Neuropathies Flashcards
What is the pathogenesis of GBS
immune response to non self antigens (usually infection) that misdirect to nerve tissue through molecular mimicry
Immune response is directed at myelin or axon
What are some variants of GBS
Acute inflammatory demyelinating polyneuropathy (AIDP)
Acute motor axonal neuropathy (AMAN)
Acute motor sensory axonal neuropathy (AMSAN)
Miller-fisher syndrome
What are some triggers for GBS
campylobacter most common
CMV, EBV, mycoplasma, URTIs, influenza, HIV
Clinical features of GBS
Rapidly evolving areflexic, motor paralysis +/- sensory disturbance
Evolves over hours to days
Typically begins in legs
Can involve facial muscles and bulbar weakness
Pain in back and shoulders
Autonomic dysfunction - fluctuating BP, arrythmias, postural hypotension
Affects muscles of respiration - 30% require ventilation
What investigations are involved in the diagnosis of GBS
CSF - elevated protein without pleocytosis
Elevated protein occurs in 60% after 1 week (not seen initaly)
Nerve conduction studies: slowing of conduction velocity, conduction block, can get secondary axonal degeneration
Treatment of GBS
high dose IVIG or plasmapharesis (will decrease need for ventilation by 50%, increase likelihood of full recover and shortens recovery time)
Cardiac monitoring, BP, vital capacity
Early consideration of ventilation
Prognosis of GBS
85% achieve full functional recovery
Mortality
Poor prognostic features of GBS
Advanced age
Rapid onset/severe attack
Delay in onset of treatment
What is CIDP
Chronic inflammatory demyleinating polyneuropathy
- similar to GBS but slower onset over a few months
Subtypes:
- chronic progressive
- relapsing remitting
- monophasic
Clinical features of CIDP
Symmetric motor and sensory deficits
Proximal and distal weakness
Absent reflexes
Distant lower limb greater then upper limb sensory loss
Autonomic and respiratory involvement is uncommon
25% of patients have MGUS
Treatment of CIDP
initiate treatment if rapid progression or walking compromised otherwise do expectant management
IvIG, steroids and plasmaphoresis
If these fail can consider MTX, azathioprine, cyclosporin, cyclophosphamide and rituximab
What are some variants of CIDP?
MADSAM - multifocal aquired demyelinating sensory and motor neuropathy = asymmetric multifocal distribution
DADS - distal acquired demyelinating sensory neuropathy = ataxia and areflexia
Chronic immune sensory polyradiculopathy
Who does multifocal motor neuropathy occur in?
Age 20-50
More common in males (75%)
Symptoms of multifocal motor neuropathy?
Asymmetric and patchy motor weakness and atrophy over years
Sensory fibres preserved
Arms affected more than legs
No UMN or bulbar signs (compared with ALS)
What marker is positive in multi-focal motor neuropathy?
Polyclonal IgM to GM1 in 60-80%
Treatment of multi-focal motor neuropathy?
IVIg
Doesnt respond to steroids or plasmaphoresis
What are the features of paraprotein neuropathies?
distal predominately symmetrical sensorimotor neuropathy
What is anti-Hu paraneoplastic neuropathy?
Sensory neuronopathy
- asymmetric dysesthesia, sensory loss in limbs progress to involve limbs/torso/face, sensory ataxia, pseudoathetosis, inability to walk/sit/stand
Associated with small cell lung cancer
What are features of a motor axon?
large myelinated fibres
What are proprioception/vibration nerve fibres?
large myelinated fibres
What are pain and temperature nerve fibres?
small myelinated and unmyelinated
What diameter are autonomic nerves?
small diameter
What are electrodiagnostic features of axonal diseases?
low amplitude potentials with preserved distal latencies
normal to slightly decreased conduction velocity
Fibrillations on needle EMG
What are electrodiagnostic features of demyelinating peripheral neuropathies?
slow conduction velocity Conduction block if severe Prolonged distal latency Preserved amplitude Absence of fibrillations
What are indications for a nerve biopsy?
Only indicated for vasculitis or amyloid
Use sural nerve as only has sensory function (no impact on motor function)
What are the inheritance patterns of charcot marie tooth?
Autosomal dominant
Autosomal recessive
X-linked
What are the 2 most common types of Charcot Marie Tooth?
CMT 1 - most common, present with distal leg weakness, foot drop, no sensory symptoms but have reduced sensation in all modalities that they are not aware of, presents age 0-30
Atrophy of muscles below knee (Champagne legs)
decreased/absent reflexes
Foot deformites and gait disturbance
NCS show decreased conduction velocity
CMT 2 - presents later in life, symptoms in teens, same symptoms as type 1 but difference is nerve conduction studies show normal conduction velocity
What is fabrys disease?
X linked dominant
mutation in alpha-galactosidase gene causes accumulation of ceramide in vessels and nerves leading to a painful neuropathy of hands and feet, renal failure, hypertension, stroke, cardiac disease
What is adrenoleukodystrophy?
X-linked dominant mutation in ABC transporter gene leading to CNS abnormalities, peripheral neuropathy and spastic paraplegia
What is the most common cause of peripheral neuropathy?
Diabetic neuropathy
What are some types of diabetic neuropathy?
- Distal symmetric sensory and sensorimotor polyneuropathy
- due to axonal degeneration, NCS shows decreased amplitude, mild slowing of velocity - Autonomic neuropathy
- abnormal sweating, temperature control, dry eyes/mouth, pupillary abnormalities, cardiac arrthymia, postural hypotension, gastroparesis, post prandial bloating, impotence, incontinence - Diabetic amyotrophy
What are some features of diabetic amyotrophy?
Presenting feature in 1/3 of diabetics
Severe pain in lower back/hip/thigh in one leg followed by atrophy, weakness of proximal/distal muscles withing days to weeks with associated weight loss
Progresses over weeks/months then slow recovery
NCS show denervation
What are features of peripheral neuropathy in amyloid?
30% present with painful neuropathy with pain over feet that progresses and causes weakness and autonomic involvement
