Electrical Stimulation and improved outcomes for Brachial Plexus injuries
In this article, we step back and consider how brachial plexus injuries are treated and then look at how forms of electrical stimulation might contribute to achieving the best clinical outcome.
Brachial plexus injuries present a complex challenge in medical practice, with the potential to produce significant functional impairment and reduced quality of life. Effective treatment requires a meticulous, multifaceted approach, combining surgical and non-surgical interventions tailored to the patient's specific needs. This article explores current treatment strategies, focusing on the potential role of electrical stimulation as a complementary therapy. By examining its applications and efficacy, we aim to highlight how this innovative technique could enhance recovery and optimise clinical outcomes for individuals affected by these injuries.
What is a brachial plexus injury?
A brachial plexus injury refers to damage to the network of nerves originating in the spinal cord and extending through the neck, shoulder, and arm. These nerves control muscle movements and sensations in the upper limb. Such injuries can range from minor nerve compressions to severe cases involving nerve ruptures or avulsions.
Common causes include trauma from accidents, sports-related injuries, or complications during childbirth. Prompt diagnosis and treatment are critical, as delays can result in permanent nerve damage and loss of function. Treatment options vary depending on the severity of the injury and may include physical therapy, nerve grafts, or surgical interventions.
A bit of history
The historical treatment of brachial plexus injuries has evolved significantly over centuries, from ancient times to modern surgical and neurological approaches. The first documented clinical description in Homer's Iliad (8th-7th century BCE) describes brachial plexus palsy resulting from battlefield injuries. William Smellie provided the first widely recognized clinical description of brachial plexus palsy in the 18th century. Treatment remained largely conservative during this period, with limited surgical interventions.
Until the 1970s, severe cases (especially avulsions) were primarily treated with amputation of the affected limb, or with shoulder arthrodesis, elbow and wrist fusion or prosthetic/orthotic interventions.
In 1963, Seddon introduced nerve grafting techniques, and by the 1970s, Neurotisation techniques emerged, starting with intercostal nerve transfers. Current approaches emphasise early intervention and microsurgical techniques, with something to offer for all injury types regardless of severity.
As we will see, electrical stimulation has emerged as a promising adjunctive treatment for promoting nerve regeneration and functional recovery in brachial plexus injuries.
The RISE Stimulator from Schuhfried Austria
This technique involves applying low-level electrical currents to stimulate nerves and muscles affected by the injury. The underlying principle is that carefully controlled electrical impulses can enhance neuronal activity, prevent muscle atrophy, improve muscle bulk and tissue quality, and support the regrowth of damaged nerve fibres.
Research suggests that electrical stimulation may accelerate axonal growth rates and improve neuromuscular coordination during rehabilitation. It is frequently used alongside physical therapy or surgical reconstruction, providing a synergistic effect that maximises recovery potential.
What is the statistical significance of this injury in the UK?
Brachial plexus injuries in the UK occur in two main categories; obstetric (birth-related) and traumatic (adult-onset)—with distinct incidence rates and risk factors.
Obstetric brachial plexus injuries (OBPI) have an incidence of between 0.42–0.56 per 1,000 live births, and 0.56 per 1,000 live births in the UK, depending on the study.
Some 52% of infants are expected to recover fully, whilst 46% partially recover, and 2% might be expected to show no recovery. Severe cases (e.g., total plexus injuries with Horner syndrome) have the worst prognosis, often requiring surgery.
Traumatic Brachial Plexus Injuries in adults have an Annual Incidence of 0.8–1.6 per 100,000 population in the UK . It is most common in young males (93% of cases) due to motorcycle accidents (67%) and other forms of high-energy trauma, including falls from height and sports injuries, and other forms of high-energy trauma, including falls from height and sports injuries.
Supraclavicular injuries ~90% of cases. (Meaning above the clavicle where the nerve roots exit the spine, involving C5-T1 nerve roots, including the area where roots combine to form trunks, and extends to where trunks divide into anterior/posterior divisions)
Complete lesions 53% of severe injuries.
Upper plexus (C5-C7) involvement 39%.
Key Observations
Underreporting - Obstetric BPIs may be underestimated due to transient cases resolving early [14].
Surgical Needs ~just 10% of obstetric cases require surgery, while adult traumatic injuries often demand complex reconstruction.
Prevention Training programs (e.g., PROMPT) have reduced permanent BPIs in obstetric care.
These statistics highlight the need for early intervention in infants and specialised trauma care for adults to mitigate long-term disability.
What is the impact of a brachial plexus injury on the individual?
Brachial plexus injuries have profound physical, psychological, and socioeconomic impacts on patients' lives. Physically, they can result in long-term movement paralysis, loss of sensation and neuropathic pain. Persistent pain can be particularly severe with injuries closer to the spinal cord and 76% experience regular pain.
Some studies report that 19% of patients develop clinical depression or meet the criteria for PTSD and 33.3% report suicidal ideation7
Employment and Financial Impact
Approximately 69.6% continue working after surgery
Significant financial uncertainties
Economic hardship due to unemployment
Young males are typically most affected, impacting their prime working years
Social Impact
Life-changing consequences for patients and their families
Social anxiety and relationship challenges
Significant challenges with daily living tasks
Role changes within family and society
Despite these challenges, treatment outcomes show some promise, with 82.6% of surgical patients reporting significant improvement and satisfaction with their treatment4.
How likely is it that muscles are denervated following a brachial plexus injury?
Muscle denervation is highly likely following brachial plexus injuries, with the probability and severity depending on injury type, location, and timing of intervention. Here’s a breakdown:
Key Factors Influencing Denervation Risk
1. Injury Severity
Root avulsions (nerve torn from spinal cord) cause permanent denervation without surgical repair.
Upper trunk injuries (C5-C6) often denervate shoulder and elbow flexors (e.g., biceps, deltoid), leading to atrophy and contractures.
2. Timing
Early denervation. Muscle atrophy begins within weeks, with 50% muscle fiber diameter loss by 2–3 months.
Prolonged denervation (>12–18 months): Irreversible muscle fibrosis and fatty replacement occur, reducing reinnervation success.
3. Electrophysiological Evidence
EMG studies confirm denervation in 86–97% of cases via fibrillation potentials and reduced motor unit recruitment.
Clinical Outcomes by Injury Type
Upper plexus injuries (C5-C6)
74–86% of patients show reinnervation potential with early surgery (<6 months).
Delayed repair (>6 months) reduces reinnervation rates to 50–65%.
Pan-plexus injuries (C5-T1)
38% achieve functional elbow flexion (≥M3) with surgery, but shoulder abduction recovery drops to 23.5%.
Distal muscles (e.g., hand intrinsics) rarely recover due to extended reinnervation distances.
Consequences of Denervation
Muscle atrophy
Denervated muscles lose 50% of cross-sectional area within 3 months.
Fibrosis and fatty infiltration render muscles nonfunctional by 2 years.
Contractures - Denervation-induced shortening of elbow flexors (biceps/brachialis) causes flexion contractures in neonatal BPIs.
Critical Timeframes
The optimal surgical window for nerve grafting/transfers is 3–6 months post-injury.
Post-18 months, muscle viability plummets, necessitating tendon/muscle transfers instead.
Muscle denervation occurs in ≥70% of moderate-to-severe injuries, particularly with root avulsions or upper trunk injuries. Early intervention (<6 months) improves reinnervation odds, while delayed treatment often leads to irreversible atrophy. EMG-confirmed denervation is nearly universal in traumatic cases, underscoring the need for prompt diagnosis and multidisciplinary management
The Benefits of Electrical Stimulation
Electrical stimulation offers several benefits in treating brachial plexus injuries, particularly in enhancing nerve regeneration potential, improving muscle function, and supporting rehabilitation. Here’s a detailed breakdown of its advantages:
Enhanced Nerve Regeneration and Recovery
Accelerated axonal growth. ES promotes nerve healing by increasing neurotrophic factors like BDNF and cAMP, which are critical for nerve repair. Studies show that brief electrical stimulation (e.g., 20 Hz for 1 hour) post-surgery accelerates motor and sensory recovery in peripheral nerve injuries.
Reduced muscle atrophy. By stimulating denervated muscles, we can slow and even reverse atrophy. Maintaining muscle tissue quality and mass while awaiting reinnervation is vital to improve long-term functional outcomes. As we will discuss below, electrical stimulation generally requires a product such as the RISE Stimulator which is capable of inducing direct contraction of the muscle fibres.
Improved Muscle Function and Strength
Motor re-education. If muscles remain innervated or partially innervated, then neuromuscular electrical stimulation (NMES) can be used. This directly activates motor neurons, enhancing muscle contraction and strength. When stimulation is used with functional intent (FES), this aids in performing activities like grasping or reaching by triggering coordinated muscle contractions, which is particularly beneficial for upper limb rehabilitation.
Pain Management
Neuropathic pain can sometimes be reduced via other forms of nerve stimulation and spinal cord stimulation that can modulate sensory feedback, alleviating chronic pain associated with the injury. It is common to see this nerve stimulation described as TENS (transcutaneous electrical nerve stimulation) as if this is a unique approach. In fact, many of the forms of electrical stimulation used in rehabilitation could be said to be transcutaneous in form. There are also a number of stimulation patterns that could be described as TENS, and forms of pain relief that use other patterns of stimulation.
Various approaches to pain relief using electrical stimulation
Practical and Safety Benefits
From the above discussion It is clear that brachial plexus injuries represent a significant challenge for treatment. We generally see individuals who have traumatic injuries. They often present with neuropathic pain and denervated, atrophied muscles. Treatment needs to start early and electrical stimulation can be an important modality in dealing with pain and the consequences of denervation when present. We use two products in supporting persons with these injuries: the Rise Stimulator or the Edition 5 Stimulator. The choice depends somewhat on the presentation.
Home-based usability.
Working even with denervated muscles at home is now widely recognised as safe and effective in preserving muscle and nerve tissue. In fact, it is the only practical way of applying the necessary and sufficient intensity of stimulation. We would expect users to commit to six days per week of stimulation use and some 30 minutes per muscle group per day.
If denervation is present, we often start with biphasic rectangular waveforms with a relatively long pulse width. In some cases, between 150 and 200 milliseconds.
These waveforms induce direct contraction of muscle fibres rather than relying on the intact nerve structure. On occasions when denervated muscles lie close to muscles with preserved innervation, we may vary the waveform shape to the more traditional triangular form. Both the RISE Stimulator and the Edition 5 can generate suitable waveforms. Denervated muscles are best served by covering as much of the affected muscle as possible with the activating electrode but again this can be problematic when muscles with preserved innervation are nearby.
If neuropathic pain is present, we would probably choose the Edition 5 unit, which has waveforms suitable for pain management and waveforms for both innervated and denervated muscles.
Minimal side effects
We find the electrical stimulation is well-tolerated, with rare adverse effects like transient skin irritation. Structured protocols prevent overstimulation, making it suitable for long-term use. It is possible to use gelled adhesive electrodes in some situations but often we use wet sponge and conductive rubber electrodes which tend to be kind to the skin.
Adjunct to Rehabilitation Protocols
Synergy with physical therapy
Combining specialist electrical stimulation with techniques like proprioceptive neuromuscular facilitation (PNF) can improve upper limb function and daily activity performance.
Considerations and Limitations
Variable efficacy - The outcomes of electrical stimulation depend on injury severity and timing. It is most effective in promoting functional recovery when started early and used alongside surgical interventions (e.g., nerve transfers)
Some researchers suggest that whilst animal and small-scale human studies are very positive, more extensive clinical trials are needed to standardise parameters (e.g., waveform types, frequency, intensity) and confirm long-term benefits. Of course, there is always room for more research, but we find that electrical stimulation is a versatile, non-invasive tool that supports nerve repair, muscle preservation, and functional recovery. Its integration into rehabilitation protocols offers a practical pathway to improve quality of life, though individualised treatment plans.
Perhaps the biggest issue we find is delayed adoption of electrical stimulation which in our view severely impacts upon the potential for functional gains.
Literature
Li H, Chen J, Wang J, Zhang T and Chen Z (2023) Review of rehabilitation protocols for brachial plexus injury. Front. Neurol. 14:1084223. doi: 10.3389/fneur.2023.1084223
https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2023.1084223/full
Information on neuromuscular electrical stimulation [NMES] and traumatic brachial plexus injury. By Scottish National Brachial Plexus Injury Service. https://www.brachialplexus.scot.nhs.uk/documents/Neuromuscular%20Electrical%20Stimulation%20(NMES)%20in%20Adult%20Brachial%20Plexus%20Injury.pdf
Deodhe NP, Dhage P, Harjpal P. Functional Electrical Stimulation in Conjunction With Proprioceptive Neuromuscular Facilitation (PNF) Technique to Improve Upper Limb Function in Traumatic Brachial Plexus Injury: A Case Report. Cureus. 2023 Oct 2;15(10):e46386. doi: 10.7759/cureus.46386. PMID: 37927650; PMCID: PMC10620461.https://pmc.ncbi.nlm.nih.gov/articles/PMC10620461/
Ni L, Yao Z, Zhao Y, Zhang T, Wang J, Li S and Chen Z (2023) Electrical stimulation therapy for peripheral nerve injury. Front. Neurol. 14:1081458. doi: 10.3389/fneur.2023.1081458
https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2023.1081458/full
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https://www.anatomicalconcepts.com/articles/fes-and-peripheral-nerve-injuries
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