What is Forearm Compartment Syndrome?
Compartment syndrome is a medical condition where there’s increased pressure within an enclosed space in the body. This pressure might become too much, affecting the blood flow and function of the tissues in that area. This happens if the pressure becomes high enough to interfere with blood flow in the tiny vessels, known as capillaries. This lower blood flow causes less oxygen to be carried to the nerves and muscles inside the affected area.
The condition of compartment syndrome was first identified in 1881 by a German surgeon named Richard von Volkmann. In an article called ‘Non-infective ischaemic conditions of various fascial compartments in the extremities’, Volkmann discussed this condition, known as Volkmann contracture. He suggested that it was not nerve damage but a lack of blood flow (ischemia) causing this issue.
The makeup of the forearm is quite intricate, with the bones being the ulna and the radius. This area consists of three compartments of muscles.
First, the anterior compartment holds the hand and wrist flexors — muscles that control bending. These are split into the superficial group (muscles like flexor carpi radialis FCR and palmaris longus PL) and a deeper group (muscles such as flexor digitorum profundus FDP and flexor policis longus FPL). These muscles play a primary role in wrist and finger flexing and rotating the forearm. The ulnar nerve and artery, critical for sensation and blood flow, are also held in this compartment. An important muscle called the flexor digitorum superficialis bridges these two groups of muscles.
Next, the posterior compartment houses nine muscles responsible for the extension (straightening) of the wrist and fingers and the supination (outward turning) of the forearm. The anterior and posterior compartments are separated by a structure called the interosseous membrane between the radius and ulna bones. This compartment has three groups: the superficial group (like extensor carpi ulnaris ECU), the intermediate group (like extensor digitorum), and the deep group (like abductor policis longus APL and extensor policis longus EPL). Extensor tendons pass through the extensor retinaculum at the wrist joint in 6 compartments. The muscles in the posterior compartment that do not pass through these compartments are the supinator and the anconeus.
Finally, the lateral compartment contains the brachioradialis, extensor carpi radialis longus (ECRL), and extensor carpi radialis brevis (ECRB) that are collectively called the mobile wad of Henry.
The forearm’s nerves are the radial nerve, the median nerve, and the ulnar nerve, handling sensation and movement. Circulation to the forearm is primarily through the radial artery and ulnar artery, along with connecting vessels.
What Causes Forearm Compartment Syndrome?
The leading cause of compartment syndrome (a painful condition where pressure builds up within the muscles, reducing blood flow) is usually some sort of injury or trauma. For children, it’s typically fractures to the midsection of the forearm, wrist, or above the elbow. Other trauma, like crushing injuries, deep bruises or gunshot wounds to the forearm, also contribute.
Other factors can also cause compartment syndrome, including things like casts or bandages that are on too tight, fluids or drugs leaking out of veins, burns, bleeding disorders, or swelling after the blood supply returns following lack of blood flow. Sometimes, even engaging your muscles too intensely during exercise, convulsions, eclampsia (a dangerous condition that can occur in pregnancy), or tetany (muscle spasms) can lead to this condition. Intravenous drug use can also cause this condition.
If you are on blood-thinning medication and injure your forearm, it can increase the chances of developing compartment syndrome. Some rarely seen causes are snake bites or carbon monoxide poisoning.
Risk Factors and Frequency for Forearm Compartment Syndrome
Compartment syndrome in the forearm often happens after injuries such as bone breaks, crush injuries, head injuries, and burns. Statistics show that it is a somewhat rare condition but does require specific medical attention. This condition is a bit more common in younger patients, with studies showing it is most prevalent in men around 32 years old and women around 44 years old. Men are ten times more likely than women to develop it. However, it’s important to note that it can happen to anyone, irrespective of their age or gender.
- Compartment syndrome in the forearm is typically seen following various types of injuries.
- About 1.22% of forearm fractures and 3.79% of tibial fractures lead to compartment syndrome that required a fasciotomy procedure.
- It’s more prevalent in younger patients, with the average age being 32 in males and 44 in females.
- The overall rate of acute compartment syndromes is 3.1 per 100,000 people each year in western countries.
- Men are ten times more likely to have this condition compared to women.
Signs and Symptoms of Forearm Compartment Syndrome
Compartment syndrome in the forearm is a condition that doctors usually identify based on the patient’s symptoms rather than specific tests. Patients typically come to the doctor within a few hours or even a couple of days after the event that caused the condition. They often have a swollen, firm, and tender forearm, and the skin might be pink. The key symptom is pain that is more severe than what you would expect from the injury itself, particularly when stretching the fingers. This pain usually doesn’t improve with rest, painkillers, or anti-inflammatory drugs. In some cases, the pain might go away completely, especially during the later stages of the condition or in chronic compartment syndrome. There could also be blood-filled blisters if a patient comes to the doctor a few hours after the onset of the condition.
Other symptoms that can appear include numbness or tingling, signs of reduced blood flow to the nerves in the affected area. Once paralysis sets in, it’s often a sign that the condition has progressed. The patient may still have a pulse in the wrist because the blood pressure (typically around 120 mmHg) is usually higher than the pressure inside the swollen compartment. If there’s no pulse, it’s usually a late sign, and the patient might require amputation if there’s a significant amount of tissue death from reduced blood flow.
For children, if they need increasing amounts of pain medication, it’s often a reliable sign of compartment syndrome. However, keep in mind assessing pain can sometimes be challenging or even impossible if the nerves are damaged, the patient is unconscious or sedated, the patient has multiple injuries, or in children or patients who received regional nerve blocks for pain relief.
Testing for Forearm Compartment Syndrome
If a doctor suspects you have forearm compartment syndrome, they might use a mix of physical examination and pressure measurements inside your forearm to confirm the diagnosis. This approach tends to be more accurate in correctly identifying the condition.
The doctor measures the pressure in the affected part of your forearm by inserting a small tube (catheter) connected to a pressure sensor about 5 cm into the affected area. The usual pressure inside these compartments ranges from 0 to 8 mmHg (a unit used to measure pressure). A pressure above 30 mmHg is taken as a sign of concern.
Here’s an essential bit: if the pressure in your forearm is higher than 30 mmHg of your diastolic blood pressure, it is associated with compartment syndrome. Diastolic blood pressure is the bottom number in your blood pressure reading and shows the pressure in your blood vessels when your heart rests between beats. Now, the ‘delta p’ or delta pressure is simply the difference between your diastolic blood pressure and the measured pressure in your forearm. A delta p lower than 30 mmHg is a strong indicator of acute compartment syndrome.
In some cases, this pressure measurement is vital, especially for patients with multiple trauma, those unable to respond reliably, or if a physical examination doesn’t clearly indicate the condition. When clear signs of the syndrome are present, doctors often proceed to a surgical intervention known as a fasciotomy, without needing to measure the pressure in the compartment.
Your doctor might also use other investigations like x-rays of the forearm or MRI scans. But these are more often used in chronic forms of the syndrome and not so much in acute cases.
Treatment Options for Forearm Compartment Syndrome
If you’re suspected of having a serious condition, known as acute compartment syndrome, in your forearm, medical professionals will need to promptly evaluate and manage your case in collaboration. This involves a thorough review by senior medical staff as soon as you reach the emergency room. Initial steps may include providing oxygen, keeping the arm elevated, removing or cutting open any tight cast or bandage to relieve pressure, and making sure your blood pressure is normal. If blood pressure is too low, it could worsen the injury by reducing the flow of blood.
The ultimate treatment for acute compartment syndrome is an urgent surgical procedure known as a forearm compartment fasciotomy. Here’s what to expect during this process:
The surgeon will administer general anesthesia to ensure you’re unconscious and pain-free during the operation. There are two main incision approaches for this procedure: the volar (front side of the forearm) and the dorsal (back side of the forearm).
For the volar incision, the surgeon cuts just to the thumb side of the inner wrist and extends toward the inner elbow. From here, they’ll dissect the fascia (a layer of fibrous tissue covering the muscles) over the deep muscle compartment. This releases pressure in both the front and back compartments of the forearm. The incision can also be extended to relieve pressure in the carpal tunnel, at the base of the hand.
On the other hand, the dorsal incision begins a bit below the outer elbow and extends towards the middle of the wrist. This releases pressure around the ‘mobile wad of Henry’ (a group of muscles) and the forearm’s back compartment.
The surgical wounds are usually left open and covered with sterile dressings. Subsequent check-up (second look) surgery occurs 48 to 72 hours later. Any dead muscle tissue is removed, and an attempt is made to close the wounds primarily. If that’s not possible, a technique known as negative pressure wound therapy may be used to aid in the healing process. Later, skin grafting may be necessary to cover any remaining open areas.
What else can Forearm Compartment Syndrome be?
When patients have a condition called cellulitis that is spreading, they can experience symptoms like discomfort, swelling, and redness across their forearm. Usually, the cellulitis may be spreading upwards from the hand or from the arm or elbow. There could also be a previous incident such as a trauma, a puncture wound, or insect bites that caused the cellulitis. The sections (or compartments) of the forearm stay soft, and stretching the muscles doesn’t tend to cause severe pain like it does in a condition called compartment syndrome where the compartments feel hard to the touch.
What to expect with Forearm Compartment Syndrome
The key factor that influences the outcome for patients with acute compartment syndrome of the forearm is how quickly it’s diagnosed and treated with a procedure called a fasciotomy. This condition leads to a fasciotomy in about 2% to 24% of patients, primarily due to difficulties in identifying it promptly.
The sooner this syndrome is diagnosed and treated surgically, the better chances of saving the patient’s limb. Any delay could lead to serious negative outcomes for the patient. The spectrum of patient outcomes ranges from a full recovery to amputation, depending on the timing of their arrival for medical care, the symptoms they have at that time, how quickly they are diagnosed, and when the surgery is carried out.
When patients arrive late, they often show symptoms like the loss of pulse in the affected limb and paralysis. In such cases, the chances of a full recovery are significantly reduced.
Possible Complications When Diagnosed with Forearm Compartment Syndrome
If pressure isn’t relieved in time in a particular body compartment, it can cause the tissue in that area to die.
One of the most common complications of this is Volkmann ischemic contracture. This is basically a permanent tightening of muscles in the forearm, wrist, and hand because of muscle damage or death (necrosis). Some signs of this condition include bending of the elbow, forearm, wrist, and thumb, straightening of joints in the fingers, and bending of the joints around the fingers. Volkmann contracture can vary from mild (only affecting finger muscles) to moderate (impacting wrist and finger muscles), to severe (involving wrist, finger, and extension muscles). Treatment can take different forms, ranging from using elastic braces to control muscle movement, to removing dead tissue and changing tendon locations.
Other possible problems include nerve damage, gangrene, chronic regional pain syndrome, and rhabdomyolysis, which could potentially result in kidney failure. Rhabdomyolysis has been found in almost 23% of cases diagnosed with acute compartment syndrome. Symptoms of this include muscle stiffness, muscle aches (particularly back pain), and poor urine output or dark-colored urine.
Common Complications:
- Volkmann ischemic contracture
- Nerve Damage
- Gangrene
- Chronic Regional Pain Syndrome
- Rhabdomyolysis and possible kidney failure
Preventing Forearm Compartment Syndrome
Forearm compartment syndrome is a serious medical condition that requires immediate surgery. It can sometimes be difficult to identify. If you come in with signs that suggest you might have forearm compartment syndrome, your doctor should tell you about the potential complications linked to this condition. If the doctor isn’t entirely sure, they might use a special measurement tool to check if you have this condition. If a patient can’t make decisions for themselves because they’re sedated or unconscious, the doctor will make the best decision for the patient’s health, involving the patient’s family when possible and as time allows.
