11
Q

What is carpal tunnel syndrome?

A

When the carpal tunnel starts to cause compression on the median nerve as it travels through

Flexor retinaculum compressed nerve

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12
Q

What causes carpal tunnel syndrome?

A

Often idiopathic

Can be associated with

  • hypothyroidism
  • diabetes
  • pregnancy
  • obesity
  • RA
  • work related
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13
Q

Clinical features of carpal tunnel syndrome?

A

Pain and paraesthesia of the hand

Particularly the index, middle finger, lateral half of ring finger (these are supplied by median nerve)

Worse at night

Wasting of thenar muscles

Tinnel’s sign: pain occurs when you tap the carpal tunnel

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14
Q

What travels through the carpal tunnel?

A

Nine flexor tendons:

  • flexor digitorum profundus
  • flexor digitorum superficialis
  • flexor pollicus longus
  • flexor carpi radialis

The median nerve

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15
Q

What is Tinnel’s sign?

A

Tapping the carpal tunnel area causes pain in people with carpal tunnel syndrome

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16
Q

Which part of the hand does the median nerve supply?

A

Thumb
Index, middle and lateral part of ring finger

And more lateral palm region

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17
Q

Management of carpal tunnel syndrome?

A

Nocturnal splint
Local steroid injections

Surgical decompression if the condition does not resolve

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18
Q

What is mononeuritis multiplex?

A

Loss of sensory and motor function in individual nerves, the pattern of nerve involvement is asymmetrical

Caused by a systemic disorder

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19
Q

What causes mononeuritis multiplex?

A 
Diabetes
Vasculitis
Immune disorders: RA, SLE
Infections
Sarcoidosis
Amyloidosis
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20
Q

Clinical features of mononeuritis multiplex?

A

Motor and sensory loss in some nerves

Deep, aching pain

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21
Q

Does polyneuropathy affect autonomic nerves as well as sensory and motor nerves?

A

Yes!

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22
Q

Describe the symptoms caused by damage to:

  • sensory
  • motor
  • autonomic nerves?
A

Sensory: tingling, numbness, pins & needles, pain

Motor: weakness

Autonomic: postural hypotension, urinary retention, erectile dysfunction, diarrhoea, many more

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23
Q

In which polyneuropathies are autonomic nerves the most affected?

A

Guillain-Barre syndrome
Diabetes mellitus
Amyloidosis

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24
Q

Investigations of a patient with polyneuropathy?

A

Blood:

  • FBC
  • ESR
  • vitamin B12
  • serum glucose
  • U&E

Nerve conduction tests

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25
Q

List some causes of polyneuropathy?

A 
Guillain-Barre syndrome
Diabetes Mellitus
Amyloidosis
Vitamin deficiency
Drugs
Idiopathic sensorimotor neuropathy
Many many more!
26
Q

What is Guillain-Barre syndrome?

A

A polyneuropathy causing inflammatory demyelination

It is often triggered by an infection

27
Q

What infections cause Guillain-Barre syndrome?

And how long after the infection does GBS occur?

A

Camplylobacter jejuni

Epstein-Barr virus

Cytomegalovirus

2-4 weeks post infection

28
Q

Pathogenesis of GBS?

A

The infectious organism antigens share epitopes with the antigens of the peripheral nerve cells

So antibodies that were created to fight the pathogen start to attack the nerve cells, damaging the nerves

29
Q

Clinical features of GBS?

A

Progressive onset symmetrical limb weakness

Loss of reflexes

Sensory symptoms: paraesthesia

In some cases the facial and respiratory muscles are involved

Autonomic features:

  • bladder problems
  • cardiac arrhythmias

Respiratory involvement can cause death

30
Q

Investigations of GBS?

A

Lumbar puncture:

  • raised protein in CSF
  • normal white count

Nerve conduction tests: slowed

31
Q

Treatment of GBS?

A

At first signs of resp involvement, intubate and refer to ITU

IV immunoglobulins

Don’t use corticosteroids, they don’t help

32
Q

Which vitamin deficiencies can cause polyneuropathies?

A

Thiamin (B1)

Pyridoxine (E6)

B12

33
Q

What causes thiamin deficiency?

A

Reduced food intake:

  • alcoholism
  • starvation
34
Q

Clinical features of thiamin deficiency?

A

Polyneuropathy

Wernicke-Korsakoff syndrome

35
Q

How does Wernicke-Korsakoff syndrome present?

A

Ocular disturbances (ophthalmoplegia)

Changes in mental state (dementia)

Unsteady stance and gait (ataxia)

36
Q

Treatment of polyneuropathy caused by thiamin deficiency?

A

Thiamin supplement, IV for 3 days

37
Q

Clinical features of pyridoxine deficiency?

A

Sensory polyneuropathy

38
Q

What causes pyridoxine deficiency?

A

Some people taking isoniazid therapy for TB get this as a side effect

39
Q

Treatment of pyridoxine deficiency?

A

More prevention

People taking isoniazid are given prophylactic pyridoxine

40
Q

Clinical features of B12 deficiency (in terms of nervous system)?

A

Polyneuropathy

Subacute combined degeneration of the spinal cord

Distal sensory loss
Absent ankle jerks
Evidence of cord disease

41
Q

Treatment of B12 deficiency?

A

IM injection of B12

42
Q

What is hereditary sensorimotor neuropathy?

A

An umbrella term for a number of inherited conditions that cause polyneuropathy

The most common being Charcot Marie Tooth syndrome

43
Q

What is Charcot Marie Tooth syndrome?

A

Progressive loss of muscle tissue and touch sensation in the distal limbs, as well as weakness

44
Q

What is the inheritance pattern of Charcot Marie Tooth syndrome?

A

Autosomal dominant

45
Q

Clinical features of Charcot Marie Tooth syndrome?

A

Distal limb muscle wasting and weakness

Mostly affects the legs

Loss of sensation and reflexes

Legs look like inverted champagne bottles

High arched feet and hammer toes

46
Q

Management of Charcot Marie Tooth syndrome?

A

Incurable

Physical therapy, moderate exercise

Braces and splints

Specially modified shoes or surgery for foot deformities

47
Q

Name CN I.

How would a lesion of CN I present?

What causes CN I lesions?

A

Olfactory nerve

Loss of sense of smell and taste

Tumours, trauma, infection

48
Q

Name CN II.

How would a lesion of CN II present?

What causes CN II lesions?

A

Optic nerve

Visual field defects
Visual acuity
Blindness: mono or bi
Hemianopia: homo or bi

Pupillary abnormalities:

  • size
  • shape

Causes: MS, occlusion of retinal artery, trauma, anaemia, drugs

49
Q

Name CN III.

How would a lesion of CN III present?

What causes CN III lesions?

A

Oculomotor

Fixed dilated pupil
Ptosis
DOWN + OUT deviation of eye

Causes: Diabetes M, temporal arteritis, syphilis

50
Q

Name CN IV.

How would a lesion of CN IV present?

What causes CN IV lesions?

A

Trochlear

Diplopia: double vision
Eyes move down and in
Head tilt down and to side opposite side of lesion

Causes: trauma, diabetes

51
Q

Name CN V.

How would a lesion of CN V present?

What causes CN V lesions?

A

Trigeminal

Reduced sensation in areas supplied by trigeminal
Weakness of jaw clenching
Jaw deviates to side of lesion when mouth opens

Causes: trigeminal neuralgia, herpes zoster, more

52
Q

Name CN VI.

How would a lesion of CN VI present?

What causes CN VI lesions?

A

Abducens

Inability to look laterally in one eye
INWARD deviation of eye
Horizontal diplopia

Causes: MS, pontine stroke

53
Q

Name CN VII.

How would a lesion of CN VII present?

What causes CN VII lesions?

A

Facial nerve

If UMN:
- Facial weakness, find it hard to puff out cheeks, show teeth

If LMN:
- The above + paralysed forehead

Causes:

  • UMN: stroke, tumour
  • LMN: polio, bell’s palsy
54
Q

Name CN VIII.

How would a lesion of CN VIII present?

What causes CN VIII lesions?

A

Vestibulocochlear

Unilateral deafness
Tinnitus

Causes: loud noise, herpes zoster, brainstem CVA

55
Q

Name CN IX.

How would a lesion of CN IX present?

What causes CN IX lesions?

A

Glossopharyngeal

Impaired gag reflex: IX controls the afferent arm of the reflex

Causes: trauma, brainstem lesions, polio

56
Q

Name CN X.

How would a lesion of CN X present?

What causes CN X lesions?

A

Vagus

Weakness of palate: nasal voice, nasal regurgitation of food
Impaired gag reflex: X controls the efferent arm of the reflex

Causes: trauma, brainstem lesions, tumours

57
Q

Name CN XI.

How would a lesion of CN XI present?

What causes CN XI lesions?

A

Accessory

Weakness and wasting of sternocleidomastoid and trapezius

Causes: trauma, brainstem lesions, tumours

58
Q

Name CN XII.

How would a lesion of CN XII present?

What causes CN XII lesions?

A

Hypoglossal

Wasting of ipsilateral side of tongue with fasciculation
Tongue deviates to side of lesion

Causes: polio

59
Q

What does palsy mean?

60
Q

Which cranial nerve(s) control(s) the gag reflex?

A

IX controls afferent arm

X controls efferent arm

61
Q

What is Bell’s palsy?

A

Inability to control facial muscles on one side of the face, due to a facial nerve problem on that side

Neurology (23 decks)

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