Patterns of intraneural ganglion cyst descent

Abstract

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 branches 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.

Intraneural ganglion cyst: A 200‐year‐old mystery solved

“…The fusiform configuration of the cyst is characteristic of this lesion, akin to the shape of an inflated long, thin circus balloon (i.e., the ''balloon sign''), a reflection of hydrodynamic principles . Preferential cyst extension in a proximal direction (''ascent") rather than in a distal direction (''descent") is also typical (Spinner et al, 2008). It would seem that, due to pressure differences in overlying tissues, the balloon-like expansion occurred proximal to the region of the cubital tunnel.…”

The almost-invisible perineurioma

“…The most common nerve affected is the common peroneal nerve, although involvement of other nerves has also been reported. 10 On MRI, the normal morphology of the nerve is replaced by a unilocular or multilocular cystic lesion that follows the path from the joint along the parent nerve. Cysts appear hypointense on T1-weighted images (Fig.…”

Two different pathways for suprascapular intraneural ganglion cysts along two distinct articular branches from the glenohumeral joint

“…We believe that in this instance, the inferior, rather than the superior, articular branch of the suprascapular nerve provided the neural joint connection for the intraneural cyst formation. Propagation along this inferior pathway would explain the appearance of the intraneural cyst described by these authors and would be consistent with the pattern of predominant proximal ascent that is seen in intraneural ganglion cysts (Spinner et al, 2008b). Coincidentally, we recently evaluated a 38 year-old woman with a suprascapular neuropathy who was found to have an extensive intraneural ganglion cyst which propagated by this newly appreciated neural pathway (Fig.…”