Mortality.
From earlier records the immediate mortality was estimated at 30-40 per cent. Duret, however, records 400 cases with a mortality of 19·5 per cent., 58 cases dying from shock, 10 from hyperpyrexia, and 10 from hæmorrhage. In my own practice, the mortality may be estimated at a much lower figure. Perhaps I may be too conservative, but I hold the view that, unless the tumour is readily exposed and equally readily removable, it is inadvisable to carry out further measures for its eradication. Moreover, the general technique of brain surgery has advanced with rapid strides, and the question of early and accurate localization has received equal attention. The mortality has diminished proportionately, and may be estimated at less than 20 per cent. So much depends on the surgeon and on the nature of the tumour, its position and localization, that it is impossible to make any absolute statement as to the risk to life attendant on operation. If all tumours were fibromata, cortically situated, and accurately diagnosed, the operation, in the hands of a skilled neurological surgeon, should present but a very low mortality. So long, however, as surgeons will persist in burrowing into the brain substance for a supposed subcortical tumour, so long will the mortality remain high. The great secret in operating on a brain tumour lies in knowing when to terminate the attempt at removal of the tumour and when to rest content with a pure ‘decompression’.
It is obvious, therefore, that cortical tumours—more especially such as give rise to early localizing symptoms, e.g. Rolandic tumours—offer a better prognosis than when the surgeon has to deal with subcortical, central, and basal tumour formation.
The mortality according to the region affected.
The following table, from a series collected by Knapp, supplies valuable information as to the regional mortality.
| Frontal | tumours | 32 | cases | Mortality, | 25 | per cent. |
| Central | „ | 231 | „ | „ | 23 | „ |
| Parietal | „ | 29 | „ | „ | 41 | „ |
| Temporal | „ | 17 | „ | „ | 29 | „ |
| Occipital | „ | 10 | „ | „ | 20 | „ |
| Cerebellar | „ | 54 | „ | „ | 45 | „ |
Sir Victor Horsley draws attention to this question in the following manner: ‘If a line be drawn from the frontal eminences to the occipital protuberance, it is obvious that more shock results from operations below that line than from above, and as we proceed from the frontal to the cerebellar pole of the encephalon.’
The mortality according as to whether the tumour is found or not.
According to Horsley, of 79 cases in which a correct diagnosis was made and the tumour removed, 7 died from shock; whilst in 16 cases inaccurately diagnosed, 6 died—a mortality of 9 per cent. in the first case as against 37 per cent. in the second.
The added danger resulting from unsuccessful attempts at finding the tumour must not be advanced as an argument against the palliative operations, for the failure to find and remove the tumour implies diligent search for the neoplasm, with necessary prolongation of operative procedures, and perhaps extensive manipulation of the brain substance. Statistics and experience both afford conclusive evidence that accurate localization is essential for the success of the operation.