Cubital tunnel syndrome is a type of ‘compression neuropathy’, whereby a nerve (called the ulnar nerve) becomes abnormally compressed (squashed) within the cubital tunnel at the inner aspect of your elbow. The ulnar nerve supplies sensation to the little finger and part of the ring finger (and also power to many small muscles in your hand). Cubital tunnel syndrome typically causes numbness and pins and needles (tingling) of the little finger, part of the ring finger, and sometimes clumsiness, weakness and pain.

The cubital tunnel is a narrow tunnel on the inner aspect of your elbow which contains only the ulnar nerve as it travels down your arm towards the hand. A ligament helps to stabilise the nerve and muscle and other soft tissues also cover the nerve in this region. Elbow position (especially when bent) or resting it on a tabletop can increase the pressure within the cubital tunnel.

The ulnar nerve can get compressed within the cubital tunnel, especially when the elbow is bent or rested on a tabletop. Abnormally increased pressure will squash (compress) the ulnar nerve and reduce the nerve’s blood supply and cause symptoms in the little and ring fingers. Night times can be particularly problematic due to our tendency to bend our elbows (curl up) when we sleep.

The thumb, index and middle fingers are not typically affected in cubital tunnel syndrome and numbness here may represent a different condition such as carpal tunnel syndrome.

There are other causes of finger numbness and a thorough assessment will help to identify the cause.

Some of the potential symptoms of cubital tunnel syndrome are listed below.

Typically present:

• Numbness and pins and needles (tingling) in the little finger (pinkie) and ring finger.

• Finger tingling that is worse at night, when bending your elbow (e.g. when holding your phone) or when leaning on a tabletop.

Sometimes present:

• Pain at the inner elbow (and sometimes along the inner forearm or hand).

• Constant numbness and pins and needles (that can be unrelated to position or activity).

• Weakness of grip and/or clumsiness (including dropping of objects).

• Muscle wasting (muscles appear smaller, especially in the webspace between your thumb and index finger).

• Involuntary or jerking movements of the little finger (pinkie).

Rarely present:

• Clicking or snapping feeling along the inner elbow.

It is important to correctly diagnose cubital tunnel syndrome and exclude other causes of hand numbness, pins and needles or elbow pain; such as carpal tunnel syndrome, nerve entrapment in the neck, golfer’s elbow or arthritis. The diagnosis is usually made on the history (your symptoms), clinical examination and, commonly, nerve conduction studies (also called neurophysiology testing) are used. Nerve conduction studies assess the speed of nerve signal transmission (termed conduction) - such as across your elbow - to help confirm the diagnosis and the severity of nerve dysfunction. Nerve conduction studies can be uncomfortable but are usually well tolerated. Assessment with X-rays, ultrasound or MRI is sometimes required.

It is not uncommon for mild forms of cubital tunnel syndrome to have a normal nerve conduction study result. Although a normal result provides some reassurance regarding nerve function, the cause of your symptoms can sometimes remain unclear.

Occasional and mild numbness or tingling in the little finger with prolonged bending of the elbow (flexion) is common and will often settle in early cases by changing the position of your elbow during activities (such as holding your phone further away from you), avoiding direct pressure on the inner elbow and taking frequent rests.

Non-surgical treatment options can include elbow splintage and physiotherapy (for nerve gliding exercises).

Surgical treatment is cubital tunnel decompression (also termed release), whereby the ligament and other structures overlying the nerve at the inner elbow are opened up to provide more space for the nerve to function and recover. Surgery is reserved for severe cases or when troublesome sensory symptoms do not respond to the above treatments. Sometimes the nerve is also moved to a new location at the front of the elbow (called transposition). Following surgery, nerve recovery and symptom improvement can be incomplete (especially for more severe forms of cubital tunnel syndrome).

Matthew offers all of the above treatments. He can refer you for physiotherapy if required.

Cubital tunnel surgery is usually performed under general or regional anaesthesia.

You can read more detailed information regarding cubital tunnel syndrome on the Lothian Hand Unit website here.

The British Society for Surgery of the Hand (BSSH) has an informative webpage on cubital tunnel syndrome here which can be downloaded as a patient information leaflet PDF here.