Electrodiagnostic approach to the patient with suspected mononeuropathy of the upper extremity

Mapping Neurophysiological Patterns in Carpal Tunnel Syndrome: Correlations With Tinel's and Phalen's Signs

Background This study aimed to observe the neurophysiological severity grading of carpel tunnel syndrome (CTS) using nerve conduction studies (NCSs) and the correlation between Tinel's and Phalen's signs. Methodology In this cross-sectional study, 240 patients of CTS were enrolled. NCSs were conducted in 480 hands. Various variables such as distal latency, amplitude, and nerve conduction velocity in both sensory and motor median nerves were recorded. The provocative tests capable of reproducing patients' symptoms such as Phalen's test and Tinel's test were performed on all 480 hands studied. Results Neurophysiological variables were affected in 449 out of 480 hands. Tinel's sign was observed in 59% of cases (265 hands) while Phalen's sign was positive in 37.2% (167 hands) of cases. Severity grading of CTS based on neurophysiological variables resulted in Grade I (mild) in 202 hands, Grade II (mild to moderate) in 56 hands, Grade III (moderate) in 39 hands, and Grade IV (severe) in 152 hands. Provocative tests (Tinel's and Phalen's) used for the diagnosis of CTS were positive in 68 hands (36.66%) and 26 hands (12.8%), respectively, in mild Grade I. However, as the CTS severity grade increased, the provocative test success rate also increased simultaneously. In severe Grade IV CTS, Tinel's and Phalen's tests were positive in 134 (88.1%) hands and 94 (61.8%) hands, respectively. Conclusions This study underscores the unreliability of Tinel's and Phalen's signs as screening methods for CTS severity. With moderate sensitivity and specificity, NCSs are deemed essential for confirming CTS diagnosis and assessing severity, especially in mild cases that might be mistakenly perceived as normal hands by consultants.

Mixed Latency Difference for Diagnosis of Ulnar Neuropathy at the Elbow

OBJECTIVE

To provide reference values and to compare this technique with the standard motor conduction velocity (MCV) of the ulnar nerve.

DESIGN

Retrospective unmasked study.

SETTING

Private and institutional practice.

PARTICIPANTS

The reference group included 57 healthy volunteers. Patients included 100 subjects with suspected ulnar neuropathy at the elbow (UNE) referred for neurophysiologic evaluation. This group was subdivided into 2 groups: group A was composed of 45 patients with UNE confirmed by MCV of the ulnar nerve, and group B included 55 patients with suspected UNE in whom the diagnosis could not be established by MCV of the ulnar nerve.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Differences between peak latencies of ulnar and median mixed nerve action potentials at the arm, after stimulating these nerves at the wrist. This was called mixed latency difference.

RESULTS

The upper normative limit of the mixed latency difference was 1.1 ms, and there was a significant correlation with height. In group A, the mixed latency difference was abnormal in 80% of the cases and could not be calculated in 18%. In group B, the mixed latency difference was abnormal in 8 (15%) patients. All of these had abnormal "inching" of the ulnar nerve across the elbow.

CONCLUSIONS

The mixed latency difference was particularly useful in cases of mild UNE.