Neuropathy Flashcards
Differentiate between upper and lower motor neuron signs
An upper motor neuron lesion (also known as pyramidal insufficiency) occurs in the neural pathway above the anterior horn cell of the spinal cord or motor nuclei of the cranial nerves.
weakness, increased reflexes and tone are seen. no atrophy or fasciculations are seen
A lower motor neuron lesion is a lesion which affects nerve fibers traveling from the ventral horn or anterior grey column of the spinal cord to the relevant muscle
weakness, atrophy and fasciculations occur. decreased reflexes and tone seen
Classify neuropathy
-Anatomical Classification
Mononeuropathy
Multiple mononeuropathies
Polyneuropathy
-Pathological Classification
Axonal
Demyelinating
-Nerve Fibre Classification Large fibre Small fibre Cranial Autonomic
Epidemiology of neuropathy
any age; most common - middle aged/elderly
Causes of neuropathy
ACQUIRED
VITAMIN D
V: vasculities , SLE, PAN
I:infection : HIV, CMV, EBV, Lyme, leprosy etc
T:trauma
A:autoimmune
M:metabolic :DM, hypothyroidism, renal,hepatic,porphyria, vit B12,B1 def
I:infiltrative: sarcoidosis, amyloidosis
N:neoplasm:paraneoplastic
D: drugs: dapsone, disulfiram, amiodarone,colchicine
HEREDITARY Charcot Marie Tooth -Axonal -Demyelinating Freidrichs ataxia Refsum Disease Spinal Muscular Atrophy Kennedy Disease
Pathogenesis of neuropathy
The response of the nerves to insult or injury
Wallerian degeneration
-Trauma, compression, infarction
Axonal degeneration
-Most are distal to proximal “dying back phenomenon”
-Proximal to distal in some conditions
Demyelination
-Generalised Charcot Marie Tooth
-Segmental Acquired Inflammatory Demyelination-Guillian Marie Syndrome
Diagnosis of neuropathy
detailed hx , physical exam , neurophysiology, blood tests
Discuss the history taken for neuropathy?
-Which nerve fibre types? (small nerve fibre neuropathy -> severe neuropathic pain) eg dull , burning, poorly localised pain due to polymodal C nociceptor fibres, whereas a lancinating, prickly, sharp , epicritic pain felt due to Adelta fibres.
-Pattern: sensory, motor (or both),sensorimotor,automatic
(sensory- paraesthesia, numbness, tingling , autonomic - impaired sweating, faecal/urinary urgency,erectile dysfunction) any incoordination&ataxia primarily a/w ganglionopathy,neuronopathy
Positive symptoms a/w acquired causes- paraethesia, tingling, burning
negative symptoms- numbness,weakness- hereditary
Location**
Legs > Arms. Can be length dependent
Proximal or distal weakness (stocking/glove)?
Symmetrical or asymmetrical?
Face or trunk involved?
Arms > legs, prox > distal => not length dependent
No sensory symptoms: myopathy, Neuromuscular junction disease, Motor Neuron Disease
- Timeline-acute,subacute,chronic, monophasic, relapsing-remitting,slowly/rapidly progressive
- Past medical hx?
- Family hx
Signs of UMN / LMN deficit
UMN
- weakness ; low power
- increased reflexes; hyperreflexia
- increased tone
- atrophy rare
- fasciculations absent
LMN
- weakness; low power
- low/absent reflexes; hyporeflexia
- low tone; hypotonic
- atrophy present
- fasciculations present
Physical Examination to be conducted w neuropathy
If pt is well enough ask pt to stand on heels stand on toe get up from a low chair crutches calipers
Inspection: CHAIRSAW C-consciousness level H-hearing aid A-asymmetry I-involuntary movements R-rash S-scars A-abnormal gait W-walk aid around the bed
Inspect (for signs) – atrophy, fasciculations, deformities, pes-cavus, hammer toes, charot joints, ulcers.
Tone – normal or reduced usually, but can be increased with ALS
Pattern of muscle weakness
- Proximal or distal
- Nerve territory e.g. median, ulnar, radial, peroneal
- Radicular (myotomal)
- footdrop
Reflexes
- reduced or absent - distally or generalized areflexia - increased: ALS?
Plantar responses
- flexor or mute - extensor: ALS?
Assess sensation ; light/sharp touch, vibration w tuning fork
What investigations are to be conducted to diagnose neuropathy
Sensory and motor nerve conduction studies
bloods to deduce patterns : HbA1c,FBC U&E ,LFTs ,TSH ,B12/Folate, ESR
Serum protein electrophoresis (SPEP)
Which condition do the varying results for nerve conduction studies correlate with?
Decreased amplitudes = Axonal
Prolonged distal latencies AND slow conduction velocities = demyelination
Uniform and diffuse slow conduction velocities=hereditary
Focal slow conduction velocity or conduction block = acquired
What is the commonest pattern seen in neuropathy?
symmetric distal weakness and sensory loss
usually subacute/insidius onset ; causes DM/idiopathic
Tx for neuropathy
Treat cause
Treat symptoms:pain, orthodics,splints
Surgery
