Title : Posterior anterior brachial cutaneous neuropathy: Clinical evaluation and implications for elbow pain
Abstract:
Posterior anterior brachial cutaneous (PABC) neuropathy is a rare neuropathy that can be iatrogenic or uncommonly spontaneous. Few cases of PABC neuropathy have been reported following surgery, injection, or trauma, suggesting that PABC nerve may not be sufficiently evaluated for elbow pain in clinical practice. While it is clinically important to evaluate this nerve electrophysiologically, there is a scarcity of studies that have undertaken such assessments. In this context, we present an intriguing case involving a 22-year-old male patient who developed PABC neuropathy subsequent to orthopedic surgery aimed at correcting right elbow cubitus valgus.
Case Presentation: The patient initially presented to the hospital with persistent pain in the lateral posterior aspect of his right forearm. Noteworthy, he had undergone a corrective osteotomy eight years earlier with internal fixation using a plate and a geographic wedge osteotomy with screws inserted into the right elbow to address a hallux valgus deformity.
The patient had been experiencing painful symptoms for several years, including pain and paresthesia in the area.To investigate potential neurologic involvement, electromyography with bilateral posterior PABC nerve sensory nerve conduction studies were performed. Superficial electrical stimulation of the PABC nerve was performed using a bipolar stimulator with the subject's elbow outstretched and forearm muscles relaxed. The nerve was stimulated 2 cm proximal to the lateral epicondyle of the arm between the triceps and biceps brachii muscles. The active recording surface electrode was positioned 12cm distal along a line extending from the stimulation point to the mid-dorsum of the wrist. The PABC sensory nerve action potential (SNAP) test results revealed notable differences between the right and left sides. The amplitude of the SNAP on the left side was 7.3μV, with a peak latency of 2.83ms. In contrast, on the right side, the amplitude of the SNAP was reduced, measured at 3.3μV, with a peak latency of 2.92ms. Given that the PABC nerve is a branch of the radial nerve, we conducted a superficial radial sensory study and a radial nerve motor study, both of which yielded normal results. These findings suggest a reduced amplitude in the sensory nerve conduction on the right PABC nerve, indicating potential nerve dysfunction or compression in the region of the previous surgery.
Conclusion: Previous literature on iatrogenic elbow nerve injuries extensively details damages to the ulnar palmar cutaneous nerve, medial pronator cutaneous nerve, and lateral pronator cutaneous nerve. However, only a limited number of cases involving PABC nerve injury have been reported. This suggests that PABC nerve may be less susceptible to injury compared to other cutaneous nerves in the forearm, but it also indicates that it may be underappreciated in the assessment of elbow pain in clinical settings. Surgical procedures with potential injury risks include elbow arthroscopy, surgery for lateral epicondylitis, distal humeral fractures, and myocutaneous flaps using the triceps. In instances where sensory symptoms manifest in the lateral posterior elbow after surgery or injury, electrodiagnostic evaluation should encompass a thorough PABC nerve examination.
Audience Take Away:
- Identification of PABC Neuropathy Risk Factors: Recognizing the various factors contributing to PABC neuropathy, such as surgical procedures, injection, or trauma, is crucial for understanding and preventing its development.
- Importance of Electrophysiological Evaluation: Understanding the clinical significance of electrophysiological evaluations, particularly in assessing the PABC nerve for elbow pain, provides a key diagnostic tool for healthcare professionals. This knowledge is essential for accurate and timely intervention.
- Clinical Practice Improvement: Incorporating electrophysiological assessments into clinical practice, especially in cases of persistent elbow pain post-surgery or injury, can significantly improve diagnostic accuracy and guide appropriate treatment strategies for better patient outcomes.
- Diagnostic Skills Enhancement: Clinicians and diagnosticians gaining enhanced skills in diagnosing and assessing PABC neuropathy contribute to improved patient care and can lead to earlier and more effective interventions.
- Awareness of Underappreciated Nerve Injuries: Developing awareness of the underappreciation of PABC nerve injuries in the assessment of elbow pain is crucial for healthcare professionals. This knowledge can prompt a more comprehensive approach to diagnosis and treatment, potentially preventing oversight in patient care.
