Surgical management of sciatica involving anomalous lumbar nerve roots

Conjoined lumbosacral nerve root: a case report

BACKGROUND

In patients with conjoined nerve roots, hemilaminectomy with sufficient exposure of the intervertebral foramen or lateral recess is required to prevent destabilization and ensure correct mobility of the lumbosacral spine. To the best of our knowledge, no case reports have detailed the long-term course of conjoined nerve roots after surgery.

CASE PRESENTATION

We report the case of a 51-year-old Japanese man with a conjoined nerve root. The main symptoms were acute low back pain, radiating pain, and right leg muscle weakness. Partial laminectomy was performed with adequate exposure to the conjoined nerve root. The symptoms completely resolved immediately after surgery. However, the same symptoms recurred 7 years postoperatively. The nerve root was compressed because of foraminal stenosis resulting from L5-S disc degeneration. L5-S transforaminal lumbar interbody fusion was performed on the contralateral side because of an immobile conjoined nerve root. At 44 months after the second surgery, the patient had no low back pain or radiating pain, and the muscle weakness in the right leg had improved.

CONCLUSIONS

This is the first report of the long-term course of conjoined nerve root after partial laminectomy. When foraminal stenosis occurs after partial laminectomy, transforaminal lumbar interbody fusion from the contralateral side may be required because of an immobile conjoined nerve root.

Intraspinal characteristics of thoracic spinal nerve roots anomalies

Purpose: The anomalous anatomical arrangement of the thoracic spinal nerve roots within the spinal canal can complicate the surgical treatment of several pathologies. The aim of this work was to reveal intraspinal anatomical variations of the thoracic spinal nerve roots.Methods: Anatomical study on 43 cadavers with a mean age of 53.7. After opening the spinal canal and dural sac, intradural and extradural anomalies of the thoracic spinal nerve roots were documented. Extradural communicating branches were excised, histologically processed and examined for the presence of nervous tissue.Results: We found 14 cases (32.6%) of intraspinal thoracic nerve root variations: intradural in 8 cases (18.6%), intradural communicating branches in 3 cases (6.97%), extradural anatomical variations occurred 6 cases (13.95%), 2 cases (4.65%) had extradural communicating branches between the nerve roots, 1 case had simultaneous occurrence of intradural and extradural communications (0.23%). All the results are differentiated according to the plexus type. In macroscopic extradural thoracic communicating branch had no nervous tissue on microscopy.Conclusions: This study describes intraspinal anatomical variations of thoracic spinal nerve roots. Knowledge of these variables should help prevent the failure of several medical procedures.

Intraspinal intradural variations of nerve roots

PURPOSE

The aim of this work is to point out the intraspinal anatomical variations of nerve roots and their possible participation in radiculopathy.

METHODS

The anatomical study was performed in 33 cadavers. There were 25 male cadavers aged 30-75 years and 8 female cadavers aged 45-77 years, with a mean age of 46.5 years to 24 h from death. All intradural rami communicantes between nerve roots were excised and examined histologically for the presence or absence of nervous tissue. The type of the plexus was defined by subtracting from the root C2.

RESULTS

Findings of the normotype of plexus formation occurred in 24 cases (72.7%). Variations in its formation were observed in nine cases (27.3%). The prefixed type was observed in six cases (18.2%), postfixed type in three cases (9.1%). The formation of isolated prefixed or postfixed type of the brachial and lumbosacral plexus was not observed. Anatomical preparations revealed intradural variations in all cases of the lumbosacral plexus, 22 times (66.7%) in cases of cervical roots, and in the thoracic region seven times (21.2%). Variations occurred more frequently in variations of plexus formation.

CONCLUSIONS

This study allowed us to identify and describe unpublished intraspinal intradural anatomical variations of nerve roots, and their interrelationships throughout the spinal canal with their potential influence on the clinical picture. Anatomical preparations revealed a higher incidence of intraspinal intradural variations, particularly between sacral roots. Reliance of their incidence of the plexus type was observed.

Nerve root anomalies: implications for transforaminal lumbar interbody fusion surgery and a review of the Neidre and Macnab classification system

Lumbar nerve root anomalies are uncommon phenomena that must be recognized to avoid neural injury during surgery. The authors describe 2 cases of nerve root anomalies encountered during mini-open transforaminal lumbar interbody fusion (TLIF) surgery. One anomaly was a confluent variant not previously classified; the authors suggest that this variant be reflected in an amendment to the Neidre and Macnab classification system. They also propose strategies for identifying these anomalies and avoiding injury to anomalous nerve roots during TLIF surgery. Case 1 involved a 68-year-old woman with a 2-year history of neurogenic claudication. An MR image demonstrated L4–5 stenosis and spondylolisthesis and an L-4 nerve root that appeared unusually low in the neural foramen. During a mini-open TLIF procedure, a nerve root anomaly was seen. Six months after surgery this patient was free of neurogenic claudication. Case 2 involved a 60-year-old woman with a 1-year history of left L-4 radicular pain. Both MR and CT images demonstrated severe left L-4 foraminal stenosis and focal scoliosis. Before surgery, a nerve root anomaly was not detected, but during a unilateral mini-open TLIF procedure, a confluent nerve root was identified. Two years after surgery, this patient was free of radicular pain.

Clinical features of conjoined lumbosacral nerve roots versus lumbar intervertebral disc herniations

Unidentified nerve root anomalies, conjoined nerve root (CNR) being the most common, may account for some failed spinal surgical procedures as well as intraoperative neural injury. Previous studies have failed to clinically discern CNR from herniated discs and found their surgical outcomes as being inferior. A comparative study of CNR and disc herniations was undertaken. Between 2002 and 2008, 16 consecutive patients were diagnosed intraoperatively with CNR. These patients were matched 1:2 with 32 patients diagnosed with intervertebral disc herniations. Matching was done according to age (within 5 years), gender and level of pathology. Surgery for patients with CNR or disc herniations consisted of routine microsurgical techniques with microdiscectomy, hemilaminotomy, hemilaminectomy and foraminotomy as indicated. Outcomes were measured using the Oswestry Disability Index and the Short Form-36 Questionnaire. Clinical presentation, imaging studies and surgical outcomes were compared between the groups. Conjoined nerve root's incidence in this study was 5.8% of microdiscectomies performed. The S1 nerve root was mainly involved (69%), followed by L5 (31%). Patients with CNR tended to present with nerve root claudication (44%) compared to the radiculopathy accompanying disc herniations (75%). Neurologic deficit was less prevalent among patients with CNR. Nerve root tension tests were not helpful in distinguishing between the etiologies. Radiologist's suspicion threshold for nerve root anomalies was low (0%) and no coronal reconstructions were obtained. The surgeon's clinical suspicion accurately predicted 40% of the CNRs. Surgical outcomes did not differ between the cohorts regarding the rate of postoperative improvement, but CNR patients showed a trend toward having mildly worse long-term outcomes. Suspecting CNRs preoperatively is beneficial for appropriate treatment and avoiding the risk of intraoperative neural injury. With nerve root claudication and imaging suggestive of a "disc herniation", the surgeon should be alert to the differential diagnosis of a CNR. Treatment is directed at obtaining adequate decompression by laminectomy and foraminotomy to relieve the lateral recess stenosis. Outcomes can be expected to be similar to routine disc herniations.