Migraines, throbbing, sometimes one-sided severe headaches which are not infrequently accompanied by nausea, vomiting and hyper-sensitivity to light and sound is one of the most frequent neurological diseases (14% of the population are affected annually) and affect female significantly more frequent than male patients.

In general, the mechanism causing migraines is not well understood.

Vascular compression syndromes however give us a clue for the development of migraine, especially the left-sided one.

Functional colour Doppler ultrasound with the PixelFlux technique is able to precisely describe the anatomical structures and the functional impact of increased intraspinal and intracranial pressure as a consequence of the collateralization of congested venous blood.

In a group of patients with a severe left renal vein compression (often falsely referred to as nutcracker syndrome) but also in patients with a haemodynamically relevant compression of the left common iliac vein in front of the sacral bone (so-called May Thurner syndrome) large volumes of blood are trapped on the left side of the spine. The venous blood returning from the left hemisphere must cross the midline, the spine, to enter the vena cava which returns the blood to the heart and closes the circuit of the blood stream.

In some patients collateral vessels  connect the congested left renal vein or left common iliac vein with veins at the surface of the spine or within the spinal canal. The influx of additional blood volume into the spatially contained space of the spinal canal produces increased pressure of the cerebro-spinal fluid. This increased pressure transgresses via the greater occipital foramen into the skull and is exerted on the brain. The venous influx is not a steady continuous blood stream but a pulsatile one.

Since the left renal vein is compressed by the aorta and sometimes the right renal artery and the superior mesenteric artery their pulse is transferred onto the pressure inside the congested left renal vein. Thus, the rhythmic cardiac pressure waves are superimposed on the blood stream not only of the left renal vein but also of the tronc réno-rachidièn which is the connection of the left renal vein with the spine in a subgroup of the affected patients.

These rhythmic pulsations explain the rhythmic throbbing of the migraine headaches.

Since the blood enters the left side of the spine the pressure on the left side of the brain higher than on the right side is midline barriers restrict the pressure exchange between the spinal and cerebral hemispheres.

This way pulsating migraine headaches which sometimes are restricted to the left side of the skull and spine are physically explained.

Since the treatment of migraine is in some cases difficult it might be worthwhile to look for such  venous compression syndromes since they can be effectively treated by a surgical and nonsurgical means which regularly implies relieve for migraine patients.

This patient suffered from daily throbbing migraine headaches so extreme that no medication helped. Characeristically, the headaches of this patient are restricted to the left side of the skull accompanied by a hemianopsy (lateral vision loss) and aura. The only little relief for her is to get up and walk around. Lying down makes the headaches worse. The functional color Doppler ultrasound provides a perfect explanation:

The compression of her left renal vein increases the pressure in her collateral pathway, the tronc réno-rachidièn. While standing the tronc réno-rachidièn, connecting the left renal vein with the spinal canal, drains blood away from the spinal canal thus relieving the pressure and subsequently the headaches. The flow signal is below the zero-line. The collateral flow now runs mainly into the left ovarian vein. Pain in the genitals and deep pelvis increases.

While lying horizontally the bloodstream is changing its direction now pouring blood into the spinal canal. The flow signal is now above the zero-line. This pulsatile influx triggers the pulsating headaches and in her also thoracic spinal pain as a consequnece of the additional pressure the additional volume causes.