_Special points in prognosis and treatment._ It is not possible to formulate any very definite prognosis when the hæmorrhage takes place from one ear only, though the mortality is about 40 per cent. When bleeding takes place from both ears the outlook is more grave, the mortality being about 66 per cent. With regard to special treatment, two points are obvious: (1) that syringing of the ear is absolutely contra-indicated, on the ground that such treatment carries with it a considerable risk of bringing about meningeal infection; and (2) that plugging the external meatus with strips of gauze is an unsurgical form of treatment, insomuch as the escape of blood from the ear is an important factor in preventing compression of the brain, more especially in those cases where hæmorrhage is profuse. Under the last named conditions, operative measures--exploration for a torn meningeal artery or lacerated venous sinus--are to be carried out. Hæmorrhage from the mouth may be slight or copious, according to the source from which the blood is derived. In the former case, the bleeding takes place from sphenoidal and pharyngeal vessels, in the latter from the cavernous sinus or from the internal carotid artery (see p. 148), the bone being shattered in the region of the sphenoidal body, with comminution of the walls of the contained air-sinus. =Escape of cerebro-spinal fluid.= This condition was first investigated by Van der Wiel in 1727, and more completely by Langier in 1839. The majority of those middle fossa fractures which involve the petrous portion of the temporal bone pass immediately anterior to the genu of the facial nerve (see p. 102), and it follows, therefore, that the fracture cannot so involve the dural and arachnoid prolongations of that nerve in such a manner as to allow of the escape of cerebro-spinal fluid. This fact probably explains another fact, namely, that aural cerebro-spinal discharge is an infrequent symptom in middle fossa fractures. On the other hand, as a result of blows applied to the occipital region, a fracture originating in the posterior fossa may cut across the petrous bone, almost at right angles, in such a manner as to sever the seventh nerve in the region of the genu (see Fig. 41). This is the usual nature of a basic fracture associated with the escape of cerebro-spinal fluid from the external auditory meatus. More rarely, this particular class of fracture is unaccompanied by any injury to the tympanic membrane, in which case the fluid may escape along the Eustachian tube into the nose and naso-pharynx (see p. 91). Cerebro-spinal fluid may also escape from the nose and mouth in middle fossa fractures in the event of extensive injury to the basi-sphenoid with involvement of the overlying cisterna basalis. The following case exemplifies that condition:--