Traumatic Brachial Plexus Preganglionic Injury: What to look for at MR Neurography?

Transcription

1 Traumatic Brachial Plexus Preganglionic Injury: What to look for at MR Neurography? Poster No.: C-1225 Congress: ECR 2017 Type: Authors: Keywords: DOI: Educational Exhibit D. Binaghi 1, M. Socolovsky 2, K. Haddad 2, P. Omoumi 3 ; 1 Capital Federal/AR, 2 Buenos Aires/AR, 3 Lausanne/CH Imaging sequences, Neural networks, MR, Neuroradiology peripheral nerve, Diagnostic procedure, Trauma /ecr2017/C-1225 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 14

2 Learning objectives To review Magnetic Resonance Neurography (MRN) in traumatic brachial plexus injuries and highlighting the challenges in diagnosing this complex pathology. In particular, we will review the direct and indirect findings allowing the diagnosis and differentiation between preganglionic and postganglionic injuries. Page 2 of 14

3 Background Brachial plexus injuries (BPI) are an increasingly prevalent health problem especially affecting the economically active population. These traumatic injuries leave serious and permanent neurological sequelae affecting the upper limbs, especially when the patient develops a flail arm after the accident. Diverse methods of microsurgical repair are performed in order to restore mobility and sensation. MRN plays a major role in the selection and surgical timing as this method distinguishes between preganglionic (cervical root avulsion from the spinal cord) and postganglionic injuries (distal to sensory ganglion). Clinical examination cannot precisely distinguish between those entities. Management strategies differ entirely depending on the information given by MRN. Anatomy: The BP is an intricate neural network responsible for both sensory and motor innervation of the upper limb. It is most commonly formed by the anterior branches of the C5 through T1 spinal nerves. Spinal nerves (Figure 1) derive from dorsal and ventral roots, which are composed of rootlets. Most cervical rootlets are approximately 1 mm thick and they can join the cord almost one intervertebral disc above their intervertebral neuroforamen. Pathophysiology: The preganglionar BP is vulnerable to injury because of the great range of motion between the shoulder girdle and neck. The main cause of root avulsion is a tractioninduced injury, primarily from motorcycle accident in adults and shoulder dystocia in neonates. Preganglionic injury: Root avulsion may be complete or partial, and may be seen directly with MRN (Figure 2). Indirect signs of root avulsion can also be seen (Figures 3 and 4), their presence is useful; however, clear visualization of the nerve root is of utmost significance. Page 3 of 14

4 Images for this section: Fig. 1: A) MRN with axial reformat shows the normal ventral (arrow) and dorsal (dashed arrow) roots of a spinal nerve attaching to the cord. B) MRN with coronal reformat demonstrates the rootlets (dashed circle) at the intra-dural space. Fig. 2: Nerve root avulsion seen on MRN with axial reformats. A) Partial ventral root avulsion (arrow). B) Complete root avulsion (dashed circle). Page 4 of 14

5 Fig. 3: Indirect signs of root avulsion. Page 5 of 14

6 Fig. 4: Indirect signs. A) MRN with axial reformat shows right-sided pseudomeningocele (tear in the meningeal sheath with extravasation of the CSF) related to complete root avulsion. B) Axial reformat shows lateral cord displacement. C) Sagittal T2-w image demonstrates spinal cord edema in a patient with C5-T1 nerve root avulsions. D) Coronal reformat shows left-sided intra-dural root fibrosis. E) Coronal STIR image shows denervation of the multifidus muscle (asterisk). Page 6 of 14

7 Findings and procedure details We performed a retrospective review of a series of 198 BPI for which MRN was undertaken over a 6-year period in our institution. The patients were examined with a 1.5 T MRI system using a neurovascular array, and they were asked to avoid deep breathing and swallowing throughout the procedure to minimize any motion artifact. MRN protocol (Figure 5) includes sagittal STIR, T1- and T2-weighted sequences to detect spinal cord and/or ligament injuries. Coronal 3-D myelographic sequence to rule out pseudomeningocele formation, and axial T2-w isotropic to visualize the intradural nerve roots. Depending on the case, sequences may have been added. BPI were caused by motor vehicles accidents (171), obstetric (24) and extreme sport injuries (3)(Figure 6). The most common and important abnormality seen at high-resolution images was complete root avulsion (Figure 7). Pseudomeningoceles were the most frequent indirect finding seen (Figure 8). It is important to note that nerve root avulsion may occur without pseudomeningocele formation, and a pseudomeningocele occasionally occurs without nerve root avulsion (Figures 9 and 10). Page 7 of 14

8 Images for this section: Fig. 5: Brachial plexus protocol Fig. 6: Brachial plexus injuries. Page 8 of 14

9 Fig. 7: Pie-chart shows the percentage distribution of pseudomeningocele and avulsion. Fig. 8: Indirect signs distribution. Page 9 of 14

10 Fig. 9: 21-year-old-male, motorcycle accident, presented with right motor & sensory BPI with a previously normal MRI exam. Axial reformatted images. A-B) show absence of the ventral C5 and C6 nerve roots due to partial avulsion. C-D-E) Demonstrate complete avulsion (dashed circles) of C7, C8 and T1 nerve roots. Page 10 of 14

11 Fig. 10: 33-year-old male, motorcycle accident, presented with left motor & sensory BPI. A) Sagittal T2 shows traumatic pseudomeningoceles due to complete avulsion of C8 and T1 nerves, also seen at B) Myelographic Reconstruction (asterisks). C) Coronal reformatted image shows absence of C6 and C7 nerves due to complete avulsion. Axial reformatted images show normal C5 roots (D), complete avulsion of C6 and C7 (E-F), and traumatic pseudomeningoceles due to complete avulsion of C8 and T1 (G-H). Page 11 of 14

12 Conclusion MRN, through the evaluation of direct and indirect signs of preganglionic nerve root avulsions, provides valuable information to the surgeon. The presence of a non-avulsed root is an extremely important finding when planning the surgical strategy in PBI, since those nerve roots are a source of fresh axons that can be used for reconstructive purposes. Given the fact that this essential information is not obtainable from surgical exploration, a preoperative MRN is vital for surgical planning. Page 12 of 14

13 Personal information Daniela Binaghi Department of peripheral nerve imaging, Neurocience Institute, Favaloro University. Mariano Socolovsky Peripheral nerve & Plexus surgery Unit, Department of Neurosurgery, University of Buenos Aires School of Medicine. Karim Haddad MRI Department, Favaloro University. Patrick Omoumi Department of Diagnostic and Interventional Radiology, Lausanne University Hospital, Switzerland. Page 13 of 14

14 References 1- J.J.Rankine. Adult traumatic brachial plexus injury. Clinical Radiology 2004; 59: Doi K, Otsuka K, Okamoto Y, Fujii H, Hattori Y, Baliarsing A. Cervical nerve root avulsion in brachial plexus injuries: Magnetic Resonance Imaging classification and comparison with myelography and computerized tomography myelography. J Neurosurg: Spine 2002; (3) 96: Jennifer L. Giuffre, Sanjiv Kakar, Allen T. Bishop, Robert J. Spinner, Alexander Y. Shin. Current Concepts of the Treatment of Adult Brachial Plexus Injuries. The journal of hand sugery 2010; 35: Debora Garozzo, Elisabetta Basso, Roberto Gasparotti, Piero Di Pasquale, Fabrizio Lucchin and Stefano Ferraresi. Brachial Plexus Injuries in Adults: Management and Repair Strategies in our Experience. Results from the Analysis of 428 Supraclavicular Palsies. J Neurol Neurophysiol 2013; 5:1. Page 14 of 14