Polyneuropathy Flashcards

1
Q

What are polyneuropathies?

A

Motor and/ or sensory disorders of multiple peripheral or cranial nerves.

Usually symmetrical and widespread

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2
Q

Are polyneuropathies usually worse distally or proximally?

A

Distally - glove and stocking distribution

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3
Q

How are they usually classed?

A

Chronicity
Function - sensory, motor, autonomic, mixed
Pathology - demyelination, axonal degeneration, both

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4
Q

What metabolic conditions can cause polyneuropathy?

A

DM
Hypothyroidism
Renal failure
Hypoglycaemia

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5
Q

What infections can cause polyneuropathy?

A

Leprosy
HIV
Syphilis
Lyme disease

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6
Q

What nutritional factors can cause polyneuropathy?

A

Low B1
Low B12/ folate
Low vit E
High B6

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7
Q

What inflammatory conditions can cause polyneuropathy?

A

Guillian Barre syndrome

Sarcoidosis

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8
Q

What inherited syndromes can cause polyneuropathy?

A

Charcot-Marie- Tooth

Porphyria

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9
Q

What types of malignancy can cause polyneuropathy?

A

Paraneoplastic syndromes

PV

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10
Q

What vasculitides can cause polyneuropathy?

A

RA

Polyarteritis nodosa

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11
Q

What drugs can cause polyneuropathy?

A
Vincristine 
Cisplatin
Isoniazid
Nitrofurantoin 
Phenytoin 
Metronidazole
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12
Q

If there is palpable nerve thickening, what should you think of?

A

Leprosy

Charcot-Marie-Tooth

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13
Q

What tests should be done?

A

FBC, ESR, glucose, U&E, TSH, B12, electrophoresis, ANA, ANCA, CXR, urinalysis

Consider LP and specific genetic testing

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14
Q

How do you distinguish demyelination from axonal causes?

A

Nerve conduction studies

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15
Q

What type of polyneuropathy is Guillian Barre syndrome?

A

Acute, predominantly motor demyelinating neuropathy

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16
Q

What type of polyneuropathy does chronic alcohol abuse lead to?

A

A chronic, initially sensory then mixed axonal neuropathy

17
Q

What things should you ask in the history?

A
Time course
Precise nature of symptoms 
Preceding or associated events e.g D&V before Guillian Barre, reduce weight in cancer, arthralgia from a connective tissue disease 
Travel
Alcohol and drug use 
Sexual infections
FH
18
Q

What are some examples of conditions that cause sensory neuropathy?

A

DM
CKD
Leprosy

19
Q

What symptoms are associated with sensory neuropathy?

A

Numbness
Pins and needles
Paraesthesia

Glove and stocking distribution
Difficulty handling small objects such as buttons
Signs of trauma - burns or joint deformity may indicate sensory loss

Diabetic and alcoholic neuropathies typically painful

20
Q

What are some examples of conditions that cause motor neuropathy?

A

Guillian Barre
Lead poisoning
Charcot-Marie-Tooth syndrome

21
Q

What character are associated with motor neuropathies?

A

Often progressive (may be rapid)
Weak, clumsy hands
Difficulty walking - falls, stumbling
Difficulty breathing - reduced vital capacity

Signs of LMN lesion - wasting, weakness, areflexia

22
Q

In terms of sensory neuropathy management, what is important to minimise trauma?

A

Foot care

Show choice

23
Q

All peripheral nerves are myelinated except…

A

C fibres which carry information about pain

Called slow fibres - signal travels slow due to lack of myelination

24
Q

What mnemonic can be used to remember specific causes of peripheral neuropathies?

A

DAVID

Diabetes
Alcoholism 
Vitamin deficiency e.g B12
Infective or inherited - Guillian Barre or CMT 
Drugs e.g isoniazid
25
Q

What are the 6 main mechanisms of peripheral nerve degeneration?

A
Demyelination 
Axonal degeneration
Wallerian - fibre cut or crushed 
Compression - not as severe as Wallerian 
Infarction 
Infiltration
26
Q

What is an example of compressive degeneration?

A

Carpal tunnel syndrome

There is local demyelination at site of compression

27
Q

What are examples of infiltrative degeneration?

A

Leprosy
Malignancy
Inflammation
Sarcoidosis

28
Q

What are examples of degeneration due to infarction?

A

Diabetes
Polyarteritis nodosa
Chung-Strauss syndrome

There is also Wallerian degeneration distal to infarct

29
Q

When does axonal degeneration typically occur?

A

In toxic neuropathies

30
Q

What is leprosy?

A

An infection by the bacteria mycobacterium leprae or mycobacterium lepromatosis

Nerve damage - sensory, motor and autonomic
Skin lesions - red or hypopigmented patches with reduced sensation
Thickened peripheral nerves
Loss of sensation produces loss of protective reactions, which can lead to trauma and infections

The bacteria acts on Schwann cells producing a chronic granulomatous reaction - destruction of both myelin and underlying nerve cells