Peripheral Neuropathy Flashcards by Aliya Hussain

5 questions to consider when approaching a peripheral nerve issue?

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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Common methods by which nerve damage occurs?

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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Useful test of the PNS?

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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Signs of a neuropathy that affects the ANS?

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

From largest to smallest:
• Motor
• Sensory
• Autonomic

As nerve size decreases, the surrounding myelin also decreases

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Symptoms and examination signs of a large fibre motor issue?

Symptoms:
• Weakness
• Unsteadiness
• Wasting

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

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Symptoms and examination signs of a large fibre sensory issue?

Symptoms:
• Numbness
• Paraesthesia
• Unsteadiness

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

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Symptoms and examination signs of a small fibre issue?

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

Symptoms:
• Pain
• Dysesthesia

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

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Symptoms and examination signs of an autonomic fibre issue?

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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What is pseudoathetosis?

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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Examination of reflexes in a patient with pseudoathetosis would reveal?

Areflexia

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What does a bilateral foot drop suggest?

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

Common peroneal / fibular nerve is affected

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Basis for the terminology of nerve damage?

Depends on where the nerve damage specifically occurs

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Terminology for nerve damage?

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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Symptoms and signs of a radiculopathy?

Radicular pain in dermatomal distribution

Weakness in myotomal distribution

Numbness

Difficulty controlling specific muscles

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Symptoms and signs of a plexopathy?

Pain

Loss of motor control

Sensory deficits

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Symptoms and signs of a length-dependent peripheral neuropathy?

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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

Signs of long-standing carpal tunnel syndrome?

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Wasting of thenar eminence

Another cause of a carpal tunnel like presentation?

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

MND (rare but always consider if their wasting)

2 broads pathogeneses by which nerve damage occurs?

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Axonal loss (of the axon itself)

2. Peripheral nerve demyelination

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

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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

Types of demyelinating neuropathY?

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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)

What is Guillain-Barre syndrome (GBS)?

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

Symptoms of GBS?

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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

Examination signs of GBS?

Can be normal in the initial phases of the illness Eventually develop areflexia

Complications of GBS?

Need for mechanical ventilation Death due to autonomic failure and resulting cardiac arrhythmia

Treatment of GBS?

Ig infusion and / or Plasma exchange NOTE - steroids have a minimal role

What is hereditary neuropathy?

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

Nerves that can be affected by a hereditary neuropathy?

Pure motor Sensory Sensorimotor Small fibre Autonomic variants

Ix for hereditary neuropathy??

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

Cause of congenital insensitivity to pain syndrome?

Small fibre issue

Signs of Hereditary Motor and Sensory Neuropathy (HMSN), AKA Charcot-Marie-Tooth Disease? NOTE - this is a specific type of hereditary neuropathy

Champagne bottle deformity of calves High-arched foot (pes cavus) NOTE - pes cavus is a buzzword for Charcot-Marie-Tooth disease

Causes of axonal neuropathies?

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 ```

Types of autonomic neuropathy and causes of each?

Chronic: • Diabetes (e.g: can cause gastroparesis) • Amyloidosis • Hereditary Acute: • GBS • Porphyria (rare)

Other symptoms of a porphyria?

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

Treatment of peripheral neuropathies where the issue is axonal loss?

Treat the cause, e.g: clear Hep C Symptomatic treatment: • Physiotherapy • Orthotics • Neuropathic pain relief

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

Pulsed IV methylprednisolone + Cyclophosphamide

Treatment of a peripheral neuropathy where the issue is demyelination?

IV Ig (pooled Ig from donors) Steroids Azathioprine, mycophenalate, cyclophosphamide

What is the issue in the following case? ADD IMAGE

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

What is the issue in the following case? ADD IMAGE

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

What is the issue in the following case? ADD IMAGE

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

Peripheral Neuropathy Flashcards

(41 cards)