Author: Chloe Wilson - BSc(Hons) Physiotherapy
Blue toe syndrome, also known as Trash Foot or Purple Toe Syndrome, is caused by a blockage of the small blood vessels in the foot that reduces the flow of blood and oxygen to the tissues. It usually develops due to a problem higher up the blood stream such as an aneurysm or atherosclerosis.
The condition develops suddenly and can be really painful. It may affect one toe or a number of toes. The toes turn a blue colour due to the lack of oxygen and if left untreated the skin can ulcerate, tissues begin to die and eventually gangrene sets in. If this happens, amputation may be necessary so early treatment is essential.
Here we will look at the common symptoms, causes, diagnosis and treatment options for blue toe syndrome. For other causes of toe pain, visit the toe pain diagnosis section.
Blue foot syndrome usually develops suddenly and rapidly. It may affect one or more toes but is usually confined to one foot.
The most common presentation of trash foot is the combination of:
1) Pain: High levels of pain. This tends to be in the foot and can sometimes also occur further up the leg
2) Livedo Reticuarlis: this is a lace-like bluey purplish discoloration of the skin
3) Foot Pulses: The peripheral foot pulses are usually still palpable
4) Age: The syndrome usually affects people over the age of fifty
Blue toe syndrome develops when there is a blockage in the small blood vessels of the foot which reduces the blood flow to the toes, known as ischaemia. The blockage is usually caused by either cholesterol crystals or a lump of plaque getting stuck.
Plaque deposits are a waxy substance made up of things like fatty acids, cholesterol and calcium. They build up on the inner lining of arterial walls over a number of years. Sometimes, small bits of plaque break off (known as embolisation) and then travel round the body in the blood stream.
In blue toe syndrome, the plaque tends to break off from blood vessels near the groin and abdomen (known as the abdominal aorta-iliac-femoral arterial system). It travels through the blood stream and gets lodged in the small blood vessels of the foot.
This limits the flow of oxygen and glucose to the toes, both of which are needed to keep cells alive. The result is destruction and death of the surrounding tissues. The toes start to turn a bluey purple colour (known as cyanosis) due to the lack of oxygen, hence the name blue toe syndrome.
Trash foot is most common in men over the age of 40. Embolization and resultant blockage of the blood vessels can occur for a number of reasons:
1) Spontaneously: a piece of plaque breaks off with no specific cause
2) Surgical Procedure: most commonly vascular surgery or angiography (where a small catheter is passed through the blood vessels to examine the arteries)
3) Medical Treatment: Anti-coagulants (blood thinners such as warfarin) or thrombolytic treatment (to break up large blood clots)
Blue toe syndrome can be difficult to diagnosis. Usually, the most common sign of a blockage in the blood vessels is the loss of foot pulses but in this case, they are usually unaffected.
Diagnosis also concentrates on finding the source of the problem i.e. where the embolus blockage came from in the first place. Usually there will be a problem further up the arterial tree in one of the proximal blood vessels such as an aneurysm (balloon-like bulge filled with blood in the wall of a blood vessel) or plaque deposits (known as atherosclerosis). Ultrasound scans and CT angiograms are the diagnostic tools of choice.
Once the underlying cause of blue foot syndrome has been found, it can be treated by:
1) Stenting: this is where a mesh tube is inserted into a blood vessel to hold it open and prevent restriction of blood flow
2) Bypass Surgery: where blood flow is diverted around major arteries that are narrow or partially blocked. A healthy blood vessel is taken from another part of the body and attached above and below the affected area so that the blood flow diverts around the blockage
3) Anti-coagulants and anti-platelet therapy: These can help in the short time but are associated with a high recurrence rate of blue toe syndrome
If left untreated, gangrene can set it. Gangrene is a serious condition where a lack of blood supply causes the tissue to die. Early treatment involves debridement (surgical removal of the dead tissue) and antibiotics to treat infection. If allowed to progress, amputation of the affected body part may be required.
Trash foot is not the only cause of pain and discoloration of the skin. Another common cause is Raynaud’s Disease, a condition where the blood vessels spasm, limiting flow to the fingers and toes. Treatment here is usually with medication, avoiding the cold by wearing gloves and relaxation techniques
If blue toe syndrome is not sounding quite like your problem, visit the toe pain diagnosis section for help working out what may be causing your pain.