UNUSUAL ANATOMIC VARIANT OF THE CAUDA EQUINA AND SPINAL NERVE ROOTS

Abstract

Nerve roots emerging from the spinal cord and contributing to the cauda equina are typically cylindrical and smooth upon gross observation. In the fall of 2013 a variant of this characteristic presentation was noted when small, but macroscopic, striations were noted on the cauda equina of several cadavers being dissected for a human gross anatomy course. Upon closer inspection it was discovered that raised circular bands were present at corresponding intervals along the length of each individual rootlet, resulting in a gross appearance of striations or banding along the root. The bands tended to diminish distally and were absent in peripheral nerves. A literature search produced no previous descriptions matching this pattern and none of the experienced anatomists or pathologists consulted were familiar with the feature. This study sought to describe and determine the etiology of the striations. Over the course of two years, ninety human cadavers were inspected for this feature, resulting in a total of n=38 individuals (42%) displaying the anomaly. Death certificates were examined for commonalities, but none were noted. Embalming artifact was ruled out by contacting other institutions that utilize the same procedures. Histological examination was conducted in order to better describe the striations. Additional targeted immunostaining was performed to investigate the type of cells forming the bands. Several possible explanations were eliminated and the micro- and macrostructure of this previously undescribed feature were thoroughly documented.