Does an intraoperative finding of an intact dural sac help to prognosticate neurological recovery in cauda equinal and epiconal injuries in thoracolumbar fractures? An analysis of 31 patients

Objective: To evaluate the effect of integrity of dural sac in determining motor neurological recovery in patients with cauda equinal and epiconal injuries in vertebral fractures at thoracolumbar junction.

Methods: Thirty-one patients with single-level vertebra fracture over T12-L2 with cauda equinal or epiconal injuries that underwent posterior spinal decompression and stabilization were evaluated in the period between 2006 and 2012. All patients included had motor incomplete ASIA C in neurology and were either Type B or C (AO/Magerl classification) of fracture morphology. Radiologist opinion to confirm the level of conus in MRI was done preoperatively. Intraoperative findings with respect to intactness of dura was noted. All MRI images were postoperatively evaluated by an independent, blinded radiologist for evidence of dural breach caused by the trauma. All participants provided basic demographic data, ambulatory status, and current neurology and received neurologic examination at intervals. The differences in neurologic injury sites and functional walkers in patients with different levels of vertebral injury were analyzed. Receiver operating characteristic curve analysis was used to define the cut-off value of lower extremities motor score (LEMS) in functional walkers and non-walkers. All patients were seen at a postoperative follow-up of minimum 18 months.

Results: Data of the 31 patients were analyzed. Seventeen patients (55%) had epiconus and lumbar roots lesions and 14 (45%) had cauda equina lesions. The injury was at the T12 vertebra in 9 patients (29%), L1 in 12 (39%) and in L2 in 10 patients (32%). Mean LEMS for patients with T12, L1, and L2 fractures were calculated. Fourteen patients had intraoperative findings of intact dura as against 17 patients with dural breach. MRI images when revisited by an independent radiologist by keeping him blind about the intraoperative surgeons findings showed statistically very good interobserver agreement (κ = 0.618) with regard to integrity of the dural sac. Postoperative neurological assessment at minimum 18 months follow-up showed that four out of the 14 patients with intact dura were walkers (28%) whereas of the 17 patients with dural breach, 13 were walkers (82%).

Conclusion: Neurological recovery in cauda equinal and epiconal injuries in thoracolumbar fractures is significantly less likely in an intact dural sac, probably because the dural breach prevents the roots to take as much impact as compared to an intact dural sac.