Accessory Flexor Digitorum Longus Presenting as Tarsal Tunnel Syndrome: A Case Series.

ABSTRACT: Tarsal tunnel syndrome (TTS) typically occurs from extrinsic or intrinsic sources of compression on the tibial nerve. We present 3 cases of patients, all of whom have a prolonged time to diagnosis after evaluation with multiple specialties, with foot pain ultimately secondary to an accessory flexor digitorum longus muscle causing TTS. The literature describing the association between TTS and accessory musculature has been limited to single case reports and frequently demonstrate abnormal electrodiagnostic testing. In our series, 2 cases had normal electrodiagnostic findings despite magnetic resonance imaging (MRI) that later revealed TTS and improvement with eventual resection. A normal electromyogram should not preclude the diagnosis of TTS and MRI of the ankle; it should be considered a useful diagnostic tool when examining atypical foot pain.

Can Carpal Tunnel Syndrome be Appropriately Diagnosed in a Cold Hand?

INTRODUCTION: The diagnosis of carpal tunnel syndrome (CTS) with nerve conduction studies traditionally involves warming the hand to avoid misleading prolongation of distal latency (DL). Comparing the median nerve DL to the ulnar and radial nerves using the combined sensory index (CSI) has been reported to improve the accuracy of CTS diagnosis. During this study, the authors examined the effect of hand temperature on the CSI and diagnosis of CTS. METHODS: The authors conducted a prospective, controlled, cohort study with 20 asymptomatic control patients and 21 symptomatic patients with confirmed CTS. Symptomatic patients underwent nerve conduction studies with the CSI calculated under both cold and warm conditions. RESULTS: Control subjects with warm hands had an average CSI of 0.0 milliseconds (ms), and -0.3ms with cold hands. CTS subjects with warm hands had an average CSI of 3.2ms, and 3.7ms with cold hands. Although hand temperature was shown to slow sample latencies, differences calculated with the CSI did not misclassify any of the 41 sample subjects. CONCLUSIONS: During this study, cold temperature did not result in misclassification of either control patients or CTS patients when CSI was diagnostically used. Based on these results, peak latency comparisons in cold hands can be considered as diagnostically reliable as under standard hand temperature ranges for the diagnosis of CTS, with caution warranted in borderline cases. This diagnostic technique can save time for the patient, physician, and care team without compromising quality of care. Future larger sample blinded studies at multiple electrodiagnostic sites are indicated.

An Additional Electrodiagnostic Tool for Ulnar Neuropathy: Mixed across the Elbow.

Background Diagnosing ulnar neuropathy at the elbow (UNE) remains challenging despite guidelines from national organizations. Motor testing of hand intrinsic muscles remains a common diagnostic method fraught with challenges. Objective The aim of the study is to demonstrate utility of an uncommon nerve conduction study (NCS), mixed across the elbow, when diagnosing UNE. Methods Retrospective analysis of 135 patients, referred to an outpatient University-based electrodiagnostic laboratory with suspected UNE between January 2013 and June 2019 who had motor to abductor digiti minimi (ADM), motor to first dorsal interosseus (FDI), and mixed across the elbow NCS completed. To perform the mixed across the elbow NCS, the active bar electrode was placed 10-cm proximal to the medial epicondyle between the biceps and triceps muscle bellies. The median nerve was stimulated at the wrist followed by stimulation of the ulnar nerve at the ulnar styloid. The difference between peak latencies, labeled the ulnar-median mixed latency difference (U-MLD), was used to evaluate for correlation between the nerve conduction velocities (NCV) of ADM and FDI. Results Pearson r -values = -0.479 and -0.543 ( p < 0.00001) when comparing U-MLD to ADM and FDI NCV across the elbow, respectively. The negative r -value describes the inverse relationship between ulnar velocity across the elbow and increasing U-MLD. Conclusion Mixed across the elbow has moderate-strong correlation with ADM and FDI NCV across the elbow. All three tests measure ulnar nerve function slightly differently. Without further prospective data, the most accurate test remains unclear. The authors propose some combination of the three tests may be most beneficial when diagnosing UNE.