Cubital tunnel syndrome is the second commonest entrapment neuropathy in the upper limb. Recovery following cubital tunnel release could be prolonged. Persistent or worsening of symptoms have been reported to occur in 10-20% of cases.
When it has not worked, how should one approach this problem?
Is it cubital tunnel syndrome?
There are many mimics of cubital tunnel syndrome and the following list is by no means exhaustive. One should consider both distal and proximal sites of compression or a more generalised pathology causing the symptoms.
• Cervical radiculopathy
• Thoracic outlet syndrome
• Guyon's canal syndrome
• Brachial neuritis
• Systemic neuropathy (diabetes mellitus, chronic alcoholism)
• Multiple sclerosis
• Peripheral nerve tumour
Careful clinical assessment
The key lies in history and examination. Allow the patient to recount their experience of the index procedure, noting any immediate postoperative complications. I would specifically ask about pre- and post-operative symptoms and establish if there had been any symptom-free period. During examination, pay attention to the position of the scar and note any associated tenderness or numbness. I have found Tinel’s sign to be the most useful test in localising potential sites of nerve compression. In addition, I would look for evidence of traction neuropathy by asking the patient to flex and extend the elbow repeatedly (traction Tinel’s sign). Carefully document any sensory loss or muscle weakness in the hand.
Do I need to have repeat neurophysiology?
Neurophysiology is a vital aid in the context of failed surgery. Most patients would have pre-operative NCS/EMG and I would obtain repeat testing (ideally by the same neurophysiologist) for comparison. If the results are worse, then that is a strong indication for re-exploration. It is reassuring if the results have normalised or improved.
Do I need further imaging?
Generally it is not necessary unless there is concern with a ganglion or osteophytes causing ongoing compression, in which case ultrasound or radiographs are indicated. CT or MRI are reserved for cases with more complex anatomy of the elbow.
The symptoms can be broadly divided into:
1. Persistent Symptoms
• No or minimal relief after cubital tunnel release
• Could be due to incomplete release or wrong diagnosis or instability of the nerve (after in-situ decompression)
2. Recurrent Symptoms
• There has to be a defined symptom-free period for at least 3 months (often it is longer)
• Could be due to perineurial fibrosis
3. New Symptoms
• Nerve injury (ulnar nerve, medial antebrachial cutaneous (MABC) nerve branch)
Do I need revision surgery?
Before one undertakes revision surgery on the ulnar nerve, there are a number of factors to consider:
- the intrusiveness of the symptoms
- the presence of any sensory/motor deficit
- the likelihood of nerve injury
- the likelihood of improvement after revision surgery
There are occasions when surgery is performed to preserve the protective sensation and to prevent further deterioration.
The key in revision decompression of the ulnar nerve is thorough and meticulous dissection of the ulnar nerve at the elbow. All potential sites of compression are carefully released. Following that, there are a number of techniques for anterior transposition, including subcutaneous, subfascial or submuscular. This is influenced by the surgeon's preference as well as intraoperative findings.