The mechanism responsible for exceptional examples of intraneural ganglia with extensive longitudinal involvement has not been understood. Such cases of intraneural cysts, seemingly remote from a joint, have been thought not to have articular connections. Decompression and attempted resection of the cyst has led to intraneural recurrence and poor neurological recovery. The purpose of this report is not only to clarify the pathogenesis of these cysts, but also to discuss their treatment based on modern concepts of intraneural ganglia.
Two examples of extreme longitudinal propagation of intraneural ganglia are presented.
A patient with a moderate tibial neuropathy was found to have a tibial intraneural ganglion. Prospective interpretation of the MR imaging study demonstrated the cyst's origin from the posterior portion of the superior tibiofibular joint (STFJ), with proximal extension within the sciatic nerve to the lower buttock region. Communication between the STFJ and the cyst was confirmed with direct knee MR arthrography. The tibial intraneural cyst was treated successfully by a relatively limited exposure in the distal popliteal fossa: the cyst was decompressed, the articular branch disconnected, and the STFJ resected. Postoperatively, the patient improved neurologically and there was no evidence of recurrent cyst on postoperative MR imaging. A second patient, previously reported by another group, was reexamined 22 years after surgery. This patient had an extensive peroneal intraneural ganglion that extended into the sciatic nerve from the knee to the buttock; no joint connection or recurrent cyst had initially been described. In this patient, the authors hypothesized and established with MR imaging the presence of both: a joint connection to the anterior portion of the STFJ from the peroneal articular branch as well as recurrent cyst within the peroneal and tibial nerves.
This paper demonstrates that extreme intraneural cysts are not clinical outliers but represent extreme examples of other more typical intraneural cysts. They logically obey the same principles, previously described in the unified articular (synovial) theory. The degree of longitudinal extension is probably due to high intraarticular pressures within the degenerative joint of origin. The generalizability of the mechanistic principles is highlighted by the fact that these 2 cases, involving the tibial and the peroneal nerve respectively, both extended well distant (that is, to the buttock) from the STFJ via their respective articular branch of origin. These extensive intraneural cysts can be treated successfully by disconnecting the affected articular branch and by resection of the joint of origin, rather than by a more aggressive operation resecting the cyst and cyst wall.
Abbreviations used in this paper: FSE = fast spin echo; STFJ = superior tibiofibular joint.
Address correspondence to: Robert J. Spinner, M.D., Mayo Clinic, 200 First Street NW, Gonda 8S-214, Rochester, Minnesota 55905. email: firstname.lastname@example.org.Please include this information when citing this paper: published online May 21, 2010; DOI: 10.3171/2010.4.JNS091969.
SpinnerRJAmramiKKAngiusDWangHCarmichaelSW: Peroneal and tibial intraneural ganglia: correlation between intraepineurial compartments observed on magnetic resonance images and the potential importance of these compartments. Neurosurg Focus22:6E172007
SpinnerRJ, AmramiKK, AngiusD, WangH, CarmichaelSW: Peroneal and tibial intraneural ganglia: correlation between intraepineurial compartments observed on magnetic resonance images and the potential importance of these compartments. 22:6E17, 2007)| false
SpinnerRJAmramiKKWolanskyjAPDesyNMWangHBenarrochEE: Dynamic phases of peroneal and tibial intraneural ganglia formation: a new dimension added to the unifying articular theory. J Neurosurg107:296–3072007
SpinnerRJ, AmramiKK, WolanskyjAP, DesyNM, WangH, BenarrochEE, : Dynamic phases of peroneal and tibial intraneural ganglia formation: a new dimension added to the unifying articular theory. 107:296–307, 2007)| false
SpinnerRJMokhtarzadehASchieferTKKrishnanKGKliotMAmramiKK: The clinico-anatomic explanation for tibial intraneural ganglion cysts arising from the superior tibiofibular joint. Skeletal Radiol36:281–2922007
SpinnerRJ, MokhtarzadehA, SchieferTK, KrishnanKG, KliotM, AmramiKK: The clinico-anatomic explanation for tibial intraneural ganglion cysts arising from the superior tibiofibular joint. 36:281–292, 2007)| false
SpinnerRJScheithauerBWDesyNMRockMGHoldtFCAmramiKK: Coexisting secondary intraneural and vascular adventitial ganglion cysts of joint origin: a causal rather than a coincidental relationship supporting an articular theory. Skeletal Radiol35:734–7442006
SpinnerRJ, ScheithauerBW, DesyNM, RockMG, HoldtFC, AmramiKK: Coexisting secondary intraneural and vascular adventitial ganglion cysts of joint origin: a causal rather than a coincidental relationship supporting an articular theory. 35:734–744, 2006)| false