Brachial Plexus and Peripheral Nerve FRCS Refresher 9/09/2026

Introduction to Brachial Plexus Anatomy

Overview of Spinal Cord and Nerve Roots

• The discussion begins with the anatomy of the spinal cord, highlighting the anterior root (efferent signals) and posterior root (afferent signals).

• Both roots combine to form a spinal nerve that exits through the intervertebral foramen, transitioning into the peripheral nervous system.

• The brachial plexus is formed from C5 to T1 roots, which are crucial for arm function.

Structure of Brachial Plexus

• The brachial plexus consists of roots, trunks, divisions, cords, and branches; understanding this structure is essential for surgeries involving peripheral nerves.

• A color-coding system helps identify different sections: upper plexus (shoulder), middle plexus (elbow), lower plexus (hand).

Clinical Relevance of Brachial Plexus Injuries

Identifying Pathologies

• Clinicians can quickly assess shoulder and hand functionality to determine injury locations based on muscle strength.

• Understanding horizontal levels of injury is critical; injuries at the infraclavicular level may indicate cord-level pathology rather than root-level issues.

Examination Techniques

• When examining patients with potential brachial plexus injuries, focus should shift from specific nerve roots to broader cord assessments.

• Misidentifying intact nerves can lead to incorrect diagnoses; clinicians must consider both peripheral and cord-level injuries.

Detailed Anatomy of Brachial Plexus

Muscle Innervation Mapping

• Different muscles have distinct nerve roots; this knowledge aids in planning nerve transfers during surgical interventions.

• Drawing a clear diagram of the brachial plexus is vital for understanding its anatomy during patient examinations or surgeries.

Diagramming Techniques

• A systematic approach involves labeling roots (C5-T1), trunks, divisions, cords, and branches using Y-shaped diagrams for clarity.

Key Nerves in Brachial Plexus

Branches from Cords

• Mnemonics help remember branches: "ULTRA" for posterior cord branches includes upper subscapular and radial nerves.

• Understanding these branches is crucial as they play significant roles in motor functions across various muscles.

Surgical Considerations in Thoracic Outlet Syndrome

Anatomical Relationships

• The subclavian artery's proximity to lower trunk nerves highlights important anatomical relationships relevant during thoracic outlet procedures.

Dissection Insights

• During dissection approaches like superclavicular access, preserving key structures such as the supraclavicular nerves is essential to prevent postoperative complications.

Exploring Peripheral Nerves

Median Nerve Pathway

• The median nerve travels down alongside major arteries and can be compressed at several points along its course through the forearm.

Compression Points

• Specific ligaments like the ligament of Struthers can compress the median nerve; awareness of these points aids in surgical planning.

Ulnar Nerve Functionality

Ulnar Nerve Course

• Known as a "musician's nerve," it plays a critical role in finger movement necessary for playing instruments like piano.

Compressive Points

• Key compression sites include areas around medial epicondyle where careful dissection techniques are required during surgery.

Overview of Brachial Plexus Anatomy and Injuries

Ganglion Compression and Nerve Anatomy

• A patient presented with a ganglion from the piso-triquetral joint compressing the ulnar nerve and artery, leading to rapid clawing due to limited space for pathology.

• The radial nerve originates from all five roots of the posterior cord, supplying various muscles including triceps and brachioradialis as it traverses through the arm.

• The radial nerve pierces the intermuscular septum, entering the forearm between brachialis and brachioradialis, supplying ECRL before reaching supinator.

Radial Nerve Branches

• The deep branch of the radial nerve passes under the leading edge of supinator muscle (arcade of Frohse), which is crucial during decompression procedures.

• The anatomy includes a cutaneous branch that supplies sensation to the back of the forearm; this nerve can be used for grafting with minimal deficit.

Sensory Supply and Clinical Implications

• Misconceptions exist regarding sensory supply; while many believe it covers more area, it primarily supplies specific regions like thumb and three-and-a-half fingers on dorsal side.

• Understanding that distal areas are supplied by median nerves is essential for accurate anesthetic blocks during surgical procedures.

Examination Techniques in Brachial Plexus Injury

• Key functions assessed include shoulder abduction, external rotation, elbow flexion/extension, finger flexion/extension; these guide management decisions in injuries.

• Classification of brachial plexus injuries into open or closed types aids in understanding injury mechanisms; type II is most commonly discussed.

Injury Localization and Severity Assessment

• When examining patients with brachial plexus issues, it's vital to localize lesions along both horizontal (level of injury) and vertical axes (pre/post-ganglionic).

• Seddon’s classification helps determine recovery potential based on injury severity; lower grades indicate quicker recovery chances.

Surgical Management Considerations

• Identifying whether a patient falls within 'green zone' (no surgery needed for recovery) or 'red zone' (requires intervention for recovery).

• Simplifying examination processes is crucial due to time constraints during assessments; focus on history first to tailor examinations effectively.

Differentiating Pre-Ganglionic vs. Post-Ganglionic Injuries

• Pre-ganglionic injuries involve avulsed rootlets from spinal cord while post-ganglionic injuries affect both motor/sensory nerves after dorsal root ganglion.

• Clinical differentiation relies on Tinel's sign presence indicating post-ganglionic rupture versus intact sensory cell bodies in pre-ganglionic cases.

Prognosis Factors in Infraclaviular Injuries

• Infraclaviular injuries often have better prognoses than supraclavicular ones due to shorter distances for reinnervation despite being mixed patterns complicating diagnosis.

Examination Steps for Brachial Plexus Assessment

• Focus on six key functions: shoulder abduction/external rotation, elbow flexion/extension, finger movements—these guide reconstructive efforts post-injury.

Visual Inspection During Physical Exam

• Inspect shoulder contour for signs like deltoid wasting or trapezius droop indicating possible auxiliary nerve involvement or C5 injury.

Simplified Muscle Examination Protocol

• Streamline muscle examinations by focusing on critical nerves such as dorsal scapular and long thoracic before assessing shoulder girdle muscles together.

This structured summary provides an organized overview of critical concepts related to brachial plexus anatomy and injury assessment based on provided timestamps.

Understanding Brachial Plexus Injuries and Management

Assessment of Nerve Function

• Assess the function of C6 and C7 elements when evaluating shoulder, pec major, elbow, and hand functionality to determine nerve involvement.

• The presence or absence of C7 affects management decisions; understanding its role is crucial for donor selection and reconstruction strategies.

• Investigations may include radiographs for fractures and chest X-rays to identify potential phrenic nerve injuries indicating root-level issues.

Imaging Techniques

• CT myelography is effective in identifying root avulsions, while MRIs are less useful acutely due to their inability to differentiate injury types.

• MRI can reveal neuromas and denervation edema over time but is not typically performed immediately after injury due to limited information yield.

Electromyography (EMG) Insights

• EMGs assess muscle activity through needle insertion; they help distinguish between different types of nerve injuries based on muscle response.

• Nerve conduction studies are generally not conducted acutely; however, EMGs provide critical insights into muscle innervation status post-injury.

Case Study: Road Traffic Accident

• A case study illustrates the importance of timing in EMG assessments; early evaluations may show absent voluntary activity but could misclassify injury severity.

• Optimal timing for EMGs is around three weeks post-injury when signs like fibrillations begin to appear, aiding in accurate diagnosis.

Long-term Evaluation and Management Decisions

• At 12 weeks post-injury, increased insertional activity indicates at least a Sunderland 2 level injury; spontaneous activity confirms denervation has occurred.

• If no voluntary activity is present at nine months despite signs of denervation, surgical intervention becomes necessary as the patient falls into the red zone for treatment.

Examination Techniques

• Early examination techniques focus on assessing grade one power in muscles even if overall arm function appears flaccid; this helps gauge nerve continuity.

• To evaluate specific muscles like deltoids or biceps, palpate during attempted movements to detect any contraction that suggests nerve function.

Scapular Winging Types

• Medial scapular winging occurs with long thoracic nerve injuries affecting serratus anterior function; lateral winging results from trapezius or rhomboid dysfunction.

Nerve Root Avulsion Clarifications

• Distinguishing between pre-ganglionic avulsions (no proximal end available for grafting) versus ruptures (where exploration may allow repair).

Surgical Considerations

• Timing for interventions such as neurolysis or grafting depends on the nature of the injury; ideally performed within six months for optimal outcomes.

Nerve Grafting and Transfers in Plexus Injuries

Grafting Techniques

• When grafting larger nerves, multiple cables are necessary to bridge the gap with smaller nerves due to size mismatch.

• For nerve grafting in plexus injuries, using multiple cables of small nerves like sural nerve is essential; thicker options like MABC may require fewer cables.

• Reversing nerve grafts can potentially improve axonal growth by redirecting branches away from branching points that cause axonal escape.

• The effectiveness of reversing nerve grafts is theorized but lacks strong evidence; it remains a common practice among surgeons.

Nerve Transfers

• In cases where direct grafting isn't possible due to severe injuries or avulsions, nerve transfers become a viable option for restoring function.

• Avulsions prevent grafting because the proximal segment of the nerve is absent, making it impossible to bridge any gaps.

• A successful nerve transfer involves taking fascicles from a functioning nearby nerve and connecting them to restore function in an injured area without denervating the donor site.

Specific Injury Scenarios

• C5-C6 injuries often result in shoulder dysfunction while preserving hand function; treatment focuses on restoring elbow flexion and shoulder abduction.

• If repair or grafting fails in C5-C6 injuries, surgeons resort to nerve transfers as a solution for restoring lost functions.

Surgical Techniques for Restoration

• For shoulder abduction restoration, transferring the spinal accessory nerve to the suprascapular nerve can help reinnervate muscles responsible for this movement.

• Further improvements can be made by transferring branches from the long head of triceps to enhance anterior deltoid function without compromising stability.

Advanced Reconstruction Strategies

• Elbow flexion can be reconstructed through various methods including oblong transfers or muscle transfers when traditional methods are not feasible.

• Free functioning muscle transfers provide additional options for elbow flexion and finger movements when other techniques fail.

Addressing Complex Injuries

• In cases involving C7 injuries alongside C5-C6 deficits, reconstructive strategies must adapt since triceps functionality also needs addressing.

• Intercostal nerves may serve as donors for triceps reconstruction while ensuring balance between agonist and antagonist muscles during rehabilitation.

Managing Pan Plexus Injuries

• Pan plexus injuries complicate surgical interventions due to extensive damage; focus shifts towards preserving donor sites for critical functions like elbow flexion.

• The spinal accessory nerve serves as a valuable donor for free functioning muscle transfers aimed at improving overall limb functionality.

Discussion on Donor Issues and Lung Function Tests

Overview of Donor Usage

• The group discusses a potential donor that is not frequently used due to donor-related issues.

• A question arises about the necessity of lung function tests before using the donor, which is clarified as unnecessary if the other side is functioning well.

Agenda Options for Discussion

Choosing Between Topics

• The facilitator suggests two topics: TMR (Targeted Muscle Reinnervation) and RPNI (Regenerative Peripheral Nerve Interface), or discussing viviver cases.

• A participant expresses interest in being involved in a viviver case, indicating a preference for practical engagement over theoretical discussion.

Preference for Case Discussions

Focus on Relevant Cases

• One participant prefers discussing cases over TMR and RPNI, citing relevance to exam preparation.

• A question about RPNI techniques leads to clarification on using free muscle grafting methods.

Understanding RPNI Techniques

Mechanism of RPNI

• The speaker explains that with RPNI, denervating the muscle increases the likelihood of axons growing towards neuromuscular junctions.

• It’s noted that while muscle atrophy occurs due to devascularization, functionality can still be preserved.

Break Announcement

Short Break Before Continuing

• A brief break is suggested for participants to recharge before continuing discussions.

Introduction of Clinical Case Study

First Patient Case Presentation

• The first case involves a 24-year-old motorcyclist with severe arm injuries following an accident, including flail arm and midshaft clavicle fracture.

Imaging Findings Discussion

MRI Insights

• Participants discuss MRI findings suggesting possible nerve root avulsion based on symptoms like burning pain and Horner's syndrome.

Clinical Examination Expectations

Expected Symptoms from Avulsion

• Clinical examination expectations include signs consistent with nerve root avulsion such as insensate upper limb and absence of Tinel's sign.

Reconstructive Priorities

Management Strategies

• In cases of pan plexus avulsion, priorities include alleviating pain and restoring gross motor functions like shoulder abduction and elbow flexion.

Importance of Shoulder Stability

Justification for Surgical Decisions

• Shoulder arthrodesis may be necessary to provide stability when limited options are available for movement control post-injury.

Biomechanical Considerations

Enhancing Functional Outcomes

• Emphasizing shoulder stability prevents subluxation and improves biomechanical function crucial for subsequent reconstructions like elbow flexion.

Alternative Treatment Approaches

Considering Amputation

Discussion includes considering amputation combined with prosthetic stabilization as an alternative treatment strategy in severe cases.

Sensory Restoration Importance

Protective Sensation Needs

• Restoring protective sensation through surgical interventions is critical; options include vascularized nerve transfers to enhance hand functionality.

13 Timing Considerations

Surgical Intervention Timing

• Discusses timing for surgical interventions based on patient recovery progress; emphasizes waiting until physiotherapy goals are met before proceeding.

14 Pain Management Strategies

Addressing Neuropathic Pain

• Neuropathic pain management requires different approaches than nociceptive pain; treatments may include mirror therapy or spinal cord stimulation rather than opioids alone.

15 Confirmation Questions

Clarifying Surgical Plans

• Clarifies plans regarding utilizing spinal accessory nerves in conjunction with functional muscle transfers during reconstructive surgery.

16 Second Patient Case Introduction

New Injury Scenario

• Introduces a new case involving a semi-professional rugby player who sustained an anterior dislocation leading to significant loss of function in shoulder abduction and elbow flexion.

17 EMG Findings Analysis

Evaluating Nerve Involvement

• EMG results indicate denervation across multiple muscles; further investigation into specific nerve injuries required based on clinical presentation.

18

Differentiating Nerve Injuries

Identifying Specific Nerve Damage

• Discusses how to differentiate between isolated nerve injuries by examining preserved functions in surrounding muscles during physical assessments.

19

Significance of Paraspinal Muscles

Implications for Injury Assessment

• Preservation of cervical paraspinal muscles indicates injury likely not at root level but rather post-ganglionic, guiding treatment decisions accordingly.

20

Decision-Making After Four Months

Evaluating Need for Surgery

• If no voluntary activity observed after four months post-injury, consideration shifts toward surgical intervention options such as nerve transfers instead of repairs or grafting alone.

21

Recommended Nerve Transfers

Options Based on Injury Type

• Suggested nerve transfer strategies involve utilizing spinal accessory nerves along with other functional transfers tailored specifically towards restoring biceps function effectively.

22

Spinal Accessory Nerve Injury Case Study

Exploring Common Injuries

• Presents another case involving spinal accessory nerve injury resulting from lymph node biopsy complications leading to shoulder dysfunction requiring careful evaluation and management strategies.

Exploring Nerve Injuries and Repair Techniques

Understanding Neuroma and Nerve Function

• Discussion begins on sharp injuries and the potential for nerve grafting, emphasizing the importance of exploring the injury site.

• The need to assess functioning axons across a neuroma is highlighted, suggesting intraoperative stimulation as a method to evaluate nerve function.

• If no function is detected, resection of the neuroma is recommended, with considerations for direct repair versus grafting based on size.

• The speaker discusses appropriate graft sources, mentioning lateral antebrachial cutaneous nerve as a viable option for small defects.

Grafting Considerations

• A case example illustrates a significant gap requiring about 20 cm of graft due to extensive scar tissue removal.

• Alternatives are considered if grafting isn't possible; local options or muscle transfers may be explored when proximal stumps are absent.

Nerve Transfers and Exploration

• Nerve transfer from triceps or posterior cord is suggested as an option when traditional grafting fails.

• A patient case is introduced involving radial nerve palsy post-fracture fixation, prompting examination of wrist drop symptoms.

Examination Protocol

• Observations during physical examination reveal scapular winging patterns indicative of specific muscle involvement in shoulder movement.

• Lateral winging noted in one arm suggests intact upper trapezius but loss of middle trapezius function due to nerve injury.

Assessing Radial Nerve Injury

• A detailed history review focuses on determining whether wrist drop occurred preoperatively or postoperatively to assess iatrogenic injury risk.

• Urgent re-exploration is advocated if there’s concern over surgical complications leading to radial nerve damage.

Clinical Examination Insights

• Comprehensive examination includes assessing motor function and sensory changes related to radial nerve distribution after surgery.

• Tinel's sign evaluation discussed; its presence indicates potential axonal injury rather than neuropraxia.

Decision-Making in Surgical Intervention

• Factors influencing exploration decisions include pain levels and symptom onset timing relative to surgery.

• An urgent exploration plan involves consulting orthopedic surgeons regarding metalwork removal if it compresses the injured nerve.

Post-Surgical Management Strategies

• After addressing any compression issues, evaluating whether to leave the nerve in continuity or proceed with grafting based on observed condition becomes crucial.

Evaluating Graft Success

• If no recovery occurs six months post-grafting, further investigations like nerve conduction studies are warranted to assess functionality across the grafted segment.

Alternative Options After Failed Graft

• In cases where no recovery is evident after six months, tendon transfers become a consideration alongside potential additional nerve transfers depending on distal viability.

Planning for Tendon Transfers

• Discusses suitable donor nerves for transfer that minimize morbidity while ensuring effective coaptation distance for functional restoration.

Conclusion: Integrating Tendon and Nerve Transfers

• Hybrid approaches combining tendon transfers with ongoing nerve regeneration strategies can optimize patient outcomes while awaiting full recovery from surgical interventions.