The possible role of regenerating axons in pain persistence after brachial plexus grafting

Elbow flexion reconstruction with nerve transfer or grafting in patients with brachial plexus injuries: A systematic review and comparison study

INTRODUCTION

Posttraumatic brachial plexus (BP) palsy was used to be treated by reconstruction with nerve grafts. For the last two decades, nerve transfers have gained popularity and believed to be more effective than nerve grafting. The aim of this systematic review was to compare elbow flexion restoration with nerve transfers or nerve grafting after traumatic BP injury.

METHODS

PRISMA-IPD structure was used for 52 studies included. Patients were allocated as C5-C6 (n = 285), C5-C6-C7 (n = 150), and total BP injury (n = 245) groups. In each group, two treatment modalities were compared, and effects of age and preoperative interval were analyzed.

RESULTS

In C5-C6 injuries, 93.1% of nerve transfer patients achieved elbow flexion force ≥M3, which was significantly better when compared to 69.2% of nerve graft patients (p < 0.001). For improved outcomes of nerve transfer patients, shorter preoperative interval was a significant factor in all injury patterns (p < 0.001 for C5-C6 injuries and total BP injuries, p = 0.018 for C5-C6-C7 injuries), and young age was a significant factor in total BP injury pattern (p = 0.022).

CONCLUSIONS

Our analyses showed that nerve transfers appear superior to nerve graftings especially in patients with a C5-C6 injury. Unnecessary delays in surgery must be prevented, and younger patients may have more chance for better recovery.

LEVEL OF EVIDENCE

Level II.

Brachial plexus injury: treatment options and outcomes

The brachial plexus is a series of nerves formed by roots of cervical segments 5 to 8 (C5-C8) as well as the first thoracic nerve (T1). It functions to provide sensation and motor innervation to the skin and muscles of the chest and upper limb. It does so through different segments: roots, trunks, divisions, and cords. Injuries to the brachial plexus occur relatively frequently and are due mainly to traumatic accidents that lead to traction or compression of the nerve roots. When considering the etiology and treatment of such injuries, it is important to make a distinction between adult versus obstetric brachial plexus injury. Although several surgical treatment options are described and used for patients with brachial plexus injury, no perfect remedy currently exists. Prevention and safety should be the focus. At the same time, high-quality studies and new technology and techniques are needed to determine more effective treatments for this group.

Neuropathic pain in brachial plexus injury

BACKGROUND

In Thailand, brachial plexus injury is a common traumatic injury that affects the function of the upper extremity. The current treatments focus mainly on improving the motor and sensory function. Apart from the motor and sensory deficit, these patients usually suffer from pain.

OBJECTIVE

The purpose of this study was to determine the prevalence and factors that relate to neuropathic pain in patients with brachial plexus injury.

METHODS

We collected data from March 2008 to July 2011. The DN4 Questionnaire was used to diagnose neuropathic pain in 95 patients.

RESULTS

The prevalence of neuropathic pain was as high as 76%. Majority of patients presented with hypoesthesia to pin prick, hypoesthesia to touch and numbness. Severity of neuropathic pain was significantly correlated with the type of brachial plexus injury. There was no difference between demographic characteristics of patients.

CONCLUSION

Our study showed that the prevalence of neuropathic pain was high in brachial plexus injured patients. Therefore, surgeons should be aware of this common, yet underestimated, problem in brachial plexus injured patients.

Neurolysis, neurectomy, and nerve repair/reconstruction for chronic pain

Neuropathic pain may be a result of focal injury to a peripheral nerve. The treatment algorithm begins with nonoperative, then operative, options. In our practice, first-line surgical treatment should directly treat the injured nerve. Nerve decompression or neurolysis is useful in patients with entrapment syndromes and in cases where the course and/or the function of the nerve is altered by local scar or pathoanatomy. Neurectomy is an option in primary cases where numbness is an acceptable alternative to dysesthetic pain, or as an alternative following failed neurolysis. Nerve repair or reconstruction may improve pain by guiding axons past the neuroma.

The C5 root dermatome enlarges and modulates hand pain in total brachial plexus palsy

Hand pain is a major complaint in 80% of the patients with complete brachial plexus palsy; and, in 80% of these patients, the C5 root is ruptured and the C6-T1 roots avulsed from the spinal cord. It has been suggested that pain in brachial plexus injuries may not arise from avulsed roots, but rather from ruptured roots. Traditionally the C5 root dermatome does not extend to the hand. We have hypothesized that in total lesions of the brachial plexus the C5 root dermatome expands, reaching the hand. In 20 patients with confirmed C5 root rupture and C6-T1 root avulsion, we investigated the distribution of C5 root paresthesia six to eight weeks after grafting. After cervical percussion in search of Tinel’s sign, maps related to reported paresthesia were drawn on the affected limb. We observed that paresthesia following C5 root percussion reached the hands and fingers, dermatomes linked to the C6 and C8 roots. Immediately after percussion, for a few seconds, 14 patients who complained of pain during examination reported the augmentation of numbness and pain resolution. After brachial plexus injury, the C5 root dermatome expands and modulates hand pain.

The effects of minocycline or riluzole treatment on spinal root avulsion-induced pain in adult rats

Spinal root avulsion produces tactile and thermal hypersensitivity, neurodegeneration, and microglial and astrocyte activation in both the deafferented and the adjacent intact spinal cord segments. Following avulsion of the fifth lumbar spinal root, immediate and prolonged treatment with riluzole or minocycline for 2 weeks altered the development of behavioral hypersensitivity. Riluzole delayed the onset of thermal and tactile hypersensitivity and partially reversed established pain behavior. Minocycline effectively prevented and reversed both types of behavioral change. Histologic analysis revealed that both drugs reduced microglial staining in the spinal cord, with minocycline being more effective than riluzole. Astrocyte activation was ameliorated to a lesser extent. Surprisingly, neither drug provided a neuroprotective effect on avulsed motoneurons.

PERSPECTIVE

Immediate treatment of spinal root avulsion injuries with minocycline or riluzole prevents the onset of evoked pain hypersensitivity by reducing microglial cell activation. When treatment is delayed, minocycline, but not riluzole, reverses pre-established hypersensitivity. Thus, these drugs may provide a new translational treatment option for chronic avulsion injury pain.

Results and current approach for Brachial Plexus reconstruction

We review our experience treating 335 adult patients with supraclavicular brachial plexus injuries over a 7-year period at the University of Southern Santa Catarina, in Brazil. Patients were categorized into 8 groups, according to functional deficits and roots injured: C5-C6, C5-C7, C5-C8 (T1 Hand), C5-T1 (T2 Hand), C8-T1, C7-T1, C6-T1, and total palsy. To restore function, nerve grafts, nerve transfers, and tendon and muscle transfers were employed. Patients with either upper- or lower-type partial injuries experienced considerable functional return. In total palsies, if a root was available for grafting, 90% of patients had elbow flexion restored, whereas this rate dropped to 50% if no roots were grafted and only nerve transfers performed. Pain resolution should be the first priority, and root exploration and grafting helped to decrease or eliminate pain complaints within a short time of surgery.