title: MR imaging of foraminal and extraforaminal lumbar disk herniations.
abstract: Foraminal and extraforaminal disk herniations are less frequent than intraspinal herniations at the lumbar level and more difficult to diagnose. They are undetected by myelography and distinction between them and an enlarged nerve root may be difficult with CT. Thirty-three patients presenting with persistent radiculopathy and showing an image suggesting a far lateral disk herniation on CT at 34 disk levels were prospectively imaged with magnetic resonance (MR). In all cases the disk fragment was identified and its separation from the nerve root was possible. This separation was more readily visible on sagittal or angled coronal views. The exact location of the herniation in relation to the facet joints and the pedicles was best assessed with MR: Ten were purely intraforaminal, 8 extraforaminal, and 15 both. Cephalad migration was noted on the sagittal lateral facet plane in 71% of cases. Surgical correlations were available for 25 disks. Three were falsely positive for disk herniation. Enlarged foraminal veins were responsible for this appearance as confirmed by surgery in two of these. When a prediction of disruption of the lateral extension of the posterior longitudinal ligament was made, it was confirmed at surgery in 52% of cases because of extreme lateralization of the herniations.
authors.affiliation: Service de Radiologie, Hôpital Pellegrin, Bordeaux, France.
authors.forename: N
authors.initials: N
authors.lastname: Grenier
authors.forename: J F
authors.initials: JF
authors.lastname: Gréselle
authors.forename: C
authors.initials: C
authors.lastname: Douws
authors.forename: J M
authors.initials: JM
authors.lastname: Vital
authors.forename: J
authors.initials: J
authors.lastname: Sénégas
authors.forename: J
authors.initials: J
authors.lastname: Broussin
authors.forename: J M
authors.initials: JM
authors.lastname: Caillé
mesh_terms: D000328:Adult; D000368:Aged; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000175:diagnosis* / Q000601:surgery; D008159:Lumbar Vertebrae / Q000473:pathology / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009942:Organometallic Compounds; D004369:Pentetic Acid; D011237:Predictive Value of Tests
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D004369:Pentetic Acid; D019786:Gadolinium DTPA