Median nerve injury

1. Seminar on
Median nerve injury
Presenter : Biswajit Deka

2. Anatomy of a peripheral
nerve

3. Brachial plexus
Anterior rami of C5,6,7,8, & T1 (+C4 & T2)
It consists of roots, trunks, divisions, cords & branches
The roots & trunks- lie in the neck
Divisions - behind the clavicle
Cords & branches - axilla
Cords end up by giving off their terminal branches at
the lower border of the pectorals minor

8. Injury to median nerve
Trauma
Leprosy
Poliomyelitis
Carpel tunnel syndrome

9. Motor paralysis of
1. The pronators
2. The radial flexors of wrist
3. Flexors of all proximal interphalangeal joints
4. Flexors of terminal joints of thumb , index & middle
finger
5. Flexors of 1st & 2nd MCP joints (+ flexor policies
brevis)
6. Abductor & opponens pollicis

10. Sensory loss
1. C6 &C7 - vital sensory post. Nerve roots of
median nerve
2. Deep pressure pain is lost in above muscles
3. Joint sense lost in IP joints of index,& last joints of
thumb & middle fingers
4. Cutaneous loss- the loss of sensation over the
thumb & index finger renders the hand virtually
useless in fine movements - buttoning a coat….so
median nerve is aka EYE OF THE HAND
5. Trophic changes are prominent because the
median N carries most of the sympathetic nerve
supply of the hand.

13. Carpal tunnel syndrome
1. Size & shape of the tunnel itself
2. Oedema (pregnancy)
3. synovial swelling (RA)
4. Bony encroachment (OA / injury)
5. Myxoedema

14. Symptoms
painful paraesthesia & numbness of radial three & half
digit
Wakes the patient up at night - tissue fluid accumulation
in the absence of forearm muscle pump action with the
arm at rest
Motor - inability to perform fine movements & clumsiness
follow later.

15. Examination
Wasting of thenar eminence
Hypoaesthesis to light touch & pinprick
(however the skin over the thenar eminence is not
affected, as it is supplies by the palmer cutaneous
branch of median nerve which arise proximal tp carpal
tunnel)

16. The most reliable clinical diagnostic test of carpal
tunnel compression involves inflation of a
sphygmomanometer cuff around the arm to a point
above systolic pressure.
This reproduces patient’s symptoms within 1 min ,
presumably as a result of ischaemia superimposed on
an irritable nerve.
Electrical conductivity tests confirms the diagnosis &
should be performed prior to surgery
Normal conduction velocity of motor fibre : 50 m/s
<40 m/s : suspicious
<30 m/s :diagnostic

17. Nerve repair
1. EPINEURAL REPAIR: alignment of the proximal and
distal ends of the nerve is ensured by inspection of the
pattern of longitudinally running blood vessels in the
epineurium and the fascicular pattern of each cut surface.
The epineurium is coated with fine non absorbable sutures,
maintaining the alignment
2.INTERFASCICULAR REPAIR: using the operating
microscope ,the epinurium is trimmed away from the cut
surface , exposing the fasciculi. The fascicular pattern of
proximal and distal ends are matched & oriented in terms
of rotation & appropriate fascicule coated by sutures

18. Passing through the perinurium. Microsurgeons consider
this to be the treatment of choice for cleanly incised fresh
nerve injuries within loss of nerve substance.
3. NERVE GRAFTING: required when primary nerve
repair cannot be performed without tension because
there has been a considerable loss of nerve substance.
The mc nerve used is SURAL NERVE

19. THANK YOU