Clinical anatomy : official journal of the American Association of Clinical Anatomists & the British Association of Clinical Anatomists
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The appearances of intraneural ganglion cysts are being elucidated. We previously introduced the cross-over phenomenon to explain how a fibular (peroneal) or tibial intraneural ganglion cyst arising from the superior tibiofibular joint could give rise to multiple cysts: cyst fluid ascending up the primarily affected nerve could reach the level of the sciatic nerve, fill its common epineurial sheath and spread circumferentially (cross over), at which time pressure fluxes could result in further ascent up the sciatic or descent down the same parent nerve or the opposite, previously unaffected fibular or tibial nerves. In this study, we hypothesized that cross-over could occur in other nerves, potentially leading to the formation of more than one intraneural ganglion cyst in such situations. ⋯ The injection study also demonstrated the cross-over phenomenon and produced a similar pattern as the cyst dissection. This article illustrates that cross-over can occur in another nerve (apart from the prototype fibular nerve). Furthermore, understanding the more complex anatomic nature of the upper trunk cross-over model provides insight into important mechanistic information regarding the bidirectional propagation patterns and formation of primary and secondary intraneural ganglion cysts not afforded by the previously described sciatic nerve cross-over model.
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The conventional approach to the fourth ventricle is by splitting the vermis on the suboccipital surface of the cerebellum. By a unilateral transcerebellomedullary fissure approach, it is possible to provide sufficient operative space from cerebral aqueduct to obex without splitting the vermis. This approach needs meticulous dissection of the cerebellomedullary fissure and preservation of the posterior inferior cerebellar artery (PICA) and its branches. ⋯ When the PICA arose from the lateral medullary (LM) segment of the vertebral artery (VA), a caudal loop was present in 90%, when the PICA originated from the premedullary segment of the VA, the loop was present in 87.5% specimens. When the PICA arose from the basilar artery (BA), the loop was absent, and the tonsillomedullary segment of the PICA showed a straight course (100%). A thorough understanding of the relationship of the branches of the PICA to the cerebellar tonsils are prerequisites for surgery in and around the fourth ventricle.
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Central venous catheter fracture is a rare complication of long-term indwelling subclavian venous access. Subclavian vein access has been the recommended approach for placing central venous catheters. The anatomical landmark method for subclavian access remains a highly successful and nonequipment-dependent method for rapid central access. ⋯ A case of central venous catheter fracture initiated an internal review of long-term central venous access procedures. We have converted to a predominantly internal jugular vein approach. This case report and literature review may assist other physicians and institutions in re-evaluating long-term central venous access protocols.