=The prognosis in brain abscess, meningitis, and sinus thrombosis.= A patient may be expected to recover from _brain abscess_, whether temporo-sphenoidal, cerebellar, or frontal, if an early diagnosis be made, if the case be uncomplicated by meningeal infection or sinus thrombosis, and if the evacuation be carried out without any great difficulty. As Sir William Macewen[58] pointed out, ‘an uncomplicated brain abscess may be regarded as the most hopeful of all cerebral affections.’ In fatal cases, death results from general meningeal infection or from the bursting of the abscess into the lateral ventricles. In _meningitis_ the prognosis is bad, more especially when the process is widespread. Early exposure of the affected region and the supply of adequate drainage offer the only hope of recovery. This, even under the most favourable circumstances, is a desperate remedy. The prognosis in _lateral sinus thrombosis_ hinges to a large extent on the time at which operative procedures are carried out. When the case is seen and operated on at an early date in the history of the disease, recovery may be anticipated in about 50 per cent. cases. Hunter Tod states that, when all cases are considered of whatever grade, about one-third recover. Death results from pyæmia, septicæmia, meningitis, or brain abscess. _Cavernous sinus thrombosis_ of the infective variety almost necessarily terminates fatally. Death results from causes similar to those observed in cases of lateral sinus thrombosis. HERNIA CEREBRI The term Hernia cerebri was formerly used as inclusive of all those conditions in which the brain protruded through some aperture in the skull, whether such opening was congenital, traumatic, or post-operative. Owing to the recent advances in cranio-cerebral surgery, especially with reference to the frequent adoption of decompression operations, it is advisable that the cases should be classified into two groups:-- =1. Cases of hernial protrusion=, including cephaloceles (see Chapter I), protrusions intentionally produced by the surgeon in a decompression operation, and those which follow after unsuccessful operations for tumour removal. It will be observed that, in all these cases, the projecting brain, though bulging through its osseous barrier, is still protected by a more or less normal scalp-covering. =2. Cases of hernia cerebri.= Here, as the result of injury to scalp, bone, dura, and brain, the cerebral substance bulges through a deficiency in the vault and presents on the surface, uncovered by integument. Hernia cerebri _can_ develop under non-infective conditions, the congested state of the bruised or lacerated brain bringing about that degree of intracranial tension which can only be relieved by the outward projection of the brain. Still it must be accepted that Hernia cerebri almost invariably implies some bacterial infection.