Akhnoukh Cervical Ultrasound Technique

Akhnoukh Cervical Ultrasound Technique

ACUT, Akhnoukh Cervical Endoscopic Discectomy, was designed to optimize a long-standing surgery by improving efficiency, accuracy, and most importantly safety. This technique uses ultrasonography as an imaging tool to successfully access the surgical site.

Initially, fluoroscopy is used to accurately identify the surgical level(s) for treatment. If the shoulders are obstructing the view, the shoulders should be taped to caudally displace them with an appropriate amount of tension. We start off in a lateral orientation in order to count the cervical vertebral bodies and identify the appropriate disc space(s). Once identified, the patient should be marked using a marking pen at the lowest disc space.

As with any surgery, Standard protocols are used for sterility and draping of the patient. The sheets and drapes utilized should only expose the anterior portion of the neck of the side, in which the surgery will take place. For the lateral approach, the practitioner should draw an imaginary line from the mastoid process to the midclavicular line of the appropriate side longitudinally and from this line out to the contralateral side of the trachea transversely.

After sterile precautions, the ultrasound is placed in a transverse orientation over the anterior aspect of the patient’s neck on the side of the designated approach. It is important to identify the following anatomical landmarks: trachea, esophagus, carotid artery, internal jugular vein, transverse process and depending on the desired disc space, the thyroid and its associated arteries and veins. the goal is to improve safety and efficacy in accessing the cervical spine. 

In beginning the surgery, we utilize the ultrasound in the orientation previously described to apply pressure on the trachea to deviate it away from the surgical site to the contralateral side and identify the carotid artery laterally. 

NOTE: make sure to identify any collateral vessels or thyroid vessels before penetrating the skin. Utilizing an out-of-plane technique, we enter with the 25 gauge needle lateral to the trachea and medial to the carotid artery avoiding any additional vessels. The out-of-plane technique, if used appropriately, allows us to visualize the needle tip and the shadow of the shaft of the needle. Using the local anesthetic we can then inject 5-10 mL in the tract to the surgical site, which will also assist in displacing the carotid artery further laterally.

At this point, we will exchange the needle for the 16 gauge access needle under direct visualization, using the same out-of-plane technique, between the trachea and carotid artery. As the needle approaches the surgical site, it is important that we course medially with the intent of resting the needle tip on the appropriate disc or adjacent vertebral body, which will be met with a degree of resistance. It is crucial that we identify the depth of the needle as it passes both the carotid artery and trachea utilizing the markings on the access needle. If at any point the needle is withdrawn passed this specific marker, it is recommended to utilize ultrasonography to re-access the surgical site in order to avoid puncturing any vital structures.

Once we have passed these vital structures and have met the appropriate resistance, we will utilize fluoroscopy again. Using fluoroscopy in the lateral position, we want to make sure that we are at the appropriate level and immediately anterior to the disc. We then will utilize the fluoroscopy in an AP position to identify the needle immediately lateral to the spinous process, which should be in the center of the disc. At this point, we can penetrate the disc space and administer contrast, with or without antibiotics, to confirm that we are in the contained disc space.

After we complete intradiscal access, we can now exchange the access needle over a guide wire. We then utilize an 11 mm blade scalpel in a longitudinal fashion immediately cephalad to the guide wire in order to exchange a trochar, dilator and working cannula, over the guide wire to avoid a dermal tear. Once, the trochar is in the 1/3 marker of the disc in a lateral view, the dilator can be removed. Additional tools can be introduced through the cannula to perform an endoscopic discectomy, and/or an ablation of the nucleus pulposus and annuloplasty using radiofrequency.

Depending on the proximity of additional levels, the guide wire may be reinsterted via an exchange through the cannula for the access needle. The access needle can be withdrawn to immediately anterior to the disc and can be walked up the next level. If unable to access the levels above with the same incision, the process can be restarted from the beginning by removing all the tools and creating a new access site.