Peripheral Neuropathies
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Introduction
Mononeuropathy (focal, entrapment, compression)
carpal tunnel syndrome is most common (median neuropathy at the wrist)
radial neuropathy at the humeral groove can cause wrist drop
thoracic outlet syndrome
peroneal neuropathy at the fibular head
Evaluating mononeuropathy
- demonstrate motor/sensory abnormality in the affected nerve
- demonstrate normality in adjacent similar nerves
- use EMG
- MRI is best for determining cervical radiculopathy
Carpal Tunnel Syndrome
sensory symptoms
- median nerve distribution
- numbeness, paresthesia, pain
- nocturnal symptoms
Polyneuropathy (diffuse, distal, symmetric snensorimotor neuropathy)
common symptoms:
- numbness
- positive sensory symptoms: paresthesias, buringing, shooting sensations, allodynia
- weakness
- sometimes muscle cramps
- sometimes autonomic dysfunction
patterns of manifestations
- lower motor neuron weakness
- more distal than proximal
- stocking and glove distribution
differential diagnosis
100's of different causes
inherited vs acquired
- Charcot-Marie-Tooth Disease
acute vs chronic
- Guillain Barre syndrome
- porphyria
- diphteria
- toxins - arsenic, lead, organophosphates, thallium
- Lyme disease
- tick paralysis
- metabolic - diabetes, chronic renal failure
- inherited
- autoimmune (conenctive tissue diseases, chronic inflammatory demyelinating polyneuropathy
- toxins (alcohol, medications
- paraneoplastic
- nutritional - vitamin deficiencies
- infections (HIV, leprosy, etc
demyelinating vs axonal
- Demyelination is responsible for Charcot-Marie-Tooth, GBS, diptheria, and rarely diabetic polydeuropathy
axonal degeneration is involved in most polyneuropathies, including:
- diabetes
- toxins
- paraneoplastic
- infections
- porphyria
- nutritional
Medication Induced Neuropathy
- Vitamin B6
- HIV drugs
- chemotherapy
- metronidazole
- lithium
- amiodarone
- colchicine
- phenytoin
Bloodwork
- fasting serum glucose
- TSH
- B12
- CBC, ESR, CRP
- electrolytes
- creatine
- BUN
- liver function tests
- protein electrophoresis
- ANA, ENA
- electromyography
Mononeuritis Multiplex
- acquired, acute, axonal neuropathies
- multiple mononeuropathies at uncommon sites
- often systemically unwell
- vasculitis is a bad thing
investigate with:
- CBC
- eosinohil count, ESR, CRP
- ANA,
treat with steriods, immunosuppression (ie cyclophosphamide)
The Case of...
a simple case introducing clincial presentation and calling for a differential diagnosis. To get students thinking.
Causes and Risk Factors
Pathophysiology
Signs and Symptoms
- numbness
- positive sensory symptoms: paresthesias, buringing, shooting sensations, allodynia
- weakness
- sometimes muscle cramps
- sometimes autonomic dysfunction
- history
- physical exam
History
Physical Exam
Investigations
- lab investigations
- diagnostic imaging
Lab Investigations
Diagnostic Imaging
Differential Diagnosis
Treatments
Consequences and Course
The Case of...
Case #2 - a small story wrapping it all up and asking about esp management.
Additional Resources
Topic Development
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