Cleft cavum of the septum pellucidum in victims of fatal road traffic accidents: a distinct type of cavum associated with severe diffuse axonal injury

Abstract

Background

The cavum of the septum pellucidum (CSP) is a small cavity constantly present in fetuses and newborns, of variable frequency among necropsied adults and with a high frequency in professional boxers.

Method

A pathologic study was conducted on brains of 626 patients without a history of head trauma (group 1) autopsied consecutively from a general hospital and of 120 random victims of fatal road traffic accidents (group 2).

Results

In group 1, 237 (37.9%) cases of CSP were observed, virtually all in a triangular or trapezoidal shape. In group 2, 65 (54.2%) cases of CSP were observed, 50 (76.9%) in triangular or trapezoidal shape and 15 (23.1%) in cleft shape. Cleft CSP was always associated with severe diffuse axonal injury (grades 2 and 3).

Conclusion

Although described in boxers, the CSP has not been reported in other types of head injury. The largest frequency of CSP found in fatal victims of head trauma, particularly in patients with severe diffuse axonal lesion (grades 2 and 3), when compared with the individuals without a history of head trauma, suggests that the high-intensity angular acceleration of the head causes complementary and independent displacement of the 2 cerebral hemispheres and dislocation of one of the leaves of the septum pellucidum on the other. This could result in separation of the 2 leaves and formation of CSP, usually in cleft shape.

Resumo

Contexto

O cavum do septo pelúcido (CSP) é uma pequena cavidade presente constantemente em fetos e recém-nascidos, com freqüência variável em adultos necropsiados e com elevada freqüência em boxeadores profissionais.

Método

Realizou-se o estudo anatomopatológico macro e microscópico do encéfalo de 626 pacientes provenientes de um hospital geral, necropsiados consecutivamente, sem história de trauma cranioencefálico (grupo 1) e de 120 vítimas fatais de acidente de trânsito, selecionadas aleatoriamente (grupo 2).

Resultados

No grupo 1 foram observados 237 (37,9) casos de CSP, virtualmente todos sendo de forma triangular ou trapezóide. No grupo 2 ocorreram 65 (54,2%) cava, sendo que 50 (76,9%) eram de forma triangular ou trapezóide e 15 (23,1%) em forma de fenda. O cavum em fenda estava sempre associado a lesão axonal difusa grave (graus 2 e 3).

Conclusão

Embora descrito em boxeadores, o CSP não havia sido relatado em outros tipos de trauma cranioencefálico. A maior freqüência de CSP em vítimas fatais de trauma cranioencefálico, particularmente em pacientes com lesão axonal difusa grave (graus 2 e 3), quando comparada com os indivíduos sem história de trauma cranioencefálico, sugere que a aceleração angular da cabeça de alta intensidade provoca deslocamento complementar e independente dos dois hemisférios cerebrais e deslizamento de uma das folhas do septo pelúcido sobre a outra, podendo resultar em separação das duas folhas e formação do CSP, usualmente em forma de fenda.

Introduction

The septum pellucidum, a thin vertical partition between the 2 lateral ventricles, consists of 2 parallel glial leaves that may either overlap each other or be separated by a space of variable width. When the separation between the leaves is wide, it is called the cavum of the septum pellucidum (CSP), bounded above by the corpus callosum and laterally by the 2 leaves of the septum pellucidum and the fornices. The cavity is almost triangular, trapezoidal, or, rarely, cleft and is found in 12% to 85% of adults subjected to postmortem examination [8], [18], [27], [31], [38].

A high incidence of CSP has been reported in autopsies of professional boxers and such finding has been explained by the rupture of the leaves of the septum pellucidum as a result of repeated traumas [8], [37]. Although extensively studied in boxers, the CSP has not been reported in other types of head injury.

The purposes of this paper are (1) to study the frequency of the CSP in victims of fatal road traffic accidents and to compare it with a series of consecutive autopsies from general hospital patients without a history of head trauma and (2) to demonstrate that a distinct type of CSP (cleft shape) is always associated with severe diffuse axonal injury (DAI).