Cubital Tunnel Syndrome
Background
Cubital Tunnel Syndrome, also called ulnar neuropathy at the elbow is a very common peripheral nerve compression that occurs in healthy, young adults, but also in older, less active patients alike. The ulnar nerve travels in a tight space around the back of the elbow on the medial side. The ulnar nerve is particularly important for hand and upper extremity function and provides the following innervation:
- forearm muscles, in particular the flexor carpi ulnaris which is one of the two wrist flexors.
- deep flexor tendons to ring and small fingers.
- fine motor intrinsic muscles to fingers and thumb.
- sensation to the ring and small finger, as well as to the dorsal aspect of the hand.
Causes
SInce there are several sites of potential compression, the causes vary. Abnormal attachments of the triceps muscle (Arcade of Struthers) can compress the nerve above the elbow. Tumors such as lipomas or ganglion cysts aren’t common but can compress the nerve near the elbow. Most often, fascial bands at the elbow are the cause of the compression (ligament of Osborne). On occasion, within the flexor-pronator mass there can be a fascial layer that can compress the ulnar nerve. In some cases, the ulnar nerve can be unstable and subluxate (dislocate/slide) during elbow flexion and this can lead to compression.
Symptoms
Numbness and tingling in the ring and small fingers are commonly reported. Pain may or may not be present and often runs along the course of the ulnar nerve at the forearm. Weakness of the ulnar innervated muscles can lead to significant hand deformity and greatly affect hand function. In its most advanced form it can lead to an ulnar claw hand.
Diagnosis
The history and physical exam are critical. Xrays can help determine if there is any bony abnormality at the elbow. An MRI of the ulnar nerve can be helpful in cases of prior surgery on the nerve or the nearby elbow joint and its ligaments. Also in cases of recent trauma. SInce the ulnar nerve is rather superficial, ultrasound using a high frequency probe can aid in the diagnosis. EMG and NCS (nerve testing) can help ascertain the site of compression and also determine its severity, although it can sometimes be normal.
Treatment
Depending on the individual circumstances, and the severity of the compression, conservative treatment such as nerve gliding exercises and physical therapy can be helpful, as well as splinting of the elbow at nighttime in extension. Steroid injections in this area are usually not indicated.
When conservative measures fail, the nerve can be surgically decompressed.
Dr. Dowlatshahi will discuss options with you. He offers the following procedures, depending on the individual circumstances:
- Ulnar nerve release/decompression in-situ.
- Ulnar nerve decompression + anterior transposition.
- Ulnar nerve decompression +/- anterior transposition + AIN to ulnar motor transfer at the wrist/forearm with selective decompression of the ulnar motor nerve at Guyon’s canal.
This is ultrasound imaging performed by Dr. Dowlatshahi during the clinic visit showing the degree of ulnar nerve subluxation:
In the following case, the patient had undergone a prior release procedure by a different surgeon and had persistent and worsening symptoms and weakness. During the release, a longer incision had to be made, and as seen in the photograph, the nerve is very scarred and stuck to the surrounding structures.
This is the case of a gentleman that underwent shoulder surgery and afterwards was found to have a profound ulnar nerve compression. In these images, the amount of muscle loss is visible, even to the untrained eye.
The ulnar nerve was released at the elbow, with identification of an abnormal muscle called anconeus epitrochlearis which was found to be compressing the nerve. At the same time, the nerve was transposed anteriorly.
Due to the profound weakness, the ulnar nerve was released at the wrist as well, and an Anterior Interosseous (AIN) to ulnar nerve end-to-side transfer was performed.
