NEURO 110 Peripheral Neuropathy Flashcards
What is neuropathy?
Nerve disease
How do you classify a neuropathy?
The type of and number of nerves affected, aetiology, timing and pathology
How would a motor neuropathy present?
Weakness, wasting, fasiculations and areflexia
How can a sensory neuropathy present?
Parasthesia, burning, allodynia, ataxia, loss of pain sensation or hypersensitivity, ulcers, loss of vibration sense, loss of proprioreception, areflexia
What would an autonomic neuropathy present?
Dry eyes, dry mouth, GI disturbance, impotence, loss of heart rate variability, bladder hypersensitivity, excessive/inadequate sweating, orthostatic hypotension
Describe a compression neuropathy
Focal demyelination where compression occurs, and reduced conduction velocity across compression area
Usually a mononeuropathy
What are the two common mononeuropathies/compression neuropathies
Median nerve compression - Carpal Tunnel Syndrome
and Ulnar nerve compression
What are the risk factors for carpal tunnel syndrome
Diabetes, pregnancy, acromegaly, weight gain, repetiitive wrist movements, wrist fracture, artritis
What are the signs and symptoms of carpal tunnel syndrome?
Numbness - waking at night and with certain daytime postures, in the lateral 3.5 fingers, weak thumb abduction and wasting of the thenar eminence
What are the treatments for carpal tunnel syndrome?
Wrist splints, steroids, decompression surgically
what are the risk factors for ulnar nerve compression?
elbow trauma, RA, leaning on elbow
what are the signs and symptoms of ulnar nerve compression?
hypothenar wasting, weakness of finger abduction and opposition of little finger, sensory changes to medial 1.5 fingers
What are the treatments for ulnar nerve compression?
Avoid resting on elbows, night time splints, nerve gliding exercises, decompression surgery
What is guillian barre syndrome?
Acute demyelinating polyneuropathy with preceding infection
What are the signs and symptoms and GBS?
Numbness and paralysis beginning distally
What will investigations show in GBS?
increased protein concentration in the CSF, slowed nerve conduction belocities and action potential delay and dispersion
What are the treatments for GBS?
Intravenous immunoglobulin pooled from blood donations, or plasma exchange
Both expensive and high risk
What is the potential difference between ICF and ECf?
~70mV
What ion concentrations are higher extracellularly
Sodium, calcium and chloride
What ion concentration is higher intracellularly and what maintains this balance?
Potassium - the Na+/K+ pump
How is an AP initiated?
Na ligand gated channels open after binding of excitatory NT and Na+ floods in
What is the rising phase of an AP?
Threshold reached due to ligand mediated Na+ influence and there is further Na+ influx and K+ efflux
Why does the membrane hyperpolarise?
Due to the magnitude of K+ extracellularly
What is the refractory period of an AP?
Peak depolarisation to hyperpolarisation and where Na+ channels become inactive for 1ms after closing
What is the relative refractory period of an AP?
Re-establishment of resting potential
What occurs when acetylcholine binds to its receptors at the NMJ?
It causes K+ channels to open post synaptically and triggers AcH reuptake
What is Lambert Eaton Myasthenic syndrome?
An autoimmune disease with antibodies against the voltage gated calcium channel
What is neuromyotonia?
When the muscles don’t relax there is twitches and cramp
What is myasthesia gravis due to?
Antibodies against the acetylcholine receptor
What does myasthesia gravis present with?
Fatiguable weakness Eyes: diplopia, ptosis Speech, chewing and swallowing trouble Neck extension weakness Respiratory failure Late onset: thymic atrophy
How would you treat Myasthesia gravis?
IV immunoglobulin exchange or plasma exchange, acetylcholinesterase inhibitors, immunosuprresants
