Intraoperative ultrasound imaging in lumbar disc herniation surgery

The diagnosis of lumbar disc herniation has improved with metrizamide rhizography and CT. Also, visualization of the operative site has been enhanced with use of the operating microscope. However, evaluation of the completeness of herniated disc removal can be difficult, especially in the case of medially located lesions. Also, intradural extension of the herniation can be impossible to rule out in some cases without intradural exploration. Intraoperative ultrasound imaging is safe, rapid and readily available in most hospitals. Its application to real-time imaging control of 10 selected cases of herniated lumbar disc showed that the herniated material could be visualized in relation to the interspace and dural sac in all cases. The effect of removal of the herniation on nerve root compression could also be evaluated. Especially in cases involving extension of the herniation to the medial region under the dura, or into the intradural space, the removal of herniated material could be adequately confirmed without the need for further manipulation with surgical instruments. With appropriate transducer design and frequency, the method can be applied to microsurgical technique to rule out sequestration outside of the surgical exposure.