The question of whether carpal tunnel syndrome (CTS) can occur in the elbow is common because symptoms often travel through the arm. True carpal tunnel syndrome is strictly confined to the wrist, where the median nerve is compressed. However, the feeling of a compressed nerve in the elbow is a distinct and frequently occurring condition. This confusion is understandable because both conditions involve a nerve being squeezed within a narrow anatomical passageway, leading to sensory and motor dysfunction in the hand.
Carpal Tunnel Syndrome: A Definition
Carpal Tunnel Syndrome (CTS) is a specific type of entrapment neuropathy that occurs at the wrist. The condition arises when the median nerve, one of the main nerves of the arm, becomes compressed as it travels through the carpal tunnel. This tunnel is a narrow, rigid passageway formed by the wrist bones on the bottom and the transverse carpal ligament across the top.
The median nerve provides sensation to the thumb, index finger, middle finger, and the thumb-side half of the ring finger. It also controls the movement of some muscles at the base of the thumb. When pressure within this confined space increases, it impairs the nerve’s function, leading to characteristic symptoms of numbness and tingling. This pressure can be caused by swelling, inflammation of the tendons that also pass through the tunnel, or conditions like rheumatoid arthritis or diabetes.
The Elbow’s Nerve Compression: Cubital Tunnel Syndrome
The condition often mistaken for carpal tunnel in the elbow is known as Cubital Tunnel Syndrome (CUBTS). This is the second most common compression neuropathy in the upper extremity, involving the ulnar nerve rather than the median nerve. The ulnar nerve, often referred to as the “funny bone” nerve, travels down the arm and is most vulnerable to compression where it passes behind the inner side of the elbow.
The cubital tunnel is the small space where the ulnar nerve passes through a groove between the two bony prominences of the elbow joint. Common mechanisms for compression include prolonged or repetitive bending of the elbow, which stretches the nerve. Resting the elbow on hard surfaces for extended periods can also cause irritation. When the elbow is held in a flexed position, such as when sleeping or holding a phone, the volume of the cubital tunnel is reduced, which increases pressure on the ulnar nerve.
Mapping the Numbness: Distinguishing Symptoms
The most reliable way to distinguish between the two conditions is by mapping the exact location of the numbness and tingling in the hand. Carpal Tunnel Syndrome causes sensations primarily in the thumb, index finger, middle finger, and the half of the ring finger nearest the thumb. These symptoms are frequently reported to be worse at night, often waking the person from sleep. Symptoms can also occur during activities that involve prolonged wrist flexion, such as driving or typing.
In contrast, Cubital Tunnel Syndrome specifically affects the little finger and the adjacent half of the ring finger. Individuals with CUBTS may also experience pain localized to the inner elbow or pain that radiates down the forearm. As the condition progresses, a person might notice a decrease in grip strength. Difficulty with fine motor tasks, like buttoning a shirt, can occur due to weakness in the small muscles of the hand controlled by the ulnar nerve.
Treatment Approaches for Nerve Entrapment
Initial treatment for both Carpal Tunnel Syndrome and Cubital Tunnel Syndrome focuses on non-surgical methods aimed at relieving pressure and reducing inflammation. Activity modification is a primary strategy, which involves avoiding positions that provoke symptoms. This includes repetitive wrist movements for CTS or prolonged elbow flexion for CUBTS. Non-steroidal anti-inflammatory drugs (NSAIDs) may be used to help manage pain and temporary inflammation.
Splinting is another common non-operative approach, though the type of splint differs depending on the location of the nerve compression. For CTS, a wrist splint is worn, often at night, to keep the wrist in a neutral position and reduce pressure on the median nerve. For CUBTS, an elbow brace or splint is used, typically to prevent the elbow from bending excessively during sleep. Corticosteroid injections can also be administered directly into the carpal tunnel to reduce swelling and provide temporary relief for CTS symptoms.
If conservative measures fail to provide lasting relief, or if there is evidence of muscle wasting or progressive nerve damage, surgical intervention may be considered. For CTS, this involves a carpal tunnel release, where the transverse carpal ligament is cut to create more space for the median nerve. For CUBTS, surgical options include releasing the pressure on the ulnar nerve (in situ decompression). Another option is moving the nerve to a new, less compressed location in front of the elbow, a procedure known as ulnar nerve transposition.