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Year 3 Clinical > Peripheral Neuropathy > Flashcards

Peripheral Neuropathy Flashcards

1
Q

5 questions to consider when approaching a peripheral nerve issue?

A

Which nerves are damaged?

Where are they damaged?

How are the nerves damaged?

Why are the nerves damaged?

Can the nerve damage be stopped / prevented?

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2
Q

Common methods by which nerve damage occurs?

A

Idiopathic, age-related neuropathies are the most common (almost all individuals in their 80s-90s will have some degree of peripheral neuropathy)

Compression neuropathies

Immune-driven nerve damage

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3
Q

Useful test of the PNS?

A

Stretch reflex:
• Hyporeflexia (decreased reflex) in PERIPHERAL NERVE / LMN issues
• If there is a central / UMN issue, this generally causes hyperreflexia (increased reflex)

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4
Q

Signs of a neuropathy that affects the ANS?

A

Often a patient presents with both motor / sensory symptoms (peripheral neuropathy) and signs of autonomic dysfunction, e.g:
• Postural hypotension
• Gastroparesis

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5
Q

3 types of nerve fibres are how they vary in size?

A

From largest to smallest:
• Motor
• Sensory
• Autonomic

As nerve size decreases, the surrounding myelin also decreases

ADD IMAGE

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6
Q

Symptoms and examination signs of a large fibre motor issue?

A

Symptoms:
• Weakness
• Unsteadiness
• Wasting

Examination signs:
• Reduced power
• Normal sensation
• Areflexia (absent reflexes)

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7
Q

Symptoms and examination signs of a large fibre sensory issue?

A

Symptoms:
• Numbness
• Paraesthesia
• Unsteadiness

Examination signs:
• Normal power
• Sensation - vibration and proprioception reduced
• Areflexia

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8
Q

Symptoms and examination signs of a small fibre issue?

NOTE - small fibres tend to only transmit info about pain, touch and temperature

A

Symptoms:
• Pain
• Dysesthesia

Examination signs:
• Normal power
• Sensation - pinprick and temperature reduced
• Reflexes are present and normal

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9
Q

Symptoms and examination signs of an autonomic fibre issue?

A

Symptoms:
• Dizziness due to postural hypotension
• Impotence
• N&V due to gastroparesis

Examination signs:
• Normal power
• Normal sensation
• Reflexes are present and normal

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10
Q

What is pseudoathetosis?

A

Abnormal writhing movements, usually of the fingers; occurs due to a failure of proprioception

NOTE - looks like chorea but it is not; chorea is caused by issues with the basal ganglia whereas pseudoathetosis is caused by a large sensory fibre neuropathy (as proprioception is lost)

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11
Q

Examination of reflexes in a patient with pseudoathetosis would reveal?

A

Areflexia

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12
Q

What does a bilateral foot drop suggest?

A

These patients will have a HIGH-STEPPING GAIT, as the ankles cannot be dorsiflexed

Common peroneal / fibular nerve is affected

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13
Q

Basis for the terminology of nerve damage?

A

Depends on where the nerve damage specifically occurs

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14
Q

Terminology for nerve damage?

A

Radiculopathy - issue is at the level of the nerve root/rootlets

Plexopathy - issue is at the level of the nerve plexus, i.e: brachial or lumbosacral

Peripheral neuropathy - issue is at the level of the peripheral nerve:
• Mononeuropathy (most common)- peripheral neuropathy affecting just 1 nerve
• Mononeuritis multiplex - affects multiple nerves in disparate areas of the body; often caused by vasculitis
• (Length dependent) peripheral neuropathy -

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15
Q

Symptoms and signs of a radiculopathy?

A

Radicular pain in dermatomal distribution

Weakness in myotomal distribution

Numbness

Difficulty controlling specific muscles

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16
Q

Symptoms and signs of a plexopathy?

A

Pain

Loss of motor control

Sensory deficits

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17
Q

Symptoms and signs of a length-dependent peripheral neuropathy?

A

Axonal peripheral neuropathies affect the longest axons first

Results in the classic “STOCKING-GLOVE” distribution of symptoms and signs; this can progress from mild and moderate to severe, depending on how far the nerve damage extends up the limb

NOTE - this is why sensation is always tested distally before moving proximally in an examination

18
Q

Signs of long-standing carpal tunnel syndrome?

A

Wasting of thenar eminence

19
Q

Another cause of a carpal tunnel like presentation?

A

C8 radiculopathy (e.g: due to a congenital cervical rib)

MND (rare but always consider if their wasting)

20
Q

2 broads pathogeneses by which nerve damage occurs?

A
  1. Axonal loss (of the axon itself)

2. Peripheral nerve demyelination

21
Q

Ix for differentiating a demyelinating neuropathy from a neuropathy due to axonal loss?

A

Nerve conduction studies:
• In demyelinating neuropathies, there is a bizarre wave form (as responses arrive at different times)
• In axonal neuropathies, there is a decrease in conduction

22
Q

Types of demyelinating neuropathY?

A

Acute (develops over days - weeks:
• Guillain Barre syndrome

Chronic (develops over months - years):
• Chronic Inflammatory Demyelinating Polyradiculopathy (CIDP)
• Hereditary motor and sensory neuropathy (AKA Charcot-Marie-Tooth disease)

23
Q

What is Guillain-Barre syndrome (GBS)?

A

Autoimmune attack of the PNS; tends to be POST-INFECTIOUS, there is part. a Campylobacter assoc.

24
Q

Symptoms of GBS?

A

Progressive paraplegia over days for up to 4 weeks

Assoc. sensory symptoms include:
• Pain (VERY COMMON)
• Weakness
Peak symptoms are 1-14 days into onset of the illness

25
Q

Examination signs of GBS?

A

Can be normal in the initial phases of the illness

Eventually develop areflexia

26
Q

Complications of GBS?

A

Need for mechanical ventilation

Death due to autonomic failure and resulting cardiac arrhythmia

27
Q

Treatment of GBS?

A

Ig infusion

and / or

Plasma exchange

NOTE - steroids have a minimal role

28
Q

What is hereditary neuropathy?

A

AKA Hereditary neuropathy

There are many potential mutations so it can be autosomal dominant, autosomal recessive or X-linked

29
Q

Nerves that can be affected by a hereditary neuropathy?

A

Pure motor

Sensory

Sensorimotor

Small fibre

Autonomic variants

30
Q

Ix for hereditary neuropathy??

A

Genetic testing is available for the most common mutations, e.g: CMT1A

31
Q

Cause of congenital insensitivity to pain syndrome?

A

Small fibre issue

32
Q

Signs of Hereditary Motor and Sensory Neuropathy (HMSN), AKA Charcot-Marie-Tooth Disease?

NOTE - this is a specific type of hereditary neuropathy

A

Champagne bottle deformity of calves

High-arched foot (pes cavus)

NOTE - pes cavus is a buzzword for Charcot-Marie-Tooth disease

33
Q

Causes of axonal neuropathies?

A

Idiopathic (age-related)

Vasculitis (mainly causes mononeuritis multiplex)
• ANCA +ve
• Rheumatoid arthritis / Sjogren’s syndrome (ANA +ve)

Paraneoplastic:
• Myeloma
• Antibody-mediated, e.g: breast cancer)

Infections:
• HIV
• Syphilis
• Lyme
• Hepatitis B / C 
Drugs / toxins:
• Alcohol
• Amiodarone
• Pheyntoin
• Chemotherapy 
Metabolic:
• Diabetes
• B12 / folate deficiencies
• Hypothyroidism
• Chronic uraemia
• Porphyria
34
Q

Types of autonomic neuropathy and causes of each?

A

Chronic:
• Diabetes (e.g: can cause gastroparesis)
• Amyloidosis
• Hereditary

Acute:
• GBS
• Porphyria (rare)

35
Q

Other symptoms of a porphyria?

A

Often present with unexplained abdominal pain (useless diagnostic laparoscopies), peripheral neuropathy, rash, etc

Often misdiagnosed with psychosis

36
Q

Treatment of peripheral neuropathies where the issue is axonal loss?

A

Treat the cause, e.g: clear Hep C

Symptomatic treatment:
• Physiotherapy
• Orthotics
• Neuropathic pain relief

37
Q

Treatment of peripheral neuropathies where the issue is axonal loss caused by a vasculitis?

A

Pulsed IV methylprednisolone

+

Cyclophosphamide

38
Q

Treatment of a peripheral neuropathy where the issue is demyelination?

A

IV Ig (pooled Ig from donors)

Steroids

Azathioprine, mycophenalate, cyclophosphamide

39
Q

What is the issue in the following case?

ADD IMAGE

A

Damaged nerves are the large and small fibre motor and sensory fibres; they are damaged in the ulnar territory, due to compression in the Guyon canal

Nerve conduction studies will demonstrate an axonal picture

Sounds like an ulnar neuropathy; consider occupation and diabetes as potential causes

NOTE - Guyon’s canal is in the wrist; cubital tunnel is near the elbow

40
Q

What is the issue in the following case?

ADD IMAGE

A

Damages nerves are the large and small motor and sensory fibres; the right median nerve is damaged. as is the left common peroneal / fibular nerve

Nerve conduction studies will demonstrate an axonal picture of a mononeuritis multiplex

These nerves are damaged due to his being ANCA +ve

To stop damages of the nerves:
• Pulsed steroids +/- cyclophosphamide

41
Q

What is the issue in the following case?

ADD IMAGE

A

Damaged nerves are mainly the large motor and sensory fibres; they are damaged in a length-dependent manner

Nerve conduction studies will demonstrate an axonal picture; the reason for the damage was acute intermittent porphyria

To stop damage of the nerves, treat the underlying porphyria

Year 3 Clinical (100 decks)

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