Peripheral neuropathy Flashcards
What is peripheral neuropathy?
Damage to one or more peripheral nerves
Most common cause = diabetes
Can be acute or chronic
Can be polyneuropathy or mononeuropethy
Causes:
- Diabetes
- Dietary deficiencies e.g. B12 or folate
- Medication: amiodarone, isoniazid, vincristine, nitrofurantoin, metronizadole
- CKD: electrolyte abnormalities
- Injury, infection
- Charcot Marie Tooth
- Freidreich’s ataxia
Clinical features:
Sensory: tingling/ numbness, loss of coordication, burning/ shooting pain, loss of temperature sensation
Motor: muscle weakness, muscle wasting, twitching and cramps, paralysis
Autonomic: dizziness/ fainting, anhidrosis, inability to tolerate heat, loss of bladder control, bloating, contipation, diarrhoea, impotence
Investigations for peripheral neuropathy
Bloods: B12 and folate, FBC, U&E, glucose
Nerve conduction testing
Electromyography
Nerve biopsy
Skin biopsy
Types of peripheral nerve injury
- Wallerian degeneration: nerve degeneration occurs distal to an injury. Regeneration possible le if Schwann cell basement membrane remains
- Segmental demyelination: Schwann cells are destroyed but the axon remains and regeneration can occur
- Neuronopathy: neuronal cell body degeneration e.g. in MND
- Axonal degeneration: can occur as a primary event or secondary to demyelination
Causes of mononeuropathies
- Most common being radial, ulnar and medial and common peroneal
- Most commonly occurs when the nerve goes through anatomical narrowing e.g. carpal tunnel
- Conditions that lead to tissue oedema or thickening e.g. pregnancy, thyroid disease and amyloidosis increase entrapment
Examples of focal neuropathies
Carpal tunnel syndrome
Trigeminal neuralgia
Ulnar entrapment
Peroneal nerve injury
