Abstract:A highly unusual variant of an intraneural ganglion of the common peroneal nerve in a 30-year-old male is presented. There was extrusion of the contents of the cyst into the substance of the nerve, dissecting between the fibres and expanding the nerve in such a way that it mimicked an intraneural tumour clinically, radiologically and histologically. A comprehensive review of the entity is undertaken.
“…The observation explains several provocative cases with atypical features (Fig. 1) (Jacobs et al, 1975;Bonar et al, 2006;Spinner et al, in press), ones in which cysts extend up the common fibular or tibial nerves, into the sciatic nerve and descend down the common fibular, tibial or sural nerves to form two or more cysts derived from a single joint. On the other hand, three potential explanations exist for the finding of ascent of intraneural ganglion cysts to the level of the buttock without cross over or terminal branch descent (Wadstein, 1931;Harbaugh et al, 1997;Krishnan and Schackert, 2003): (1) dissection within the inner epineurium, (2) the presence of a high sciatic nerve bifurcation, as is known to occur in approximately 10% of cadavers, with two distinct but contiguous outer epineuria separating the common fibular and Fig.…”
New patterns of intraneural ganglion cyst formation are emerging that have not previously been explained in current pathoanatomic terms. We believe there are three important elements underlying the appearance of these cysts: (a) an articular branch of the nerve that connects to a nearby synovial joint; (b) ejected synovial fluid following the path of least resistance along tissue planes; and (c) the additional effects of pressure and pressure fluxes. The dynamic nature of cyst formation has become clearly apparent to us in our clinical, operative and pathologic practice, but the precise mechanism underlying the process has not been critically studied. To test our hypothesis that a fibular (peroneal) or tibial intraneural cyst derived from the superior tibiofibular joint could ascend proximally into the sciatic nerve, expand within it and descend into terminal branches of this major nerve, we designed a series of simple, qualitative laboratory experiments in two cadavers (four specimens, six experiments). Injecting dye into the outer or "epifascicular" epineurium of the fibular and the tibial nerves we observed its ascent, cross over and descent patterns in three of three specimens as well as its cross over after an outer epineurial sciatic injection. In contrast, injecting dye into the inner or "interfascicular" epineurium led to its ascent within the tibial nerve and its division within the sciatic nerve in one specimen and lack of cross over in a sciatic nerve injection. Histologic cross-sections of the nerves at varying levels demonstrated a tract of disruption within the outer epineurium of the nerve injected and the nerve(s) into which the dye, after cross over, descended. Those specimens injected in the inner epineurium demonstrated dye within this tract but without disruption of or dye intrusion into the outer epineurium. In no case did the dye pass through the perineurial layers. Coupled with our observations in previous detailed studies, these anatomic findings provide proof of concept that sciatic cross over occurs due to the filling of its common epineurial sheath; furthermore, these findings, support the unifying articular theory, even in cases wherein patterns of intraneural ganglion cyst formation are unusual. Additional work is needed to be done to correlate these anatomic findings with magnetic resonance imaging and surgical pathology.
“…The observation explains several provocative cases with atypical features (Fig. 1) (Jacobs et al, 1975;Bonar et al, 2006;Spinner et al, in press), ones in which cysts extend up the common fibular or tibial nerves, into the sciatic nerve and descend down the common fibular, tibial or sural nerves to form two or more cysts derived from a single joint. On the other hand, three potential explanations exist for the finding of ascent of intraneural ganglion cysts to the level of the buttock without cross over or terminal branch descent (Wadstein, 1931;Harbaugh et al, 1997;Krishnan and Schackert, 2003): (1) dissection within the inner epineurium, (2) the presence of a high sciatic nerve bifurcation, as is known to occur in approximately 10% of cadavers, with two distinct but contiguous outer epineuria separating the common fibular and Fig.…”
New patterns of intraneural ganglion cyst formation are emerging that have not previously been explained in current pathoanatomic terms. We believe there are three important elements underlying the appearance of these cysts: (a) an articular branch of the nerve that connects to a nearby synovial joint; (b) ejected synovial fluid following the path of least resistance along tissue planes; and (c) the additional effects of pressure and pressure fluxes. The dynamic nature of cyst formation has become clearly apparent to us in our clinical, operative and pathologic practice, but the precise mechanism underlying the process has not been critically studied. To test our hypothesis that a fibular (peroneal) or tibial intraneural cyst derived from the superior tibiofibular joint could ascend proximally into the sciatic nerve, expand within it and descend into terminal branches of this major nerve, we designed a series of simple, qualitative laboratory experiments in two cadavers (four specimens, six experiments). Injecting dye into the outer or "epifascicular" epineurium of the fibular and the tibial nerves we observed its ascent, cross over and descent patterns in three of three specimens as well as its cross over after an outer epineurial sciatic injection. In contrast, injecting dye into the inner or "interfascicular" epineurium led to its ascent within the tibial nerve and its division within the sciatic nerve in one specimen and lack of cross over in a sciatic nerve injection. Histologic cross-sections of the nerves at varying levels demonstrated a tract of disruption within the outer epineurium of the nerve injected and the nerve(s) into which the dye, after cross over, descended. Those specimens injected in the inner epineurium demonstrated dye within this tract but without disruption of or dye intrusion into the outer epineurium. In no case did the dye pass through the perineurial layers. Coupled with our observations in previous detailed studies, these anatomic findings provide proof of concept that sciatic cross over occurs due to the filling of its common epineurial sheath; furthermore, these findings, support the unifying articular theory, even in cases wherein patterns of intraneural ganglion cyst formation are unusual. Additional work is needed to be done to correlate these anatomic findings with magnetic resonance imaging and surgical pathology.
“…In fact, the actual quote is found in a different reference (Houle, 1878b, p.259) (Table 1f). Unfortunately but understandably, the few incorrect citations in the paper by Moreau and Van Bogaert (1923) have been repeated by subsequent authors over the ensuing decades, including a recent report (Bonar et al, 2006). The widespread problems surrounding such inaccuracies were the focus of editorials (Spinner and Northouse, 2004;Spinner et al, 2005).…”
We describe the first reported case of an intraneural ganglion cyst, an ulnar (''cubital'') intraneural cyst, which, on literature review, dated to 1810. For over 80 years, its original brief description by Beauchêne was wrongly attributed to Duchenne, effectively making the reference and specimen inaccessible to scrutiny. Fortunately, the intact cyst had been safely housed in the Musée Dupuytren, Paris, France, thus permitting its examination. Although originally described as a ''serous'' cyst, our present understanding of the anatomy of the ulnar nerve and of peripheral nerve pathology allowed us to reinterpret it as a mucin-filled, elbow-level, ulnar intraneural ganglion cyst. In addition to its description as a fusiform cystic enlargement of the nerve, we documented similar enlargement of a lumen-bearing branch, the articular branch at the level of the elbow. Based on our assessment of the specimen and with a modern perspective, we concluded that the origin of the cyst was from the posteromedial aspect of the elbow joint and that its fluid content, having dissected through a capsular defect, followed the path of the articular branch into the parent ulnar nerve. The purpose of this report is to clarify historical misconceptions regarding the pathogenesis of this controversial entity. Clin. Anat. 21:611-618, 2008. V V C 2008 Wiley-Liss, Inc.
“…They have no capsule and show no enhancement after administration of gadolinium contrast. A case has been reported in which there was some, mostly peripheral enhancement; this may lead to confusion with a cystic schwannoma [38]. Fig.…”
Section: Spectrum Of Pathologic Conditionsmentioning
confidence: 99%
“…Occasionally in large or long-standing schwannomas intralesional degeneration with fibrosis, haemorrhage, calcification and cystic necrosis occurs, leading to a so-called ancient schwannoma [36, 37]. In case of an elongated cystic mass along the peroneal nerve, an intraneural ganglion is a more likely diagnosis [38]. …”
Section: Spectrum Of Pathologic Conditionsmentioning
BackgroundPeroneal nerve lesions are not common and are often exclusively assessed clinically and electromyographically.MethodsOn a routine MR examination without dedicated MR-neurography sequences the peroneal nerve can readily be assessed. Axial T1-weighted sequences are especially helpful as they allow a good differentiation between the nerve and the surrounding fat.ResultsThe purpose of this article is to review the normal anatomy and pathologic conditions of the peroneal nerve around the knee.ConclusionIn the first part the variable anatomy of the peroneal nerve around the knee will be emphasized, followed by a discussion of the clinical findings of peroneal neuropathy and general MR signs of denervation. Six anatomical features may predispose to peroneal neuropathy: paucity of epineural tissue, biceps femoris tunnel, bifurcation level, superficial course around the fibula, fibular tunnel and finally the additional nerve branches. In the second part we discuss the different pathologic conditions: accidental and surgical trauma, and intraneural and extraneural compressive lesions.Teaching Points• Six anatomical features contribute to the vulnerability of the peroneal nerve around the knee.• MR signs of muscle denervation within the anterior compartment are important secondary signs for evaluation of the peroneal nerve.• The most common lesions of the peroneal nerve are traumatic or compressive.• Intraneural ganglia originate from the proximal tibiofibular joint.• Axial T1-weighted images are the best sequence to visualise the peroneal nerve on routine MRI.
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