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MBBS IV - Junior Clerkship WCS > JC32 (Medicine) - Neuropathy, Myopathy > Flashcards

JC32 (Medicine) - Neuropathy, Myopathy Flashcards

1
Q

List 5 major categories of generalized weakness

A
  1. Polyneuropathies
  2. Muscular Dystrophies
  3. MG
  4. Inflammatory Myopathies
  5. Floppy infant syndrome
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2
Q

Ddx peripheral neuropathies/ Polyneuropathies

A

Peripheral neuropathies

  • Hereditary neuropathies
  • GBS,
  • Toxins
  • DM,
  • uraemia,
  • Vit B12 def,
  • paraproteinaemia and immune neuropathies
  • CIDP
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3
Q

Ddx NMJ diseases with generalize weakness

Pertinent features

A
  • * MG**
  • * LEMS**
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4
Q

Ddx muscle diseases with generalize weakness/ Myopathies

A
  1. Dystrophies,
  2. congenital myopathy, channelopathy
  3. Myositis,
  4. toxic or metabolic myopathy,
  5. rhabdomyolysis
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5
Q

Symmetrical, Fluctuating proximal weakness + ocular and bulbar involvement

Normal reflexes

No wasting

Most likely lesion? Ddx

A

NMJ disease

e.g. MG, LEMS

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6
Q

Symmetrical distal weakness

Absent or hyporeflexia

Muscle wasting

Non-dissociated sensory involvement

Trophic changes

Steppage gait

Sensory symptoms/ pain

Ocular-sparing

Autonomic signs

Most likely lesion? Ddx

A

Peripheral neuropathies

  • Hereditary neuropathies
  • GBS,
  • Toxins
  • DM,
  • uraemia,
  • Vit B12 def,
  • paraproteinaemia and immune neuropathies
  • CIDP
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7
Q

Symmetrical proximal weakness

Fasciculation and wasting present

Reflexes intact

Waddling gait

+/- ocular and bulbar involvement

+/- pain and tenderness

Most likely lesion? Ddx

A

Muscle diseases

  • Dystrophies,
  • congenital myopathy, channelopathy, mitochondrial disease
  • Myositis,
  • toxic or metabolic myopathy,
  • rhabdomyolysis**
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8
Q

Asymmetrical weakness

Involves UL extensors and LL flexors

UMN signs - hypertonia, Babinski, Hoffman, Hyperreflexia

Dissociated sensory involvement

Spastic/ plegic gait

Sensory and bulbar symptoms

+/- Sphincter dysfunction

Most likely lesion

A

CNS lesion

Cervical myelopathy, Brainstem pathology

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9
Q

Investigation for CNS lesion causing generalize weakness

A

 CT/MRI brain

 LP and CSF analysis

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10
Q

Investigation of peripheral nerve lesion with generalize weakness/ polyneuropathies

A
  1. Electrophysiological studies - Nerve Conduction Study
  2. R/o systemic diseases: e.g. HbA1c for DM, Vit B12 for SCCD, TFT for thyroid proximal myopathy
  3. Lumbar Puncture and CSF analysis
  4. Nerve biopsy (rare)
  5. Genetic tests
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11
Q

Investigations for NMJ diseases **

A

Repetitive nerve stimulation test

Tensilon test

Anti-AChR

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12
Q

Investigations for muscle diseases

A

 Muscle Enzymes: CK, lactate
 Electrophysiological studies - EMG
 MRI
 Muscle Biopsy

Genetic tests

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13
Q

Differentiate radiculopathy, plexopathy, and neuropathy with subtypes

A

□ Radiculopathy involving nerve roots

□ Plexopathy involving nerve plexus

□ Neuropathy involving nerves
→ Mononeuropathy: only one nerve affected
→ Mononeuritis multiplex: multiple sequential mononeuropathies
→ Polyneuropathy: symmetrical involvement of all/most peripheral nerves

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14
Q

4 key questions to classify exact type of peripheral nerve lesion

A

□ Time course: acute, subacute, chronic, relapsing

□ Distribution: generalized, focal; symmetrical, asymmetrical

□ Type of fibres involved:
→ Large (mostly -ve symptoms) vs small fibers (mostly +ve symptoms)
→ Motor, sensory, autonomic, mixed

□ Pathology:
→ Axonal: damage to nerve cell
→ Demyelinating: damage to Schwann cells making up the myelin sheath

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15
Q

Motor features of peripheral nerve lesion

A

LMN Motor: weakness, wasting, fasciculation, hyporeflexia

→ Distal weakness: difficulty in tip-toeing, foot drop, ↓manual dexterity

→ Proximal weakness: difficulty in climbing stairs, combing hair, standing up from siting position

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16
Q

Sensory features of peripheral neuropathy

A

Sensory:
→ Large, myelinated fibres: loss of touch/proprioception (-ve) or pins-and-needle (+ve)

→ Small, unmyelinated fibres: loss of pain/temperature (-ve) or pain (+ve)

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17
Q

Autonomic features of peripheral neuropathy

A

Autonomic: rarely occurs alone, usually complicates other neuropathies
→ Postural hypotension → postural BP for all neuropathy to detect autonomic involvement
→ Disturbance in sweating, cardiac rhythm, GI/bladder functions, sexual function

18
Q

Trophic changes asso. with peripheral neuropathy

A

Trophic changes: disuse atrophy, hair loss, brittle nails, trophic ulcers, Charcot’s joints

19
Q

Ddx Nerve thickening syndromes

A

leprosy, acromegaly, HMSN, CIDP, neurofibromatosis

20
Q

Main causes of mononeuropathy

A

□ Entrapment/ Compressive mononeuropathy: damage to a nerve where it passes through a tight space
□ Trauma
□ Other focal lesions, eg. granulomatous inflammation

21
Q

Entrapment neuropathy

Predisposing factors

Management

A

Predisposing factor:
→ Generalized soft tissue swelling, eg. acromegaly, myxedema, pregnancy
→ Others: DM, excess alcohol/toxins, genetic syndromes

Mx: remove entrapment by avoiding precipitating factors or surgical decompression

22
Q

Median nerve entrapment

  • Site
  • Symptoms
  • Muscle weakness
  • Area of sensory loss
A
  • Site - at wrist, carpal tunnel syndrome
  • Symptoms - Pain and paresthesia at palmar hand, may extend to arm and shoulder
  • Muscle weakness - Abductor pollicis brevis
  • Area of sensory loss - Lateral palm and thumb, index, middle and lateral half of 4th finger
23
Q

Ulnar nerve entrapment

  • Site
  • Symptoms
  • Muscle weakness
  • Area of sensory loss
A
  • Site - Elbow at Cubital tunnel at medial epicondyle
  • Symptoms - Paraesthesia on medial border of hand, wasting and weakness of hand muscles
  • Muscle weakness - All hand muscles except abductor pollicis brevis
  • Area of sensory loss - Medial palm and little finger + medial half of 4th finger
24
Q

Radial nerve entrapment

  • Site
  • Symptoms
  • Muscle weakness
  • Area of sensory loss
A
  • Site - area of frosche, radial tunnel syndrome
  • Symptoms - weakness of wrist and finger extension, precipitate by abnormal position (e.g. arm over back of chair)
  • Muscle weakness - Wrist and finger extensors, supinators
  • Area of sensory loss - Dorsum of thumb
25
Q

Common peroneal nerve entrapment

  • Site
  • Symptoms
  • Muscle weakness
  • Area of sensory loss
A
  • Site - proximal fibula fracture/ entrapment/ trauma to head of fibula
  • Symptoms - Foot drop
  • Muscle weakness - Dorsiflexion and eversion of foot
  • Area of sensory loss - Dorsum of foot, web between 1st and 2nd toe
26
Q

Lateral cutaneous nerve of thigh

  • Site
  • Symptoms
  • Muscle weakness
  • Area of sensory loss
A
  • Site - hypertrophy or abnormal piriform muscle compressing onto nerve from top
  • Symptoms - Tingling and dysaesthesia on lateral border of thigh
  • Muscle weakness - None
  • Area of sensory loss - Lateral aspect of thigh
27
Q

Mononeuropathy Multiplex (-)

Definition

S/S

A

Mononeuropathy multiplex: simultaneous or sequential occurrence of mononeuropathies affecting multiple non-contiguous nerve trunks

Vasculitic Neuropathy leading to nerve infarction

□ Acute pain followed by focal neuropathy
□ Gradual spread from focal → multifocal → generalized

28
Q

Causes of mononeuropathy multiplex (-)

A

□ Axonal due to nerve infarction from small-to-medium arterial diseases
→ DM-associated atherosclerosis
→ Vasculitis
→ Infections: syphilis, HIV, leprosy, Lyme disease, diphtheria
□ Demyelinating, eg. multifocal motor neuropathy (MMN)

Causes of mononeuritis multiplex:
Wegener’s granulomatosis
Amyloidosis
Rheumatoid arthritis
Diabetes mellitus
SLE
Polyarteritis nodosa
Leprosy
Carcinomatosis and Churg-strauss syndrome

29
Q

4 clinical types of polyneuropathy

Typical S/S of polyneuropathy

A

Acute and Chronic axonal lesion

Acute and chronic demyelinating lesion

S/S: most typically symmetrical sensorimotor but other patterns possible
□ Motor: ascending weakness from distal LL
□ Sensory: ascending ‘glove-and-stocking’ sensory loss or paraesthesia from distal limbs
□ Autonomic: diarrhoea/constipation, brady/tachycardia, urinary disturbance, BP changes

30
Q

GBS

  • Pertinent features
  • Pathophysiology
  • Clinical course
  • S/S
  • First-line investigation
  • Treatment
A
  • Pertinent features: Rapidly progressive flaccid paralysis + areflexia + high CSF protein
  • Pathophysiology: Recent VIRAL/ bacteria infection (e.g. COVID, URTI, GE) >>> acute neuritis from autoAb attack >> Acute inflammatory demyelinating polyneuropathy
  • Clinical course: 4 weeks
  • S/S: ascending weakness with facial involvement, LMN signs, Autonomic dysfunctions
  • First-line investigation: Anti-Gangliocyte Antibody, High CSF without pleocytosis, Electrophysiology study
  • Treatment: Plasmapheresis, IV immunoglobulins, Mechanical ventilation, Treat complications
31
Q

Name the most commonly inherited neurological disorder

A

Charcot Marie Tooth Disease

32
Q

Charcot Marie Tooth disease

  • Features
  • Mutation
A

Features: distal wasting, Foot drop, Pes cavus

Mutation: HMSN-I to HMSN-VII

33
Q

Ddx motor neuron diseases

Pathophysiology

Treatment

A

ALS - Amyotrophic Lateral Sclerosis

PLS

Pseudobulbar palsy, PMA, PBP

Patho: Alpha motor neuron degeneration, No sensory involvement, Both UMN and LMN signs

Tx: None, general supportive only (ventialtion, euthansia, nutrition)

34
Q

Ddx neurotoxic agents

A

Alcohol

Solvents

Industrical chemicals

Heavy metals

Anti-cancer agents, Anti-biotics

Colchine, Thalidomide…etc

35
Q

Ddx Muscular dystrophies

3 ways to classify muscular dystrophies

A
  1. Dunchenne DMD
  2. Becker BMD
  3. Limb-girdle (LGMD)
  4. Myotonic dystrophy MyoD
  5. Fascioscapulohumeral FSHD

^^ Phenotype classification

  1. Immunohistochemical classification
  2. Genetic classification - e.g dystrophin gene deletion
36
Q

Inflammatory myopathies ddx

A
37
Q

Inclusion body myositis

Features

Investigations

A
38
Q

Dermatomyositis

Features

A
39
Q

Myositis investigations

A

Muscle MRI

PET scan for malignancy

Myositis - autoantibodies

ELISA

Electromyography

40
Q

MG *

  • Features
  • Associated diseases
  • First line IX
  • Tx
A

Features: Fluctuating/ intermittent weakness, Anti-AchR antibodies, ocular manifestation first

Associated: Thymic Cancer, Autoimmune Thyroiditis

Ix: Anti-AchR Ab + Electrophysiology Tensilon test (injection Edrophonium) + CT thorax + Thyroid function test

Tx:

  • Plasmapheresis, IV immunoglobulin
  • Anti-cholinesterase (Pyridostigmine)
  • Thymectomy
  • Immunotherapy - Steroids, Azothioprine
41
Q

Ddx Presynaptic NMJ disorder

A
42
Q

Tests for clinical neurophysiology

A

Nerve conduction study

Needle electromyography (EMG)

Electrodiagnostic studies

MBBS IV - Junior Clerkship WCS (131 decks)

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