Carpal Tunnel vs Cubital Tunnel Syndrome: What's the Difference?

Numbness and tingling in the hand can come from more than one place, and two of the most common causes, carpal tunnel syndrome and cubital tunnel syndrome (ulnar nerve entrapment), are often confused with one another. Both involve a nerve being compressed, both cause numbness and tingling, and both are very treatable. The key difference is which nerve is affected and, therefore, which fingers are involved.

In short: if the numbness and tingling affects the thumb, index and middle fingers, it is more likely carpal tunnel syndrome, caused by compression of the median nerve at the wrist. If it affects the ring and little fingers, and is worse with the elbow bent, it is more likely cubital tunnel syndrome, caused by compression of the ulnar nerve at the elbow.

Carpal tunnel syndrome

The median nerve passes through a narrow tunnel at the palm side of the wrist alongside several tendons. When the tunnel narrows or the surrounding tissue thickens, the nerve becomes compressed. Symptoms typically involve the thumb, index, middle and part of the ring finger, notably sparing the little finger, and are often worse at night or when holding a phone or steering wheel.

Cubital tunnel syndrome

The ulnar nerve, the nerve responsible for the sharp tingling felt when you knock your "funny bone", passes through a narrow tunnel behind the bony point on the inside of the elbow. Prolonged or repeated elbow bending narrows this tunnel and compresses the nerve. Symptoms affect the ring and little fingers, and are typically worse with the elbow bent, such as when sleeping or holding a phone to the ear.

Carpal tunnel vs cubital tunnel at a glance

• Nerve affected: median nerve for carpal tunnel, ulnar nerve for cubital tunnel
• Location of compression: wrist for carpal tunnel, elbow for cubital tunnel
• Fingers affected: thumb, index and middle fingers for carpal tunnel; ring and little fingers for cubital tunnel
• Typically worse with: holding a phone, driving, or sleeping with the wrist bent for carpal tunnel; bending the elbow, such as sleeping or holding a phone to the ear, for cubital tunnel
• Relative frequency: carpal tunnel syndrome is more common, though cubital tunnel is the second most common nerve compression in the upper limb

Why the confusion happens

Both conditions cause numbness, tingling and, in longstanding cases, weakness and muscle wasting in the hand. Because both are nerve entrapments with overlapping symptoms, people often assume any hand numbness is carpal tunnel syndrome. The pattern of which fingers are affected, and whether symptoms relate to wrist or elbow position, is usually the clearest way to tell them apart, though a nerve conduction study can confirm the diagnosis when the picture is unclear or both nerves seem to be involved.

How both are assessed

Assessment includes a history of symptom pattern and aggravating positions, examination of hand strength and sensation, and typically a nerve conduction study, which identifies which nerve is affected, where the compression is occurring, and how severe it is.

Treatment

Both conditions are managed in a similar staged way.

• Activity and position modification, avoiding the postures that compress the nerve, a bent wrist for carpal tunnel or a bent elbow for cubital tunnel
• Splinting, worn particularly at night, to keep the wrist neutral or the elbow straighter
• Corticosteroid injection, which can help carpal tunnel syndrome in particular
• Surgery, carpal tunnel release or ulnar nerve transposition, considered when symptoms are persistent or associated with weakness, where earlier surgery tends to give the nerve the best chance of recovery

The bottom line

Carpal tunnel and cubital tunnel syndrome are both common, treatable nerve compressions that are frequently confused because of their overlapping symptoms. The fingers affected, and the position that aggravates symptoms, are the most useful clues to which nerve is involved. If numbness, tingling or weakness in the hand is persistent, an assessment of both the wrist and the elbow can confirm the diagnosis and set out the right treatment plan.