Maintaining the patient's elbow at full extension or 70[degrees] flexion during SSNCS made no difference in diagnosis of CubTS.
SSNCS are now widely used for diagnosis and prognosis of CubTS, and our previous studies have proved its sensitivity and accuracy.[sup],, However, technical problems reduced the credibility of SSNCS, some reports said flexed elbow would add technique error in NCS while others vice versa.
To solve this paradoxical problem, two studies had investigated the influence of elbow position in sensitivity of CubTS diagnosis by NCS but drew different conclusions.
There was also no statistically significant difference in abnormality and diagnosis of CubTS between full elbow extension and 70[degrees] elbow flexion as measured by SSNCS.
In our study, maintaining the patient's elbow in full extension or 70[degrees] flexion made no statistically significant difference in diagnosis of CubTS, and results were highly correlated across the elbow where most CubTS occurred.
This supports the American Association of Electrodiagnostic Medicine's recommendation that stimulation at positions more than 3 cm distal to the medial epicondyle of humerus should be avoided as the nerve is usually deep within the flexor carpi ulnaris muscle by this point, and there is substantial risk of submaximal stimulation.[sup] We suggest that results from 4 cm below the medial epicondyle of humerus should be used cautiously to diagnose CubTS.
Probable pathogenesis of CubTS includes: (1) When elbow is in flexion, the fibrous aponeurosis becomes thicker between the two heads of musculi flexor carpi ulnaris, which is the lateral wall of cubital tunnel, narrowing the cubital tunnel lacuna, making ulnar nerve compressed; [sup] (2) Compression of ulnar nerve across the elbow by hyperosteogeny or osteophyma, which aggravates the tunnel's narrowing; [sup] (3) Induced by soft tissue adjacent to the ulnar nerve in the tunnel; [sup] (4) Compressed by intraluminal mass; [sup] (5) When flex the elbow, cubital tunnel volume decreased, elbow support ligament contracted, and ulnar nerve compressed.
So far for the Chinese patients who are clinical suspicion of CubTS, routine MNCS is used to detect ulnar nerve dysfunction.
[sup] reported that in 53 patients who were diagnosed CubTS by short-segment conduction study, 27% lesions were in the medial epicondyle, 20% in the digital of medial epicondyle.
And 2 cm above medial epicondyle should be paid highly attention in diagnose and evaluation of therapeutic effects of CubTS. It helps clinician in diagnosing, prognostic and evaluation of therapeutic effects of CubTS.
In this study, all the patients diagnosed CubTS by routine motor nerve conduction test, had symptoms such as limb numbness.
Our study showed that percentage of decreased CMAP was statistical significance related to CubTS' prognosis.