Intraoperative Ultrasound Imaging Characteristics in Severe Spinal Cord Compression Due to Spinal Metastasis

Introduction: The use of intraoperative tools to assess epidural decompression in cases of spinal cord compression due to spinal metastasis is sparsely documented in the literature. This study aims to identify and characterize intraoperative ultrasound imaging (ioUS) features during the resection of epidural tumors causing high-grade spinal cord compression

Methods: A retrospective review of ioUS obtained during surgery for spinal metastasis was collected. Image features assessed included the thickness of the subarachnoid space anterior and posterior to the spinal cord, anteroposterior and lateral diameters of the spinal cord, presence of spinal cord deformation, area of hyperechogenic signal within the spinal cord, and measurement of the angular deformation of the spinal cord in the sagittal plane. A chart review was performed to correlate the presence of clinical signs of myelopathy and neurologic deficit before and after surgery. Surgical data, such as estimated blood loss, neurophysiological changes, and procedure type, were documented.

Results: Eight patients with high-grade spinal cord compression due to metastasis were included. Seven patients had an Epidural Spinal Cord Compression (ESCC) grade 3, and one presented had ESCC grade 2. A mean separation of 6mm between the dura mater and the residual tumor was recorded. Additionally, an increase in the length of subarachnoid space up to 5 mm was documented, with a mean increase of 1.5 mm in the anterolateral compartments. The mean sagittal deformation angle after decompression was 172 degrees. The presence of hyperechoic punctuate areas in the white matter of the spinal cord correlated with the persistence of neurological deficits, which improved during the length of hospitalization compared to the pre-operative period.

Conclusion : Ventral and dorsal subarachnoid compartment length, spinal cord diameters, degree of spinal cord deformation, and area of hyper-echogenic signals are measurable parameters through ioUS during spinal cord decompression. Identification of these image features is the basis for evaluating the utility of ioUS as a prognostication tool for recovery of neurological function at the time of surgery for spinal cord decompression.