MS tutorial Flashcards
What is MS?
An autoimmune disorder which results in loss of myelin from neurones of the central nervous system
MS symptoms?
Blurred vision
Fatigue
Difficulty walking
Numbness or tingling (paraesthesia) in different parts of the body
Muscle stiffness and spasms
M-wave?
Activation of motor axons that cause action potentials to travel along the nerve to cause muscle contraction - a twitch
Can be recorded with EMG
Fast response
Response from stimulating motor pathway directly
H-reflex?
Measure of a true reflex arc. Arc not wave, uses sensory nerves to go to spine then back to toe.
Later response
F-wave
examines transmission between stimulation sites in the arm and leg and the related motor neurones in the cervical and lumbosacral cord. Only motor nerve. Antidromic stimulation. Stimulation goes from site then to spinal cord then to toe. Uses WAVE. Antidromic.
Not a reflex
Orthodromic?
Travelling in the normal direction in a nerve fibre
Antidromic?
Travelling in the opposite direction to that normal in a nerve fibre
Transcranial magnetic stimulation?
Activates upper motor neurones
Causes action potentials to travel along entire motor pathway
Known as motor evoked potential
Total motor conduction time?
time from brain to muscle (MEP latency)
Peripheral motor conduction time?
Time from spinal cord to muscle along motor axon
=(M latency + F latency -1)/2
-1 in PMCT calculation?
Estimated time for the action potentials arriving at the LMN cell body to turn around
Central motor conduction time?
TMCT-PMCT
MS effect on brain stimulation?
Longer than usual MEP latency
MS effect on TMCT?
Delayed
MS effect on peripheral nerve stimulation?
Normal F wave latency (no issue with LMN)
