Pain or swelling after an injury or workout is common. But in some cases, these symptoms can mean something more serious. Compartment syndrome is a condition that needs medical attention and, sometimes, emergency care.

Understanding the warning signs can help prevent long-term damage and ensure you get the right treatment at the right time.

What is compartment syndrome?

Compartment syndrome occurs when pressure builds up inside a muscle compartment. This pressure can block blood flow and damage nerves and muscle tissue.

“Muscle compartments are defined spaces that are not very elastic,” says Nebraska Medicine emergency medicine physician Alex Tomesch, MD. “The compartment holds the muscle, nerves and blood vessels inside a fibrous tissue called fascia. When pressure rises inside that space, it can become dangerous.”

Because this tissue doesn’t stretch easily, swelling or bleeding inside the compartment can quickly increase pressure.

What causes compartment syndrome?

Compartment syndrome is caused by increased fluid buildup inside the compartment. There are two types of compartment syndrome: 

Acute compartment syndrome

• Develops after an injury and doesn’t resolve on its own.
• Usually caused by trauma, especially fractures.
• Shin bone fractures have the highest risk.

“Acute compartment syndrome is typically caused by bleeding into the compartment secondary to a fracture,” says Dr. Tomesch.

Chronic exertional compartment syndrome (CECS)

• Happens with activity and improves with rest.
• Caused by muscle swelling during repetitive activities.
• Common in runners and walkers. 

“In chronic exertional compartment syndrome, the fascia tends to be less elastic, so when muscles swell during activity, symptoms occur,” says Dr. Tomesch.

The key difference is that CECS symptoms resolve when activity stops, while acute compartment syndrome will not improve without intervention.

Symptoms to watch for

Acute compartment syndrome symptoms 

With acute compartment syndrome, look for the “five P’s”:

• Pain that feels worse than expected (often the first symptom).
• Paresthesia (numbness or tingling).
• Poikilothermia (difficulty feeling hot or cold).
• Paralysis.
• Pallor (loss of color).

“Pain is typically the first symptom, followed by numbness,” says Dr. Tomesch. “If it goes untreated, it can progress and cause permanent damage.”

Acute symptoms typically start within hours after an injury. High-risk patients, including those with bone fractures, severe trauma to the arms or legs or significant bleeding, should be monitored for 12 to 24 hours.

“Outside that window, it’s very unlikely for acute compartment syndrome to develop,” says Dr. Tomesch.

CECS symptoms

With CECS, symptoms often include pain or tightness during activity, which improves with rest. Pain will often resolve within 20 minutes after stopping activity. 

“Someone may notice that after running for 10 minutes, they develop pain that continues until they stop,” says Dr. Tomesch. “Once they rest, the symptoms go away.”

How is compartment syndrome diagnosed? 

Compartment syndrome can be mistaken for a muscle strain, especially CECS. One key difference is that acute compartment syndrome worsens over time instead of improving.

“CECS is often mistaken for shin splints, stress fracture or muscle strains,” says Dr. Tomesch. “A detailed history and physical exam often point us toward the correct diagnosis.”

Diagnosing acute compartment syndrome

If there’s a concern for acute compartment syndrome after an injury, compartment pressure testing may be done to confirm the diagnosis. This involves a one-time pressure measurement using a specialized needle and does not involve exercise. 

Anyone with concern for acute compartment syndrome should seek immediate emergency medical care. CECS can be evaluated during an outpatient visit. 

Diagnosing CECS

Compartment pressure testing is also used to diagnose CECS. Pressure is measured before exercise, then again immediately after exercise once symptoms occur.

“If testing isn’t done immediately after exercise, results can be falsely negative,” says Dr. Tomesch.

CECS can be evaluated during an outpatient visit.

Compartment syndrome treatment options

Acute compartment syndrome treatment

Acute compartment syndrome requires emergency surgery. Fasciotomy surgery, or cutting the fascia to relieve pressure, is done to save the limbs. Any delayed treatment can cause permanent muscle and nerve injury. 

CECS treatment

CECS is treated non-urgently. Patients should stop the activity and take ibuprofen to help with inflammation. Additionally, shoe inserts and low-impact activity may also help. 

While these strategies may help manage symptoms, they may not fully resolve CECS for all patients. 

CECS can be challenging to treat. Even with surgical intervention, symptoms don’t always completely resolve. Emerging treatment options, such as Botox injections, are being studied, but there’s not enough long-term data yet to know their effectiveness or how long the benefits last.

Most patients recover fully after treatment. For acute cases, recovery from the injury may take longer than recovery from surgery.

“Recovery includes wound healing and physical therapy to safely return to activities,” says Dr. Tomesch. 

Compartment syndrome is rare, but recognizing the symptoms after an injury is critical. Fast evaluation and treatment can prevent long-term damage and help patients return to daily life and activities.