Download Nerve conduction

Nerve conduction
Sompol Tapechum M.D., Ph.D.
Department of Physiology
Faculty of Medicine Siriraj
Hospital
Objectives
• นักศึกษาสามารถบอกประโยชน์ของการวัด nerve
conduction velocity ได้
• นักศึกษาสามารถบอกวิธีการวัด nerve conduction
velocity ได้
• นักศึกษาสามารถบอกปั จจัยที่มีผลต่อ nerve
conduction velocity ของ axon ได้
Nervous system
Structure of Nervous system
• Central nervous system
(CNS)
– Brain
• Cerebrum
• Cerebellum
• Brainstem
– Spinal cord
• Peripheral nervous
system (PNS)
– Nerves
• Cranial nerve 12 pairs
• Spinal nerve 31 pairs
Spinal nerve and Cranial nerve
Nerve structure
• Nerve = Bundle of axon
• Component of nerve
– Motor
• Somatic
• Autonomic
– Sensory
• Somatic
• Visceral
Axon
Sensory neurons
Motor neurons
Orthodromic
Antidromic
Orthodromic
Antidromic
Types of axon
Type of axon
Table I
Somatosensory Receptors and their Peripheral Axons
Receptor Type
Axon3 Group
CAP Peak
Conduction Velocity
Axon Diameter
Information Processed
Muscle Spindle: Annulospiral endings
Ia
Aa
70 - 120 m/sec
12 - 20 mM
Muscle length and velocity
Muscle Spindle: Flower Spray endings
II
Ab
30 - 70 m/sec
6 - 12 mM
Muscle length
Golgi Tendon Organ
Ib
Aa
70 - 120 m/sec
12 - 20 mM
Muscle tension
Joint: Pacinian
II
Ab
30 - 70 m/sec
6 - 12 mM
Joint movement
Joint: Ruffini
II
Ab
30 - 70 m/sec
6 - 12 mM
Joint angle
Joint: Golgi Tendon Organ
II
Ab
30 - 70 m/sec
6 - 12 mM
Joint torque
Meissner corpuscle
II
Ab
30 - 70 m/sec
6 - 12 mM
Touch, flutter or movement
Pacinian corpuscle
II
Ab
30 - 70 m/sec
6 - 12 mM
Vibration
Ruffini corpuscle
II
Ab
30 - 70 m/sec
6 - 12 mM
Skin stretch
Hair follicle
II & III
Ab & Ad
10 - 70 m/sec
2 -12 mM
Touch movement
Merkel complex
II
Ab
30 - 70 m/sec
6 - 12 mM
Fine touch
Free Nerve Endings
III
Ad
5 - 30 m/sec
1 - 6 mM
Sharp pain or cool/cold
Free Nerve Endings
IV
C
0.5 - 2 m/sec
< 1.5 mM
Dull or aching pain, or touch or warm
Nerve conduction
Sensory conduction study
• Antidromic
Sensory conduction study
• Orthodromic
Motor conduction study
• Orthodromic
Median nerve
Motor conduction study:
Median nerve
Motor neuron
Neuromuscular
junction
Neuromuscular junction
Nerve conduction velocity
D2
D1
Latency (s)
L2
L1
NCV = D1-D2
L1-L2
Sensory conduction study:
Median nerve
Purposes of
Nerve conduction study
• To diagnose nerve damage or destruction
• To follow up nerve regeneration after
damage
• To evaluate diseases of nerve or muscle
Normal nerve conduction velocity
• normal conduction velocity
– approximately 50 to 60 meters per second.
– may vary from one individual to another and from
one nerve to another.
Carpal tunnel syndrome
Nerve injury
Axon regeneration
2-4 mm/day
Myasthenia gravis