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MY ANSWER to: Diagnosis and treatment of the J3 Internal Jugular stenosis
The question was about the upper jugular vein narrowings. The writer was asking whether MR venography would be useful as a nonoperative imaging tool in assessment.
The management of the upper jugular vein narrowing is quite enigmatic. This is an area prone to phasic narrowing, that is, narrowing that comes and goes. In some circumstances, the vein is large during expiration and narrow during inspiration; in other circumstances, the vein looks normal with the head flexed but when flexion is present, the vein may appear so narrow that no contrast can be seen within the lumen. At other times it is a segmental hypoplasia that results in a small diameter. So the first thing to decide when detecting a narrowing of the J3 segment is whether this narrowing is phasic or persistent.
MRV and CTV, for that matter, are snapshots. They are not going to determine whether the narrowing is phasic or not. Also flow disturbance and ample collaterals that do not allow the vein to distend in the time of imaging make it difficult to determine narrowing is transient. I cannot rely upon these signs. Similarly, i have seen the "pancake" sign in a patient with a normal diameter vein on venography. Perhaps flow quantification could be helpful. I don't have the experience to comment further.
MRI may be helpful in assessing the dural sinus to jugular vein continuity. CT of the skull may be useful in looking at the cranial foramina and canals.
Ultrasound is useful in assessing flow and distention. However the J3 segment of the vein is surrounded by dense bone of jaw and spine. There is not an easy acoustical "window" to peer through, making it harder still in this area.
Venography is also a static image sequence that may not show a narrowing or show a narrowing that changes with respiration and positioning. However one can perform several different views using various manuevers of respiration and positioning
IVUS is well suited for this investigation. One can do all these manuevers in real time without stopping to get another view. IVUS provides a cross sectional view and the study can image from manuever to manuever in seconds without additional radiation.
When I see a stenosis of the upper jugular vein, that is NOT part of a hypoplastic segment, i first need to determine whether it is phasic, so I go through IVUS and venographic manuevers that enable me to make that determination. If the stenosis is fixed, then i would treat the lower stenosese that are almost always problematic. Then go back and take another look at the J3 segment. if stenoses persist, then I have a real long talk with the patient. How we proceed depends upon patient finance, distance from my center, prior treatment, severity of symptoms, etc. We might decide to angioplasty and if we get some improvement and if the patient is not from a far off country, i would suggest observation to see whether angioplasty was effective. It often isn't, but i think it is worth a try. I like to save stenting as often as possible, for failures of angioplasty because of some unique risks.
The veins travel in adjacency to some nerves in the J3 area. Expansion of a stent may injure these delicate nerves and this may result in injury, most likely ischemic, to the nerve. These neuropraxias can have significant adverse outcomes to shoulder functions. In a patient with preexisting weakness or paralysis in other extremities, this injury can be quite disabling. Furthermore, this is the smallest part of the vein and stent size is correspondingly smaller. Migration is a concern, although this has not been a common problem to date.
If the J3 narrowing is intermittent and changes with respiration or position, i am inclined to do nothing about it and see how other treatments affect patient symptoms before attempting angioplasty or stenting.
If the J3 segment is hypoplastic, it is vital to assess the transverse sinus/IJV continuity. The appearance of hypoplasia is likely to be caused by either arrested development or recanalized thrombosis. There are potientially big differences between these two conditions. In an arrested development in the J3 region, there will be an effect on the jugular canal. Remember that the veins of the dural sinuses and the internal jugular vein are a continuous conduit. The bones of the skull grow around these vascular and neural structures, leaving holes in the bones (canals and foramina) through which the blood vessels and neural tissue travel. If the vein is small during bony development, the canal will be small and there will be little opportunity for expansion of venous foramina at a later date.
One clue in differentiating these two circumstances is the size of the condylar emissary veins. These veins were part of the fetal circulation that is supposed to atrophy as the adult system develops the jugular vein. If jugular hypoplasia occurs, then condylar emissary vein flow dominates and the condylar fossa is enlarged considerably. This is an important observation.
Angioplasty of a hyoplastic vein in a narrow canal will do nothing but injure the small vein. Angioplasty obviously cannot dilate bony canals. So if there is a hypoplasia, at the skull neck junction, I tend to leave this alone. On the other hand, a recanalized occlusion may look hypoplastic but often has collateral veins outside the skull. Often the jugular bulb and the jugular canal are normal in size. This can be treated by angioplasty and, if necessary by a stent, (timing considerations for stenting as previ,ously described.)