Medial and lateral antebrachial nerve conductions: Orthodromic or antidromic?

Introduction: Antidromic stimulation is usually used in the evaluation of lateral antebrachial cutaneous nerve (LABCN) and medial antebrachial cutaneous nerve (MABCN). This study was conducted to evaluate the relationship between orthodromic and antidromic stimulations of these nerves. Materials and Methods: Medial and lateral antebrachial conduction studies by antidromic and orthodromic stimulation. Results: Sensory nerve action potential (SNAP) amplitudes were larger with antidromic stimulation in the majority of subjects. The lateral antebrachial SNAP amplitude was 20.5 ± 9.29 μV with antidromic stimulation and 14.6 ± 6.13 μV with orthodromic stimulation (P < 0.001). Medial antebrachial SNAP amplitudes were 12.8 ± 4.93 μV using antidromic stimulation and 6.5 ± 3.84 μV with orthodromic stimulation (P < 0.001). Sensory conduction velocities were faster with orthodromic lateral antebrachial stimulation (P = 0.002) whereas velocities were similar in medial antebrachial nerve. Supramaximal stimulation of MABCN was not possible in half of the nerves sampled to avoid the muscle artifact. Conclusion: Orthodromic stimulation of LABCN and MABCN are easy to perform and can be supplanted for antidromic stimulation in which Supramaximal stimulation may not be possible in some individuals.