Neuropathies Flashcards
Neurological side effect of the AZ covid vaccine?
GBS (can happen with any vaccine) + bilteral facial weakness
COmplication of B12 def and NO use?
Brief phathophys? Treatment?
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
Treatment with isoniazid for TB / BCGosis etc. WHat should always be given with this drug and why?
Pyridoxine (B6)
- Prevents development of painful peripheral neuropathy
B6 toxicity can cause…?
painful peripheral neuropathy, can be irreversible
- too much B6 stops B6 working normally, similar to if there was B6 def
All muscle disease (myopathy) results in proximal then distal weakness except…?
All neuropathy results in distal then proximal weaknessness except…?
Myotonic dystrophy
CIDP
- can cause proximal hip flexor weakness initially
What do these aspects of a NCS tell us about the nerves:
- Amplitude?
- Velocity?
- Dispersion? conduction block?
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
Features of demyelination on NCS?
slowed conduction velocity, dispersion and conduction block
How does EMG differ from NCS?
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
Difference between myositis and myopathy and denervation?
myositis - normal invervation but inflamed muscle
Myopathy - intrinsic problem with muscle
Denervation - muscle normal but less nerves feeding it
EMG recording feature in neuropathic conditions (ie denervation)?
EMG recording feature in myopathic conditions?
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
Common sensory, motor and painful neuropathies?
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)
Neuro side effect of metronidazole exposure?
peripheral neuropathy
What is GBS/AIDP?
What causes GBS / what is the most common antecedant condition?
Diagnostic tests (bloods, NCS, CSF)?
Treatment?
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
What is CIDP?
Diagnostic tests?
Treatment?
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
Nodopathies are now a seperate entity from CIDP. What is a nodopathy and when should it be considered as a differential?
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
What are some examples of IgG4 abs that cause resistant CIDP? which one of these abs also causes protinuria?
antibodies to neurofascin, CASPR and contactin 1
Abs to neurofascin 1A6 also cause renal involvement
What is 2x example of conditions that is a demyelinating neuropathy similar to GBS or CIDP that is associated with systemic disease?
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
CIDP like presentation but with raised VEGF. What condition?
POEMS
Painful CIDP like presentation but with large lymph nodes and B symptoms. What condition?
Lymphoma
CIDP and AIDP/GBS are aquired demyelinating polyneuropathies. What is the most common hereditary demyelinating neuropathy?
Charcot Marie Tooth (CMT)
- type 1 is most common
Charcot Marie Tooth (CMT) inheritance pattern?
What is the most common genetic abnormality and how does this result in CMT?
Autosomal dominant
- inherited extra copy of the PMP-22 gene causing over expression and unstable myelin
Clues that the patient may have an inherited demyelinating polyneuropathy rather than aquired (ie CIDP or GBS)?
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)
CMT is caused by an extra copy of PMP22 gene. WHat condition is caused by deletion of this gene?
Hereditary sensativity to pressure palsies
- develop palsy from minor pressure
Neuropathy, diabetes and hearing loss = …?
Mitochondrial disease
Features of amyloid neuropathy?
Pathophys?
Dx?
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
When to suspect amyloid neuropathy?
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
Amyloid on histo stains?
Congo red and biurefringent green
Features of diabetic neuropathy?
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
What are other types of nueropathies that DM can cause?
Mononeuritis multiplex
Entraptment neuropathies (ie carpel tunnel)
Diabetic lumbosacral radiculoplexus neuropathy
- this occurs when bad sugar control to good sugar control
GLucose control alone halts neuroapthy in T1DM but not always in T2DM. Why?
this is because aspects of the metabolic syndrome also cause peripehral neuropathy in T2DM, not just glucose control
Glycaemic control and foot care work for DM PN Rx. What medication can be used for DM painful neuroapthy?
Duloxetine
Clinical features of a vasculitis neuropathy?
Sudden onset, progressive, asymmetric in setting of systemic features
- usually mononeuritis multiplex or distal symetric
Pt having sudden attacks falls due to sudden increased tone and rigidity? What condition?
Stiffman syndrome
- Anti-ampiphysin antibodies associated with SCLC and breast cancer
Pt with breast cancer or SCLC and neuropathy. Which antibody?
Anti-ampiphysin
