title: Migration patterns of herniated disc fragments: a study on 1,020 patients with extruded lumbar disc herniation.
abstract: BACKGROUND
  Herniated disc fragments are known to migrate in various directions within the spinal canal. To date, no comprehensive studies have been undertaken to examine the migration patterns of herniated disc material using a standard nomenclature and classification system.
  
  
  OBJECTIVE
  To report migration patterns of extruded lumbar disc fragments.
  
  
  METHODS
  A review of magnetic resonance (MR) images.
  
  
  METHODS
  A total of 1,020 consecutive Azeri patients with symptomatic extruded lumbar intervertebral disc herniation.
  
  
  METHODS
  Migration patterns of extruded lumbar disc fragments in vertical and horizontal planes and their association with age, gender, body mass index (BMI), and the level of herniation.
  
  
  METHODS
  High-quality axial and sagittal MR images of the lumbar spine were used. Disc material that was displaced away from the site of extrusion, regardless of continuity, was considered "migrated." The migration patterns observed were rostral or caudal in the vertical plane and central, paracentral, subarticular, foraminal, or extraforaminal in the horizontal plane.
  
  
  RESULTS
  In the vertical plane, rostral and caudal migrations were observed in 27.8% and 72.2% of the patients, respectively. The number of rostral migrations increased significantly with increasing age and in higher levels in the lumbar spine (p<.001 for both). Radiculopathy was significantly more frequent in caudal migrations than in rostral migrations (78.9% vs. 65.1%, p<.001). There was no significant association between gender or BMI and migration patterns in the vertical plane. In the horizontal plane, central, paracentral, subarticular, foraminal, and extraforaminal migrations were reported in 17.3%, 74.2%, 4.3%, 2.5%, and 1.8% of the patients, respectively. The youngest (median age 39 years, interquartile range [IQR] 13 years) and the oldest (median age 55 years, IQR 15 years) groups of patients (p<.001) had the most formainal and extraforaminal migrations, respectively. Radiculopathy was present in 66.5%, 76.8%, 88.6%, 96%, and 27.8% of the patients with central, paracentral, subarticular, foraminal, and extraforaminal migrations, respectively (p<.001). No significant association was found between gender, BMI, or the level of herniation and migration pattern in the horizontal plane.
  
  
  CONCLUSIONS
  Caudal and paracentral migrations are the most common patterns of migration in patients with extruded lumbar disc herniation in the vertical and horizontal planes, respectively. Age and the level of herniation may affect the migration patterns of herniated lumbar disc material.
authors.affiliation: Department of Radiology, Tabriz University of Medical Sciences, Tabriz 51656-65811, Iran.
authors.forename: Mohammad Hussein
authors.initials: MH
authors.lastname: Daghighi
authors.affiliation: Department of Radiology, Tabriz University of Medical Sciences, Tabriz 51656-65811, Iran.
authors.forename: Masoud
authors.initials: M
authors.lastname: Pouriesa
authors.affiliation: Department of Radiology, Tabriz University of Medical Sciences, Tabriz 51656-65811, Iran.
authors.forename: Mirjalil
authors.initials: M
authors.lastname: Maleki
authors.affiliation: Drug Applied Research Center, Tabriz University of Medical Sciences, Pashmineh Building, Daneshgah St, Tabriz 51656-65811, Iran. Electronic address: medicorelax@yahoo.com.
authors.forename: Daniel Fadaei
authors.initials: DF
authors.lastname: Fouladi
authors.affiliation: Department of Community Medicine, Tabriz University of Medical Sciences, Tabriz 51656-65811, Iran.
authors.forename: Mohammad Zakaria
authors.initials: MZ
authors.lastname: Pezeshki
authors.affiliation: Department of Radiology, Urmia University of Medical Sciences, Resalat Boulevard, Jahad Street, Urmia 57147-83734, Iran.
authors.forename: Ramin
authors.initials: R
authors.lastname: Mazaheri Khameneh
authors.affiliation: Department of Neurosurgery, Urmia University of Medical Sciences, Resalat Boulevard, Jahad Street, Urmia 57147-83734, Iran.
authors.forename: Amir Mohammad
authors.initials: AM
authors.lastname: Bazzazi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000175:diagnosis*; D008159:Lumbar Vertebrae / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged
keywords: Age; Body mass index; Extrusion; Gender; Level of herniation; Lumbar disc herniation; Migration pattern