title: A radiological classification system for intraneural vascular anomalies: assessment of potential for resection with high-resolution MRI.
abstract: BACKGROUND
  Intraneural hemangiomas and vascular malformations are rare, with approximately 50 cases reported in the literature. They present a therapeutic challenge; surgical resection can result in damage to the nerve and lesion recurrence is common. We introduce a new framework to classify intraneural vascular anomalies in relation to the anatomic compartments of the nerve and assess amenability to surgical resection.
  
  
  METHODS
  We retrospectively reviewed cases of intraneural hemangiomas and vascular malformations treated at our institution between 2003 and 2013 that had high-resolution 3-T magnetic resonance imaging (MRI). A review of the literature was also performed. Our cases and reports in the literature with available MRI data were sub-categorized according to their relationship to the paraneurium and epineurium of the nerve.
  
  
  RESULTS
  Nine patients were identified with intraneural (subparaneurial or subepineurial) vascular lesions. Two patients had a predominantly subparaneurial involvement of the nerve, six patients had predominantly subepineurial involvement, and one patient exhibited extensive involvement in both compartments. Four patients were managed surgically and the rest conservatively. Targeted resection of two subparaneurial hemangiomas provided complete relief of symptoms and freedom from recurrence at 18 month and 24 months respectively. One patient with extensive subepineurial and extraneural vascular malformations did not appear to benefit from sub-total resection with interfascicular dissection. No surgical morbidity was noted in any of the cases.
  
  
  CONCLUSIONS
  We believe that the subparaneurial compartment-a potential space between the epineurium and paraneurium-provides a tissue plane within which benign vascular lesions can occur. Hemangiomas and vascular malformations are complex and can occupy different intraneural and extraneural compartments. The anatomic framework aids surgical decision-making and ensures that all components of the lesion are considered. We advocate a multimodal approach in the treatment of these rare lesions.
authors.affiliation: Department of Neurosurgery, Mayo Clinic Rochester, Gonda 8-214, Rochester, MN, 55905, USA.
authors.forename: Nikhil K
authors.initials: NK
authors.lastname: Prasad
authors.affiliation: Department of Orthopedic Surgery, Wake Forest Medical Center, Winston-Salem, NC, USA.
authors.forename: Aditya
authors.initials: A
authors.lastname: Chawla
authors.affiliation: Department of General Surgery, Jewish Hospital, Cincinnati, OH, USA.
authors.forename: Sepehr
authors.initials: S
authors.lastname: Lalezari
authors.affiliation: Department of Neurosurgery, Medical Center Haaglanden, The Hague, The Netherlands.
authors.forename: Godard C
authors.initials: GC
authors.lastname: de Ruiter
authors.affiliation: Department of Radiology, Mayo Clinic Rochester, Rochester, MN, USA.
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Howe
authors.affiliation: Department of Radiology, Mayo Clinic Rochester, Rochester, MN, USA.
authors.forename: Kimberly K
authors.initials: KK
authors.lastname: Amrami
authors.affiliation: Department of Neurosurgery, Mayo Clinic Rochester, Gonda 8-214, Rochester, MN, 55905, USA. spinner.robert@mayo.edu.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Spinner
mesh_terms: D005260:Female; D006391:Hemangioma / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010524:Peripheral Nervous System Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000601:surgery; D011859:Radiography; D055815:Young Adult
keywords: Hemangiomas; Magnetic resonance imaging; Peripheral nerves; Vascular malformations