Neuropathies

Question 1

Neurological side effect of the AZ covid vaccine?

Answer 1

GBS (can happen with any vaccine) + bilteral facial weakness

Question 2

COmplication of B12 def and NO use?
Brief phathophys? Treatment?

Answer 2

Peripheral nephropathy, initially sensory but if use a lot of NO then can be weakness as well
- irreversible usually

Block conversion of B12 to active B12
- therefore need to check total B12 and active B12

Treat with very high doses of B12

Question 3

Treatment with isoniazid for TB / BCGosis etc. WHat should always be given with this drug and why?

Answer 3

Pyridoxine (B6)
- Prevents development of painful peripheral neuropathy

Question 4

B6 toxicity can cause…?

Answer 4

painful peripheral neuropathy, can be irreversible
- too much B6 stops B6 working normally, similar to if there was B6 def

Question 5

All muscle disease (myopathy) results in proximal then distal weakness except…?
All neuropathy results in distal then proximal weaknessness except…?

Answer 5

Myotonic dystrophy

CIDP
- can cause proximal hip flexor weakness initially

Question 6

What do these aspects of a NCS tell us about the nerves:
- Amplitude?
- Velocity?
- Dispersion? conduction block?

Answer 6

Amplitude - how many axons
- more amplitude = more axons

Velocity
- how fast the signal travels is a results of how well insulated the wires are (ie ? demyelination)
- If there is demyelination there will be slowed velocities

Dispersion
- THis is when a signal spread out
- due to demyelination
Conduction block
- this is when there are two or more distinct peaks when only one peak was used as stimulus
- again due to demyelination

Question 7

Features of demyelination on NCS?

Answer 7

slowed conduction velocity, dispersion and conduction block

Question 8

How does EMG differ from NCS?

Answer 8

NCS
- measure the nerves functioning
- Can perform motor nerve consuction studies that measure the response signal over the muscle belly but this is still looking at the nerve
- NON INVASIVE

EMG
- this is a more invasive test that involves a needle in the muscle belly
- used to measure the NMJ, such as denervation, myositis, myopathy

Question 9

Difference between myositis and myopathy and denervation?

Answer 9

myositis - normal invervation but inflamed muscle
Myopathy - intrinsic problem with muscle
Denervation - muscle normal but less nerves feeding it

Question 10

EMG recording feature in neuropathic conditions (ie denervation)?
EMG recording feature in myopathic conditions?

Answer 10

Big response
- this is because there is onyl a few nerve cells left that conseqwuently try to inervated everything by themselves

Very small response
- only little bit of muscle left

Question 11

Common sensory, motor and painful neuropathies?

Answer 11

Sensory:
- Diabetic peripheral neuropathy
- B12 and thiamine (excluding B12 with NO)
- Paraneoplastic / drug related

Motor:
- GBS/AIDP
- Lead related
- Multifocal motor neuropathy

Painful neuroapthy
- DIabetic: proximal / small fibres affected
- Nutrition /etoh
- B6 toxicity
- Cryoglobulinaemia

Note amyloid can cause any type of neuroapthy and can presaent in different ways (ie rapidly progressive, slowly progressive etc)

Question 12

Neuro side effect of metronidazole exposure?

Answer 12

peripheral neuropathy

Question 13

What is GBS/AIDP?
What causes GBS / what is the most common antecedant condition?
Diagnostic tests (bloods, NCS, CSF)?
Treatment?

Answer 13

Motor weakness characterised by ascending weaknerss, numbness or both over a period of 4 weeks
- Hall mark is loss of reflexes over time

GBS is usually caused by cross reactivity between antibodies produced in response to an infection and the myelin fibes in nerves (autoimmunity condition similar to RHD)
- Most commonly following Campylobactor Jejuni infection, also viruses or vaccines)

Dx test inc:
- Antibodies: Anti BM1, anti GM2, anti GDa1
- NCS: demyelination, delayed F waves
- CSF (raised protein nil cells (ie not infectious))

Treatment:
- IVIG or PLEX
- NOT STEROID, it is immune mediated not cell mediated so dont work

Question 14

What is CIDP?
Diagnostic tests?
Treatment?

Answer 14

Basically GBS that onset over more than 8 weeks
- different in that this condition can have proximal then distal weakness, or both at same time (ie doesnt nec ascend)
- also will have reduced or absent reflexes
- Often combined sensory and motor

Diagnosis
- CSF: raised protein and nil cells
- NCS - demyelination in 2x motor and 2x sensory nerves

Treatment:
- IVIG/PLEX
- Steroids (unlike GBS)
- Steroid sparing agents (mycophenytlate, aza, cyclophos)
- Refractory disease: rituxumab

Question 15

Nodopathies are now a seperate entity from CIDP. What is a nodopathy and when should it be considered as a differential?

Answer 15

This is a disease in which the nodes of renvier (proteins at the nodes of ranvier) are targeted by autoantibodies rather than the myelin
-THis gives a similar clinical picture to demyelination but is distinct

If pt has refractory CIDP (ie not responding to IVIG or steroids) then this is a differential

Also if pt has renal disease in addition to CIDP picture, this may be IgG4 related nodopathy. THis is becasue lots of teh nodopathy antibodies are IgG4 antibodies which can have significant renal involvment

Question 16

What are some examples of IgG4 abs that cause resistant CIDP? which one of these abs also causes protinuria?

Answer 16

antibodies to neurofascin, CASPR and contactin 1

Abs to neurofascin 1A6 also cause renal involvement

Question 17

What is 2x example of conditions that is a demyelinating neuropathy similar to GBS or CIDP that is associated with systemic disease?

Answer 17

POEMS
- polyneuropathy
- organomegally
- endocrinopathy
- M protein
- sclerotic lesions

These pts will look like CIDP but will have a lot on angioedema and it is due to an underlying plasma cell dyscrasia (myeloma)
Will have raised VEGF

Lymphoma is the other condition

Question 18

CIDP like presentation but with raised VEGF. What condition?

Answer 18

POEMS

Question 19

Painful CIDP like presentation but with large lymph nodes and B symptoms. What condition?

Answer 19

Lymphoma

Question 20

CIDP and AIDP/GBS are aquired demyelinating polyneuropathies. What is the most common hereditary demyelinating neuropathy?

Answer 20

Charcot Marie Tooth (CMT)
- type 1 is most common

Question 21

Charcot Marie Tooth (CMT) inheritance pattern?
What is the most common genetic abnormality and how does this result in CMT?

Answer 21

Autosomal dominant
- inherited extra copy of the PMP-22 gene causing over expression and unstable myelin

Question 22

Clues that the patient may have an inherited demyelinating polyneuropathy rather than aquired (ie CIDP or GBS)?

Answer 22

Very good clinical picture relative to the NCS (pt has learnt to compensate over their life)

Symmetrical NCS throughout (not much variability because every thing is progressing at same rate)

Question 23

CMT is caused by an extra copy of PMP22 gene. WHat condition is caused by deletion of this gene?

Answer 23

Hereditary sensativity to pressure palsies
- develop palsy from minor pressure

Question 24

Neuropathy, diabetes and hearing loss = …?

Answer 24

Mitochondrial disease

Question 25

Features of amyloid neuropathy?
Pathophys?
Dx?

Answer 25

Can cause any type of neuropathy but typically:
- Typically painful
- Can be rapidly progressive
- Can have autonomic neuropathy

Caused by mutations in the transthyretin (TTR) gene that destabilise the tetramer and or accelerate teramer dissociation -> amylodogenesis

Dx on fat pad Bx

Question 26

When to suspect amyloid neuropathy?

Answer 26

Pt with progressive peripheral sensory motor neuropathy with family or personal Hx of:
- Cardiomyopathy
- Renal impairment
- GI symptom involvement

Ie some form of systemic involvement characteristic of amyloid

Question 27

Amyloid on histo stains?

Answer 27

Congo red and biurefringent green

Question 28

Features of diabetic neuropathy?

Answer 28

Distal symetrical sensory>motor axonal neuropathy
- feature of axonal neuropathy compared to demyeliniating neuroapthy is that tendon reflexes tend to be preserved

Can also have autonomic neuropathy and small fibre painful burning neuropathy

Question 29

What are other types of nueropathies that DM can cause?

Answer 29

Mononeuritis multiplex
Entraptment neuropathies (ie carpel tunnel)
Diabetic lumbosacral radiculoplexus neuropathy
- this occurs when bad sugar control to good sugar control

Question 30

GLucose control alone halts neuroapthy in T1DM but not always in T2DM. Why?

Answer 30

this is because aspects of the metabolic syndrome also cause peripehral neuropathy in T2DM, not just glucose control

Question 31

Glycaemic control and foot care work for DM PN Rx. What medication can be used for DM painful neuroapthy?

Answer 31

Duloxetine

Question 32

Clinical features of a vasculitis neuropathy?

Answer 32

Sudden onset, progressive, asymmetric in setting of systemic features
- usually mononeuritis multiplex or distal symetric

Question 33

Pt having sudden attacks falls due to sudden increased tone and rigidity? What condition?

Answer 33

Stiffman syndrome
- Anti-ampiphysin antibodies associated with SCLC and breast cancer

Question 34

Pt with breast cancer or SCLC and neuropathy. Which antibody?

Answer 34

Anti-ampiphysin