 |
 |
 |
|
| home | CME | help | feedback | subscriptions | archive |
|
© 1999 The Journal of Bone and Joint Surgery, Inc. Partial Avulsion of the Cauda Equina Associated with a Lumbosacral Fracture-Dislocation. A Case Report*  , CHIBA, JAPANInvestigation performed at Funabashi-Municipal Medical Center, Chiba
Avulsion of the lumbosacral nerve roots is rare. Since 1960, when, we believe, a case was reported for the first time, only thirty-five of these avulsions have been reported2,3,5,6, to our knowledge. In most patients, unilateral avulsion of the lumbosacral nerve roots is associated with a fracture of the pelvis and the lower limb. The diagnosis of a nerve-root avulsion is difficult to confirm. Radiographic evidence of a pseudomeningocele is the most reliable sign of such an avulsion, but a pseudomeningocele is not always present6. The role of magnetic resonance imaging and computed tomography myelograms in the diagnosis of nerve-root avulsions is unclear. We report the case of a patient who had a partial avulsion of the cauda equina associated with a lumbosacral fracture-dislocation that was diagnosed with magnetic resonance imaging and computed tomography myelograms.
A nineteen-year-old man was first seen at the Funabashi-Municipal Medical Center in Chiba, Japan, after he had sustained a lumbosacral fracture-dislocation and fractures of the left second, third, and fourth lumbar transverse processes in a motor-vehicle accident (Figs. 1-A and 1-B). He was transported by ambulance and arrived at the hospital about thirty minutes after the accident. The initial neurological examination revealed flaccid paralysis and a complete sensory deficit from the second lumbar level (including the second lumbar nerve) caudally and the absence of reflexes in the knee and ankle of both lower limbs. He had no control of bladder and bowel function, and he had loss of sphincter tone. A computed tomography scan demonstrated a horizontal fracture at the base of the inferior articular process of the fifth lumbar lamina with a unilateral jumped-and-locked facet joint on the left between the fifth lumbar and first sacral vertebrae, with a resultant rotatory instability due to the fracture of the superior articular process of the first sacral vertebra.
The patient was managed in bed with a mat rolled under the back. Sixteen kilograms of skeletal traction was applied to the distal aspects of the femora, and a successful reduction was achieved. Steroids (twenty milligrams of Solu-Cortef [hydrocortisone sodium succinate] per kilogram of body weight) were administered intravenously, but this therapy was discontinued two days after the injury because a complete ileus developed. A neurological examination performed seven days after the injury showed recovery of the sensory function of the second and third lumbar nerve roots and paresthesia of the fourth lumbar dermatome. The strength of the iliopsoas and quadriceps muscles was fully recovered within one week, but weakness of the gluteal and hamstring muscles (grade 3 of 5) and of the tibialis anterior and gastrocnemius-soleus muscles (grade 0 of 5) persisted. The patellar ligament reflex returned, but the Achilles tendon reflex did not. An electromyogram made two weeks after the injury showed no voluntary action potential in the fifth lumbar myotome or those caudad to it. As the fracture-dislocation would not have caused the initial neurological findings, we proceeded with a detailed radiographic assessment of the spine and its neural elements. A magnetic resonance imaging scan made one week after the injury revealed an area of high signal intensity in the conus medullaris that was consistent with a hematoma on the T1 and T2-weighted images (Figs. 2-A and 2-B). Two weeks after the injury, the cauda equina could not be visualized in the dural sac on myelograms or computed tomography myelograms and only the fifth lumbar nerve roots were apparent at the fourth lumbar level (Fig. 3-A). Both the fourth and the fifth lumbar nerve roots were seen at the third lumbar level (Fig. 3-B), and the third, fourth, and fifth lumbar nerve roots were seen at the second lumbar level (Fig. 3-C). We could not visualize any first or more caudad sacral nerve roots at any level. These findings on the computed tomography myelograms suggested the diagnosis of partial avulsion of the cauda equina from the conus medullaris.
Although the postural reduction was initially successful, the reduction of the fifth lumbar vertebra on the first sacral vertebra could not be maintained because of the instability of the fracture. Therefore, open reduction, a modified laminaplasty of the fourth lumbar vertebra, and posterolateral arthrodesis of the fifth lumbar through first sacral vertebrae with pedicle-screw instrumentation was performed eighteen days after the injury. Most of the cauda equina was found to be avulsed from the conus medullaris with extrusion of the multiple nerve roots through the fracture of the fifth lumbar lamina. The dural sac was torn at the level of the fracture-dislocation. To improve visualization and to document the nerve-root injury, we performed a modified laminaplasty of the fourth lumbar vertebra—that is, we opened the lamina to visualize the dura and then replaced the lamina—and a durotomy. Only the fifth lumbar nerve roots were intact bilaterally. In order to confirm the avulsion of the cauda equina, it would have been preferable to perform a laminaplasty at the location of the conus medullaris. However, it was impossible to carry out such a laminaplasty without making another incision. Therefore, a laminaplasty was performed on the fourth lumbar vertebra. A groove was made on the left lamina to create a hinge. Next, the right lamina was cut. Then the fourth lumbar lamina was opened like a door, and a durotomy was performed. The opened lamina was repaired with 1-0 nylon thread. Postoperatively, the patient was managed with bed rest for three weeks and he wore a thoracolumbosacral orthosis brace for six months. Eighteen months after the operation, fusion of the spine from the fifth lumbar to the first sacral vertebra was radiographically evident and there was no loss of reduction. Although there was no further neurological recovery, the patient was able to walk a short distance with use of crutches and a knee-ankle-foot orthosis on each lower limb.
Traction injuries of the lumbosacral nerve roots are rare because the stability of the osseous pelvis and the lower limbs protect the nerve roots from sudden tensile loads. Since Finney and Wulfman1 first reported a case of avulsion of the lumbosacral nerve roots in 1960, all thirty-five cases that we know of were associated with severe disruption of the pelvis2,3,5,6 or the lower extremity6, resulting in unilateral neural injuries. In most patients, the shear and rotatory forces on the limb caused tension on the nerves of the lumbar and sacral plexuses. If the load is transferred up to the root sleeves, avulsion at this level of the nerves is possible. The site of neural disruption is difficult to document. In a report on a small series of patients, Goodell speculated that the rupture of the nerve root occurred near or beyond the intervertebral foramina2. Huittinen studied autopsy specimens from individuals who had a severe pelvic fracture and found that nerve ruptures occurred between the spinal ganglion and the lumbar enlargement of the spinal cord5. He did not note nerve-root avulsions from the spinal cord. Most investigators have diagnosed nerve-root avulsion by detection of a pseudomeningocele on delayed myelography and computed tomography myelograms. Moossy et al. reported on six patients with spinal transverse-process fracture and pelvic trauma in whom operative exploration of the conus medullaris revealed avulsion of the cauda equina from the conus medullaris6. All of the avulsions were caused by extraforaminal nerve traction. In our patient, the vertebral dislocation caused severe traction on the intradural cauda equina. Although Moossy et al. directly visualized the avulsion, we diagnosed the pathoanatomy in our patient by assessing the number of nerves in the spinal canal on computed tomography myelograms. The laminaplasty and durotomy of the fourth lumbar vertebra allowed us to confirm these radiographic findings at the time of the operation. Disruptive or compressive injuries of the cauda equina are often associated with fracture-dislocations caudad to the second lumbar vertebra. Holdsworth and Hardy classified nerve injuries of the thoracolumbar spine as a complete division of the sacral cord and all lumbar nerve roots at the thoracolumbar junction, as a complete division of the sacral cord with escape of the nerve roots on one side or both sides, or as an incomplete division of the sacral cord with escape of the nerve roots4. We believe that this is the first report of a partial avulsion of the cauda equina associated with a lumbosacral fracture-dislocation that was diagnosed preoperatively with radiographic imaging studies.
*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.
  CiteULike  Connotea  Del.icio.us  Facebook  Technorati  Twitter What's this?
This article has been cited by other articles:
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Top
Introduction
Case Report
| home | CME | help | feedback | subscriptions | archive | site index |
|
Stanford University Libraries' HighWire Press (TM) assists in the publication of JBJS Online. |