This 33-year-old male patient suffers from headaches that are reliably triggered by turning his head to the right. Within minutes, he experiences increasing pressure in his skull, which he describes as feeling like his head is going to explode. If he holds this position for too long, he experiences painful, involuntary restriction of head movement, which may last for days or even weeks. This is characterised by painful muscle tension on the right side of the neck that sometimes radiates down to the right arm. In addition to these headache attacks, he experiences a constant, pressure-like headache centred around the sixth cervical vertebra on the right side, which radiates towards the base of the skull and the occipital region and sometimes the right shoulder. This headache is rated at 5/10 and is present 24 hours a day.

Conventional B-mode ultrasound readily demonstrated bilateral narrowing of the internal jugular vein.

The constriction was stronger on the left side than on the right, but in both cases it was situated where the vein crossed the central portion of the omohyoid muscle. The jugular veins were squeezed between the bulb of the carotid artery and the omohyoid muscle, which could not give way to the vein due to the sternocleidomastoideus muscle.
However, the true pathophysiological effect of the venous narrowing could not be reliably evaluated using conventional B-mode and Doppler techniques. But it was possible to correlate the volumetric flow measurement using the four-dimensional PixelFlux volume flow measurement technique with the patient’s symptoms.

This could explain the patient’s headaches and how they were triggered and exacerbated when he looked to the right.

In contrast to jugular vein narrowing when looking straight ahead, B-mode sonograms changed significantly when the patient turned his head to the right. The left jugular vein now enlarged substantially, the former compression disappeared, and the right internal jugular vein was completely compressed at the former compression site.
Without volumetric flow measurements, one might assume that blood was now being transported more efficiently via the left internal jugular vein.
However, this could be disproved by PixelFlux measurements, which showed a bilateral collapse of the venous drainage of the skull.
The reason for the distension of the left internal jugular vein was primary subclinical compression of the left anonymous vein by the aortic arch, which worsened and became sonographically evident when the patient turned his head to the right.

Even when looking straight ahead, a pressure gradient reduced venous flow in the left anonymous vein. However, when the patient turned their head to the right, the pressure gradient increased, further obstructing the drainage of the skull via the left internal jugular vein.
Turning the head to the right also caused subtotal compression of the right internal jugular vein. Consequently, both internal jugular veins suddenly ceased to function, resulting in an immediate increase in venous pressure inside the skull, causing headaches and a sensation of an exploding head.
Comparing the patient’s flow volumes with normal volumes from the literature clearly shows that the right internal jugular vein was haemodynamically insufficient from the beginning. This impairs venous drainage from the skull chronically, producing a permanent tension headache on the right side of the neck and head.

In general, there are three venous routes to drain the skull: the epidural plexus, the vertebral veins, and the internal jugular veins. The internal jugular veins are by far the most capacious. However, the vertebral veins cannot adapt to a sudden increase in demand as they are segmentally encircled by the foramina of the lateral processes of the cervical vertebrae.

In this patient, blood flowing in from the compressed left renal vein and left common iliac vein blocked the epidural route. Therefore, the jugular veins were crucial for normal brain function. Their permanent obstruction resulted in continuous headaches. Turning the head to the right increased intracranial pressure to such an extent that the patient experienced unbearable headaches on the right side of their head.

The 4D volumetric PixelFlux measurement of jugular venous outflow easily explains conflicting sonographic findings obtained using conventional techniques, as well as the peculiar symptoms experienced by patients.