Nerve conduction

Sompol Tapechum M.D., Ph.D.Department of PhysiologyFaculty of Medicine Siriraj

Hospital

Objectives

• นั�กศึ�กษาสามารถบอกประโยชนั�ของการวั�ด nerve conduction velocity ได�

• นั�กศึ�กษาสามารถบอกวั�ธี�การวั�ด nerve conduction velocity ได�

• นั�กศึ�กษาสามารถบอกป�จจ�ยที่�!ม�ผลต่%อ nerve conduction velocity ของ axon ได�

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

AxonS

enso

ry n

euro

nsM

otor

neu

rons

Orthodromic

Antidromic

Orthodromic

Antidromic

Types of axon

Type of axon

Table ISomatosensory Receptors and their Peripheral Axons

Receptor Type Axon3 Group CAP Peak Conduction Velocity Axon Diameter Information Processed

Muscle Spindle: Annulospiral endings Ia A 70 - 120 m/sec 12 - 20 M Muscle length and velocity

Muscle Spindle: Flower Spray endings II A 30 - 70 m/sec 6 - 12 M Muscle length

Golgi Tendon Organ Ib A 70 - 120 m/sec 12 - 20 M Muscle tension

Joint: Pacinian II A 30 - 70 m/sec 6 - 12 M Joint movement

Joint: Ruffini II A 30 - 70 m/sec 6 - 12 M Joint angle

Joint:  Golgi Tendon Organ II A 30 - 70 m/sec 6 - 12 M Joint torque

Meissner corpuscle II A 30 - 70 m/sec 6 - 12 M Touch, flutter or movement

Pacinian corpuscle II A 30 - 70 m/sec 6 - 12 M Vibration

Ruffini corpuscle II A 30 - 70 m/sec 6 - 12 M Skin stretch

Hair follicle II & III A & A 10 - 70 m/sec 2 -12 M Touch movement

Merkel complex II A 30 - 70 m/sec 6 - 12 M Fine touch

Free Nerve Endings III A 5 - 30 m/sec 1 - 6 M Sharp pain or cool/cold

Free Nerve Endings IV C 0.5 - 2 m/sec < 1.5 M 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

Neuromuscularjunction

Neuromuscular junction

Nerve conduction velocity

D1

D2

Latency (s) L1

L2

NCV = D1-D2L1-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