Intraoperative sonography of cervical spinal cord injury: results in 30 patients.

Abstract

Intraoperative spinal sonography (IOSS) with a 7.5-MHz sector transducer was performed in 30 patients with cervical spine injury associated with neurologic deficits. A laminectomy (25 patients) or anterior corpectomy (five patients) during spinal surgery provided the IOSS imaging window. The surgery was performed for either spinal decompression or fixation as part of the initial care of these patients and occurred 1 to 39 days (mean, 12.4 days) after injury. Parenchymal spinal cord lesions at the level of cervical fracture or stenosis that were compatible with the initial neurologic deficits were detected by IOSS in 28 (96.5%) of 29 patients with technically adequate studies. Lesions appeared as foci of increased echogenicity and were sorted into five injury grades (0 through IV). The IOSS injury grade in each patient was determined by the maximal diameter of regions of increased echogenicity and/or cyst formation in either the sagittal or transverse image plane. The extent of initial neurologic injury and its recovery was assessed by using the ASIA motor score (0 to 100 unit scale) at admission and during follow-up. The IOSS injury grade was correlated with the initial ASIA motor score (p less than 0.009, Spearman's Rank Order Test), indicating that the IOSS echogenicity is related to the extent of initial clinical motor deficit. Regression analysis disclosed that both the IOSS injury grade and the initial ASIA score were correlated with the follow-up ASIA score (p less than 0.05 and p less than 0.001, respectively). However, the the addition of IOSS injury grade to the initial ASIA motor score did not improve the predictive ability of the follow-up ASIA motor score. This was interpreted as indicating that the IOSS injury grade and initial ASIA motor score contain similar information about the extent of the traumatic spinal cord injury. IOSS was compared with concurrently performed cervical spine MR images in 12 patients. IOSS confirmed parenchymal lesions demonstrated by MR (five patients), revealed cord lesions not detected by suboptimal MR studies (three patients), and better characterized lesions with early cyst formation (two patients). IOSS did not detect possibly significant herniated intervertebral disks in two patients because of its limited field of view.