{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,29]],"date-time":"2026-01-29T22:36:00Z","timestamp":1769726160831,"version":"3.49.0"},"reference-count":30,"publisher":"Journal of Neurosurgery Publishing Group (JNSPG)","issue":"25","license":[{"start":{"date-parts":[[2025,12,22]],"date-time":"2025-12-22T00:00:00Z","timestamp":1766361600000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J Neurosurg Case Lessons"],"published-print":{"date-parts":[[2025,12,22]]},"abstract":"\n BACKGROUND<\/jats:title>\n Recently, the distribution of subparaneurial ganglion cysts involving the common peroneal and tibial nerves was described based on MRI analysis. Crossover in extreme cases was observed at the sciatic bifurcation through a mechanism comparable to a geyser, enabled by fenestrations in the epi- and paraneurium at the level of the bifurcation. The goal of this study was to investigate whether the geyser theory for crossover holds for other locations.<\/jats:p>\n <\/jats:sec>\n \n OBSERVATIONS<\/jats:title>\n The authors\u2019 prospectively maintained database of > 1100 cases of intraneural ganglion cysts in the world\u2019s literature was queried for the existence of subparaneurial ganglion cysts at locations other than the knee. A previously unrecognized case involving the ulnar nerve originating from the elbow joint was found. Reinterpretation of the patient\u2019s MRI studies showed circumferential subparaneurial distribution of a cyst over a long distance. Based on their previously reported geyser theory, the authors wondered if crossover had occurred at the level of the medial cord. A fenestration in the epi- and paraneurium at this level was confirmed on histological analysis of a normal cadaveric specimen.<\/jats:p>\n <\/jats:sec>\n \n LESSONS<\/jats:title>\n This illustrative case shows that the geyser theory also holds in other locations. Surgical treatment of these subparaneurial cysts still follows the principles of the unified articular theory.<\/jats:p>\n \n https:\/\/thejns.org\/doi\/10.3171\/CASE25671<\/jats:ext-link>\n <\/jats:p>\n <\/jats:sec>","DOI":"10.3171\/case25671","type":"journal-article","created":{"date-parts":[[2026,1,22]],"date-time":"2026-01-22T11:59:55Z","timestamp":1769083195000},"source":"Crossref","is-referenced-by-count":0,"title":["Circumferential subparaneurial ganglion cyst involving the ulnar nerve at the elbow: illustrative case"],"prefix":"10.3171","volume":"10","author":[{"given":"Godard C. W.","family":"de Ruiter","sequence":"first","affiliation":[{"name":"Department of Neurosurgery, Haaglanden Medical Center, The Hague, The Netherlands"},{"name":"Department of Neurosurgery, Mayo Clinic, Rochester, Minnesota"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kimberly K.","family":"Amrami","sequence":"additional","affiliation":[{"name":"Department of Radiology, Mayo Clinic, Rochester, Minnesota"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9078-1020","authenticated-orcid":true,"given":"Miguel A.","family":"Reina","sequence":"additional","affiliation":[{"name":"CEU San Pablo University School of Medicine, Madrid, Spain"},{"name":"Department of Anesthesiology, University of Florida College of Medicine, Gainesville, Florida"},{"name":"Department of Anesthesiology, Madrid-Montepr\u00edncipe University Hospital, Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9739-1946","authenticated-orcid":true,"given":"Byung-chul","family":"Son","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, College of Medicine, Seoul St. Mary\u2019s Hospital, The Catholic University of Korea, Seoul, Republic of Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0443-7763","authenticated-orcid":true,"given":"Robert J.","family":"Spinner","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Mayo Clinic, Rochester, Minnesota"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1754","reference":[{"issue":"7","key":"bib1","series-title":"Clin Anat","first-page":"925","article-title":"The subparaneurial compartment: a new concept in the clinicoanatomic classification of peripheral nerve lesions","volume":"28","author":"Prasad","year":"2015","unstructured":"Prasad NKCapek Sde Ruiter GCWAmrami KKSpinner RJ.The subparaneurial compartment: a new concept in the clinicoanatomic classification of peripheral nerve lesions. Clin Anat. 2015;28(7):925-930."},{"issue":"4","key":"bib2","series-title":"Clin Anat","first-page":"530","article-title":"Subparaneurial ganglion cysts of the fibular and tibial nerves: a new variant of intraneural ganglion cysts","volume":"29","author":"Prasad","year":"2016","unstructured":"Prasad NKDesy NMHowe BMAmrami KKSpinner RJ.Subparaneurial ganglion cysts of the fibular and tibial nerves: a new variant of intraneural ganglion cysts. Clin Anat. 2016;29(4):530-537."},{"key":"bib3","series-title":"J Neurosurg","article-title":"Extreme subparaneurial ganglion cysts. Part 1: Principles and implications","author":"de Ruiter","year":"2025","unstructured":"de Ruiter GCWSon BCHayford KMExtreme subparaneurial ganglion cysts. Part 1: Principles and implications. J Neurosurg. Published online July 4, 2025. doi:10.3171\/2025.2.JNS242815"},{"key":"bib4","series-title":"J Neurosurg","article-title":"Extreme subparaneurial ganglion cysts. 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Neurosurg Focus. 2007;22(6):E17."},{"issue":"4","key":"bib7","series-title":"Skelet Radiol","first-page":"281","article-title":"The clinico-anatomic explanation for tibial intraneural ganglion cysts arising from the superior tibiofibular joint","volume":"36","author":"Spinner","year":"2007","unstructured":"Spinner RJMokhtarzadeh ASchiefer TKKrishnan KGKliot MAmrami KK.The clinico-anatomic explanation for tibial intraneural ganglion cysts arising from the superior tibiofibular joint. Skelet Radiol. 2007;36(4):281-292."},{"issue":"8","key":"bib8","series-title":"Clin Anat","first-page":"1133","article-title":"Elaborating upon the descent phase of fibular and tibial intraneural ganglion cysts after cross-over in the sciatic nerve","volume":"27","author":"Colombo","year":"2014","unstructured":"Colombo EVHowe BMAmrami KKSpinner RJ.Elaborating upon the descent phase of fibular and tibial intraneural ganglion cysts after cross-over in the sciatic nerve. 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J Neurosurg. 2007;107(2):296-307."},{"issue":"3","key":"bib11","series-title":"J Neurosurg","first-page":"615","article-title":"Intraneural ganglion cysts: a systematic review and reinterpretation of the world\u2019s literature","volume":"125","author":"Desy","year":"2016","unstructured":"Desy NMWang HElshiekh MAIIntraneural ganglion cysts: a systematic review and reinterpretation of the world\u2019s literature. J Neurosurg. 2016;125(3):615-630."},{"issue":"3","key":"bib12","series-title":"Indian J Neurosurg","first-page":"260","article-title":"Ulnar neuropathy due to intraneural ganglion cyst of the ulnar nerve a the elbow","volume":"7","author":"Son","year":"2018","unstructured":"Son BCChoi JGKo HC.Ulnar neuropathy due to intraneural ganglion cyst of the ulnar nerve a the elbow. Indian J Neurosurg. 2018;7(3):260-264."},{"key":"bib13","series-title":"Clin Anat","article-title":"Natural openings in the paraneurium and epineurium of the human sciatic nerve and their relationship to the entry and exit of blood vessels. A microanatomical study","author":"de Ruiter","year":"2025","unstructured":"de Ruiter GCWSpinner RJSala-Blanch XReina MA.Natural openings in the paraneurium and epineurium of the human sciatic nerve and their relationship to the entry and exit of blood vessels. A microanatomical study. Clin Anat. 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