Revisiting thoracic splanchnic nerve anatomy: implications for thoracoscopic splanchnicectomy and pain management

The thoracic splanchnic nerves-greater (GSN), lesser (LSN), and least (lSN)-are important targets in thoracic surgery and image-guided interventions, yet detailed quantitative characterization of their anatomy remains limited. This study aimed to define the morphometry, segmental origins, and anatomical variability of these nerves to improve understanding of clinically relevant anatomy.

Eighty sets of thoracic splanchnic nerves from 42 formalin-embalmed donors were dissected. Segmental contributions were recorded and classified, and morphometric measurements were obtained relative to the sympathetic trunk, transverse processes, midline, and aorta. Statistical analyses were performed to evaluate differences in morphometric parameters by configuration, laterality, and sex.

The GSN was present in 100% of specimens, the LSN in 93.75%, and the lSN in 28.75%. Substantial variability in segmental origin was observed. The most common GSN configuration was T6-T10 (42.5%), whereas the classically described T5-T9 pattern occurred in only 8.75% of cases. For the LSN, T11-T12 (34.67%) and T11 alone (29.33%) were the most common origins, while only 13.33% conformed to the traditionally described T10-T11 pattern. The lSN most commonly originated from T12 (78.26%). Statistically significant differences in nerve position and dimensions were identified with respect to laterality and sex.

Thoracic splanchnic nerve anatomy is highly variable, and classically described segmental patterns represent a minority of cases. These findings provide clinically relevant morphometric data that may improve localization during thoracoscopic surgery, splanchnic nerve block, and other interventions involving the thoracic sympathetic system while reducing the risk of iatrogenic injury.