Cubital Tunnel Syndrome

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Introduction

Cubital tunnel syndrome occurs when the ulnar nerve becomes compressed or irritated as it passes behind the inner side of the elbow.

The ulnar nerve provides sensation to the little finger and part of the ring finger. It also controls several muscles responsible for grip, coordination and fine movements of the hand. Compression of this nerve can therefore cause numbness, tingling, weakness or loss of hand dexterity.

Mild cases can often be managed without surgery. However, persistent numbness, progressive weakness or muscle wasting may indicate more significant nerve dysfunction requiring specialist assessment.

What is the cubital tunnel?

The ulnar nerve travels from the neck down the arm and passes behind the medial epicondyle—the prominent bone on the inner side of the elbow. This is the area commonly known as the “funny bone”.

The nerve then enters a confined passage called the cubital tunnel before continuing into the forearm and hand.

When the elbow is bent, the shape of the cubital tunnel changes and the ulnar nerve is placed under greater pressure and tension. Repeated elbow bending, prolonged pressure over the inner elbow or narrowing around the nerve can eventually cause irritation or compression.

What are the symptoms of cubital tunnel syndrome?

Symptoms may initially be intermittent, especially when the elbow has been bent for a prolonged period. They can become more frequent as the condition progresses.

Common symptoms include:

• Numbness or tingling in the little finger and ring finger
• An “electric shock” sensation along the inner forearm or hand
• Symptoms when sleeping with the elbow bent
• Tingling while holding a telephone, driving or reading
• Discomfort around the inner side of the elbow
• Reduced grip strength
• Difficulty with fine tasks such as using buttons or typing
• A tendency to drop objects
• Loss of coordination in the fingers

In more advanced cases, there may be persistent numbness, weakness of the small muscles of the hand or visible muscle wasting. Some patients develop clawing of the ring and little fingers.

Assessment should not be delayed when weakness or muscle wasting is present because longstanding nerve dysfunction may not recover completely, even after the compression has been relieved.

What causes cubital tunnel syndrome?

Cubital tunnel syndrome does not always have a single identifiable cause. Factors that may contribute include:

• Prolonged or repeated bending of the elbow
• Sleeping with the elbow tightly bent
• Leaning directly on the inner side of the elbow
• Repetitive throwing or overhead activity
• Previous elbow fracture or dislocation
• Elbow arthritis or bone spurs
• Swelling or a cyst around the elbow
• Thickening of the tissues covering the cubital tunnel
• An ulnar nerve that moves abnormally over the medial epicondyle
• Previous surgery or scar formation around the elbow

Certain medical conditions, including diabetes and thyroid disorders, may also make peripheral nerves more vulnerable to compression.

Is a subluxing ulnar nerve the same as cubital tunnel syndrome?

No. Although the conditions can occur together, they are not identical.

A subluxing ulnar nerve moves out of its normal groove and passes over the medial epicondyle when the elbow bends. This may produce a snapping or shifting sensation at the inner elbow.

Some people have a mobile ulnar nerve without pain or neurological symptoms and do not require treatment. In others, repeated movement of the nerve causes irritation, numbness or weakness.

Snapping at the inner elbow can also come from the medial portion of the triceps rather than the ulnar nerve. A careful dynamic examination—and sometimes dynamic ultrasound—can help identify which structure is moving.

This distinction is important because simple decompression may not be appropriate if the nerve is clinically unstable. Selected patients with symptomatic ulnar nerve instability may require anterior transposition of the nerve.

Read more about a subluxing ulnar nerve

How is cubital tunnel syndrome diagnosed?

Diagnosis begins with a detailed assessment of the symptoms and activities that provoke them.

During the examination, the doctor may evaluate:

• Sensation in the ring and little fingers
• Strength of the hand and finger muscles
• Grip and pinch function
• Signs of muscle wasting
• Irritability of the ulnar nerve at the elbow
• Whether elbow bending reproduces the symptoms
• Whether the ulnar nerve remains stable during movement
• The neck, shoulder, wrist and hand for other potential causes

Numbness in the hand is not always caused by cubital tunnel syndrome. Similar symptoms can arise from a pinched nerve in the neck, compression of the ulnar nerve at the wrist or other peripheral nerve conditions.

More than one site of nerve compression can occasionally be present.

What investigations may be required?

Not every patient requires every investigation. Depending on the clinical findings, investigations may include:

Nerve conduction studies and electromyography

Nerve conduction studies assess how electrical signals travel through the ulnar nerve. Electromyography evaluates the function of the muscles supplied by the nerve.

These tests can help:

• Confirm ulnar nerve dysfunction
• Estimate the severity of nerve involvement
• Identify the likely level of compression
• Assess for muscle denervation
• Look for other neurological conditions

Early or intermittent cubital tunnel syndrome can occasionally be present despite a normal nerve conduction study. Results should therefore be interpreted together with the symptoms and physical examination.

Ultrasound

Ultrasound can assess the size and appearance of the ulnar nerve. A dynamic ultrasound examination can also show whether the nerve moves or subluxes when the elbow is bent and straightened.

X-rays

Elbow X-rays may be useful when there has been a previous injury or when arthritis, deformity or bone spurs are suspected.

MRI

MRI is not routinely required but may be considered if there is concern about a mass, cyst or another structural cause of nerve compression.

Can cubital tunnel syndrome be treated without surgery?

Mild or intermittent symptoms can often be managed without an operation, particularly when there is no significant weakness or muscle wasting.

Non-surgical treatment may include:

Activity modification

Avoid prolonged elbow bending and direct pressure over the inner elbow. Changing telephone, computer, driving or sleeping positions may reduce irritation of the nerve.

Night positioning

Keeping the elbow relatively straight while sleeping can reduce pressure on the ulnar nerve. This may be achieved with a purpose-made splint or a simple padded support, depending on the individual.

Elbow padding

Padding can protect the nerve when the elbow rests against a desk, armrest or other hard surface.

Hand therapy

A therapist may advise on ergonomics, activity modification and appropriate nerve-mobility exercises. Exercises should not be forced if they reproduce marked tingling or pain.

Medication may help accompanying discomfort, but it does not reverse significant mechanical compression or established nerve damage.

When might surgery be considered?

Surgery may be discussed when:

• Symptoms persist despite appropriate non-surgical treatment
• Numbness becomes frequent or constant
• Hand weakness is developing
• There is loss of dexterity or repeated dropping of objects
• Muscle wasting is present
• Nerve tests show significant dysfunction
• The nerve is symptomatically unstable or subluxing
• A structural problem is compressing the nerve

The type of surgery depends on the severity of the compression, the stability of the nerve, previous procedures, elbow anatomy and the patient’s individual needs.

Endoscopic cubital tunnel release

Cubital tunnel release creates more room for the ulnar nerve by dividing restrictive tissues along the cubital tunnel.

In an endoscopic release, the nerve is decompressed through a smaller access incision with the assistance of an endoscope. This can allow the surgeon to visualise and release the constricting tissues along the course of the nerve.

Endoscopic release may be considered when decompression is required and the nerve is suitable for an in-situ procedure. It is not necessarily appropriate when the ulnar nerve is unstable or when other anatomical factors require the nerve to be repositioned.

Open and endoscopic techniques both have recognised indications. The choice should be based on the individual nerve and elbow rather than incision size alone.

Ulnar nerve transposition

Ulnar nerve transposition involves fully decompressing the nerve and moving it from behind the medial epicondyle to a position in front of it.

Transposition may be considered in selected circumstances, including:

• A symptomatic subluxing or dislocating ulnar nerve
• Excessive tension or traction on the nerve
• Significant local deformity
• Certain revision operations
• Situations in which stable in-situ decompression is unsuitable

Different forms of transposition place the nerve within the subcutaneous tissue, muscle or beneath the muscle. The appropriate technique depends on the clinical situation and the surgeon’s assessment.

[Read more about cubital tunnel release and ulnar nerve transposition →]

What is recovery like after cubital tunnel surgery?

Recovery depends on the procedure performed and the severity and duration of nerve dysfunction before surgery.

After an isolated cubital tunnel release, gentle elbow movement is usually encouraged relatively early. Wound care and activity restrictions will be advised during the initial healing period.

Recovery following ulnar nerve transposition may be more protected because the nerve has been mobilised and repositioned. Rehabilitation is adjusted according to the surgical technique and the individual patient.

Pain around the surgical site generally settles before the nerve fully recovers. Tingling may improve gradually over weeks or months. Recovery of strength and sensation can take longer when compression has been severe or longstanding.

Surgery aims to relieve ongoing pressure on the nerve and prevent further deterioration. Complete recovery cannot be guaranteed, particularly when there was constant numbness, marked weakness or muscle wasting before treatment.

When should I seek an assessment?

Consider seeking medical assessment if you have:

• Recurrent numbness in the ring and little fingers
• Symptoms that disturb sleep
• Persistent hand numbness
• Weakness or loss of hand coordination
• Visible wasting of the hand muscles
• Snapping over the inner elbow associated with tingling
• Symptoms following an elbow injury
• Symptoms that have not improved with activity modification

Earlier assessment is particularly important when weakness, muscle wasting or constant loss of sensation is present.

Cubital tunnel syndrome assessment in Singapore

Dr Puah Ken Lee is an orthopaedic surgeon with a clinical focus on shoulder, elbow and sports-knee conditions. Assessment of suspected cubital tunnel syndrome includes evaluating the site and severity of nerve dysfunction, determining whether the ulnar nerve is stable and considering other possible sources of hand numbness.

Where surgery is appropriate, treatment options may include endoscopic cubital tunnel release or ulnar nerve decompression with anterior transposition. The recommended procedure is individualised according to the clinical findings rather than using the same operation for every patient.

To arrange an assessment for numbness in the ring and little fingers, hand weakness or snapping at the inner elbow, contact 360 Orthopaedics.

Frequently asked questions

Which fingers are affected by cubital tunnel syndrome?

Cubital tunnel syndrome typically causes altered sensation in the little finger and the adjacent half of the ring finger. The exact distribution can vary, and examination may be required to distinguish it from other nerve conditions.

Why are my fingers numb when I sleep?

Sleeping with the elbow bent can increase pressure and tension on the ulnar nerve. Some patients also sleep with the inner elbow resting against a firm surface. Both factors can provoke cubital tunnel symptoms.

Can cubital tunnel syndrome come from the neck?

A nerve problem in the neck can produce symptoms resembling cubital tunnel syndrome. Some patients may also have nerve irritation at more than one level. Examination and, when appropriate, nerve studies can help distinguish these conditions.

Does every patient need a nerve conduction study?

No. The need for nerve testing depends on the clinical presentation. It is particularly helpful when the diagnosis is uncertain, weakness is present, the severity needs to be established or another neurological condition is suspected.

Can a subluxing ulnar nerve be treated with cubital tunnel release alone?

Not always. If the nerve is symptomatically unstable, releasing the surrounding tissues without stabilising or repositioning the nerve may be unsuitable. The movement of the nerve should be assessed before selecting the procedure.

Is endoscopic cubital tunnel release better than open surgery?

Neither technique is best for every patient. Endoscopic surgery permits decompression through a smaller access incision, while an open approach may be more suitable when the nerve must be transposed or when other anatomy needs to be addressed. The appropriate technique depends on the individual case.

Will the numbness recover immediately after surgery?

Not necessarily. Relief of night-time or intermittent tingling may occur relatively early, but nerve recovery can take months. Persistent numbness, weakness or muscle wasting present before surgery may recover incompletely.

What happens if severe cubital tunnel syndrome is left untreated?

Ongoing compression can lead to persistent loss of sensation, reduced hand strength, impaired coordination and wasting of the small muscles of the hand. Advanced nerve damage may not be fully reversible.

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Specialist Care for Elbow Injuries in Singapore

Dr Puah is an orthopaedic surgeon specialising in shoulder, elbow and sports injuries. He provides personalised care tailored to each patient’s condition and activity level.

Consultations are available at Mount Elizabeth Novena.

If you are experiencing elbow pain or hand numbness that is affecting your daily life or sports, early assessment can help guide appropriate treatment.

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Cubital tunnel syndrome is common but treatable. Early diagnosis and appropriate management can improve outcomes and prevent long-term problems.
Dr Puah Ken Lee is an orthopaedic surgeon in Singapore specialising in shoulder, elbow and sports injuries at 360 Orthopaedics, Mount Elizabeth Novena. Patients with persistent elbow pain or hand numbness are encouraged to seek specialist evaluation.