Intraoperative Ultrasound Elastography is a Promising Technology to Quantify Reduced Spinal Cord Tension During Posterior Vertebral Column Subtraction Osteotomy for Recurrent Tethered Cord Syndrome

INTRODUCTION: Tethered cord syndrome (TCS) has been traditionally treated with detethering surgery. 1,2 Posterior vertebral column subtraction osteotomy (PVCSO) is a novel surgery that can treat TCS while avoiding complications of detethering surgery, such as retethering or cerebrospinal fluid leaks. 2-6 The pathophysiology of PVCSO is not completely understood. However, the hypothesis is that shortening the vertebral column decreases the spinal cord (SC) tension thereby improving neurological function. Intraoperative ultrasound elastography (USE) is well suited to elucidate the changes that can occur in SC parenchyma secondary to PVCSO. 7,8 Through different modalities, such as superb microvascular imaging (SMI) and elastography (USE), US can analyze changes in blood flow and tissue tension. 9 METHODS: Three patients with recurrent TCS underwent PVCSO and intraoperative USE to analyze the tension of the SC at 3 timepoints: pre-, mid- and post-shortening. RESULTS: All three patients (two female, one male) had undergone multiple detethering surgeries. Prior to shortening, the median SC elasticity of all patients was 9.8 kPa (IQR 9.7-12.4 kPa). After complete compression of the rods, the SC elasticity decreased by 17.4% to 7.7 kPa (6.5-9.7 kPa). All patients had significant improvement in sensation and reduction in pain at their 2 month follow up appointment. CONCLUSIONS: Here we report the first use of USE to demonstrate decreased SC tension after PVCSO for TCS. All patients reported improved symptoms and USE demonstrated decreased SC tension after shortening. USE is a promising tool for evaluating tissue elasticity and blood flow in spinal pathologies, including TCS. This technology serves as an intraoperative confirmation that SC tension decreases after PVCSO. Patients and neurosurgeons both benefit from an intraoperative objective tool to demonstrate reduced SC tension.