Everything you
should know

What is lacertus

Lacertus syndrome is a common hand condition, but the general public and even many health professionals aren’t very familiar with it. It occurs when the median nerve is compressed at the elbow under a sheet of ligamentous tissue called the lacertus fibrosus.

Its symptoms are very similar to those of carpal tunnel syndrome, which means doctors often diagnose it incorrectly or late because it’s so often mistaken for carpal tunnel syndrome. These conditions can also appear at the same time. When this happens, it’s called double crush syndrome.

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Lacertus syndrome is often confused with carpal tunnel syndrome.

What causes
lacertus syndrome?

As with carpal tunnel syndrome, it can be hard to pinpoint exactly why the median nerve is being compressed at the elbow.

Lacertus syndrome can develop after intense physical effort, repeated gripping, or wrist pronation (where your palm faces the ground) when the elbow is bent. Jobs that are frequently associated with the condition include those that involve working at a computer or doing precise work with the hands, like dentistry or surgery.

Studies have shown that certain health conditions or lifestyle factors can lead to an increased likelihood of developing lacertus syndrome. These include hormonal or endocrine imbalances, smoking, and obesity, all of which are risk factors for nerve compression syndromes.

Lacertus syndrome affects people of all genders, usually after age 35.

Do you think you have lacertus syndrome?

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How does lacertus syndrome
affect the body?

Lacertus syndrome affects your sense of touch and motor skills. Its main symptoms are paraesthesia (tingling), muscle fatigue, and pain that can radiate up to the shoulder. Patients might also experience a loss of sensitivity and dexterity. This can happen in just one or both hands over months or even years.

Symptoms may appear suddenly after intense physical effort, overexertion, or repetitive movements where the palm is facing down and the elbow is bent.

  • Tired or heavy feeling
  • Forearm and elbow pain that can radiate to the shoulder blade
  • Muscle weakness
  • Loss of endurance and dexterity (tendency to lose your grip)

How is lacertus
syndrome diagnosed?

Lacertus syndrome is hard to diagnose because it’s still an under-researched, lesser-known condition. In fact, it’s very often mistaken for carpal tunnel syndrome (CTS) and misdiagnosed or only partially diagnosed, leading to inadequate care.

Few doctors have the knowledge they’d need to first suspect and then look for lacertus syndrome, which leads to an overdiagnosis of CTS. Consequently, many patients undergo carpal tunnel releases they don’t need and that don’t help. No or only partial symptom relief after carpal tunnel surgery may mean an incorrect diagnosis, or that there is another compression area.

To make the right diagnosis, doctors need to recognize their patients’ symptoms and do a complete physical exam of the entire arm, not just the wrist. They should examine patients who have numbness, pain, weakness, or a loss of dexterity for both carpal tunnel and lacertus syndrome.

The scratch collapse test, originally developed by Susan Mackinnon, is a provocative test that is less well known but effective for locating where the nerve is compressed. It involves testing external shoulder rotation by “scratching” the area of suspected nerve compression to trigger an inhibition reflex.

Electromyograms (EMGs) are not able to conclusively diagnose lacertus syndrome but may be useful to diagnose CTS occurring at the same time.

The scratch collapse test


A first step towards recovery

What surgery is recommended
for lacertus syndrome?

Lacertus syndrome surgery involves cutting the ligament that is compressing the nerve through a small incision in the crook of the elbow. The procedure is done using the WALANT technique, which stands for Wide Awake, Local Anesthesia, No Tourniquet. It allows your surgeon to check whether your muscle strength returns during the procedure and immediately confirm whether the release was successful. For patients with double crush syndrome, the nerve can also be released at the wrist (carpal tunnel) at the same time.

Relief is almost instantaneous, and patients can generally get back to desk work only two days after their procedure. After two weeks, they can get back to all their normal work and physical activities. Physiotherapy is not required, and the conditions rarely come back.



What is lacertus syndrome?

Lacertus syndrome occurs when the median nerve is compressed at the elbow under a sheet of ligamentous tissue called the lacertus fibrosus. Because the symptoms are so similar, lacertus syndrome is often mistaken for carpal tunnel syndrome, which can lead to an incorrect diagnosis and affect patient care.

What causes lacertus syndrome?

Manual work or activities that require you to repetitively pronate your wrists (turn so your palms toward the ground) can cause median nerve pressure at the elbow. Certain health conditions or lifestyle factors can also increase the risk of developing the condition.

How can you tell lacertus syndrome apart from CTS?

Carpal tunnel syndrome patients will often wake up at night, while lacertus syndrome patients won’t—their symptoms usually occur mid-activity. A physical examination can help reveal other differences, such as where the pain is localized and muscle strength.

What is double crush syndrome?

Lacertus syndrome can present on its own or along with carpal tunnel syndrome. When patients have both, it’s called double crush syndrome.

Practical and comprehensive
medical guide

Everything you need to know to identify and treat Carpal tunnel syndrome. Written in clear and simple language by hand surgeon Dr. Jean-Paul Brutus, this e-guide identifies the causes, symptoms, and different ways to treat CTS and offers recommendations on how to ease your symptoms at home.