Key notes on plastic surgery/Adrian M. Richards

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34 GENERAL PRINCIPLES
Electrical stimulation
• Motor nerves respond to electrical stimulation for approximately 72 h following
division.
• Electrical stimulation of the distal nerve stump during this period can be used to
differentiate motor from sensory fibres.
• Awake stimulation of the nerves can be used to differentiate motor from
sensory fibres in the proximal nerve stump.
• Electrical stimulation of sensory fibres produces sharp pain.
• Similar stimulation of motor fibres is felt as a dull ache.
Knowledge of internal nerve topography
• The fascicular layout of many nerves is known and can be used to aid accurate repair.
• Ulnar-nerve motor fascicles lie centrally between the volar sensory branches
coming from the palm and the dorsal sensory branches coming from the dorsum
of the hand.
Nerve grafts
• Nerve grafts are required if primary nerve repair is not possible without undue
tension.
• If the divided nerve is large, multiple cables of a smaller donor nerve may be
required to bridge the defect.
• It may be possible to reduce the tension across the repair by mobilizing the nerve
stumps proximally or distally.
• Methods by which extra nerve length can be obtained by proximal dissection
include:
• Transposition of the ulnar nerve at the elbow.
• Intratemporal dissection of the facial nerve.
• Materials used to bridge nerve gaps are either autologous or synthetic.
• Of these, autologous nerve is the best material for bridging nerve gaps at present.
Composition
• Autologous tissues that can be used as nerve grafts include:
• Fresh nerve
• Freeze–thawed muscle
• Segments of vein.
• Synthetic nerve grafts composed of fibronectin mats impregnated with growth
factors may be available in the future.
Autologous grafts
The following nerves can be used as autologous grafts.
Sural nerve
• This nerve passes behind the lateral malleolus.
• Proximally it divides into the medial sural nerve and the peroneal communicating
branch.