neuropathy

Question 1

mononeuritis multiplex vs mononeuritis

Answer 1

Mononeuritis multiplex – in multiple locations
o Wrist drop + foot drop

Mononeuritis/mononeuropathy – single location
o Wasting of thenar in carpal tunnel

• Radiculopathy – pinching at the spinal cord
• Plexopathy – affecting plexus

Question 2

demyelinating neuropathies

Answer 2

acute (days-weeks)
- Guillane-Barre syndrome

chronic (months-years)
- chronic inflammatory demyelinating polyradiculopathy (CIDP)
- Charcot-Marie tooth disese (Hereditary sensory motor neuropathy (HSMN)

Question 3

guillain-barre syndrome

Answer 3

an acute paralytic polyneuropathy

immune mediated demyelination of peripheral nervous system usually triggered by infection

Question 4

infections that can trigger guillian barre

Answer 4

campylobacter jejuni !!!!

cytomegalovirus
epstein-barr virus

Question 5

pathophysio of guillian barre

Answer 5

molecular mimicary
- B cells of the immune system create antibodies against the antigens on the pathogen that cause the infection
–> these antibodies also match the proteins on the nerve cells

they may target proteins on the myelin sheather of the motor nerve cell or nerve axon

(cross-reaction of antibodies with gangliosides in the peripheral nervous system)

Question 6

guillian barre presentation

Answer 6

symmetrical ascending weakness - starting at feet + moving up body
reduced/absent reflexes
peripheral loss of sensation / neuropathic pain
Hx of gastroenteritis

may progress to cranial nerves - diplopia, bilateral facial nerve palsy

peripheral neuropathy - no UMN/LMN

Question 7

clinical course of guillian barre

Answer 7

Symptoms usually start 4 weeks of preceding infection
 Peak within 2-4weeks (10-14 days)

Then there is a recovery period that can last months to years

• Pain is very common
• Examination can be normal in the initial phases of illness
• assoc sensory symptoms proceed weakness

Question 8

diagnostic criteria + investigation of guillian barre

Answer 8

clinical diagnosis -> Brighton criteria

Investigations:
- Nerve conduction studies – reduced signal through nerves, decreased motor nerve conduction velocity (due to demyelination)

• Lumbar puncture
  o Raised protein with normal cell count + glucose

Question 9

management of guillian barre

Answer 9

IV immunoglobulins
plasma exchange (alternative to IV Ig)

supportive care
VTE prophylaxis (PE = leading cause of death)

Question 10

prognosis of guillain barre

Answer 10

80% fully recover
15% left with neurological disability
25% require mechanical ventilation

5-10% die, mainly from autonomic failure - cardiac arryythmia

Question 11

charcot-marie- tooth disease

Answer 11

commonest hereditary peripheral neuropathy

• Various types with different pathophysio that cause dysfunction in myelin or the axons
• Majority inherited autosomal dominant
• results in predominantly motor loss

no cure, management is focused on physical/occupational therapy

peripheral neuropathy, LMN signs only, reduced sensation esp distal

Question 12

features of charcot marie tooth disease

Answer 12

history of frequently sprained ankles
symptoms usually start to appear before age 10

high arched feet - pes cavus
foot drop
haammer toes

distal muscle weakness/atrophy - “inverted champagne bottle legs”
weakness in lower legs - esp loss of ankle dorsiflexion

Question 13

causes of peripheral neuropathy

Answer 13

A – alcohol
B – B12 deficiency
C – Cancer (myeloma) + Chronic kidney disease
D – Diabetes + Drugs – isoniazid, amiodarone, cisplatin
E – Every vasculitis - connective tissue disorder

infections - HIV, syphilis, Lyme, hepatitis B/C

Question 14

causes of autonomic neuropathy

Answer 14

chronic
- diabetes - gastroparesis
- amyloidosis
- hereditary

acute
- GBS
- porphyria

Question 15

in which 2 ways can nerves be damaged?

Answer 15

Axonal loss
- Causes
 Physical disruption of nerve
 Toxic, metabolic or genetic conditions

Peripheral nerve demyelination
- Loss or dysfunction of myelin sheath
- Causes
 Entrapment or compressive neuropathies
 Genetic – charcot marie tooth
 Toxic – diptheria
 Post immunologic attack on the myelin

Question 16

how can axonal loss and peripheral nerve demyelination be differentiated?

Answer 16

via electrical studies

Axonal loss
* Amplitude decreases
* Conduction velocities normal or slightly decreased
* Distal latencies are normal or slightly prolonged

Demyelination
* Normal amplitude
* Conduction velocities slowing
* Distal latencies prolonged

Question 17

treatment of peripheral neuropathy

Answer 17

Axonal
o Treat cause – clear hepatitis C
o Symptomatic treatment
 Physio, orthotics, neuropathic

Axonal (vasculitis)
o Pulsed IV methylprednisolone + cyclophosphamide

Demyelinating (inflammatory neuropathy)
o IV Ig – pooled Ig from donors
o Steroids
o Azathioprine, mycophenalate, cyclophosphamide