PERIPHERAL Neuropathies Flashcards
How different are the large nerve fibres from the small ones?
- Large fibres - more well myelinated
whereas the small nerve fibres are either THINLY myelinated or unmyelinated
What occurs with damage to the small sensory fibres?
- PAIN
- dysesthesia (UNPLEASANT sensation when touched)
- reduced pin prick and temperature sensation
Name the small sensory fibres.
- Adelta: thinly myelinated
- C: unmyelinated
What occurs with damage to the autonomic fibres?
- dizziness (d.t POSTURAL hypotension)
- impotence (ED)
- Nausea and vomiting (GASTROPARESIS)
- constipation/diarrhoea (esp. at night)
- bloating and belching
- tachycardia
- excessive sweating
- can’t empty bladder/ loss of bowel control
What are the symptoms of large sensory fibre damage?
- PARAESTHESIA
- unsteadiness
- numbness
- diminished vibration and JPS
- Reflexes may be lost
What occurs with large fibre motor damage?
PC:
- weakness/ unsteadiness/ wasting
SIGNS:
- REDUCED power
- absent reflexes
Name patterns of peripheral loss.
- glove and stocking
- mild/moderate/severe
- mononeuritis/ mononeuropathy
- radiculopathy
How may plexopathy occur?
- by traction of the nerve plexus
How are nerve damaged?
- axonal loss
- Peripheral nerve demyelination
Name an ACUTE demyelinating neuropathy.
- GBS (Guillaine Barre Syndrome)
- occurs within DAYS-wks
Name a chronic, progressive demyelinating neuropathy.
- CIDP (chronic inflammatory demyelinating polyradiculopathy)
- Hereditary sensory motor neuropathy (Charcot-Marie Tooth $)
How common is GBS?
1-2/ 100,000 per year
How does GBS present as?
- progressive paraplegia over days-4 weeks
- sensory symptoms precede weakness
- PAIN
- peak symptoms 10-14 days INTO onset of illness
When causes GBS?
- post-infectious CAMPYLOBACTER association
- campylobacter jejuni
WHat complications may arise from GBS?
- 25% require MECHANICAL ventilation
- 10% DIE mainly from autonomic failure (CARDIAC arrhythmia)
How is GBS treated?
- immunoglobulin infusion
AND/OR - PLASMA exchange
What is key about the pattern of muscle weakness in GBS?
- starts DISTALLY moves proximal
What is hereditary neuropathy?
- inherited
- NUMEROUS MUTATIONS (A.D, A.R and X-linked)
How may hereditary neuropathy present as?
- pure motor/ sensory/ sensorimotor/ small fibre and AUTONOMIC variants
What is the most common genetic mutation for GBS?
CMT1a
What is gr.1 of HMSN/ Charcot-Marie-Tooth?
- has SLOW nerve conduction velocities
- evidence of hypertrophic demyelinating neuropathy
What is usually seen with HMSN type 1?
- WEAKNESS and ATROPHY of lower legs in adolescence
- later WEAKNESS of HANDS
What is the type 2 HMSN variety characterised with?
- normal nerve conduction velocity
- axonal degenration
What are infectious causes of axonol neuropathy?
- HIV
- syphilis
- Lyme
- Hepatitis B and C
What are drugs/toxins that may cause axonal neuropathies?
- alcohol
- amiodarone
- phenytoin
- chemo (CISPLATIN/Vincristine)
What metabolic/endocrine causes result in axonal neuropathies?
- diabetes
- B12/Folate
- hypothyroidism
- chronic uremia
- porphyria
What vasculitic condition results in axonal neuropathies?
- ANCA +ve
- Rheumatoid Arthritis/ Sjrogens Syndrome
Can a paraneoplastic condition cause axonal neuropathies?
yes
- Myeloma
- Ab mediated (breast cancer)
What are 3 CAUSES of autonomic neuropathy?
- diabetes
- amyloidosis
- hereditary
What are acute causes of autonomic neuropathy?
GBS
porphyria
How to manage axonal peripheral neuropathy?
- treat cause
- symptomatic rx= physiotherapy/ orthotics/neuropathic pain relief
How to treat vasculitic P. neuropathy?
- pulsed IV PREDNISOLONE
+ cyclophosphamide
How to treat demyelinating, inflammatory neuropathy?
- IV immunoglobulin
- steroids
- azathioprine, mycophenate, cyclophosphamide
What is the MOA mycophenolate?
it suppresses the immune system the recipient
What is cyclophosphamide?
- it is used as chemotherapy and as a DMARD
What is a HNPP?
Hereditary Neuropathy with Pressure Palsy
- causes Numbness, tingling and muscle weakness
- d.t mutation in the (AD) PMP22 gene resp. for producing myelin in nerve cells ——weak myelin= slightest pressure> muscle weakness
Define autonomic neuropathy.
- SYMPTOMS that occur with damage to the nerves that MANAGE every day functions
- BP/ sweating/ bowel and bladder emptying/ HR/ digestion
What is porphyria?
- group of abnormalities in the chemical steps that lead to heme prodn
- the enzymatic defects of biosynthesis of heme causes tissue accumulation of porphyrins
How to recognize if its the origin of nerve damage is in the axon or the demyelination of the the axon?
- do a Nerve Conduction Study (NCS)
- demyelinating neuropathies will have reduced velocity of nerve conduction
- Axonal neuropathies will demonstarte DECR. amplitude
Describe the presentation of a person with AIP.
Acute intermittent Porphyria
- severe abdominal pain
- symmetrical limb weakness (Quadraplegia)
- autonomic instability
- SEIZURES
