Diego San Millán Ruíz and Dheeraj Gandhi
Brandon W. Smith, Kate W. C. Chang, Hemant A. Parmar, Mohannad Ibrahim, and Lynda J. S. Yang
The evaluation, treatment, and prognosis of neonatal brachial plexus palsy (NBPP) continues to have many areas of debate, including the use of ancillary testing. Given the continued improvement in imaging, it is important to revisit its utility. Nerve root avulsions have historically been identified by the presence of pseudomeningoceles or visible ruptures. This “all-or-none” definition of nerve root avulsions has many implications for the understanding and management of NBPP, especially as characterization of the proximal nerve root as a potential donor remains critical. This study examined the ability of high-resolution MRI to more specifically define the anatomy of nerve root avulsions by individually examining the ventral and dorsal rootlets as they exit the spinal cord.
This is a retrospective review of patients who had undergone brachial plexus protocol MRI for clinical evaluation of NBPP at a single institution. Each MR image was independently reviewed by a board-certified neuroradiologist, who was blinded to both established diagnosis/surgical findings and laterality. Each dorsal and ventral nerve rootlet bilaterally from C5 to T1 was evaluated from the spinal cord to its exit in the neuroforamen. Each rootlet was classified as avulsed, intact, or undeterminable.
Sixty infants underwent brachial plexus protocol MRI from 2010 to 2018. All infants were included in this study. Six hundred individual rootlets were analyzed. There were 49 avulsed nerve rootlets in this cohort. Twenty-nine (59%) combined dorsal/ventral avulsions involved both the ventral and dorsal rootlets, and 20 (41%) were either isolated ventral or isolated dorsal rootlet avulsions. Of the isolated avulsion injuries, 13 (65%) were dorsal only, meaning that the motor rootlets were intact.
A closer look at nerve root avulsions with MRI demonstrates a significant prevalence (approximately 41%) of isolated dorsal or ventral nerve rootlet disruptions. This finding implies that nerve roots previously labeled as “avulsed” but with only isolated dorsal (sensory) rootlet avulsion can yet provide donor fascicles in reconstruction strategies. A majority (99%) of the rootlets can be clearly visualized with MRI. These findings may significantly impact the clinical understanding of neonatal brachial plexus injury and its treatment.
Jacob Rahul Joseph, Michael A. DiPietro, Deepak Somashekar, Hemant A. Parmar, and Lynda J. S. Yang
Ultrasonography has previously been reported for use in the evaluation of compressive or traumatic peripheral nerve pathology and for its utility in preoperative mapping. However, these studies were not performed in infants, and they were not focused on the brachial plexus. The authors report a case in which ultrasonography was used to improve operative management of neonatal brachial plexus palsy (NBPP). An infant boy was born at term, complicated by right-sided shoulder dystocia. Initial clinical evaluation revealed proximal arm weakness consistent with an upper trunk injury. Unlike MRI or CT myelography that focus on proximal nerve roots, ultrasonography of the brachial plexus in the supraclavicular fossa was able to demonstrate a small neuroma involving the upper trunk (C-5 and C-6) and no asymmetry in movement of the diaphragm or in the appearance of the rhomboid muscle when compared with the unaffected side. However, the supra- and infraspinatus muscles were significantly asymmetrical and atrophied on the affected side. Importantly, ultrasound examination of the shoulder revealed posterior glenohumeral laxity. Instead of pursuing the primary nerve reconstruction first, timely treatment of the shoulder subluxation prevented formation of joint dysplasia and formation of a false glenoid, which is a common sequela of this condition. Because the muscles innervated by proximal branches of the cervical nerve roots/trunks were radiographically normal, subsequent nerve transfers were performed and good functional results were achieved. The authors believe this to be the first report describing the utility of ultrasonography in the surgical treatment planning in a case of NBPP. Noninvasive imaging, in addition to thorough history and physical examination, reduces the intraoperative time required to determine the extent and severity of nerve injury by allowing improved preoperative planning of the surgical strategy. Inclusion of ultrasonography as a preoperative modality may yield improved outcomes for children with NBPP.