Filling A Critical Gap in Metastatic Spine Care: A Novel Classification System for Neoplastic Cauda Equina Compression.

STUDY

DESIGN

Cross-sectional survey and retrospective-cohort study (2010-21).

OBJECTIVES

We sought to:1) create a novel epidural cauda-equina compression (ECEC) grading system, 2) determine its inter/intrarater reliability, and 3) report its ability to predict preoperative neurologic status.

SUMMARY OF BACKGROUNDS DATA: While metastatic epidural spinal-cord compression is well characterized, ECEC remains poorly understood.

METHODS

Patients undergoing ECEC surgery were included. Severity was graded on axial MRI using a novel 4-point scale:Grade-0=Bone-only; Grade-1=Thecal sac indented<50% effaced; Grade-2=≥50% thecal sac effaced; Grade-3=Entire thecal sac effaced, no cerebrospinal fluid seen; +F modifier signified foraminal stenosis. Primary outcomes were inter/intrarater reliability, and the score's ability to predict baseline neurologic deficits. Reliability was assessed among spine surgeons, trainees, and radiation oncologists using intraclass correlation coefficient.

RESULTS

The survey included 9 spine-attendings, 7 trainees, and 4 radiation oncologists. Among 45 patients (mean age:61.6±10.6 y; 64.4% male), 15.5% each had Grade-1/2 compression, while 68.9% had Grade-3; foraminal stenosis was present in 82.2%. Grade 0-3: Overall inter/intrarater reliability was good at 0.635(95%CI:0.412-0.776) and 0.676(95%CI:0.503-0.810), with similar performance among spine-attendings (inter/intrarater:0.611;0.662), trainees (inter/intrarater:0.685;0.707), and radiation oncologists (inter/intrarater:0.634;0.679). Sensory deficits (28.6% vs. 28.6% vs. 16.1%,P=0.627), motor deficits (71.4% vs. 57.1% vs. 35.5%,P=0.171) and bowel/bladder disturbances (0% vs. 28.6% vs. 19.4%,P=0.346) were similar across grades. +F Modifier: Overall inter/intrarater reliability were poor at 0.350 (95%CI:0.180-0.505) and 0.391(95%CI:0.219-0.555), with fair reliability for spine-attendings (inter/intrarater:0.421;0.485), and trainees (inter/intrarater:0.414;0.443), and poor for radiation oncologists (inter/intrarater:0.259;0.299). Baseline neurological status showed no association with foraminal stenosis.

CONCLUSION

The novel ECEC grading system provides a reliable framework for characterizing metastatic ECEC, demonstrating good reliability for Grades-0-3 across spine surgeons, trainees, and radiation oncologists. Although compression grade was not associated with neurologic deficits, bowel/bladder deficit rates were non-significantly higher in Grades-2/3. Conversely, foraminal-modifier's poor reliability underscores limitations of static MRI in assessing foraminal stenosis. Overall, ECEC scale may enhance communication in describing neoplastic ECEC.