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Spine
Published in David A Lisle, Imaging for Students, 2012
Discography is used to prove that pain is arising from one or more intervertebral discs. Under fluoroscopic guidance, a fine needle is positioned in the centre of the intervertebral disc. A small amount of dilute contrast material is injected to ‘stress’ the disc. The patient’s pain response is recorded. Contrast material is used to assess the actual morphology of the disc and to diagnose annular tears.
Use of lasers in minimally invasive spine surgery
Published in Expert Review of Medical Devices, 2018
The basic approach of this procedure is the percutaneous anterior approach [44] (Figure 4). The rationale of this approach is based on the fact that the cervical prevertebral structures are highly mobile and well compartmentalized and this allows direct access to the disc space. The visceral axis, including the trachea, esophagus, thyroid, pharynx, and larynx, is easily displaced to the opposite side with one or two fingers. The vascular axis, including the carotid artery and the internal jugular vein, is also easily palpable and displaced laterally. There are no critical neural structures between the visceral axis and the vascular axis, and the cervical spine can be palpated by the surgeon’s index and middle fingers. The side of approach can be determined by the location of disc herniation, prevertebral anatomy, and surgeon’s convenience. After confirming needle placement by fluoroscopy, the stylet is withdrawn and intraoperative discography is performed with a mixture of indigo carmine and contrast media. From 0.5 to 1 mL of the mixture may be injected to opacify the posterior part of the disc. A guidewire is inserted through the needle channel into the disc and the needle is withdrawn. Then, a small stab incision is made and serial dilators from 1 to 4 mm are passed sequentially over the guidewire under fluoroscopic guidance. The final working cannula (diameter, 4 mm) is then introduced over the dilator. A working channel endoscope (Karl-Storz, Tuttlingen, Germany) is then inserted into the working cannula (Figure 4(a)). This is a 4-mm high-resolution endoscope with a 1.9-mm working channel and two irrigation channels. The central working channel is used for introduction of forceps and laser probe, and the other channels are for the input and output of irrigation fluid. The surgeon then inspects the intradiscal space through the endoscope and confirms the initial endoscopic anatomy. The herniated fragment is then removed using microforceps and a side-firing Ho:YAG laser under direct endoscopic visualization or via fluoroscopic guidance (Figure 4(b)). The side-firing laser offers three benefits: it prepares a clear operation visual field by sculpting the endplate and removing the osteophyte; it releases annular anchorage and fibrotic adhesion; it provides direct ablation of the hernia mass. As the decompression advances, the dural sac and exiting nerve root can be exposed. The side-firing laser could also ablate the osteophyte at the foraminal area, accomplishing foraminoplastic decompression. The endpoint of the procedure is exposure or free pulsation of the neural tissues. After confirming neural decompression, the wound is then closed with subcutaneous suture.