PERCUTANEOUS retrograde cannulation of the internal jugular vein (IJV) is a widely used technique for cerebral venous sampling in intensive care treatment of head-injury patients. Although a multitude of complications associated with IJV catheterization have been described, epidural venous plexus cannulation with this technique has not been reported.
We report a case of unintentional cannulation of the anterior venous plexus of the cervical epidural space during retrograde catheterization of the right IJV in a polytrauma patient.
A 17-yr-old boy was admitted to the emergency room of the San Raffaele Hospital after a motor vehicle accident. The patient was comatose and underwent computed tomography of the head and the thorax and was found to have cerebral and pulmonary contusions.
At admission to the neurointensive care unit, he had mild anisocoria, and pupillary reflexes were bilaterally present. The Glasgow Coma Score was 6, and he was sedated and mechanically ventilated. A central venous catheter was placed in the right subclavian vein, and intracranial pressure was monitored by intraventricular catheter.
To perform serial cerebral venous sampling, it was decided to place a catheter in the right jugular bulb through the IJV, using a retrograde technique. With the patient in a flat neutral position, a point 2.5-3 cm lateral to and 2 cm above the medial end of the right clavicle is selected, and the skin is punctured with a 20-gauge needle that is passed in a cranial direction for 3 to 4 cm at an angle of 30 [degree sign] in the sagittal plane for localization of the vein. When the IJV is localized, the vein is catheterized using the Seldinger technique. 
On the first attempt, the catheter (Certofix 18-gauge; Braun, Melsungen, Germany) advanced into a branch of the facial vein, an assessed by radiograph, and was removed. On the second attempt, the vein was localized by means of a new puncture, and the catheter was moved forward for 16-18 cm to place the catheter tip in the jugular bulb. Blood was easily aspirated through the catheter, and venous oxygen saturation was normal (73%). The position of the catheter was checked with anteroposterior and laterolateral radiographs of the neck, which revealed misplacement of the catheter (Figure 1). Computed tomography of the neck and the head revealed that the catheter was positioned in the anterior epidural space of the cervical spinal canal (Figure 2). The catheter was then withdrawn and a new catheter was inserted via the right IJV, and eventually the tip of the catheter was placed correctly in the jugular bulb.
The patient showed no complication or sequelae from the unintentional cannulation of the anterior venous plexus of the cervical epidural space. The neurologic examination after the event was unchanged, the patient could easily move the neck and had no pain or function alteration of the right arm and hand.
Numerous complications using the IJV cannulation technique have been reported, including early damage to pleura, mediastinum, heart, great blood vessels, thoracic duct, and nerves in the neck and chest. [2-6]Although by using this technique, inadvertent vertebral artery puncture, resulting in fistula formation, [7-10]pseudoaneurysm, or fatal stroke, and cervical dural puncture can occur, to our knowledge, unintentional cannulation of the cervical epidural venous plexus during an IJV catheterization technique has not been reported.
According to the radiograph (Figure 1) and the computed tomography scan (Figure 2), the catheter seems to have cannulated the intervertebral vein at the emergence from the intervertebral foramen of C6-C7. Then, the catheter went forward into the anterior cervical epidural space, advanced upward into the internal venous plexus, and stopped at the level of C2-C3 intervertebral disk (Figure 1). The oxygen saturation value (73%) of the blood, easily withdrawn through the catheter, confirmed that the catheter was positioned in a vein.
One of the major factors contributing to the occurrence of this rare complication in our opinion could have been the depth of the needle insertion. In fact, the distance between the skin and C6 is almost doubled compared to the distance between the skin and the internal jugular vein. Recently, Miyamoto et al. reported cervical dural puncture in a neonate during central venous catheterization via the IJV and postulated that the dural puncture was mostly caused by the excessive depth of insertion of the needle. When performing the retrograde catheterization of the IJV, the needle should not be inserted too deeply, even if no blood in aspirated; the vein can be compressed by the needle, and blood often is aspirated during withdrawal of the needle, rather than during advancement of the needle.
There is no useful guide for the optimal depth of insertion of the needle for accessing the IJV. When cannulation of the IJV is performed by the high approach, in adult patients, the distance to the internal jugular vein ranges from 15.0 to 21.5 mm. In our patient, because of the retrograde catheterization of the IJV, the low cervical anterior approach was used. With this approach, usually the IJV is localized when the needle is passed in a cranial direction for 3 to 4 cm. 
A particular risk of this technique is the angle of insertion of the needle. A rostral directed needle will line up well with the intervertebral foramina, especially if it is at all medially directed. This allows entry into the foramen and the canal. The overhanging transverse processes make central passage quite difficult if a needle is directed caudally, as in the more common approach for simple IJV cannulation. In our patient, improper positioning of the head or direction of the needle (not precisely in the sagittal plane), or both, could have facilitated intervertebral vein cannulation.
In our patient, no complication (e.g., hematoma, infection, neural injury to the cord or to the dorsal root ganglion/peripheral nerve in the foramen) resulted from the inadvertent cannulation of the anterior venous plexus of the cervical epidural space.
In summary, excessive depth of insertion of the needle, during retrograde IJV catheterization, must always be avoided and can result in such a rare complication.