The Perplexing Plexus: An In-Depth Look at Post-Trauma Brachial Plexopathy

dc.creatorRauf, Alien_US
dc.creatorMartinez, Richarden_US
dc.creatorBejarano, Michaelen_US
dc.creatorSelod, Omaren_US
dc.description.abstractBackground: Lower trunk pathologies are a subset of brachial plexus injuries involving the C8 and T1 nerve roots. These lesions can affect all the downstream components that receive input from C8-T1, including the medial cord, median nerve, ulnar nerve, and radial nerve. Lower trunk injuries can diminish both motor and sensory components of the affected upper extremity. Common etiologies for lower trunk lesions typically involve hyperabduction trauma such as motor vehicle accidents, falls, shoulder dislocations and obstetrical traction injury. Along with a thorough history and physical, brachial plexus injuries are typically diagnosed through Nerve Conduction Study (NCS), Electromyography (EMG), and imaging. Case Presentation: A 61-year-old male with a history of bilateral carpal tunnel release and bilateral ulnar nerve decompression presented to a physiatry clinic with left hand weakness following a fall on his left elbow three months prior. The patient also reported intermittent numbness in both hands involving all digits. NCS and EMG were completed and suggested mild left and severe right carpal tunnel syndrome, respectively. Two months following the initial visit, the patient returned to the clinic presenting with improved numbness in both hands, but weakened left grip strength and persistent left elbow pain. A posterior interosseous nerve (PIN) lesion was suggested due to elbow involvement. Physical exam of the left upper extremity revealed 4/5 strength in wrist extension, extensor indicus proprius (EIP), interossei, and abductor pollicis brevis (APB). Left hand interossei atrophy was also noted on examination. Repeat NCS showed left mild carpal tunnel syndrome, consistent with his previous visit. To evaluate for a PIN lesion, the left EIP and extensor carpi radialis brevis (ECRB) was tested via EMG. The EIP showed decreased recruitment, but ECRB was normal. Further testing revealed decreased recruitment of the left first dorsal interossei (FDI) and left APB. To further specify the location of the lesion, the medial antebrachial cutaneous (MAC) nerve was tested, but NCS revealed normal findings. With clinical judgment, the patient was diagnosed with a left lower trunk brachial plexopathy due to trauma. Despite an affected EIP, a PIN lesion was ruled out due to a normal ECRB. While the APB and FDI were affected, a medial cord lesion was ruled out due to an affected left EIP, which suggested a lower trunk lesion due to radial nerve involvement. An MRI of the elbow revealed lateral epicondylitis with 25-50% intrasubstance partial thickness tearing; while shoulder MRI results are currently pending. Conclusion: This case illustrates an atypical presentation of a lower trunk brachial plexus injury following trauma. The utilization of diagnostic and clinical tools in our case proved instrumental in the differentiation of lower trunk lesions from medial cord and PIN lesions and may provide a valuable reference for physicians evaluating similar cases. Furthermore, this case demonstrates the importance of continued monitoring of upper extremity nerve injuries for progression of symptoms, especially following trauma.en_US
dc.titleThe Perplexing Plexus: An In-Depth Look at Post-Trauma Brachial Plexopathyen_US