Compartment syndrome exists when increased pressure in an enclosed space compresses blood vessels and nerves.
Groups of muscles in the arm and leg are enclosed by a layer of thick, non-stretchable tissue called fascia. This fascia separates the tissues into compartments containing the muscles, their blood supply, veins, nerves and lymphatic drainage. In addition, other blood vessels and nerves may pass through the compartment on their way to other compartments. Anything which increases the pressure inside the compartment will compress the contents (blood vessels and nerves etc) because the fascia surrounding it cannot stretch.
Common causes of increased pressure in a compartment are:
- Swelling due to inflammation, often seen with repetitive type injuries in athletes,
- Bleeding from trauma, fractures, crush injuries or haemorrhage,
- Casts: too-tight plaster casts or bandages, or
- Reperfusion following injuries.
Symptoms and signs
The patient may be unconscious, for instance after trauma or surgery, and may not be able to complain. Regular accurate observation of the limbs is vital for these people.
The classical features of compartment syndrome are:
- Pain - more than normal for that type of injury/surgery, and not relieved by standard painkillers, even morphine.
- Paraesthesia - abnormal sensations in the limb.
- Pallor of the limb (this is due to decreased blood supply).
- Pulseless - in severe compression, the artery is blocked off and blood supply to the limb below it may be compromised.
- Paralysis is a late feature.
- Pressure (and pain) is increased by passive stretching (extension) of the muscles in the compartment.
In chronic compartment syndromes, often seen in athletes, aching or cramping of the affected leg usually starts within 10-30 minutes of exercise, with everything returning to normal between episodes of exercise.
Proof of increased pressure within the compartment is obtained by inserting into it a needle connected to a pressure gauge. A difference of more than 30mmHg between the compartment pressure and the diastolic blood pressure indicates the need for urgent intervention.
The diagnosis of acute compartment syndrome is clinical, and there is seldom time for pressure measurements. Chronic conditions may be investigated with pressure studies.
The treatment of any compartment syndrome is to relieve the pressure.
Acute compression is a medical emergency: fasciotomy is a procedure in which the fascia is slit open in several places to release the pressure on the contents of the compartment. The wounds are left open and only closed during a second operation two to three days later, giving maximum time for the pressure to return to normal.
If the problem is due to a bandage or plaster cast which is too tight, this must be not just loosened, but totally removed. If a plaster cast can’t be totally removed, it must be slit open down its entire length in more than one place, to allow it to expand and accommodate the swollen limb without compression.
Chronic problems may be treated initially by rest and anti-inflammatories. If there is no improvement, open or sub-cutaneous fasciotomy is done.
Complications and outcome
If treatment is delayed, the tissue in the compartment dies due to lack of oxygen. Dead muscle tissue entering the circulation can lead to kidney failure. Gangrene may set in, leading to amputation.
In less severe cases, permanent muscle and nerve damage may occur, drastically impairing function.
With prompt and adequate treatment, the outcome is good in more than 90 percent of patients. Problems are usually due to delay in diagnosis or fasciotomy: the longer the delay, the worse the outcome.
Compartment syndrome cannot always be prevented, but awareness and prompt treatment will prevent complications.
(Dr AG Hall)