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Year : 2017  |  Volume : 9  |  Issue : 6  |  Page : 169-171

An intraoperative finding of double L5 nerve root

Department of Neurosurgery, Ali Omar Askar Hospital, Tripoli, Libya

Date of Web Publication8-Nov-2017

Correspondence Address:
Seraj Saleh Ajaj
Department of Neurosurgery, Ali Omar Askar Hospital, Tripoli
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijmbs.ijmbs_20_17

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Congenital anatomical anomalies of the lumbosacral nerve root are a rare condition. Various types of anomalies of the lumbosacral nerve roots have been described in the literature. Undiagnosed lumbosacral nerve root anomalies are at risk for iatrogenic injury, may contribute to wrong-site surgery, and contribute to continued postoperative symptoms. Here, we present the case of a 45-year-old female with discogenic back pain and L5 radiculopathy who found to have a duplicated left L5 nerve root intraoperatively.

Keywords: Conjoined nerve roots, foraminal disc protrusion, microdiscectomy, magnetic resonance neurography, nerve anomaly

How to cite this article:
Shaban AB, Atiyah Q, Ajaj SS. An intraoperative finding of double L5 nerve root. Ibnosina J Med Biomed Sci 2017;9:169-71

How to cite this URL:
Shaban AB, Atiyah Q, Ajaj SS. An intraoperative finding of double L5 nerve root. Ibnosina J Med Biomed Sci [serial online] 2017 [cited 2022 Aug 9];9:169-71. Available from: http://www.ijmbs.org/text.asp?2017/9/6/169/217867

  Introduction Top

Lumbosacral nerve anomalies are a rare phenomenon. Among these, conjoined nerve roots (CNRs) are by far the most common anomaly, and this is a distinct entity from duplicated nerve roots which represent a very small subset of nerve root anomalies. The term “CNR” refers to the roots that emerge from the dura in a common root sleeve that bifurcates after leaving the dura and exits through the foramen by showing different courses or making anastomoses between the nerve roots. The first anatomical description of CNR was provided by Zagnoni in 1949.[1] Here, we present the case of a patient with an intraoperative diagnosis of duplicated left L5 root, resulting in modification of the intended surgical plan.

  Case Report Top

A 45-year-old female presented to our outpatient clinic complaining of severe low back pain, radiating to her lower limbs, associated with muscle weakness and numbness mainly at the L4, L5, and S1 dermatomes on the left side. The patient was unable to walk and move normally and these symptoms did not relieve by the medications, physiotherapy, or rest. On examination, the patient was conscious, oriented with a good verbal contact, and the cranial nerves were intact from both sides. Straight leg raising test was positive from the both sides at 25°. Reflexes in her lower limbs were diminished. Hypoesthesia was noted at the L4, L5 dermatome bilaterally mainly from the left lower limb. On radiological investigations, plain radiograph of the lumbosacral spine showed mild degeneration of the spinal vertebrae. Magnetic resonance imaging (MRI) of the lumbosacral spine showed herniated disc at L5–S1 level lumbar spine [Figure 1]a and [Figure 1]b and foraminal stenosis. She was consented and scheduled for L5–S1 laminotomy and microdiscectomy. L5–S1 laminotomy revealed a hypertrophic ligamentum flavum crowding the L5 foramen. L5 foraminotomy revealed duplicate nerve roots exiting separately from the thecal sac and traveling to the L5 foramen within separate nerve root sleeves as shown in [Figure 2]a and [Figure 2]b. After the operation, she reported resolution of her radicular pain and was ambulatory with the assistance of a walker by postoperative day 3 and discharged to inpatient rehabilitation on the 5th postoperative day.
Figure 1: Magnetic resonance imaging, sagittal T2-weighted image, demonstrating herniated disc at L5–S1 level lumbar spine (a) and left foraminal disc protrusion (b)

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Figure 2: Intraoperative microscopic view showing (a) double nerve root (two white arrows) exiting from the left L5 intervertebral foramen (head white arrow) and (b) double nerve root (two white arrows) exiting separately from the left L5 intervertebral foramen

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  Discussion Top

Cannon et al. classified lumbosacral anomalies into three groups according to their courses: conjoined roots, a transverse course of the root, and anastomoses between roots.[2] Lumbosacral anomalies were also classified by Neidre and MacNab.[3] The latter classification is the most commonly used in clinical practice. According to Neidre and MacNab classification, Type 1 anomalies are CNR and are the most common anomaly reported in the literature; CNRs are further subdivided into those that arise from a common dural sheath (Type 1A) and those that have origins very close together on the thecal sac but do not share a common dural sheath (Type 1B). Type 2 anomalies involve redundant or “twinned” nerve roots, a situation in which two nerve roots exit through one intervertebral foramen. Type 2 nerve roots are further subdivided according to the presence of an extra root. If an extra nerve root is not present, the twinning in the intervertebral foramen will leave one foramen with no nerve roots passing through it (Type 2A). If an extra nerve root is present, it occupies the would-be empty foramen so that all the foramina are occupied (Type 2B). Type 3 anomalies involve otherwise normal nerve roots that have an anastomosis or bridging connection between two adjacent roots [Figure 3].
Figure 3: Artistic representation of the three classes described by Neidre and Macnab: Type 1A, conjoined nerve root originating from the rostral nerve root itself rather than from the thecal sac; Type 1B, conjoined nerve root arising from the thecal sac near the caudal nerve root; Type 2A, two nerve roots exiting from the same neural foramen, leaving one unoccupied neural foramen; Type 2B, two nerve roots exiting from one neural foramen with all the other foramina occupied; and Type 3, two adjacent nerve roots with an anastomosis between them

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Therefore, our case is most likely a representative of Neidre and MacNab's Type 2A anomaly with duplicated L5 roots. Radiologically, MRI is the gold standard for differentiating CNR anomalies from other space-occupying processes. The density of nerve roots is almost identical to that of the thecal sacs and is considerably less dense than that of disc materials. Several signs have been proposed to help in the preoperative diagnosis of CNRs on MRI. These include the sagittal shoulder sign, the fat crescent sign, corner sign, and the parallel sign,[4],[5] but the sensitivity of these findings has been contested. Another modality for diagnosis is MR neurography which affords direct imaging demonstration of the conjoined nerves and their different variations, and the protocol includes a coronal three-dimensional fat-suppressed imaging sequence apart from sagittal T2-weighted (T2W) and axial T2W images. Coronal imaging identifies the nerves along their long axis as they exit the thecal sac.[6] It therefore makes it easy to appreciate the neural variations including CNRs and makes it more conspicuous.

The operative management of these anomalies depends on the neurological problems and the clinical conditions existing in each individual case.[7] Asymptomatic and accidentally diagnosed cases do not require treatment. Intervertebral disc herniations, associated with root anomalies (with or without bony alterations), have to be treated in order to relieve neurological signs and symptoms. In these cases, an adequate exposure of the roots involved to avoid persistent compression as well as to reduce any traction may be necessary, keeping in mind that a hemilaminectomy with sufficient exposure of the intervertebral foramen or of the lateral recess should be performed to avoid the alterations of stability and to ensure correct mobility of the lumbosacral spine. In fact, in the presence of nerve root anomalies, a wide exposure by hemilaminectomy is necessary. It allows an adequate visualization and mobilization of the involved roots and aids in the definition of the conjoined roots and their origin, thus avoiding the risk of laceration and excessive traction.[7] Since a possible concomitant spinal stenosis may be often associated with a herniated disc, unroofing of the lateral recess, foraminotomy, and medial facetectomy are necessary to obtain a good decompression and mobilization of the roots. When the abnormal configuration and fixation of the roots (clearly depicted by computed tomography and MRI preoperative studies) prevents an adequate exposure of the disc space on the involved side, the removal of the herniated disc through a contralateral laminotomy may be advisable.[8]

  Conclusion Top

Duplicate lumbosacral nerve roots are uncommon anomalies. The clinical and radiographic presentation is often consistent with herniated lumbar discs which can be comorbid. The surgeon must remain cognizant of the broad differential diagnosis for herniated discs. This is particularly true when employing minimally invasive methods which may limit the intraoperative view and further reduce the likelihood of making an intraoperative diagnosis which increases the risk for iatrogenic injury, may contribute to wrong-site surgery, and contribute to continued postoperative symptoms.


The authors are grateful to the patient and her family for consent to publication and use of the photographs.

Authors' contributions

All authors contributed to drafting of the report, its revision, and final approval.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

Compliance with ethical principles

No prior institutional review board approval is required at our hospital for single case reports. However, the patient and her family consented to anonymous publication of the case.

  References Top

Zagnoni C. A finding of an unknown type of nerve anastomosis of the spinal roots. Padova Atti Soc Med Chir 1949;27:48-52.  Back to cited text no. 1
Cannon BW, Hunter SE, Picaza JA. Nerve-root anomalies in lumbar-disc surgery. J Neurosurg 1962;19:208-14.  Back to cited text no. 2
Neidre A, MacNab I. Anomalies of the lumbosacral nerve roots. Review of 16 cases and classification. Spine (Phila Pa 1976) 1983;8:294-9.  Back to cited text no. 3
Gomez JG, Dickey JW, Bachow TB. Conjoined lumbosacral nerve roots. Acta Neurochir (Wien) 1993;120:155-8.  Back to cited text no. 4
Lotan R, Al-Rashdi A, Yee A, Finkelstein J. Clinical features of conjoined lumbosacral nerve roots versus lumbar intervertebral disc herniations. Eur Spine J 2010;19:1094-8.  Back to cited text no. 5
Soldatos T, Andreisek G, Thawait GK, Guggenberger R, Williams EH, Carrino JA, et al. High-resolution 3-T MR neurography of the lumbosacral plexus. Radiographics 2013;33:967-87.  Back to cited text no. 6
Maiuri F, Gambardella A. Anomalies of the lumbosacral nerve roots. Neurol Res 1989;11:130-5.  Back to cited text no. 7
Postacchini F, Urso S, Ferro L. Lumbosacral nerve-root anomalies. J Bone Joint Surg Am 1982;64:721-9.  Back to cited text no. 8


  [Figure 1], [Figure 2], [Figure 3]

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