assessing nerve surgery outcomes

1. Assessment of peripheral nerve surgery

2. At the end of the lecture the participant
will be able to:
• 1. List the qualitative and quantitative
methods for nerve function understanding
their limitations
• 2. Understand the role of electro diagnosis in
nerve injury

3. Issues & Challenges
• cortical functional reorganization of hand representation
result of axonal misdirection - cortical remapping
• Modulation of central nervous processes rather than
peripheral factors
• Brain capacity for visuo-tactile and audio-tactile interaction
• selective de-afferentation enhancing the effects of sensory
relearning
• no surgical technique which can ensure recovery of tactile
discrimination in the hand of an adult after median nerve
lesion
• hand as a sense organ
• MRC Scale subjective findings - psychometric drawbacks

4. Regeneration after nerve repair
regardless of the repair technique - axonal
misdirection is unavoidable

5. Assessment of hand function
• sensibility
• motor function
• autonomic
• pain and
• discomfort

6. Model Instrument for Outcome
After Nerve Repair
• Detection tests - Semmes-Weinstein monofilaments,
• discrimination tests - two-point discrimination (2PD),
• identification tests- shape/texture-identification (STI) test
• activities of daily living (ADL) - The DASH was also the
most commonly used condition-specific patient-reported outcome in the
included clinical trials
• (McPhail, Bagraith, Schippers, Wells, & Hatton, 2012)

7. Factors influencing the outcome
• Age
• Cognitive brain capacities - Verbal learning capacity and
visuo-spatial cognitive capacity
• Timing of repair
• Type of nerve
• Level of injury
• Type of injury
• role of the brain in functional recovery - ‘new
language spoken by the hand’.

8. What happens in the brain after nerve
injury and repair
• silent ‘black hole
• adjacent cortical areas expand and occupy the
former
• distorted discontinuous islands

9. Sensory re-education and sensory
relearning
• mind does not understand the new ‘sensory
code’ associated with specific textures and
shapes
• touch modalities, localise touch, shapes and
textures
• concepts of learning mechanisms, cortical
remodelling and brain plasticity

10. New strategies in sensory re-education
and sensory relearning
• Phase 1: maintaining the cortical hand map
activate the cortical area representing the damaged nerve- visuo-tactile and
audio-tactile interaction
• Activation of motor neurones – ‘mirror neurones’ in premotor
cortex by the mere observation of hand motor actions
• activated by reading/listening to action or words
• Phase 2: enhancing the effects of sensory re-
education
de-afferentation of the forearm would hypothetically result in
expansion of the adjacent cortical hand representation
• Cutaneous de-afferentation of the forearm
(Rizzolatti et al. 2001, Rizzolatti & Craighero 2004)

13. Outcomes
• outcome shows ongoing improvements up to
5 years after the nerve repair
• 59% of patients with median or ulnar nerve
repairs returned to work within 1 year with an
average time off work of 31 weeks (Jaquet 2004)
• high education, high compliance to hand
therapy and an isolated injury predict quicker
return to work in patients with median and/or
ulnar nerve injuries.

14. Sollerman Hand Function Test
• overall measure of hand and grip function when
engaging in ADLs (Sollermen & Ejeskar 1985).
• It was designed to measure grips that are needed
for certain ADLs such as eating, driving, personal
hygiene, and writing.
• includes subtests that represent common
handgrips (volar, transverse volar, spherical volar
and pinch positions - pulp, lateral, tripod, and the
five finger) and activities (using a key; picking up
coins from a flat surface; writing with a pen; using
a phone; and pouring water from a jug)

16. Nerve Conduction Studies and
Electromyography in the
Evaluation of Peripheral Nerve Injuries

17. NCS & EMG
• essential in the evaluation of nerve disorders
• localizing the site of injury
• distinction of conduction block from axonal
degeneration
• prognostic information
• dependent on the skills of the examiner
• Augment physical examination

18. NCS and Needle EMG
• measurement of nerve response amplitude
and conduction velocity along the course of
each nerve
• sensory nerve action potential (SNAP) 5–20
mV in amplitude
orthodromically/antidromically
• compound motor action potential (CMAP)
• Needle EMG distinguish neurogenic /
myopathic causes

20. Post Injury - acute
• Motor axons remain excitable for up to 7 days
after injury. Sensory axons to 11 days
• So perform 14 days post injury
• Spontaneous activity in muscles - 2 – 6 weeks

24. References
• Lundborg G, Rosén B. Hand function after nerve repair. Acta Physiologica February
2007;189(2):207-217
• McPhail, S. M., Bagraith, K. S., Schippers, M., Wells, P. J., & Hatton, A. (2012). Use
of Condition-Specific Patient-Reported Outcome Measures in Clinical Trials among
Patients with Wrist Osteoarthritis: A Systematic Review. Advances in orthopedics,
2012,
• Jaquet, J. 2004. Median and minor nerve injuries: Prognosis and predictors for
clinical outcome. Thesis. Department of Plastic and Reconstructive Surgery,
Erasmus Medical Center, Erasmus University, Rotterdam