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Traumatic peripheral nerve lesions - pain

Updated: Sep 12, 2021

Presentation

- Symptoms occur in the distribution of the affected nerve

- Associated pathologies such as nerve compression and CRPS must be considered

- Severity can be informally graded by asking about:

1: Baseline pain, 2: Spontaneous spikes of pain 3. Pain by pressure over the nerve 4. Pain on movement of adjacent joints 5. Cutaneous 'hyperaesthesia' (1)


Grading of nerve injury

Seddon and Sunderland



Epidemiology

- [Upper limb] 66% of patients with traumatic nerve injuries recover to normal or average function while 34% exhibit incomplete motor and sensory nerve recovery and poor functional outcomes (2)

- [Upper limb] 50% of patients developed chronic pain after traumatic injury and affected the daily life of 44%


Risk factors

- [Upper limb] Younger age, type of injured nerve and time from injury (neuropathic pain is more common SOONER after injury and abates with time), are the most common predictors of chronic pain. Also more common in males (likely due to work type)


Pathophysiology

- Peripheral neuromas are formed when a nerve is transected and not surgically repaired successfully

- A neuroma is a bulbous mass of regenerating axons growing in an uncoordinated fashion from the proximal nerve end (includes schwann cells, fibroblasts, blood vessels, and regenerating axons)

- Two types - End neuroma (completely cut) and partial neuroma or 'neuroma-in-continuity' if nerve is partially intact

- Persisting pain from terminal neuromas is uncommon (3-5% of peripheral nerve injuries)

- Partial injuries to nerve trunks or branches causes more severe neuropathic pain


Two main processes:

- Persistent free nerve endings have nociceptive signals sent via A and C fibres to central somatosensory cortex. These are triggered at lower thresholds

- Spontaneous, mechanical and chemical activity occurs within the neuroma triggering spontaneous activity in neurons of the dorsal root ganglion, dorsal horn, and into the CNS. These CNS changes may occur in perpetuity even after the injury is repaired






Common types of nerve injury/lesions

Lower

Fibular nerve (acute foot drop)

Tibial nerve (Tarsal tunnel syndrome - aching/burning numbness on sole of foot anywhere towards the toes))

Sciatic nerve (Compression in gluteal region and mid thigh are possible too)

Femoral nerve (rare - weak quads)

Lateral femoral cutaneous nerve (Entrapment below inguinal ligament - paresthesias and pain down the lateral aspect of the thigh towards the knee)

Obturator nerve (sensory loss in medial thigh. Rare)


Upper

Median nerve (CTS), pronator teres syndrome, Anterior interosseous neuropathy

Ulnar nerve usually compression at the wrist in guyon's canal

Radial neruopathy (at the spiral groove - where it runs adjacent to the humerus - Saturday night palsy), posterior interosseous neuropathy

Suprascapular neuropathy (Upper branches of brachial plexus)

Long thoracic neuropathy (from 5,6,7 cervical roots = winging of scapula)

Axillary neuropathy (posteror cord of brachial plexus - oval sensation over deltoid)

Spinal accessory neuropathy (from neck dissections)


Examination

- Neurological examination of the presumed affected nerve

- Have to be careful when assessing there are no 'trick' movements - e.g. patient pulling the arm backwards to inadvertently hide a weak elbow flexion (Bartender's sign)


Investigations

- DDx from CRPS and/or compressive neuropathy can be difficult. EMG and nerve conduction studies can help in compressive. And local anaesthetic usually reduces pain in neuroma's

- In brachial plexus injuries, always important to assess for avulsion injuries (root avulsions occur BEFORE the DRG - so repairing something distal is pointless) - Assessing for sensory nerve action potential will help with this clinically, So sensory potential is preserved - in the face of profound weakness and dense sensory loss. If plexus is the avulsion site, the sensory potential disappears as it is disconnected from its cell body (in the DRG)





Treatment

- Aggressive early medical treatment and preemptive analgesia improve prognosis and reduce pain in upper limb conditions.

- Typical oral medications (Antidepressants with reuptake blocking effects, anticonvulsants with Na-blocking actions, anticonvulsants with ca-blocking actions, and opioids

- Topical treatments can be tried including capsaicin and local anaesthetics as patches


- Neuromodulation can be tried by external stimulating probe (small electrical current over the neuroma or area of hypersensitivity for 5-10 mins). (PENS)

- Typical TENS can also be tried


Interventional

Peripheral nerve block or an indwelling catheter can be used to help maintain passive range of motion


Surgery (Acutely)

Ideally repair of a clean/sharp cut occurs within 72 hrs otherwise the two ends may retract


Surgery (Neuromas from transection)

- Neuroma resection and reconstruction


- Simple neuroma resection (least successful in hand/forearm)

- Neuromas occur more readily with electrocautery than scissor cut

- They also occur less in oblique transection cw transverse


- Containment of the neuroma (not tried these days - poor outcomes)


- Relocation of nerve into different environments (skin/muscle) - most preferable


Surgery (Neuromas-in-continuity)

- Neurolysis alone

- Nerve wrapping (often using local fascia flaps)

- Neuroma resection and reconstruction

- Neuroma resection and relocation


Prognosis


Golden pearls

A neurolysis is the surgical dissection and exploration of a damaged nerve with the goal of freeing the nerve from local tissue restrictions or adhesions.

Quiz:



References / Articles / Resources

  1. Laing, T., Siddiqui, A., & Sood, M. (2015). The management of neuropathic pain from neuromas in the upper limb: surgical techniques and future directions. Plastic and Aesthetic Research, 2, 165-170. https://parjournal.net/article/view/1198

  2. Miclescu, A., Straatmann, A., Gkatziani, P., Butler, S., Karlsten, R., & Gordh, T. (2019). Chronic neuropathic pain after traumatic peripheral nerve injuries in the upper extremity: prevalence, demographic and surgical determinants, impact on health and on pain medication. Scandinavian journal of pain, 20(1), 95-108.

  3. Fonseca, P. R. B. D., Gatto, B. E. O., & Tondato, V. A. (2016). Post-trauma and postoperative painful neuropathy. Revista Dor, 17, 59-62. https://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-00132016000500059

  4. Osborne, N. R., Anastakis, D. J., & Davis, K. D. (2018). Peripheral nerve injuries, pain, and neuroplasticity. Journal of Hand Therapy, 31(2), 184-194.

  5. Seddighi, A., Nikouei, A., Seddighi, A. S., Zali, A. R., Tabatabaei, S. M., Sheykhi, A. R., ... & Naeimian, S. (2016). Peripheral nerve injury: a review article. International Clinical Neuroscience Journal, 3(1), 1-6.

  6. Campbell, W. W. (2008). Evaluation and management of peripheral nerve injury. Clinical neurophysiology, 119(9), 1951-1965.

  7. Lovaglio, A. C., Socolovsky, M., Di Masi, G., & Bonilla, G. (2019). Treatment of neuropathic pain after peripheral nerve and brachial plexus traumatic injury. Neurology India, 67(7), 32.


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