INTRACRANIAL COMPLICATIONS 357 In the final stages paralysis may develop, and may affect various parts of the body and also some of the cranial nerves, especially the third and sixth with the production of squinting. Optic neuritis is frequently met with, while the pupils are contracted and equal and react sluggishly. Coma super- venes before death. DIAGNOSIS. Meningitis has been aptly described as the 'great imitator' and must be diagnosed and treated at an early stage for the best chance of sur- vival. Diagnostic lumbar puncture in cases of high temperature alone has been recommended. The progress of the case depends as much on the resis- tance of the individual to the organism and its toxins as on the nature of the organism. The character of the cerebrospinal fluid at the point of maximum infection is not necessarily represented by the sample obtained on lumbar puncture. Meningitis is often combined with other intracranial complications. When meningitis is suspected, lumbar or cisternal puncture should be carried out, as it often gives a great deal of information. The normal pressure of the cerebrospinal fluid is 80-120 mm of water and in meningitis it is raised. It is important that there should be no blood in the fluid sent for examina- tion, and therefore the first few drops should be allowed to escape. Four cells per mm3 may be regarded as normal in cerebrospinal fluid. If the fluid is under tension, but clear and sterile, and the cell elements on exami- nation are not found to be greatly increased, the meningitis is still at the 'serous' stage. On the other hand, if the fluid is under pressure and is turbid from the presence of leucocytes, purulent meningitis may usually be diag- nosed. If organisms are present in addition to pus cells, there can, of course, be no doubt. The changes found in the cerebrospinal fluid obtained by lumbar puncture are of the greatest importance. The fluid may be clear and sterile even in purulent meningitis, especially if this is localized to the middle cranial fossa. The fluid may be turbid but sterile when a brain abscess is present. In meningitis globulin is increased, glucose is diminished or absent and the chlorides decrease in proportion to the severity of the symptoms. The temperature curve is consistently high in an uncomplicated meningitis in contrast to the hectic rises and falls of a sinus thrombosis and the subnormal temperature in brain abscess (Fig. 185). Not infrequently two or more intracranial complications may coexist. utEATMENT. Without waiting to identify the organisms responsible, 2-4 megaunits of penicillin are given intramuscularly every 4 hours. Swabs from the ear, and fluid obtained at lumbar puncture, are cultured to discover the organisms and to determine their sensitivity, and antibiotic treatment is continued with the appropriate drug until the cerebrospinal fluid and clinical examination are normal. Surgery must be considered, and if there is acute mastoid infection associated with the meningitis a cortical mastoid operation should be performed. At operation the dura mater of the middle cranial fossa is widely exposed (see Fig. 188, p. 363), and the lateral (sigmoid) sinus is carefully inspected for any evidence of thrombosis. Should the meningitis be associated with chronic otitis media, and especially if anti- biotic therapy has failed, the labyrinth operation (Neumann) may have to be performed (see Figs. 182-184, p. 353). PROGNOSIS. Uncomplicated meningitis has a more favourable outlook than one associated with sinus thrombosis or brain abscess or labyrinthitis.