Intraoperative Ultrasound in Spinal Surgery

Summary

Here, we present a protocol on the use of intraoperative ultrasound in spinal surgery, particularly in cases of intradural lesions and lesions in the ventral spinal canal when using a posterior approach.

Abstract

Since the 1980s, there have been several reports for the use of intraoperative ultrasound as a useful adjunct in spinal surgery. However, with the advent of newer cutting-edge imaging modalities, the use of intraoperative ultrasound in spine surgery has largely fallen out of favor. Despite this, intraoperative ultrasound continues to provide several advantages over other intraoperative techniques such as magnetic resonance imaging and computed tomography including being more cost-effective, efficient, and easy to operate and interpret. Additionally, it remains the only method for the real-time visualization of soft tissue and pathologies. This paper focuses on the advantages of using intraoperative ultrasound, especially in cases of intradural lesions and lesions ventral to the thecal sac when approaching posteriorly.

Introduction

Ultrasound is one of the most common diagnostic tools in medicine, particularly for visualizing pathology in the abdomen, limbs, and neck. However, its use to investigate cranial and spinal lesions is not currently widely utilized. In 1978, Reid was the first to report the use of ultrasound to visualize cervical cord cystic astrocytoma¹. Here, scans were performed with the patient's neck flexed to allow opening of the intralaminar window. Four years later, in 1982, Dohrmann and Rubin reported the use of ultrasound intraoperatively to visualize the intradural space in 10 patients². Pathologies identified with intraope....

Protocol

The protocol illustrated here follows the guidelines of the human research ethics committee at Brigham and Women's Hospital.

1. Preoperative Protocol

1. Assess patients with spinal pathology in clinic and determine eligibility for spinal surgery. Perform neurological assessment and obtain CT or MRI scan to identify spinal lesion.
2. Include patients who have an intradural pathology such as schwannoma, ependymoma, meningioma, astrocytoma, etc.; or patients who have a ventral compressive extradural pathology, such as a ventral thoracic herniated disc, fracture fragments ventrally, or a spinal bony tumor with ventr....

Results

On normal spine ultrasound imaging, the dura is an echogenic layer that surrounds the anechoic spinal fluid. The spinal cord is distinguished by its homogenous appearance and low echogenicity which is surrounded by an echogenic rim. This echogenic rim is due to the density shift from the spinal fluid to the spinal cord. The central canal appears as a bright central echo, while exiting nerve roots appear highly echogenic, particularly at the cauda equina¹⁶. Intraope.......

Discussion

Intraoperative ultrasound in the spinal surgery has largely fallen out of favor with the advent of newer technology, however, it continues to provide several advantages over the other available imaging modalities such as MRI and CT^6,9,16,17,18. In addition to being inexpensive, in this protocol we also show that it is simple to use and can provide visualizatio.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Aloka Prosound 5 mobile ultrasound machine	Hitachi	N/A	any comparable devices on the market should suffice
UST-9120 transducer probe.	Hitachi	UST-9120	Has a 20mm diameter with 10 to 4.4 MHz frequency range (any comparable compatible transducer should suffice).