23 Recurrent Cubital Tunnel
23.1 Patient History Leading to the Specific Problem
A 28-year-old man presented to the office with complaints of severe pain and numbness in the ring and small fingers of his nondominant hand. The patient had three ulnar nerve operations for recurrent symptoms: first, a subcutaneous transposition, followed by a submuscular transposition, and finally by an ulnar nerve vein wrap. Immediately after the third surgery, he experienced severe pain in the ulnar nerve distribution, dense numbness in the ring and small fingers, and developed weakness, intrinsic atrophy, and clawing of the ulnar digits.
23.2 Anatomic Description of the Patient’s Current Status
An old surgical scar is present posterior to the medial epicondyle. The patient has pronounced ulnar intrinsic atrophy on the left hand. A marked Wartenberg’s sign is noted in addition to clawing of the ring and small fingers. Motor examination illustrates minimal lumbrical function and no first dorsal interosseous function or bulk is visible when the patient is asked to pinch. A pronounced Froment’s sign is present. Ulnar-sided flexor digitorum profundus has marked weakness. Pinch and grip strengths are 6.34 and 37.7 kg, respectively, on the involved side compared to 12.7 and 56.8 kg, respectively, on the uninvolved extremity.
The involved ulnar nerve distribution has no functional 2-point discrimination on sensory testing, compared to 4 mm in the contralateral hand. Pronounced Tinel’s signs and hierarchical Scratch Collapse Tests are present first at the elbow, then Guyon’s canal, and proximally in the medial arm where an arcade of Struthers is located.
Fig. 23.1 Mark the previous incision with visual cues to notify you of the previous zone of surgery. The incision is extended proximally and distally in the shape of a smile.
The patient has completed a visual analog scale (VAS) for pain, depression, anger, frustration, and negative impact on quality of life (▶Fig. 23.1). The patient describes his pain as burning and crushing along the ulnar border of his hand, small, and ring fingers, with an average to worst pain level of 7 to 8 out of 10. The pain has had an 80% negative impact on his quality of life.
23.3 Recommended Solution to the Problem
Indications for revision cubital tunnel surgery can be classified as persistent, recurrent, or new symptoms. Recurrent cubital tunnel is a difficult problem requiring a systematic approach to the identification of the nerve and surgical decompression. Patients presenting with recurrent cubital tunnel may have different spectrums of symptoms related to the previously performed operation. The required surgical procedure differs slightly for each scenario; however, the overall approach is to turn the revision procedure into our primary operation: a transmuscular ulnar nerve decompression avoiding any kinking of the nerve and ensuring that all proximal and distal compression points are released (▶Table 23.1).
23.3.1 Recommended Solution to the Problem
Treatment priorities should focus on pain relief and restoration of ulnar nerve function:
• Pain relief.
• Protecting the ulnar nerve.
• Complete decompression of the ulnar nerve (Box 23.1).
• Restoring function (motor, sensory, possibly with distal transfers).
• Treating any medial antebrachial cutaneous (MABC) neuromas.
Box 23.1 Compressive Structures in Recurrent Cubital Tunnel Syndrome
1. Tight fascial band from previous subcutaneous transposition.
2. Medial intermuscular septum (PMIS).
3. Flexor carpi ulnaris (FCU) fascial septum between median-innervated forearm flexors and FCU (distal intermuscular septum DIMS.
4. Thin but strong FCU fascia overlying the ulnar nerve.
5. Distal crossing vessels in the FCU, kinking the nerve when transposed.
6. Intermuscular septa in the flexor mass from previous submuscular transposition.
7. Arcade of Struthers.
With the operative arm prepped to the axilla, abducted to 90 degrees, and a high above-elbow sterile tourniquet in place (to enable removal later in the procedure to check for an arcade of Struthers), mark the previous incision including a visual reminder of the zone of scarring (see ▶Fig. 23.1). Extend the incision proximal and distal. Identify the ulnar nerve widely proximal to the area of previous surgery; the ulnar nerve lies directly posterior to the remaining intermuscular septum between the biceps and triceps (▶Fig. 23.2a). The entire length of the proximal intermuscular septum (PIMS) is removed. Then identify the ulnar nerve far distal to the previous operative site by dividing the skin and dissecting down to expose the flexor carpi ulnaris (FCU) fascia. There is a thick superficial fascial band (the “unnamed” septum) that is always present in the forearm fascia, even in revision surgery, that divides the median-innervated forearm flexors laterally from the FCU medially (▶Fig. 23.2b). This distal septum and its relationship to the ulnar nerve mimics its proximal counterpart (PMIS) and it can similarly be used as a helpful anatomic landmark to identify the unscarred distal nerve. The ulnar nerve lies directly under this unnamed distal intermuscular septum (DIMS), and deep to the FCU fibers.
In the primary operation after identification of the ulnar nerve, we dissect to identify the medial antebrachial cutaneous nerve (MABC). In revision cubital tunnel surgery, we ignore the MABC until the entire ulnar nerve is exposed in order to prevent inadvertent injury to the ulnar nerve in its unpredictable course through scar tissue. After identification proximally and distally, we carefully dissect the ulnar nerve into the previous zone of surgery, understanding that the nerve, scar tissue, and fascia are all white in appearance, making it imperative to work from “known to unknown.” The “tug test” can be used to anticipate the course of the ulnar nerve and ensure that it is in continuity within the scarred surgical field.
After a previously performed simple decompression, the ulnar nerve will lie posterior to the medial epicondyle, or on the epicondyle as it subluxes across the bony prominence (▶Fig. 23.3a). A circumferential decompression is performed until the entire ulnar nerve is identified and mobile. The flexor–pronator origin is then exposed. Fascial flaps are created with the flexor–pronator fascia. A central “T” of thick fascia between the forearm flexors is identified and excised to prevent an area of kinking or compression on the ulnar nerve when it is transposed to this new anterior location. A flexor muscle slide is performed for at least 1 inch distally using bipolar cautery (▶Fig. 23.3b). Distally where the ulnar nerve courses through the FCU, the “unnamed” septum (DIMS) is removed. Very thin but tight fascia overlies the ulnar nerve within the FCU and must be released. Also within the FCU, small crossing vessels superficial and perpendicular to the ulnar nerve are routinely encountered and must be divided to prevent kinking of the nerve when transposed. Small motor branches to the FCU should be neurolysed proximally off the main ulnar nerve to enable a tension-free transposition while preserving the critical motor innervation to the FCU. Once transposed anteriorly, the nerve should lie tension free, straight, within the trough created by the flexor slide. The fascial flaps should be very loosely approximated over the ulnar nerve (▶Fig. 23.3c).
In patients with a previous subcutaneous transposition, the dissection through the zone of injury can be very difficult as the nerve and subcutaneous scar will look the same. Often after a subcutaneous transposition, there is a tight compressive band over the ulnar nerve usually from the strategy used to keep the nerve anterior. In this scenario, the medial intermuscular septum (PIMS), unnamed septum (DIMS), and distal crossing vessels are often intact and must be released or removed. The flexor slide is performed. This allows the nerve to sit gently in an anterior trough with no kinking or compression. Typically, the nerve has “memory” and does not require fascial flaps to maintain its anterior position. A limited neurolysis is performed only on the anterior surface of the nerve to release any compressive scarred epineurium.