title: Subparaneurial ganglion cysts of the fibular and tibial nerves: A new variant of intraneural ganglion cysts.
abstract: Over the last decade, the mechanism of formation of intraneural ganglion cysts has been established through a meticulous review of clinical findings and correlation with patterns produced on magnetic resonance imaging (MRI). Pathognomonic imaging patterns distinguish these rare lesions from the more common extraneural variants in almost all cases. In this report, we present a new pattern of cyst occurrence in the subparaneurial compartment of the nerve and provide potential anatomic explanations for its pathogenesis. Using an anatomic framework of connective tissue compartments of the nerve, we reviewed 63 (56 fibular and seven tibial) intraneural ganglion cysts in the knee region evaluated at our institution and all reports with MRI in the world's literature for evidence of cyst occurrence in the subparaneurial compartment. We identified six cases (five in the common fibular nerve and one in the tibial nerve) at our institution that had MR evidence of cyst in the subparaneurial compartment with a new complex lobulated pattern. All cases had articular branch connections to the superior tibiofibular joint, which at operation were resected along with the joints. Follow-up revealed complete recovery in all instances and no clinical or radiological signs of recurrence. Three cases out of 80 in the literature exhibited the new complex lobulated MRI pattern. We present a new pattern of intraneural ganglion cyst occurrence in a potential space that surrounds peripheral nerves--the subparaneurial compartment. We believe that the unifying articular theory applies to the pathogenesis and management of these rare variants.
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota.
authors.forename: Nikhil K
authors.initials: NK
authors.lastname: Prasad
authors.affiliation: Department of Orthopedics, Mayo Clinic, Rochester, Minnesota.
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Desy
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota.
authors.forename: B Matthew
authors.initials: BM
authors.lastname: Howe
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota.|Department of Radiology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Kimberly K
authors.initials: KK
authors.lastname: Amrami
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota.|Department of Orthopedics, Mayo Clinic, Rochester, Minnesota.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Spinner
mesh_terms: D000328:Adult; D003238:Connective Tissue / Q000000981:diagnostic imaging / Q000294:innervation*; D005260:Female; D005360:Fibula / Q000473:pathology; D045888:Ganglion Cysts / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007717:Knee / Q000000981:diagnostic imaging / Q000294:innervation*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D013977:Tibia / Q000473:pathology; D013979:Tibial Nerve / Q000473:pathology
keywords: MRI; fibular nerve; ganglion cysts; knee joint; tibial nerve