Trigeminal SSEP assesses sensory conduction to the brainstem and somatosensory cortex. Short-latency responses (W₁–W₃, < 10 ms) reflect peripheral conduction to the brainstem; medium- and long-latency components (N13, P19, N27, P34) reflect thalamocortical pathways. Per Cruccu et al. (2008) and IFCN recommendations, within-subject side-to-side comparison is the most reliable criterion for trigeminal pathway injury.
Trigeminal (SEP)
| Parameter | Side R | Side L | Diff. R–L | Limit | Result |
|---|
About trigeminal SSEP
Trigeminal SSEP evaluation comprises subcortical (peripheral conduction to the brainstem) and cortical (thalamocortical) responses. Normative data below support International Federation of Clinical Neurophysiology (IFCN) recommendations.
1. Short-latency (subcortical) potentials
Recorded within the first 10 ms; «W» morphology described by Leandri et al.
| Component | Generator site | Mean latency | Reference |
|---|---|---|---|
| W₁ | Gasserian ganglion / peripheral nerve | 1.8 ± 0.2 ms | Leandri et al. (1985) |
| W₂ | Root entry zone (REZ) | 2.5 ± 0.2 ms | Leandri et al. (1985) |
| W₃ | Trigeminal sensory nuclear complex | 3.5 ± 0.2 ms | Leandri et al. (1985) |
2. Medium- and long-latency (cortical) potentials
Slight variation by stimulated branch (mental vs infraorbital). Alternative nomenclature varies across laboratories.
| Component | Alt. name | Generator site | Mean latency | Reference |
|---|---|---|---|---|
| N13 | N1 / N14 | Primary somatosensory cortex (arrival) | 12.5 – 14.1 ms | Singh et al. (1982) / Rossini et al. (2006) |
| P19 | P1 / P20 | Primary somatosensory cortex | 18.5 – 20.6 ms | Stöhr et al. (1981) / Cruccu et al. (2008) |
| N27 | N2 / N26 | Early associative parietal cortex | 26.0 – 27.6 ms | Findler et al. (1984) / Rossini et al. (2006) |
| P34 | P2 / P30 | Late cortical component | 34.0 ± 6.8 ms | Rossini et al. (2006) |
Abnormality criteria (Cruccu et al., 2008)
- Latency asymmetry: N13/P19 difference > 0.6–1.0 ms between affected and unaffected side — most reliable conduction delay marker (selectable in the calculator).
- Amplitude asymmetry: N13–P19 peak-to-peak reduction > 50% vs the asymptomatic side — suggests axonal loss or severe conduction block.
See also: SSEP median and tibial · SSEP pudendal · SSEP lateral femoral cutaneous
Clinical support tool only. Does not replace a report from a clinical neurophysiology specialist.