Vascular Compression Syndromes
Vascular Compressions occur when arteries or veins become compressed between two structures (e.g., another artery and a bone or muscle). The compression anatomy can be present but with no obvious symptoms. At this stage it is known as a compression phenomenon (e.g. Nutcracker phenomenon). However, when there are recognizable symptoms, there may be a diagnosis of the related Vascular Compression Syndrome.
Below is a list of Vascular Compression Syndromes. This list is not exhaustive but covers most of the compressions that will are discussed in research on this site. It covers Abdominal Vascular Compression Syndromes (AVCS: NCS, MTS and MALS), as well as a few others.
RENAL NUTCRACKER SYNDROME (NCS)
Renal Nutcracker Syndrome (Nutcracker Syndrome, or NCS), is typically the symptomatic compression of the renal vein between two or more structures. The most common anatomical variant is called anterior NCS, and occurs when the left renal vein (LRV) is compressed between the superior mesenteric artery (SMA) and the aorta. Posterior NCS can occur when there is a compressed retroaortic LRV present that passes between the aorta and the spine. In some cases, there may both an anterior and posterior vein present; this is known as a circumaortic vein and can show compressions at both the locations previously mentioned. There are other anatomical variants that can cause a narrowing of the vein, such as stretched veins due to connective tissue issues and viceroptosis. There are also variants where the LRV is compressed by one of the renal arteries, and even, very rarely, where the right renal vein is compressed,
Symptoms include flank and abdominal pain, and micro or macro-hematuria and proteinuria. Blood or protein in the urine occurs due to increased pressure in the renal vein at the hilum and blood refluxing into the fragile structures of the kidney, causing damage. However these two findings are often overlooked in urine test analyses results. NCS is a major cause of Pelvic Congestion Syndrome (PCS, see below). Other symptoms can include headaches, nausea, pelvic pain, abdominal bloating, pre-syncope/syncope, although some of these may be caused by conditions secondary to the compression (see Comorbidities).
MAY-THURNER SYNDROME (MTS)
May-Thurner Syndrome (MTS, also Cockett's Syndrome) is the narrowing of the iliac vein (common or external), either through external compression, or from internal scarring or collapse. It is most commonly found in the left external iliac vein, being compressed externally by the right common iliac artery passing over it and the vertebrae behind it at the level of L5/ S1. Other variants are possible, including compression of the right iliac vein and stenosis of both iliac veins. There may be leg swelling and DVT present, but these are not necessary for diagnosis. Other symptoms include leg, groin and lower back pain. Leg weakness and numbness have been reported.
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MTS is a direct cause of Pelvic Congestion Syndrome due to the compression causing blood to reflux into other veins in the pelvis. Reflux can occur in the internal iliac vein leading to pudendal issues. It can also be a cause of Peripheral Venous Insufficiency in the legs. It has been linked to other comorbid conditions such as POTS.
MEDIAN ARCUATE LIGAMENT SYNDROME (MALS)
MALS is the compression of the Celiac artery and surrounding nerve plexus by the Median Arcuate Ligament at the level of the diaphragm. Symptoms include pain just under the sternum on eating (sometimes even on drinking), early satiety, and vomiting. The inability to breathe deeply without pain is also common. These symptoms can make getting proper nutrition very difficult.
THORACIC OUTLET SYNDROME (TOS)
The nerves of the brachial plexus, as well as the arteries and veins of the arm, all pass through the small channel between the neck and pectoral muscles and the clavicle, the first rib, and the shoulder joint. This space is known as the Thoracic Outlet. Depending on small anatomical differences caused by joint movement, injury, scar tissue build-up, etc., the arteries, veins and/ or nerves can become compressed by any of these structures, causing Thoracic Outlet Syndrome (TOS).
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There are 3 types of TOS, depending on which of the three conduits is compressed. Symptoms vary slightly depending on the type, but typically are present or more severe on raising the arm. The most common type of TOS is neurogenic TOS. The pinching of the nerves of the brachial plexus can cause pain in the arm and numbness is the and tingling fingers and hand. Venous TOS can cause pain, swelling and discoloration of the arm. Arterial TOS can cause pain in the shoulder and weakness and pallor in the arm and hand.
INTERNAL JUGULAR VEIN COMPRESSION SYNDROME (IJVCS)
The internal jugular vein is sometimes subject to compression from various structures in the neck such as the styloid process, the transverse process of C1, the digastric muscle, calcification of the stylohyoid ligament, etc. This compression can also be referred to as the Stylo-jugular form of Eagle's Syndrome.
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Common symptoms include side of neck pain, headaches, pain behind the ear, dizziness, brain fog and tinnitus. Comorbidities of IJVCS include Idiopathic Intracranial Hypertension (IIH), thrombosis or stenosis of the transverse sigmoid sinus. Craniocervical Instability (CCI) is a common comorbidity.
PELVIC CONGESTION SYNDROME (PCS)
Pelvic Congestion Syndrome, also known as Pelvic Venous Insufficiency (PVI), is not a vascular compression syndrome as such. However, it is an extremely important consequence of two of the abdominal vascular compression syndromes: NCS and MTS. Due to the compressions in the renal and iliac veins respectively, blood refluxes into pelvic veins or slows/ stagnates in them. The reduction in blood flow velocity causes changes to the endothelial cells lining the vein walls, causing them to become tortuous and widen (varicosed). It can also cause many other new veins to be created as the body tries to find ways of rerouting the blood that is pooling.
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Symptoms include pelvic pain, abdominal bloating, groin pain, pain during intercourse, painful and heavy periods, visible varicose veins. Rectal pain and hemorrhoids are also common.
SUPERIOR MESENTERIC ARTERY SYNDROME (SMAS)
While not technically a vascular compression as a vein or artery is not being compressed, Superior Mesenteric Artery Syndrome (SMAS) is closely related. In SMAS, part of the duodenum is compressed between the superior mesenteric artery (SMA) and the aorta. This is the same area where the left renal vein can be compressed in anterior Nutcracker syndrome (NCS) (see above), so it is common that patients with NCS also have SMAS, although it is not always the case.
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The compression of the intestine in SMAS causes symptoms such as pain on eating, early satiety, vomiting, and gastroparesis. These symptoms are very similar to those found in MALS sufferers and it can be difficult to distinguish the effects between the two. As with MALS, getting proper nutrition can be very challenging, and weight loss is common.