Peripheral Nerve Injuries: Preoperative Evaluation and Postoperative Imaging

• Abstract
• Anatomy, Imaging Techniques, and Approach
• Pre- and Postoperative Imaging for Common Indications
• Carpal Tunnel Syndrome
• Cubital Tunnel Syndrome
• Trauma/Surgery
• Neurogenic Tumors
• Conclusion
• References

Abstract

Imaging plays an important role in evaluating peripheral nerves. In the preoperative setting, imaging helps overcome pitfalls of electrodiagnostic testing and provides key anatomical information to guide surgical management. In the postoperative setting, imaging also offers key information for treating physicians, although it comes with several challenges due to postsurgical changes and alteration of normal anatomy. This article reviews our approach to peripheral nerve imaging, including how we use imaging in the pre- and postoperative setting for several common indications.

Many pathologic conditions involve peripheral nerves, such as compressive neuropathies, inflammatory neuropathies, traumatic nerve injuries, and neurogenic tumors. Evaluation always begins with a detailed history and physical exam, often followed by electrodiagnostic testing. Although clinical and electrodiagnostic evaluation can go a long way in lesion localization and grading the degree of nerve injury, imaging helps overcome several diagnostic pitfalls and plays a key role in identifying causes of nerve symptoms, better localizing the site of nerve pathology, and planning potential surgical intervention.[1] [2] A major pitfall of electrodiagnostic testing is associated with fascicular lesions, where a lesion can be falsely localized to a more distal site than the injury.[2] [3]

Magnetic resonance imaging (MRI) and ultrasound (US) are excellent for nerve evaluation with each modality having advantages and disadvantages depending on the suspected etiology of the nerve symptoms and lesion location.[4] [5] In the postoperative setting, imaging plays an essential role in helping evaluate the surgical site and identify potential causes of recurrent or residual symptoms. This article reviews nerve anatomy and multimodality imaging of peripheral nerves, highlighting factors that dictate management in the preoperative setting and our approach to imaging in the postoperative setting for common indications. We discuss our US and MRI techniques for imaging peripheral nerves and provide several case examples, highlighting findings important to treating physicians.

Anatomy, Imaging Techniques, and Approach

Nerves consist of highly ordered bundles of nerve fibers (axons) called fascicles, connective tissue, and surrounding fat. The connective tissue structure of the nerve consists of endoneurium surrounding individual nerve fibers within a fascicle; perineurium, a sheath of tissue surrounding a fascicle; and epineurium, dense tissue surrounding multiple nerve fascicles and forming the outer layer of the nerve. Especially in larger nerves, much of this anatomy can be demonstrated on both MRI and US.

On MRI, nerve fascicles demonstrate intermediate signal on T1, T2, and proton-density (PD)-weighted sequences and do not enhance. Perifascicular fat allows nerves to be more easily identified on T1 and PD non–fat-suppressed sequences, allowing for evaluation of nerve course and nerve caliber. Nerves generally travel in a predictable location and maintain a consistent caliber until they branch. On US, nerve fascicles are hypoechoic and can be seen surrounded by hyperechoic perineurium and epineurium, giving rise to a honeycomb appearance ([Fig. 1]). This anatomy is best seen on short-axis images, especially when evaluating larger and more superficial nerves.

Both US and MRI allow for excellent evaluation of peripheral nerves when performed correctly using appropriate techniques. US should be performed with high frequency linear transducers to best take advantage of the high spatial resolution, especially when evaluating superficial structures. Higher spatial resolution is a major advantage of using US over MRI and why we prefer US for evaluating smaller nerves. US also allows for imaging in nonstandard imaging planes and dynamic evaluation that can be helpful when assessing for normal nerve gliding in the setting of a soft tissue mass or perineural fibrosis and when assessing for nerve stability in the setting of suspected cubital tunnel syndrome.

MRI should be performed with dedicated MR neurogram protocols, taking advantage of recent advancements such as simultaneous multislice acquisition and parallel imaging.[6] [7] These innovations allow for faster high-resolution imaging, especially when using 3-T magnets that we strongly prefer. Advantages of MRI over US are its better evaluation of deeper nerves and more accurate assessment of the surrounding muscles for denervation changes. On MRI, patients with acute to subacute muscle denervation demonstrate diffuse muscle edema and often corresponding muscle enhancement.[8] As denervation becomes more chronic, often  > 6 months after injury, fatty infiltration becomes the dominant finding and edema decreases. Abnormal peripheral nerves demonstrate T2 hyperintense signal on MRI and a hypoechoic appearance on US, and they often demonstrate enlargement surrounding a site of compression or injury. A number of mechanisms have been proposed for these changes, such as block of axoplasmic flow, vascular congestion, and Wallerian degeneration.[9]

For imaging peripheral nerves in the extremities, we often prefer US, especially in cases of suspected carpal tunnel syndrome and cubital tunnel syndrome. We often perform both US and MRI in the setting of complex traumatic injury to fully evaluate the extent of nerve injury, injury to the surrounding soft tissue structures, and extent of muscle denervation changes. For cases involving the brachial plexus, we often perform both US and MRI, although we prefer MRI where nerve root avulsion or involvement of the C8 or T1 nerve roots or lower trunk is suspected. US has the advantage, however, of allowing for concurrent evaluation of the distal branch nerves in the arm in the setting of a potential distal injury. For cases involving the lumbosacral plexus, we prefer MRI, although we occasionally use US to evaluate the proximal sciatic nerve where it travels posterior to the hip joint. Importantly, we limit MRI of the extremity to a maximum of 35 cm from proximal to distal to keep scan times within an acceptable range and produce adequate spatial resolution on three-dimensional sequences.

Postoperative changes pose several challenges in nerve evaluation that affect both imaging technique and interpretation. Surgery often produces scarring and distortion of the subcutaneous adipose tissue, fascia, and muscles that can alter the native anatomy and lead to difficulties identifying the nerve of interest and evaluating nerve course and caliber accurately. These changes can lead to difficulty achieving adequate fat suppression on MRI, making evaluation of nerve signal challenging, and can produce shadowing and other artifacts on US. If orthopaedic hardware is present, artifacts on MRI can significantly limit evaluation of the surrounding soft tissues.

When performing MRI in the postoperative setting, we use our standard MR neurogram protocols including imaging patients on 3-T magnets. We do scan patients on 1.5-T magnets, however, if the nerve in question is close to hardware, especially joint prostheses or spinopelvic fusion hardware, and we sometimes use slice encoding for metal artifact reduction (SEMAC) sequences in this setting. We also sometimes change the method of fat suppression on our two-dimensional sequences from T2 Spectral Adiabatic Inversion Recovery (SPAIR) to short tau inversion recovery (STIR) to provide more robust fat suppression, noting that this choice does reduce the signal-to-noise ratio.[10] We prefer noncontrast examinations, although contrast does help delineate postoperative fluid collections, perineural scarring, and recurrent tumors.

Pre- and Postoperative Imaging for Common Indications

Carpal Tunnel Syndrome

Carpal tunnel syndrome is the most common upper extremity compressive neuropathy. We prefer US over MRI when evaluating the carpal tunnel due to the superficial location of the median nerve and the abundance of literature supporting its utility. Prior research showed US to be as accurate and slightly more specific than electrodiagnostic testing in evaluating for carpal tunnel syndrome using a clinical tool as the reference standard.[11] In general, carpal tunnel syndrome results in enlargement of the median nerve within the carpal tunnel.

Several imaging criteria have been described and assessed in the literature. Klauser et al showed in 2009 that a US cross-sectional area (CSA) cutoff of 10 mm² within the carpal tunnel resulted in a sensitivity of 100% although a specificity of only 57% when using electrodiagnostic testing as the reference standard.[12] Using a slightly larger cross-sectional area cutoff of 12 mm² resulted in a sensitivity of 94% and a specificity of 95%. Importantly, the authors also compared nerve CSA in the distal forearm at the level of the pronator quadratus with nerve CSA in the carpal tunnel and found that patients with carpal tunnel syndrome demonstrated an increase in nerve CSA within the carpal tunnel of 7.4 mm² on average, whereas healthy volunteers only showed an average increase of 0.25 mm². Using a threshold of an increase in 2 mm² in CSA in the carpal tunnel versus in the distal forearm resulted in a sensitivity of 99% and specificity of 100% in identifying patients with carpal tunnel syndrome.

In a follow-up study, the same authors showed that the degree of increased nerve CSA in the carpal tunnel compared with the distal forearm correlated well with the severity of disease on nerve conduction studies.[13] We therefore routinely measure nerve CSA in the distal forearm and within the carpal tunnel and provide this information in our reports ([Fig. 2]).

Preoperatively, we also evaluate for a mass lesion along the course of the nerve and assess whether the nerve has a bifid morphology within the carpal tunnel and if a persistent median artery is present. These factors can affect whether surgeons perform open or endoscopic carpal tunnel release and if surgery can be performed using only local anesthesia. Mass lesions are important to identify to ensure they are addressed at the time of carpal tunnel release. This is especially important if they are deep to the median nerve and flexor tendons and along the volar radiocarpal joint capsule.

Recurrent or residual symptoms after carpal tunnel release can be challenging to manage for treating physicians. In the early postoperative period (< 3 months), either US or MRI can be used to evaluate for signs of an intraoperative nerve injury, postoperative fluid collection demonstrating mass effect on the nerve, or an intact flexor retinaculum, suggesting an incomplete release at the time of surgery. However, the flexor retinaculum was shown to reconstitute in > 50% of patients at 12 months, even in those with a good clinical outcome.[14] [15] Therefore, an intact retinaculum > 6 months after surgery should be interpreted as reconstituted rather than as an incomplete release. Perineural scarring/fibrosis is a common cause of recurrent symptoms after carpal tunnel release.[16] It can appear as intermediate/low signal or hypoechoic perineural tissue with ill-defined nerve margins and often requires neurolysis to address properly. The median nerve can remain enlarged for > 12 months after release; therefore it is difficult to use the median nerve CSA to diagnose recurrent carpal tunnel syndrome ([Fig. 3]).[14] [15]

Cubital Tunnel Syndrome

Cubital tunnel syndrome is the second most common upper extremity compressive neuropathy. It can be an isolated entity or secondary to elbow instability, especially valgus instability in overhead throwers. We strongly prefer US when evaluating the cubital tunnel due to the superficial location of the ulnar nerve and the ability to perform a dynamic evaluation to look for ulnar nerve instability.

As in carpal tunnel syndrome, cubital tunnel syndrome results in enlargement of the ulnar nerve. A meta-analysis showed that using an ulnar nerve CSA cutoff of 10 to 10.5 mm² at the level of the medial epicondyle in any degree of elbow flexion results in a sensitivity and specificity of ∼ 80% and is the best US measurement to evaluate for the syndrome.[17] Therefore we always provide this measurement in our reports in addition to evaluating the nerve for a hypoechoic appearance and/or loss of the normal fascicular architecture. We also evaluate for a mass lesion along the course of the nerve or anatomical variants such as a low-lying medial head of the triceps muscle or an anconeus epitrochlearis.

Dynamic evaluation is especially important in the setting of cubital tunnel syndrome because many surgeons transpose an unstable ulnar nerve rather than simply performing an in situ decompression. A 2019 study showed preoperative dynamic US to be 88% accurate in detecting an ulnar nerve that was unstable intraoperatively after an in situ decompression.[18] Rarely, in addition to an unstable ulnar nerve, the medial head of the triceps muscle snaps over the medial epicondyle, which is important to identify preoperatively to ensure it will be addressed during surgery.[19] [20]

The postoperative appearance of the cubital tunnel depends on the initial surgery performed, although there is generally some degree of postoperative change in the overlying subcutaneous adipose tissue and scarring/granulation tissue along the course of the nerve.[21] [22] Similar to carpal tunnel syndrome, the postoperative ulnar nerve may appear mildly enlarged and abnormal.[23] As in the preoperative setting, we routinely perform dynamic evaluation to identify an unstable ulnar nerve that can be a cause of recurrent symptoms after an initial decompression ([Fig. 4]). When this finding is present, many surgeons reoperate and perform a transposition to hopefully address the patient's symptoms.

We always evaluate the ulnar nerve for areas of significant perineural scarring, abnormal nerve signal or fascicular architecture, or caliber change, although it remains to be seen whether these findings always predict recurrent/residual symptoms ([Fig. 5]).[23] Areas of caliber change are important to point out, however, because this is a commonly described intraoperative finding, with potential sites of compression often including the fascial sling in the setting of a subcutaneous ulnar nerve transposition, the flexor aponeurosis, the arcade of Struthers, and the point where the ulnar nerve transitions from its transposed course to its normal anatomical course in the proximal forearm.[24] [25]

Trauma/Surgery

Nerve injuries are commonly seen in the setting of trauma and occasionally occur due to iatrogenic injury during surgical procedures addressing orthopaedic conditions.[5] [26] [27] [28] [29] A common grading system to evaluate the severity of nerve injury is the Sunderland classification, which helps differentiate patients with high-grade nerve injuries who will require surgical intervention from those with lower grade injuries that can be managed nonoperatively.[30] [31]

[Table 1] summarizes the Sunderland classification. Sunderland grade 1 injuries, termed neuropraxia, involve injury to the myelin sheath with structurally intact axons, endoneurium, perineurium, and epineurium. Imaging can be normal or nerves can demonstrate mild T2 hyperintense signal on MRI and mild hypoechogenicity or prominent fascicles on US. Sunderland grade 2, 3, and 4 injuries, termed axonotmesis, involve injury to the axons, axons plus endoneurium, and axons, endoneurium, and perineurium, respectively. Sunderland grade 2 and 3 injuries often demonstrate similar findings on imaging with T2 hyperintense nerve signal and enlargement and effacement of nerve fascicles on MRI and nerve hypoechogenicity and enlargement on US.

Sunderland grade 4 injuries often demonstrate findings of grade 2 and 3 injuries in addition to focal nerve enlargement at the injury site, termed a neuroma-in-continuity ([Fig. 6]). Sunderland grade 5 injuries, or neurotmesis, are complete nerve transections with disruption of the epineurium and often a gap between nerve segments. Grade 4 and 5 injuries require surgical intervention for a meaningful recovery, whereas grade 3 injuries may need surgery to release scarring around injured nerve fascicles.[32] [33] The injury to the perineurium in grade 4 and 5 injuries precipitates neuroma formation because the axons are unable to regrow in the appropriate orientation without the intact connective tissue framework. Grade 6 injuries, or mixed injuries, involve varying degrees of nerve connective tissue within the nerve cross section and include partial lacerations ([Fig. 7]).

In the setting of a nerve injury, indicating the length of the nerve segment involved will help surgeons decide whether the patient is a potential candidate for a nerve graft. In general, nerve injuries that do not allow for direct repair are candidates for nerve grafting up to a length of ∼ 7 cm. The critical nature of the denervated structures, time since injury, distance of proximal nerve segment to end organ, and overall health of patient are important factors when determining if nerve grafting with a gap > 7 cm is appropriate. In some injuries, nerve wrapping is performed with either an autologous vein, allograft, or xenograft to minimize surrounding adhesions and guide axonal growth.[34] In postoperative patients with orthopaedic hardware, artifact can obscure the surrounding soft tissues.[35] Occasionally in this setting, including patients after total hip arthroplasty, we scan patients on a 1.5-T magnet to better assess the degree of nerve injury ([Fig. 8]).

We are occasionally asked to image patients in the setting of prior nerve repair, nerve graft, or nerve transfer. Although almost no literature has evaluated the usefulness of imaging in this setting, we comment on the course and caliber of the nerve in question, including whether there is gapping or caliber change at the repair/graft site and the degree of surrounding scarring and granulation tissue. In the setting of a primary repair or nerve graft, we also evaluate whether normal-appearing nerve fascicles appear to be crossing the repair/graft site or whether the fascicles appear disorganized, similar to a neuroma ([Fig. 9]).

Neurogenic Tumors

Neurogenic tumors include benign and malignant peripheral nerve sheath tumors (PNSTs). Benign PNSTs include schwannomas and neurofibromas. Neurofibromas are typically not encapsulated and grow within nerve fascicles, making resection difficult without having to remove the entire portion of the nerve. Schwannomas are typically encapsulated and slow growing, demonstrating mass effect on the surrounding nerve fascicles. They are typically easier to resect than neurofibromas although often require sacrificing of one or two nerve fascicles depending on the location, size, and anatomy of the tumor.[36]

On US, benign PNSTs appear as hypoechoic masses along the course of the nerve and sometimes demonstrate areas of internal vascularity and posterior acoustic enhancement.[37] With MRI, they often appear as fusiform masses with low to intermediate T1 signal, hyperintense T2 signal, and contrast enhancement. Several imaging signs are useful in identifying a PNST: the split fat sign (visible fat around the lesion most visible at the proximal and distal portions), fascicular sign (hypointense foci within the T2 hyperintense signal mass), and target sign (central hypointense signal within the hyperintense signal mass).[38]

Definitively differentiating a schwannoma from a neurofibroma, however, can be very difficult because several imaging findings appear in both entities.[39] An imaging finding we highlight is whether the mass appears eccentrically located within the nerve and demonstrates mass effect on the adjacent fascicles ([Fig. 10]). Anecdotally, when we see this finding in patients without neurofibromatosis type 1, we indicate it as probably a schwannoma and our surgeons feel more comfortable attempting a resection. It can be difficult to differentiate a benign from malignant PNST based on imaging. Findings suspicious for a malignant tumor include a peripheral enhancement pattern, perilesional edema, large size, and intralesional cysts.[40] With diffusion-weighted imaging, an apparent diffusion coefficient minimum ≤ 1.0 × 10⁽⁻³⁾ mm²/s combined with an average tumor diameter > 4.2 cm was shown to be 100% sensitive for identifying malignant tumors.[41]

In the postoperative setting after resection of a PNST, the clinical question is often whether residual or recurrent tumor is present. We generally perform contrast-enhanced MRI of the surgical site and evaluate for nodular enhancement to suggest residual or recurrent tumor. This can be difficult after resection of a schwannoma, however, because we sometimes see a small area of T2 hyperintense signal with occasional enhancement at the resection site, likely representing postsurgical changes from where a nerve fascicle was cut during the initial tumor resection ([Fig. 11]).

Conclusion

The imaging of peripheral nerves, either with US or MRI, provides essential information for surgeons in the preoperative setting, helping guide surgical management. Several factors make imaging in the postoperative setting difficult, but with proper technique, postoperative imaging is valuable in helping decide which patients require revision surgery. Further research is necessary to investigate normal/expected postoperative findings in the setting of many peripheral nerve surgeries.

Conflict of Interest

None declared.

• References

• 1 Daniels SP, Feinberg JH, Carrino JA, Behzadi AH, Sneag DB. MRI of foot drop: how we do it. Radiology 2018; 289 (01) 9-24
  CrossrefPubMedSearch in Google Scholar
• 2 Sneag DB, Arányi Z, Zusstone EM. et al. Fascicular constrictions above elbow typify anterior interosseous nerve syndrome. Muscle Nerve 2020; 61 (03) 301-310
  CrossrefPubMedSearch in Google Scholar
• 3 Stewart JD. Peripheral nerve fascicles: anatomy and clinical relevance. Muscle Nerve 2003; 28 (05) 525-541
  CrossrefPubMedSearch in Google Scholar
• 4 Sneag DB, Rancy SK, Wolfe SW. et al. Brachial plexitis or neuritis? MRI features of lesion distribution in Parsonage-Turner syndrome. Muscle Nerve 2018; 58 (03) 359-366
  CrossrefPubMedSearch in Google Scholar
• 5 Symanski JS, Ross AB, Davis KW, Brunner MC, Lee KS. US for traumatic nerve injury, entrapment neuropathy, and imaging-guided perineural injection. Radiographics 2022; 42 (05) 1546-1561
  CrossrefPubMedSearch in Google Scholar
• 6 Chhabra A, Zhao L, Carrino JA. et al. MR neurography: advances. Radiol Res Pract 2013; 2013: 809568
  PubMedSearch in Google Scholar
• 7 Sneag DB, Queler S. Technological advancements in magnetic resonance neurography. Curr Neurol Neurosci Rep 2019; 19 (10) 75
  CrossrefPubMedSearch in Google Scholar
• 8 Daniels SP, Ross AB, Sneag DB. et al. Intravenous contrast does not improve detection of nerve lesions or active muscle denervation changes in MR neurography of the common peroneal nerve. Skeletal Radiol 2021; 50 (12) 2483-2494
  CrossrefPubMedSearch in Google Scholar
• 9 Chhabra A, Andreisek G, Soldatos T. et al. MR neurography: past, present, and future. AJR Am J Roentgenol 2011; 197 (03) 583-591
  CrossrefPubMedSearch in Google Scholar
• 10 Del Grande F, Santini F, Herzka DA. et al. Fat-suppression techniques for 3-T MR imaging of the musculoskeletal system. Radiographics 2014; 34 (01) 217-233
  CrossrefPubMedSearch in Google Scholar
• 11 Fowler JR, Munsch M, Tosti R, Hagberg WC, Imbriglia JE. Comparison of ultrasound and electrodiagnostic testing for diagnosis of carpal tunnel syndrome: study using a validated clinical tool as the reference standard. J Bone Joint Surg Am 2014; 96 (17) e148
  CrossrefPubMedSearch in Google Scholar
• 12 Klauser AS, Halpern EJ, De Zordo T. et al. Carpal tunnel syndrome assessment with US: value of additional cross-sectional area measurements of the median nerve in patients versus healthy volunteers. Radiology 2009; 250 (01) 171-177
  CrossrefPubMedSearch in Google Scholar
• 13 Klauser AS, Abd Ellah MMH, Halpern EJ. et al. Sonographic cross-sectional area measurement in carpal tunnel syndrome patients: can delta and ratio calculations predict severity compared to nerve conduction studies?. Eur Radiol 2015; 25 (08) 2419-2427
  CrossrefPubMedSearch in Google Scholar
• 14 Ng AWH, Griffith JF, Tsoi C. et al. Ultrasonography findings of the carpal tunnel after endoscopic carpal tunnel release for carpal tunnel syndrome. Korean J Radiol 2021; 22 (07) 1132-1141
  CrossrefPubMedSearch in Google Scholar
• 15 Ng AWH, Griffith JF, Tsai CSC, Tse WL, Mak M, Ho PC. MRI of the carpal tunnel 3 and 12 months after endoscopic carpal tunnel release. AJR Am J Roentgenol 2021; 216 (02) 464-470
  CrossrefPubMedSearch in Google Scholar
• 16 Mosier BA, Hughes TB. Recurrent carpal tunnel syndrome. Hand Clin 2013; 29 (03) 427-434
  CrossrefPubMedSearch in Google Scholar
• 17 Haj-Mirzaian A, Hafezi-Nejad N, Del Grande F. et al. Optimal choice of ultrasound-based measurements for the diagnosis of ulnar neuropathy at the elbow: a meta-analysis of 1961 examinations. AJR Am J Roentgenol 2020; 215 (05) 1171-1183
  CrossrefPubMedSearch in Google Scholar
• 18 Rutter M, Grandizio LC, Malone WJ, Klena JC. The use of preoperative dynamic ultrasound to predict ulnar nerve stability following in situ decompression for cubital tunnel syndrome. J Hand Surg Am 2019; 44 (01) 35-38
  CrossrefPubMedSearch in Google Scholar
• 19 Jacobson JA, Jebson PJL, Jeffers AW, Fessell DP, Hayes CW. Ulnar nerve dislocation and snapping triceps syndrome: diagnosis with dynamic sonography—report of three cases. Radiology 2001; 220 (03) 601-605
  CrossrefPubMedSearch in Google Scholar
• 20 Vanhees MKD, Geurts GFAE, Van Riet RP. Snapping triceps syndrome: a review of the literature. Shoulder Elbow 2010; 2 (01) 30-33
  CrossrefPubMedSearch in Google Scholar
• 21 Rhodes NG, Howe BM, Frick MA, Moran SL. MR imaging of the postsurgical cubital tunnel: an imaging review of the cubital tunnel, cubital tunnel syndrome, and associated surgical techniques. Skeletal Radiol 2019; 48 (10) 1541-1554
  CrossrefPubMedSearch in Google Scholar
• 22 Daniels SP, Mintz DN, Endo Y, Dines JS, Sneag DB. Imaging of the post-operative medial elbow in the overhead thrower: common and abnormal findings after ulnar collateral ligament reconstruction and ulnar nerve transposition. Skeletal Radiol 2019; 48 (12) 1843-1860
  CrossrefPubMedSearch in Google Scholar
• 23 Sivakumaran T, Sneag DB, Lin B, Endo Y. MRI of the ulnar nerve pre- and post-transposition: imaging features and rater agreement. Skeletal Radiol 2021; 50 (03) 559-570
  CrossrefPubMedSearch in Google Scholar
• 24 Vogel RB, Nossaman BC, Rayan GM. Revision anterior submuscular transposition of the ulnar nerve for failed subcutaneous transposition. Br J Plast Surg 2004; 57 (04) 311-316
  CrossrefPubMedSearch in Google Scholar
• 25 Mackinnon SE, Novak CB. Operative findings in reoperation of patients with cubital tunnel syndrome. Hand (N Y) 2007; 2 (03) 137-143
  CrossrefPubMedSearch in Google Scholar
• 26 Mook WR, Ligh CA, Moorman III CT, Leversedge FJ. Nerve injury complicating multiligament knee injury: current concepts and treatment algorithm. J Am Acad Orthop Surg 2013; 21 (06) 343-354
  PubMedSearch in Google Scholar
• 27 Issack PS, Helfet DL. Sciatic nerve injury associated with acetabular fractures. HSS J 2009; 5 (01) 12-18
  CrossrefPubMedSearch in Google Scholar
• 28 Carender CN, Bedard NA, An Q, Brown TS. Common peroneal nerve injury and recovery after total knee arthroplasty: a systematic review. Arthroplast Today 2020; 6 (04) 662-667
  CrossrefPubMedSearch in Google Scholar
• 29 Noble J, Munro CA, Prasad VSSV, Midha R. Analysis of upper and lower extremity peripheral nerve injuries in a population of patients with multiple injuries. J Trauma 1998; 45 (01) 116-122
  CrossrefPubMedSearch in Google Scholar
• 30 Sunderland S. A classification of peripheral nerve injuries producing loss of function. Brain 1951; 74 (04) 491-516
  CrossrefPubMedSearch in Google Scholar
• 31 Mackinnon S, Dellon A. Surgery of the Peripheral Nerve. New York, NY: Thieme Medical Publishers; 1988
  Search in Google Scholar
• 32 Grinsell D, Keating CP. Peripheral nerve reconstruction after injury: a review of clinical and experimental therapies. BioMed Res Int 2014; 2014: 698256
  CrossrefPubMedSearch in Google Scholar
• 33 Campbell WW. Evaluation and management of peripheral nerve injury. Clin Neurophysiol 2008; 119 (09) 1951-1965
  CrossrefPubMedSearch in Google Scholar
• 34 Clifford AL, Klifto CS, Li NY. Nerve coaptation in 2023: Adjuncts to nerve repair beyond suture. J Hand Surg Global Online 2024 Available at: https://www.jhsgo.org/article/S2589-5141(24)00069-0/fulltext Accessed September 22, 2024
  PubMed
• 35 Sneag DB, Zochowski KC, Tan ET. MR neurography of peripheral nerve injury in the presence of orthopedic hardware: technical considerations. Radiology 2021; 300 (02) 246-259
  CrossrefPubMedSearch in Google Scholar
• 36 Stone JJ, Puffer RC, Spinner RJ. Interfascicular resection of benign peripheral nerve sheath tumors. JBJS Essent Surg Tech 2019; 9 (02) e18
  CrossrefPubMedSearch in Google Scholar
• 37 Reynolds Jr DL, Jacobson JA, Inampudi P, Jamadar DA, Ebrahim FS, Hayes CW. Sonographic characteristics of peripheral nerve sheath tumors. AJR Am J Roentgenol 2004; 182 (03) 741-744
  CrossrefPubMedSearch in Google Scholar
• 38 Kakkar C, Shetty CM, Koteshwara P, Bajpai S. Telltale signs of peripheral neurogenic tumors on magnetic resonance imaging. Indian J Radiol Imaging 2015; 25 (04) 453-458
  Thieme ConnectPubMedSearch in Google Scholar
• 39 Jee WH, Oh SN, McCauley T. et al. Extraaxial neurofibromas versus neurilemmomas: discrimination with MRI. AJR Am J Roentgenol 2004; 183 (03) 629-633
  CrossrefPubMedSearch in Google Scholar
• 40 Wasa J, Nishida Y, Tsukushi S. et al. MRI features in the differentiation of malignant peripheral nerve sheath tumors and neurofibromas. AJR Am J Roentgenol 2010; 194 (06) 1568-1574
  CrossrefPubMedSearch in Google Scholar
• 41 Demehri S, Belzberg A, Blakeley J, Fayad LM. Conventional and functional MR imaging of peripheral nerve sheath tumors: initial experience. AJNR Am J Neuroradiol 2014; 35 (08) 1615-1620
  CrossrefPubMedSearch in Google Scholar

Address for correspondence

Publication History

Article published online:
11 February 2025

© 2025. Thieme. All rights reserved.

Thieme Medical Publishers, Inc.
333 Seventh Avenue, 18th Floor, New York, NY 10001, USA

• References

• 1 Daniels SP, Feinberg JH, Carrino JA, Behzadi AH, Sneag DB. MRI of foot drop: how we do it. Radiology 2018; 289 (01) 9-24
  CrossrefPubMedSearch in Google Scholar
• 2 Sneag DB, Arányi Z, Zusstone EM. et al. Fascicular constrictions above elbow typify anterior interosseous nerve syndrome. Muscle Nerve 2020; 61 (03) 301-310
  CrossrefPubMedSearch in Google Scholar
• 3 Stewart JD. Peripheral nerve fascicles: anatomy and clinical relevance. Muscle Nerve 2003; 28 (05) 525-541
  CrossrefPubMedSearch in Google Scholar
• 4 Sneag DB, Rancy SK, Wolfe SW. et al. Brachial plexitis or neuritis? MRI features of lesion distribution in Parsonage-Turner syndrome. Muscle Nerve 2018; 58 (03) 359-366
  CrossrefPubMedSearch in Google Scholar
• 5 Symanski JS, Ross AB, Davis KW, Brunner MC, Lee KS. US for traumatic nerve injury, entrapment neuropathy, and imaging-guided perineural injection. Radiographics 2022; 42 (05) 1546-1561
  CrossrefPubMedSearch in Google Scholar
• 6 Chhabra A, Zhao L, Carrino JA. et al. MR neurography: advances. Radiol Res Pract 2013; 2013: 809568
  PubMedSearch in Google Scholar
• 7 Sneag DB, Queler S. Technological advancements in magnetic resonance neurography. Curr Neurol Neurosci Rep 2019; 19 (10) 75
  CrossrefPubMedSearch in Google Scholar
• 8 Daniels SP, Ross AB, Sneag DB. et al. Intravenous contrast does not improve detection of nerve lesions or active muscle denervation changes in MR neurography of the common peroneal nerve. Skeletal Radiol 2021; 50 (12) 2483-2494
  CrossrefPubMedSearch in Google Scholar
• 9 Chhabra A, Andreisek G, Soldatos T. et al. MR neurography: past, present, and future. AJR Am J Roentgenol 2011; 197 (03) 583-591
  CrossrefPubMedSearch in Google Scholar
• 10 Del Grande F, Santini F, Herzka DA. et al. Fat-suppression techniques for 3-T MR imaging of the musculoskeletal system. Radiographics 2014; 34 (01) 217-233
  CrossrefPubMedSearch in Google Scholar
• 11 Fowler JR, Munsch M, Tosti R, Hagberg WC, Imbriglia JE. Comparison of ultrasound and electrodiagnostic testing for diagnosis of carpal tunnel syndrome: study using a validated clinical tool as the reference standard. J Bone Joint Surg Am 2014; 96 (17) e148
  CrossrefPubMedSearch in Google Scholar
• 12 Klauser AS, Halpern EJ, De Zordo T. et al. Carpal tunnel syndrome assessment with US: value of additional cross-sectional area measurements of the median nerve in patients versus healthy volunteers. Radiology 2009; 250 (01) 171-177
  CrossrefPubMedSearch in Google Scholar
• 13 Klauser AS, Abd Ellah MMH, Halpern EJ. et al. Sonographic cross-sectional area measurement in carpal tunnel syndrome patients: can delta and ratio calculations predict severity compared to nerve conduction studies?. Eur Radiol 2015; 25 (08) 2419-2427
  CrossrefPubMedSearch in Google Scholar
• 14 Ng AWH, Griffith JF, Tsoi C. et al. Ultrasonography findings of the carpal tunnel after endoscopic carpal tunnel release for carpal tunnel syndrome. Korean J Radiol 2021; 22 (07) 1132-1141
  CrossrefPubMedSearch in Google Scholar
• 15 Ng AWH, Griffith JF, Tsai CSC, Tse WL, Mak M, Ho PC. MRI of the carpal tunnel 3 and 12 months after endoscopic carpal tunnel release. AJR Am J Roentgenol 2021; 216 (02) 464-470
  CrossrefPubMedSearch in Google Scholar
• 16 Mosier BA, Hughes TB. Recurrent carpal tunnel syndrome. Hand Clin 2013; 29 (03) 427-434
  CrossrefPubMedSearch in Google Scholar
• 17 Haj-Mirzaian A, Hafezi-Nejad N, Del Grande F. et al. Optimal choice of ultrasound-based measurements for the diagnosis of ulnar neuropathy at the elbow: a meta-analysis of 1961 examinations. AJR Am J Roentgenol 2020; 215 (05) 1171-1183
  CrossrefPubMedSearch in Google Scholar
• 18 Rutter M, Grandizio LC, Malone WJ, Klena JC. The use of preoperative dynamic ultrasound to predict ulnar nerve stability following in situ decompression for cubital tunnel syndrome. J Hand Surg Am 2019; 44 (01) 35-38
  CrossrefPubMedSearch in Google Scholar
• 19 Jacobson JA, Jebson PJL, Jeffers AW, Fessell DP, Hayes CW. Ulnar nerve dislocation and snapping triceps syndrome: diagnosis with dynamic sonography—report of three cases. Radiology 2001; 220 (03) 601-605
  CrossrefPubMedSearch in Google Scholar
• 20 Vanhees MKD, Geurts GFAE, Van Riet RP. Snapping triceps syndrome: a review of the literature. Shoulder Elbow 2010; 2 (01) 30-33
  CrossrefPubMedSearch in Google Scholar
• 21 Rhodes NG, Howe BM, Frick MA, Moran SL. MR imaging of the postsurgical cubital tunnel: an imaging review of the cubital tunnel, cubital tunnel syndrome, and associated surgical techniques. Skeletal Radiol 2019; 48 (10) 1541-1554
  CrossrefPubMedSearch in Google Scholar
• 22 Daniels SP, Mintz DN, Endo Y, Dines JS, Sneag DB. Imaging of the post-operative medial elbow in the overhead thrower: common and abnormal findings after ulnar collateral ligament reconstruction and ulnar nerve transposition. Skeletal Radiol 2019; 48 (12) 1843-1860
  CrossrefPubMedSearch in Google Scholar
• 23 Sivakumaran T, Sneag DB, Lin B, Endo Y. MRI of the ulnar nerve pre- and post-transposition: imaging features and rater agreement. Skeletal Radiol 2021; 50 (03) 559-570
  CrossrefPubMedSearch in Google Scholar
• 24 Vogel RB, Nossaman BC, Rayan GM. Revision anterior submuscular transposition of the ulnar nerve for failed subcutaneous transposition. Br J Plast Surg 2004; 57 (04) 311-316
  CrossrefPubMedSearch in Google Scholar
• 25 Mackinnon SE, Novak CB. Operative findings in reoperation of patients with cubital tunnel syndrome. Hand (N Y) 2007; 2 (03) 137-143
  CrossrefPubMedSearch in Google Scholar
• 26 Mook WR, Ligh CA, Moorman III CT, Leversedge FJ. Nerve injury complicating multiligament knee injury: current concepts and treatment algorithm. J Am Acad Orthop Surg 2013; 21 (06) 343-354
  PubMedSearch in Google Scholar
• 27 Issack PS, Helfet DL. Sciatic nerve injury associated with acetabular fractures. HSS J 2009; 5 (01) 12-18
  CrossrefPubMedSearch in Google Scholar
• 28 Carender CN, Bedard NA, An Q, Brown TS. Common peroneal nerve injury and recovery after total knee arthroplasty: a systematic review. Arthroplast Today 2020; 6 (04) 662-667
  CrossrefPubMedSearch in Google Scholar
• 29 Noble J, Munro CA, Prasad VSSV, Midha R. Analysis of upper and lower extremity peripheral nerve injuries in a population of patients with multiple injuries. J Trauma 1998; 45 (01) 116-122
  CrossrefPubMedSearch in Google Scholar
• 30 Sunderland S. A classification of peripheral nerve injuries producing loss of function. Brain 1951; 74 (04) 491-516
  CrossrefPubMedSearch in Google Scholar
• 31 Mackinnon S, Dellon A. Surgery of the Peripheral Nerve. New York, NY: Thieme Medical Publishers; 1988
  Search in Google Scholar
• 32 Grinsell D, Keating CP. Peripheral nerve reconstruction after injury: a review of clinical and experimental therapies. BioMed Res Int 2014; 2014: 698256
  CrossrefPubMedSearch in Google Scholar
• 33 Campbell WW. Evaluation and management of peripheral nerve injury. Clin Neurophysiol 2008; 119 (09) 1951-1965
  CrossrefPubMedSearch in Google Scholar
• 34 Clifford AL, Klifto CS, Li NY. Nerve coaptation in 2023: Adjuncts to nerve repair beyond suture. J Hand Surg Global Online 2024 Available at: https://www.jhsgo.org/article/S2589-5141(24)00069-0/fulltext Accessed September 22, 2024
  PubMed
• 35 Sneag DB, Zochowski KC, Tan ET. MR neurography of peripheral nerve injury in the presence of orthopedic hardware: technical considerations. Radiology 2021; 300 (02) 246-259
  CrossrefPubMedSearch in Google Scholar
• 36 Stone JJ, Puffer RC, Spinner RJ. Interfascicular resection of benign peripheral nerve sheath tumors. JBJS Essent Surg Tech 2019; 9 (02) e18
  CrossrefPubMedSearch in Google Scholar
• 37 Reynolds Jr DL, Jacobson JA, Inampudi P, Jamadar DA, Ebrahim FS, Hayes CW. Sonographic characteristics of peripheral nerve sheath tumors. AJR Am J Roentgenol 2004; 182 (03) 741-744
  CrossrefPubMedSearch in Google Scholar
• 38 Kakkar C, Shetty CM, Koteshwara P, Bajpai S. Telltale signs of peripheral neurogenic tumors on magnetic resonance imaging. Indian J Radiol Imaging 2015; 25 (04) 453-458
  Thieme ConnectPubMedSearch in Google Scholar
• 39 Jee WH, Oh SN, McCauley T. et al. Extraaxial neurofibromas versus neurilemmomas: discrimination with MRI. AJR Am J Roentgenol 2004; 183 (03) 629-633
  CrossrefPubMedSearch in Google Scholar
• 40 Wasa J, Nishida Y, Tsukushi S. et al. MRI features in the differentiation of malignant peripheral nerve sheath tumors and neurofibromas. AJR Am J Roentgenol 2010; 194 (06) 1568-1574
  CrossrefPubMedSearch in Google Scholar
• 41 Demehri S, Belzberg A, Blakeley J, Fayad LM. Conventional and functional MR imaging of peripheral nerve sheath tumors: initial experience. AJNR Am J Neuroradiol 2014; 35 (08) 1615-1620
  CrossrefPubMedSearch in Google Scholar