RESUMO
Peripheral nerves injuries are unfortunately common. Neuropathy may result from trauma, entrapment, metabolic or hereditary disturbances, inflammatory processes, iatrogenic injury from medical implants, and several other causes. We set out to create a large normative database for radial and dorsal ulnar cutaneous (DUC) sensory studies. Because comparison between two nerves of the same limb can be useful in detecting pathology, we also compared the latencies between the two nerves. Data were collected on both nerves using a 10-cm antidromic technique while controlling for temperature. Included subjects were asymptomatic: radial sensory studies were performed on 212 volunteers, DUC sensory studies were performed on 194 volunteers, and both studies were performed on 159 volunteers. Data were collected for onset and peak latencies, onset-to-peak and peak-to-peak amplitudes, area, rise time, and duration. Side-to-side differences were investigated. The data were analyzed to determine whether age, race, gender, height, weight, or body mass index (BMI) (kg/m2) correlated with different results. Differences in latencies between the nerves were analyzed as were side-to-side differences. Mean values for radial and DUC nerves, respectively, were found to be as follows: onset latency 1.9 +/- 0.2 ms and 1.8 +/- 0.3 ms, peak latency 2.4 +/- 0.2 ms and 2.3 +/- 0.4 ms, onset-to-peak amplitude 29 +/- 13 muV and 17 +/- 10 muV, peak-to-peak amplitude 33 +/- 14 muV and 20 +/- 13 muV, and area 18 +/- 7 nVs and 11 +/- 7 nVs. Mean rise time (0.5 +/- 0.1 ms) and duration (1.2 +/- 0.2 ms) were identical for both nerves. The upper limit of normal (ULN) side-to-side difference in peak latency was 0.3 ms for the radial and 0.4 ms for the DUC study. The ULN drop in peak-to-peak amplitude from one side to the other was 54% for the radial and 67% for the ulnar study. Increasing age, male gender, and increasing BMI (radial only) were associated with lower amplitudes and area, though the effects were clinically insignificant. The ULN increase in both radial-versus-DUC and DUC-versus-radial peak latency was 0.4 ms. In conclusion, a large normative database for the radial and DUC sensory studies has been derived that will assist in the diagnosis of peripheral neuropathy from a variety of etiologies. Side-to-side and internerve comparisons were also made.
RESUMO
OBJECTIVE: To evaluate the amplitude and latency for 3-cm versus 4-cm distance between the active and reference electrodes (electrode separation) used to obtain normative sensory and mixed compound nerve action potential data. DESIGN: Prospective, unblinded clinical test evaluating 3 nerves: mixed median and ulnar across wrist (8 cm), and radial antidromic sensory (10 cm). SETTING: University and private practice electrodiagnostic laboratories. PARTICIPANTS: One hundred six adult volunteers without known neuropathy. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Peak-to-peak amplitude and onset and peak latencies. RESULTS: Mean onset latencies +/- standard deviation (SD) were equal for 3-cm and 4-cm separations (median, 1.6+/-0.2 ms; radial, 1.7+/-0.2 ms; ulnar, 1.5+/-0.2 ms). Mean peak latencies were also equal for 3-cm and 4-cm separation for radial (2.2+/-0.2 ms) and ulnar (1.9+/-0.2 ms) studies but differed for the median study (3 cm, 2.0+/-0.3 ms; 4 cm, 2.1+/-0.3 ms; P<.0001). Mean amplitudes +/- SD with 3-cm and 4-cm separations were, respectively, 101+/-39 microV and 103+/-39 microV (P=.0434) for the median, 47+/-17 microV and 48+/-16 microV (P=.0209) for the radial, and 52+/-28 microV and 55+/-29 microV (P=.0001) for the ulnar study. These differences were statistically significant but clinically insignificant. CONCLUSIONS: The results support a hypothesized difference in amplitude but not latency between 3- and 4-cm separation. Clinically, however, the magnitude was insignificant.
