Compartment syndrome happens when pressure in the muscles builds to dangerous levels and decreases blood flow to the affected area.

This prevents nutrients and oxygen carried in the blood reaching nerve and muscle cells. It is very painful and usually occurs in the arms or legs.

There are two kinds of compartment syndrome. Acute compartment syndrome tends to be caused by a severe injury. It is a medical emergency, and without treatment can lead to permanent muscle damage.

The other type is chronic compartment syndrome, which is not a medical emergency. Also known as exertional compartment syndrome, it is usually caused by athletic exertion.

The syndrome usually occurs in the anterior, or front, of the calf. It can also occur in other compartments of the leg, as well as in the arms, hands, feet, and buttocks.

Fast facts on compartment syndrome:

  • There are two kinds of compartment syndrome: acute and chronic.
  • It is caused by severe injury, or athletic fatigue and exertion.
  • Symptoms include pain and paresthesia (prickling or tingling) in the muscles.
  • Treatments include surgery and physical therapy, depending on the type of compartment syndrome.

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Acute compartment syndrome may be caused by a broken arm.

Groups of muscles, nerves, and blood vessels covered by a tough membrane (called a fascia) are called compartments. The role of the fascia, which does not stretch or expand easily, is to keep all tissues in place.

Because the fascia doesn't stretch easily, any swelling or bleeding in a compartment puts pressure on the capillaries, nerves, and muscles inside the compartment.

This can decrease the amount of nutrient and oxygen-rich blood reaching the cells and nerves. Without a steady supply of blood, cells can be damaged.

Compartment syndrome can be acute or chronic.

Acute compartment syndrome

Acute compartment syndrome is usually caused by a severe injury, such as a car accident or a broken bone. It can develop after a minor injury, but that is rare.

One possible cause is when blood flow is restored after blocked circulation. This may happen after a surgeon repairs a damaged blood vessel that has been blocked for several hours. Lying too long in the same position can also block blood vessels, although most people will move in their sleep.

Other possible causes include:

  • fracture
  • badly bruised muscle
  • crush injuries
  • anabolic steroid use
  • casts or bandages that are too tight
  • burns
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Repetitive motions such as cycling, swimming, and running may cause chronic compartment syndrome.

Chronic compartment syndrome

Chronic compartment syndrome is characterized by pain and swelling and is usually caused by exercise.

Repetitive motion activities are more likely to cause chronic compartment syndrome, they include:

  • running
  • cycling
  • swimming
  • elliptical training

This type of compartment syndrome usually occurs during or shortly after exercising.

The five "P"s describe the signs and symptoms of acute compartment syndrome to look out for including:

  • Pain: the most common sign that people describe as being extreme and out of proportion to the injury. It is persistent, progressive, and does not stop. It is made worse by touch, pressure, elevation, and stretching.
  • Passive stretch: muscles lacking in blood are very sensitive to stretching, so extending the affected limb leads to extreme pain.
  • Paresthesia: this is a weird sensation, such as tingling or pricking, sometimes described as pins and needles.
  • Pallor: the affected limbs may be a pale or dusky color because of the lack of blood.
  • Pulse: there may be weak or no pulse from the affected compartment.

Chronic compartment syndrome can cause pain or cramping during exercise but usually subsides when the activity stops. It tends to happen in the leg, and the symptoms may include numbness, difficulty moving the foot, and visible muscle bulging.

People who think they have compartment syndrome should go to the emergency room.

In diagnosis of acute compartment syndrome, a doctor will measure the compartment pressure and offer treatment.

To diagnose chronic compartment syndrome, other conditions must be ruled out first. A doctor may examine an individual for tendonitis or give them an X-ray to make sure the shin is not fractured. The pressures in the compartment may be measured before and after exercise and compared.

Athletes with chronic compartment syndrome usually experience pain and tightness 20-30 minutes after exercise. People should speak to a doctor at the first sign of:

  • pain or swelling and tingling or numbness in the leg or foot
  • weakness of the lower leg, ankle, or foot
  • warmth in the affected area
  • foot drop (difficulty lifting the front part of the foot or toes)
  • pain when flexing or pointing the big toe

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If compartment syndrome is suspected, patients should be directed to the emergency room.

The only option to treat acute compartment syndrome is surgery. The procedure, called a fasciotomy, involves a surgeon cutting open the skin and the fascia to relieve the pressure.

Options to treat chronic compartment syndrome include physiotherapy, shoe inserts, and anti-inflammatory medications. People may also be advised to avoid the activity causing the problem.

Surgery is also an option if all other treatments have failed. Here, a doctor makes a cut in the fascia to give the muscles room to swell.

If surgery is undertaken, some people may need a course of physiotherapy to help with the recovery process. This may help to restore a full range of motion and muscle strength.

Possible complications

In some cases, acute compartment syndrome and its treatment can lead to:

  • permanent nerve damage
  • permanent muscle damage and reduced function in the affected limb
  • fasciotomy may cause permanent scarring
  • the surgery site may become infected
  • as the cells die, the muscle can release various chemicals that can damage the kidneys.

In acute compartment syndrome, the pressure needs to be relieved quickly. If it is not, cells may become permanently damaged or even die.

Early diagnosis of compartment syndrome is vital to avoid long-term disability. Quick treatment can make sure the blood supply is restored to the affected area before any long-term damage occurs.

This is not the case in chronic compartment syndrome, which is usually resolved by stopping the exercise causing the problem. It is not usually dangerous.