Bridging a difficult gap…

This week, our Project Archivist, Louise, has discovered more about the procedures practised by neurosurgeon Norman Dott.

Cataloguing individual case files, you never know what you will find in each one. However, something unusual caught my eye recently. In 1933, Norman Dott operated on a young man to remove a brain meningioma, a slow-growing tumour found in the meninges (the protective membrane which surrounds the brain and spinal cord). The operation was successful, but left a gap in the right frontal region of his skull. The gap left not only a cosmetic effect, but made his brain more vulnerable to injury from blows to the head. Therefore, the man consulted Dott again in 1934 with a view to correcting the defect.

Since the gap was perceived as too large to be filled by a graft of the patient’s own bone, Dott and his medical colleagues considered the alternatives: a celluloid or metal plate was rejected on account of Dott’s fears of adhesion of the brain surface, and a transplant of fresh bone from another individual was considered too hazardous. Instead, it was decided to form a plate from boiled bone, which would be more resistant to penetration by living tissue and also more solid than fresh bone.

Before they could make this plate, Dott and his team operated with the purpose of making a cast of the gap in the patient’s skull. Casting at operation used a material called Denticol, which could stand to be sterilised for use in operative conditions. A plaster cast was made of the Denticol impression immediately afterwards so that a suitable plate could be manufactured to be inserted at another operation.

Plaster cast made after operation, 1934

It was decided to make the plate from older macerated bone – bone that had been cleaned of tissue by bacteria – rather than fresher bone that had been simply boiled. When a suitable piece of bone had been cut for the plate, it was fitted onto the cast and then perforated ‘so that it resembled a piece of perforated zinc’. The plate was then thoroughly sterilised in readiness for fitting, which was carried out in a second, shorter operation in which the plate was sutured securely in position through some of the drill holes.

 Plate made of macerated bone with metal handle, 1934

However, complications following operation revealed that the plate was not accepted by the surrounding brain tissue – it had to be removed, and a piece of natural rubber was inserted temporarily with a view to replacing it with a bone graft from the patient’s own ribs. Unlike the bone fragment, the presence of the rubber ‘filling’ was tolerated by the patient’s own tissue.

 Patient showing post-operative scars, 1934