Patho- Peripheral Nerve Disease Flashcards
What cells can be damaged in peripheral nerve disease?
Nerve
Schwann cell
What is a neuropathy?
Disease affecting peripheral nerve
What is a polyneuropathy?
Diffuse, symmetrical disease, usually commencing peripherally
Widespread loss of tendon reflexes
What is a Radiculopathy?
Nerve root damage
What is a Myelopathy?
Disease of the cord
What can damage peripheral nerves?
Demyelination Axonal degeneration Wallerian degeneration Compression Infarction Infiltration
What occurs in nerve infiltration?
Infiltration of peripheral nerves by inflammatory cells occurs in leprosy and granulomas
What pathogen can infiltrate nerves?
Leprosy- Mycobacterium leprae
Where can an infarct occur to affect the peripheral nerves?
Microinfarction of vasa nervorum.
What can cause an infarct affecting nerves?
Diabetes
Vasculitis
What can cause vasculitis?
SLE
RA
Sarcoidosis
Giant cell arteritis
What can cause compression of nerves?
Entrapment neuropathies
What happens when nerves are compressed?
Focal demyelination at the point of compression causes disruption of the myelin sheath
Give some major nerve compression locations
Carpal tunnel- Median N
Cubital tunnel- Ulnar N
Spiral Groove- Radial N
Head of fibula- Common peroneal N
What nerve and muscles are affected in carpal tunnel syndrome?
Median
Thenar muscles
What nerve and muscles are affected in cubital tunnel syndrome?
Ulnar
Clawing of hand
What does compression of the radial nerve lead to?
Saturday night palsy
Wrist drop and brachioradialis weakness
What does compression of the common peroneal nerve lead to?
Foot drop
Ankle jerk preserved
How do you diagnose nerve compression?
Nerve conduction
What is Wallerian degeneration?
Changes following nerve section where both nerve and Schwann degenerate over several weeks
What can cause a peripheral nerve lesion?
Bell's palsy Disc protrusion Trauma Entrapment Neuralgic amyotrophy
What is neuralgic amyotrophy?
Nerve damage and muscle atrophy preceded by severe pain
Episodic
Autoimmune
Steroids
What are some signs of Wallerian degeneration/peripheral nerve lesion?
Weakness Wasting Hypotonia Reflex loss Fasciculation Fibrillation potentials (EMG) Muscle contractures Trophic changes in skin and nails
What happens in axonal degeneration?
Axon damage leads to dying back
What factors can cause axonal degeneration?
Metabolic
Toxic
Vitamin deficiency
Charcot-marie-tooth disease
What metabolic conditions can cause axonal degeneration?
Diabetic neuropathy
Chronic uremia
Thyroid disease
Acute intermittent porphyria
What are some symptoms of diabetic neuropathy?
Symmetrical sensory neuropathy
Acute painful neuropathy
Autonomic neuropathy- Hypertension, Urinary dysfunction, Erectile dysfunction
What are some symptoms of chronic uremia?
Progressive sensorimotor neuropathy
Usually improves on dialysis
What kind of neuropathy does thyroid disease give?
Mild
What are some symptoms of acute intermittent porphyria?
Severe intermediate proximal neuropathy
Abdo pain
Confusion and coma
Alcohol, barbiturates and infection can induce
What can cause toxic neuropathy?
Alcohol
Drugs
Where does alcohol induced neuropathy tend to show?
Lower limb
What drugs can cause neuropathy?
Lead- Motor neuropathy
Arsenic- Sensory neuropathy
Thallium- Sensory neuropathy
Lack of which group of vitamins can cause neuropathy?
B
How do you treat vitamin deficient neuropathy?
Replace vitamins
Lack of what three B vitamins tend to cause neuropathy?
B1- Thiamine
B6- Pyridoxine
B12- Cobalamin
What two diseases can be caused by B1/Thiamine deficiency?
Beri beri
Wernicke-korsakoff psychosis
What are some symptoms of beri beri?
Weight loss Emotional disturbances Impaired sensory perception Limb pain and weakness Oedema
What are some symptoms of Wernicke-korsakoff psychosis?
Encephalopathy Nystagmus Ataxia Amnesia Hypothermia Hypotension
What are some symptoms of B6/Pyridoxine deficiency?
Sensory neuropathy
Anti TB therapy
Give pyridoxine with isonaizid
What are some symptoms of B12/Cobalamin?
Damage to the spinal cord, peripheral nerves and brain
What are some symptoms of Charcot-marie-tooth disease?
Distal limb wasting and weakness- so severe legs said to resemble ‘Inverted Champagne bottles’
Slow progression
What can cause demyelination?
Guillain-Barré syndrome/post infection neuropathy
What is Guillain-Barré syndrome/post infection neuropathy?
Paralysis 1-3w after infection
What pathogens tend to cause Guillain-Barré syndrome/post infection neuropathy?
Campylobacter jejuni
Cytomegalovirus
What are some symptoms of Guillain-Barré syndrome/post infection neuropathy?
Paralysis 1-3w after infection
Symptoms progress proximally over 6w
Loss of tendon reflexes
Symptoms peak 10-14d after onset
How do you diagnose Guillain-Barré syndrome/post infection neuropathy?
Clinical
Nerve conduction studies
What is the differential for Guillain-Barré syndrome/post infection neuropathy?
Botulism
Cord compression
Muscle disease
How do you treat Guillain-Barré syndrome/post infection neuropathy?
Ventilation if affects resp muscles
Subcut heparin
IV Immunoglobulin in 2 weeks- Reduces duration and severity of paralysis
Natural recovery
