Caudal Agenesis: Classification Based on the Pathoembryogenesis of the Spinal Cord

This is a report on a new classification method for caudal agenesis:

Caudal agenesis is a congenital disorder characterized by the absence of lower vertebrae. Previous classifications of caudal agenesis were primarily based on the level of bony deficiency or the position of the terminal spinal cord, but there has been debate as to whether these classifications accurately reflect spinal cord abnormalities and neurological deficits.

This study proposes a new classification method for caudal agenesis based on the embryological development process – the embryological classification. This classification considers the position and morphology of the terminal spinal cord, as well as abnormalities of the cauda equina. Researchers retrospectively analyzed imaging and neurological assessment data of 89 patients with caudal agenesis from 1985 to 2019, and classified them into “formation disorder group”, “regression disorder group”, and “normal group” according to the new classification, aiming to evaluate the value of the new classification in reflecting patients’ neurological deficits and the possibility of requiring untethering surgery.

Research Summary

The study included 89 patients with caudal agenesis, with an average age of 39.3 months. 16% had motor deficits, 11% had sensory deficits, and 60% had sphincter dysfunction.

Patients were grouped according to three classification methods (skeletal classification, terminal spinal cord level classification, and embryological classification). The first two classifications failed to effectively differentiate patients in terms of spinal cord abnormalities and neurological deficits between groups. However, the embryological classification showed that the “formation disorder group” had a significantly higher incidence of motor and sensory deficits (42%) compared to the “regression disorder group” (16%) and the “normal group” (0%), with a statistically significant difference (p=0.039).

Further analysis revealed that in predicting motor deficits, the “formation disorder group” in the embryological classification was a strong independent predictor (OR 11.66, p=0.007). Notably, patients in the “normal group” according to the embryological classification had no neurological deficits. Additionally, this classification was able to differentiate the likelihood of patients requiring untethering surgery between groups (formation disorder group 42%, regression disorder group 81%, normal group 12%, p<0.001).

Research Significance

Overall, this study found that the classification method based on the level of bony deficiency may overstate its association with spinal cord abnormalities. The new embryological classification proposed by the researchers not only can better predict the neurological status of patients with caudal agenesis but also identify patient groups more likely to require untethering surgery, demonstrating clinical value. This classification provides a new approach for stratified management of patients with caudal agenesis.

This review report first introduces the clinical background of caudal agenesis and the shortcomings of previous classification methods. It then describes the specific approach of this study: retrospectively analyzing patient data and proposing new classification criteria based on the embryological development process, namely the “formation disorder”, “regression disorder”, and “normal” groups. Subsequently, it reports the differences between the three classification methods in reflecting patients’ clinical manifestations and the clinical application value of the new classification.