Table 3.
Results of Nerve Conduction Studies and Needle EMG in 23 Patients with TCs
| Nerves | Number of Patients with EDX Abnormalities/Total Number of Patients Examined and % | ||
|---|---|---|---|
| Nerve conduction studies | |||
| Sural nerve | |||
| Latency ≥ 3.6 ms (14 cm) | 1/16 | 6% | |
| Amplitude ≤ 6 µV | 2/16 | 13% | |
| Peroneal nerve | |||
| Conduction velocity > 39 m/s or latency > 6 ms | 0/19 | 0% | |
| Amplitude < 1000 µV | 1/19 | 5% | |
| Hoffmann reflex | |||
| Latency ≥ 32 ms; left/right difference > 2 ms | 5/20 | 25% | |
| Anal reflex | |||
| Latency > 40 ms (or > 45 ms in women who have given birth vaginally); left/right difference > 6 ms | 20/21 | 95% | |
| Amplitude: left-right difference ≥ 500 µV | 15/21 | 71% | |
| Needle EMG ≥ 50% neurogenic motor unit potentials | Mean severity score (0–3) | ||
| L2 (rectus femoris m.) | 1/18 | 6% | |
| L3 (vastus medialis m.) | 0/18 | 0% | |
| L4 (vastus lateralis m.) | 5/18 | 29% | 0.3 |
| L5 (extensor digitorum longus m.) | 13/18 | 72% | 0.6 |
| S1 (medial head of gastrocnemius m.) | 4/20 | 20% | 0.1 |
| S2 (flexor hallucis brevis m.) | 18/22 | 82% | 1.1 |
| (S2) S3, S4 (external anal sphincter) | 18/22 | 82% | 1.1 |
Notes: Severity scores: 0 = normal; 1 = slight (≥50% polyphasic MUPs); 2 = moderate (≥75% polyphasic MUPs); 3 = severe (≥90% polyphasic MUPs) abnormalities.
Abbreviations: ms, milliseconds; µV, microvolts; m, meters; s, seconds; EMG, electromyography; MUPs, motor unit potentials.