Factors Associated With Severity of Cubital Tunnel Syndrome at Presentation

Background: The outcomes of cubital tunnel syndrome surgery are affected by preoperative disease severity. The aim of this study was to identify factors associated with clinical and electrodiagnostic severity of cubital tunnel syndrome at presentation. Methods: We retrospectively identified 213 patients with electrodiagnostically confirmed cubital tunnel syndrome who underwent cubital tunnel surgery from July 2008 to June 2013. Our primary response variable was clinical cubital tunnel syndrome severity assessed by the McGowan grade. Our secondary response variables were sensory nerve action potential (SNAP) recordability, presence of fibrillations, and motor nerve conduction velocities (CVs) in the abductor digiti minimi (ADM) and first dorsal interosseous (FDI). Bivariate analysis was used to screen for factors associated with disease severity; significant variables were selected for multivariable regression analysis. Results: Older age was associated with higher McGowan grade and diabetes mellitus was associated with unrecordable SNAPs on bivariate analysis. No other variables met inclusion criteria for multivariable regression analysis for McGowan grade or unrecordable SNAPs. Multivariable regression analysis showed older age and higher Distressed Communities Index (DCI) to be associated with decreased motor nerve CVs in ADM. Multivariable regression analysis showed higher body mass index (BMI) and higher DCI to be associated with decreased motor nerve CVs in FDI. No variable was associated with the presence of fibrillations. Conclusions: A subset of patients with cubital tunnel syndrome may benefit from earlier referral for hand surgery evaluation and earlier surgery. Older patients, with higher BMI, with diabetes mellitus, and with economic distress are at higher risk for presentation with more severe disease.

Comment to: The utility of ultrasound examination in cubital tunnel syndrome caused by heterotopic ossification

Ultrasound (US) could visualize the pathological anatomy of HO and the enlargement site and compression location of the nerve in the cubital tunnel [1]. We read with great interest the article of Jačisko et al[2]. In addition, we report rare US images of HO in direct contact with the swollen ulnar nerve in the cubital tunnel that was not detected by plain radiography. A 60-year-old female presented with a six-month history of elbow pain. Her pain was located at the medial side of the right elbow joint and accompanied by numbness of the fifth finger. She had a history of excessive manual labor due to her occupation as a gardener over the past few decades. The numbness began with the fifth finger initially and gradually extended toward the medial side of the elbow joint. US images showed hyperechoic masses causing acoustic shadowing, in direct contact with the ulnar nerve in the cubital tunnel. The HO seems to be related to compression of the ulnar nerve. The ulnar nerve was swollen (Figure 1-a, b). The maximal cross-sectional-area was 0.10 cm2. Plain elbow radiographs demonstrated osteophyte formation in the coronoid process of the ulna, the coronoid fossa of the humerus, and in the radial head (Figure 1-c). Radiographic imaging showed no heterotopic bone formation in the soft tissues surrounding the medial side of the right elbow. We performed US-guided perineural injection with a mixture of 1 cc of 10 mg triamcinolone and 3 cc of 0.2 % ropivacaine. Her pain and numbness gradually diminished with no adverse effects. Her pain reduced by 70% after two weeks, with pain improvement sustained for 6 months after the injection. Jačisko et al[2]have presented some diagnostic US imaging on neuropathy caused by HO located close to the ulnar nerve in the cubital tunnel. Especially, this case showed definite heterotopic bone formation in the soft tissue surrounding the medial side of the elbow on plain radiography. The classic sonographic patterns of HO were defined by the presence of central hypoechoic area surrounded by foci of calcification [3, 4]. The distortion of normal soft tissue and the formation of hypoechoic areas, with or without foci of calcification can also be shown as early signs[3, 4]. The use of US for HO is highly sensitive and provides an earlier diagnosis compared with other radiologic modalities [3-5]. It can be an effective treatment strategy and may improve the prognosis of neuropathy. We highlight that US evaluation can provide early diagnostic information about ulnar nerve morphology and various HO formations even if plane radiographs did not show heterotopic bone formation in the soft tissues surrounding the medial side of the elbow.