John A. Skinner

Diagnostic Comparison of 1+5 Tesla and 3+0 Tesla Preoperative MRI of the Wrist in Patients With Ulnar-Sided Wrist Pain

PURPOSE The diagnostic sensitivity, specificity, and accuracy of 1.5 Tesla (T) and of 3.0T magnetic resonance imaging (MRI) are correlated with wrist arthroscopy findings in patients presenting with ulnar-sided wrist pain. METHODS The records and diagnostic MRI scans of 102 patients who presented between 1997 and 2006 with ulnar-sided wrist pain were evaluated. Preoperative MRI scans at 1.5T (n = 70) and 3.0T (n = 32) were evaluated by 2 experienced musculoskeletal radiologists with different levels of experience who were blinded to the arthroscopic findings. Preoperative MRI findings for the triangular fibrocartilage complex (TFCC), scapholunate, ulnotriquetral, and lunotriquetral ligaments were recorded and compared with findings at diagnostic arthroscopy. The sensitivity, specificity, and accuracy were calculated for both the 1.5T and 3.0T preoperative MRI scans. Statistical comparisons were made using chi-square test and JMP 6.0 software. RESULTS A tear of the TFCC was identified retrospectively on 1.5T images in 49 of 58 patients and on 3.0T images in 15 of 16 patients. Compared with the gold standard of arthroscopy, 1.5T wrist MRI in this patient population had a sensitivity of 85%, a specificity of 75%, and an accuracy of 83% for reader 1 for the detection of a tear of the TFCC. In the same patient population, 3.0T wrist MRI had a sensitivity of 94%, a specificity of 88%, and an accuracy of 91% for reader 1. For reader 2, the improvement in sensitivity for the lunotriquetral ligament between the 1.5T and 3.0T images was statistically significant. CONCLUSIONS The sensitivity, specificity, and accuracy of 3.0T wrist MRI for the TFCC is consistently higher compared with those of 1.5T wrist MRI. The trend suggests that 3.0T wrist MRI provides improved capability for detection of TFCC injuries. Given the available sample size, however, the confidence intervals around the point estimates are wide and overlapping. Further studies are needed to confirm or refute our results of the estimated sensitivity, specificity, and accuracy parameters.

Patterns of intraneural ganglion cyst descent

On the basis of the principles of the unifying articular theory, predictable patterns of proximal ascent have been described for fibular (peroneal) and tibial intraneural ganglion cysts in the knee region. The mechanism underlying distal descent into the terminal braches of the fibular and tibial nerves has not been previously elucidated. The purpose of this study was to demonstrate if and when cyst descent distal to the articular branch‐joint connection occurs in intraneural ganglion cysts to understand directionality of intraneural cyst propagation. In Part I, the clinical records and MRIs of 20 consecutive patients treated at our institution for intraneural ganglion cysts (18 fibular and two tibial) arising from the superior tibiofibular joint were retrospectively analyzed. These patients underwent cyst decompression and disconnection of the articular branch. Five of these patients developed symptomatic cyst recurrence after cyst decompression without articular branch disconnection which was done elsewhere prior to our intervention. In Part II, five additional patients with intraneural ganglion cysts (three fibular and two tibial) treated at other institutions without disconnection of the articular branch were compared. These patients in Parts I and II demonstrated ascent of intraneural cyst to differing degrees (12 had evidence of sciatic nerve cross‐over). In addition, all of these patients demonstrated previously unrecognized MRI evidence of intraneural cyst extending distally below the level of the articular branch to the joint of origin: cyst within the proximal most portions of the deep fibular and superficial fibular branches in fibular intraneural ganglion cysts and descending tibial branches in tibial intraneural ganglion cysts. The patients in Part I had complete resolution of their cysts at follow‐up MRI examination 1 year postoperatively. The patients in Part II had intraneural recurrences postoperatively within the articular branch, the parent nerve, and the terminal branches, although in three cases they were subclinical. The authors demonstrate that cyst descent distal to the take‐off of the articular branch to the joint of origin occurs regularly in patients with fibular and tibial intraneural ganglion cysts. The authors believe that parent terminal branch descent follows ascent up the articular branch from an affected joint of origin. This mechanism for bidirectional flow explains cyst within terminal branches of the fibular and tibial nerves and is dependent on pressure fluxes and resistances. This new pattern is consistent with principles previously described in a unified (articular) theory, is generalizable to other intraneural ganglion cysts arising from joints, and has important implications for pathogenesis and treatment of these intraneural cysts. Clin. Anat. 21:233–245, 2008.

Evaluation of intraneural ganglion cysts using three-dimensional fast spin echo-cube.

To compare conventional two‐dimensional fast spin echo (FSE) MRI sequences with a three‐dimensional FSE extended echo train acquisition method, known as Cube, in the evaluation of intraneural ganglion cysts. Also, to demonstrate that Cube enables the consistent identification and thorough characterization of the cystic joint connection, and therefore improves patient care by superior preoperative planning.

Evaluation of ganglion cysts using vastly undersampled isotropic projection reconstruction (VIPR)

For some atypical para‐articular ganglia, the presence of a joint connection is highly controversial. The proper preoperative diagnosis and identification of this joint connection for ganglion cysts is important for patient treatment and outcome. MRI is the imaging modality of choice when evaluating such lesions, but the detection of subtle joint connections remains difficult with conventional MR protocols. We investigated the utility of a steady‐state free‐precession acquisition with isotropic high resolution using the vastly undersampled isotropic projection reconstruction (VIPR) pulse sequence to determine if joint connections for ganglion cysts could be seen more effectively, using the knee region as a model. We evaluated four patients: two with peroneal intraneural ganglion cysts, one with adventitial cystic disease of the popliteal artery, and one patient with a more typical extraneural (intramuscular) cyst. Both conventional MR and VIPR techniques were used. In our clinical experience, we found VIPR to be superior to conventional MR techniques in detecting and depicting joint connections in typical and atypical ganglion cysts around the knee. J. Magn. Reson. Imaging 2007.

A profile of immune response to herpesvirus is associated with radiographic joint damage in rheumatoid arthritis

IntroductionProgression of joint damage despite appropriate therapy remains a significant problem for patients with rheumatoid arthritis (RA). This study was undertaken to identify profiles of immune response that correlate with radiographic joint damage as a first step toward the discovery of new pathogenic mechanisms of joint destruction in RA.MethodsThe study included 58 patients with RA and 15 healthy controls. The profiles of cytokine release from peripheral blood mononuclear cells (PBMC) in response to stimulation for 48 hours with one of six stimuli, or in media alone, were measured. Immune response profiles identified for each stimulus were correlated with radiographic joint damage as defined by the Sharp-van der Heijde score (SHS), before and after multivariable adjustment. For profiles correlated with the SHS, the distributions of individual cytokines were evaluated in patients according to the severity of joint damage and compared to healthy controls.ResultsThe immune response profile for cytomegalovirus (CMV)/Epstein-Barr virus (EBV) stimulation was correlated with both the SHS total and erosion scores (r = 0.31, P = 0.018 and r = 0.33, P = 0.011, respectively). After adjusting for age, sex, disease duration, autoantibody status, CMV/EBV serological status, current disease activity, disability and treatments, the correlation of the CMV/EBV immune response and the SHS erosion score became stronger (r = 0.43, P < 0.003). The CMV/EBV immune response correlated with CMV IgG (r = 0.44, P < 0.001), but not with EBV IgG. The most important cytokines for the CMV/EBV immune response profile were IFN-γ, IL-2, IL-4, IL-5, IL-13 and IL-17A, all of which are associated with T-cell immunity. Both the summary immune response score and the individual responses of IFN-γ and IL-13 to CMV/EBV stimulation were associated with greater joint damage.ConclusionsA profile of immune response to purified CMV/EBV lysates is associated with radiographic joint damage. The correlation of this immune response to CMV serology implies possible involvement of latent CMV infection. Therefore, the findings suggest that the immune response to latent CMV infection could play a fundamental role in the progression of inflammation and structural joint damage in patients with RA.

Sciatic cross-over in patients with peroneal and tibial intraneural ganglia confirmed by knee MR arthrography.

BackgroundA predictable mechanism and stereotypic patterns of peroneal intraneural ganglia are being defined based on careful analysis of MRIs. Peroneal and tibial intraneural ganglia extending from the superior tibiofibular joint which extend to the level of the sciatic nerve have been observed leading to the hypothesis that sciatic cross-over could exist. Such a cross-over phenomenon would allow intraneural cyst from the peroneal nerve by means of its shared epineurial sheath within the sciatic nerve to cross over to involve the tibial nerve, or vice versa from a tibial intraneural cyst to the peroneal nerve.Method and FindingsOne patient with a peroneal intraneural ganglion and another with a tibial intraneural ganglion each underwent a knee MR arthrogram. These studies were not only definitive in demonstrating the communication of the cyst to the superior tibiofibular joint connection but also in confirming sciatic cross-over. Contrast injected into the knee could be demonstrated tracking to the superior tibiofibular joint and then proximally into the common peroneal or tibial nerve respectively, crossing over at the sciatic nerve, and then descending down the tibial and peroneal nerves. The arthrographic findings mirrored MR images upon their retrospective review.ConclusionsThis study provides direct in vivo proof of the nature of sciatic cross-over theorized by critical review of MRIs and/or experimental dye injections done in cadavers. This study is important in clarifying the potential paths of propagation of intraneural cysts at points of major bifurcation.

Knee MR arthrographic proof of an articular origin for combined intraneural and adventitial cysts

To the Editor: The pathogenesis of intraneural ganglia has long been misunderstood [1]. Recent evidence, largely based on MRI analyses, has clarified the articular origin of intraneural cysts and their treatment [2]. MR arthrography has proven useful in revealing occult joint communications of intraneural cysts [3]. In a recent paper published in Acta Neurochirurgica [4], MR arthrography has also provided in vivo proof of the cross-over phenomenon, in which cyst, arising from the superior tibiofibular joint (STFJ), ascends within the parent nerve (peroneal or tibial) to the level of the sciatic nerve where it shares a common epineurial sheath and then descends down the opposite tibial or peroneal nerve. This letter highlights an extension of MR arthrography not only in confirming the previously hypothesized [5] joint-related origin of combined intraneural and adventitial cysts but also in shedding light on the pathogenesis and treatment of isolated adventitial cysts, a current topic of controversy. Two examples affecting different nerves, both derived from different portions of the same joint, are presented to underscore the versatility and generalizability of these imaging findings. The first patient (Case 1), a 49-year-old man, had initially presented at another institution with a foot drop due to a relatively large peroneal intraneural cyst (Fig. 1). Decompression and subtotal resection of the cyst were done, but the neural articular branch connection was not recognized, and the STFJ was not addressed. Transient improvement was noted for 3 months before his presentation to us with clinical deterioration (i.e., peroneal neuropathy) and imaging recurrence. The second patient (Case 2), a 46-year-old man, presented with a moderate tibial neuropathy and a cystic mass in the popliteal fossa and thigh. In both patients, high-resolution MRI (3 Tesla [T]) and direct MR gadolinium arthrography (via a patellofemoral approach) were performed. In Case 1, the peroneal intraneural ganglion cyst, now somewhat smaller than on initial MRI, was seen arising from the anterior portion of the STFJ and extending along the articular branch into the common peroneal nerve as well as into the tibialis anterior branch (Fig. 2). In Case 2, a tibial intraneural cyst extending from the posterior aspect of the STFJ to the sciatic nerve in the upper thigh was observed (Fig. 3). In both patients, cyst tracking anteriorly and posteriorly within the adventitia of the anterior tibial and popliteal veins, which had not been appreciated at the time of the initial preoperative MRI in Case 1, could also be visualized (Figs. 2 and 3). In both patients, MR arthrography demonstrated communication of the knee joint with the STFJ as well as the intraneural and adventitial components of the cyst (Figs. 2 and 3). In Case R. J. Spinner (*) :M.-N. Hébert-Blouin :K. K. Amrami Department of Neurologic Surgery, Mayo Clinic, Gonda 8S-214, 200 First Street SW, Rochester, MN 55905, USA e-mail: spinner.robert@mayo.edu

The snapping medial antebrachial cutaneous nerve

Snapping elbow is a well‐known condition where elbow flexion and extension elicits a painful, popping sensation. The most frequent etiology is anterior dislocation of the ulnar nerve over the medial epicondyle. Four patients (3 females and 1 male) presented with complaints of a popping sensation in the elbow, pain over the medial aspect of the forearm, and ulnar neuritis. All patients underwent preoperative dynamic ultrasound and surgical exploration of the medial elbow. Intraoperatively, snapping of the MABC over the medial epicondyle was discovered in all four patients. In three patients, there was abnormal displacement of the medial triceps and ulnar nerve: in two of these, both structures dislocated over the medial epicondyle and in one patient both structures subluxated. In each case, the MABC was decompressed (n = 1) and transposed (n = 3), and in three cases, the medial triceps and ulnar nerve were addressed as well. Symptomatic improvement was achieved in all cases. Retrospective review of the ultrasound revealed the snapping MABC, though it was less effective prospectively in the cases when snapping MABC was not suspected. In conclusion, snapping of the MABC broadens the spectrum of disorders that results in snapping elbow. To our knowledge, we are unaware of prior reports of this entity. Clin. Anat. 28:872–877, 2015.

The MRI appearance and importance of the “very” terminal branches of the recurrent articular branch in fibular intraneural ganglion cysts

In a recent article, we reported on the capability of highresolution MRI to display the anatomy and pathology not only of the deep and superficial branches of the fibular nerve but also the articular (‘‘recurrent articular/genicular’’ or ‘‘recurrent peroneal’’) and its tibialis anterior proximal motor branches (Hébert-Blouin et al., 2010b). Since this publication, we have treated 2 patients with fibular neuropathies due to fibular intraneural ganglion cysts derived from the superior tibiofibular joint who were noted to have cystic involvement of a ‘‘terminal’’ branch of the articular branch of the fibular nerve, i.e., one variably extending toward the patellar ligament. Pressurized by the cystic process, the enlarged terminal branch in our 2 cases could be visualized more easily than in the ‘‘normal’’ state. The terminal branch of the articular branch of the fibular nerve corresponded well to a tiny branch depicted in one of the original specimen drawings by Gardner (1948) (Fig. 1). The innervation from the fibular nerve to the patellar ligament and anterolateral knee joint is not widely appreciated and has important considerations. Limited information is available about this ‘‘very’’ terminal branch. It is not mentioned in several anatomic books (McVay, 1984; Thorek, 1985; Rohen et al., 2002; Moore et al., 2006; Stranding et al., 2008; Moore et al., 2010). The recurrent articular branch of the common or deep fibular nerve provides branches to the proximal tibialis anterior muscle and then, to both the superior tibiofibular and knee joints (Romanes, 1981). The course of the branch to the anterior portion of the superior tibiofibular joint is ushaped. This recurrent branch gives off another (recurrent) branch that supplies the periosteum of the proximal tibial, tibial tuberosity, patellar ligament, and even the infrapatellar fat pad (Gardner, 1948). Its tiny filaments have proven difficult to dissect and characterize (Gardner, 1948). Difficulties with terminology are also apparent. These very terminal branches are not included in Terminologia Anatomica (1998). The recurrent articular branch has been called the ‘‘recurrent tibial nerve’’ (Cunningham, 1918), the ‘‘anterior tibial (recurrent) nerve’’ (Hollinshead, 1982; Agur and Dalley, 2009), and even, the tibialis anterior branch (de Sèze et al., 2005). In fact, it is unclear whether the recurrent branch itself refers to the branch to the superior tibiofibular joint or the knee joint, both of which are recurrent.

Tibialis anterior branch involvement in fibular intraneural ganglia.

Fibular (peroneal) intraneural ganglia classically present with predominant tibialis anterior weakness, for which there is no clear anatomical explanation. We identified a new imaging pattern, which consisted of involvement of a proximal tibialis anterior branch, in patients with fibular intraneural ganglia. This study characterizes the cystic involvement of this tibialis anterior branch and evaluates its significance. The magnetic resonance imaging (MRI) and clinical data of 23 patients with fibular intraneural ganglia were retrospectively reviewed. The tibialis anterior branch was consistently involved with the cyst, and this involvement, although variable, was more prominent than the cystic involvement of other terminal branches of the fibular nerve. The finding of cyst extension within a muscle end‐organ branch seems likely to explain, in part, the characteristic clinical finding of preferential foot drop in patients with fibular intraneural ganglia. Muscle Nerve, 2010