_Diagnosis of Basal Fractures._--In the diagnosis of fractures of the base, reliance is to be placed chiefly upon: (1) the nature of the injury; (2) the diffuse character of the cerebral symptoms; (3) the evidence of injury to individual cranial nerves; (4) the occurrence of persistent bleeding from the nose, mouth, or ear; (5) the extravasation of blood under the conjunctiva or behind the mastoid process; and (6) the presence of blood in the cerebro-spinal fluid withdrawn by lumbar puncture. In rare cases the diagnosis is made certain by the escape of cerebro-fluid or of brain matter from the nose, mouth, or ear. It must be admitted, however, that in a large proportion of cases which end in recovery, the diagnosis of fracture of the base is little more than a conjecture. The external evidence of damage to the bone is so slight and so liable to be misleading, that little reliance can be placed upon it. The associated cerebral and nervous symptoms also are only presumptive evidence of fracture of the bone. In all cases, however, in which there is reason to suspect that the base is fractured, the patient should be treated on this assumption. It is often found that, when there are no cerebral symptoms present, it is difficult to convince the patient of the necessity for undergoing treatment, and of the risk involved in his leaving his bed and resuming work. _Prognosis in Basal Fractures._--The prognosis depends upon the severity of the cerebral lesions, and on the occurrence of traumatic œdema or infective intra-cranial complications. Many cases prove fatal within a few hours from the associated injury to the brain, the patient dying from cerebral compression due to hæmorrhage. If the patient survives two days, the prognosis is more hopeful (Wagner). It is possible that the free escape of blood from the nose or ear may in some cases prevent compression, and to a certain extent render the prognosis more favourable. Punctured fractures are frequently fatal from infective complications--meningitis, sinus thrombosis, and cerebral abscess. These complications are also liable to occur in fractures rendered compound by opening into the nose, pharynx, or ear, but they are less common than might be expected. _Treatment._--The general treatment includes that for all head injuries. In a number of cases attended with symptoms of compression, benefit has followed the relief of intra-cranial tension by a decompression operation. The withdrawal of 30 or 40 c.c. of cerebro-spinal fluid by lumbar puncture has also proved beneficial in the same way; Quenú strongly recommends repeated puncture in serious cases. In a few cases this procedure has been followed by sudden death.