Anatomy & Physiology: Current Research
Open Access

Abstract

The Subdural Myth: Space or Place?

Talbert DG

The term “Subdural” is commonly used loosely to describe any item below the Dura Mater, but when considering the mechanics of Shaken Baby Syndrome it is necessary to keep to the original definition of a space between the Dura Mater and the Arachnoid mater. In 1991, a survey of literature relating to the structure of the meninges found that 32 out of 42 articles stated that a fluid filled space (the “Subdural Space”) existed between the Dura Mater and the Arachnoid mater which allowed the brain to slide relative to the skull. This is still the case in Shaken Baby Literature. With the coming of Electron Microscopy it was found that there was no subdural space. The position was filled by a structure formed by a specialized region of the dura. Commonly known as the Dural Border Layer, it is merged below with the outer aspect of the Arachnoid. Although it is strongly attached to the main dura above and the Arachnoid below it is internally weak and easily torn along the middle during handling producing a “subdural” space. It is suggested that the “Dural Border Layer” be recognized as an independent structure, the “Subdura”. The structure of the Subdura suggests that its function is stress relief. It allows variation of brain proportions, during maturation and aging, to take place over a period of weeks or months, without producing distorting stress in the brain tissue. The Shaken Baby documents declare that subdural haemorrhages are caused by shearing forces as the brain moves. They also say that visible contusions are unusual. Since the Subdura joins the Arachnoid to the Dura the brain cannot slide unless all the subduras are torn, creating a massive contusion. Hence it appears that the Shaken Baby Syndrome cannot involve brain movement.