The temperature is always considerably elevated; doubt of the diagnosis is justified if it remains normal.
The pulse is less characteristic than in the tuberculous form; it is usually accelerated in proportion to the fever, especially in infants: in older children it is not infrequently retarded and irregular and shortly before death is abnormally rapid.
Rigidity and varying inequality of the pupils are common at the height of the disease, though by no means so constant as in the tubercu lous form. The fundus is usually normal; venous stasis and neuritis are infrequent.
Disturbances of ocular motion are much commoner, resulting either from an affection of the oculomotor nerves (of which the abducens seems affected by preference) and causing a partial or complete paralysis, or as a result of cortical irritation (spastic strabismus, nystagmus, temporary conjugate deviation) or more rarely paralysis.
The function.s of the other cranial nerves tnay be disturbed periph erally or cortically in the same manner.
From what has preceded it is obvious that certainly the course, but not the symptoms, enables us, in certain cases, to distinguish purulent from tuberculous meningitis. All other means failing, the information obtained by lumbar puncture is decisive: from it we learn at once whether we have to deal with actual meningitis or a symptom-complex simu lating it, of which we shall speak later.
Macroscopically the cerebrospinal fluid is, in disseminated purulent meningitis, always opaque, grayish yellow or green, and on standing precipitates pus. It is moreover under increased pressure; wherefore it flows in a stronger stream, unless the cannula is obstructed by masses of pus. Microscopical examination of the opaque liquid (even without obtaining a sediment) discloses large numbers of pus cells, the poly nuclear form predominating; while, as before noted, preponderance of lymphocytes is the rule in tuberculous meningitis.
To complete the examination it is necessary, at least for observa tions to possess scientific value, to make bacteriologic examinations of the sediment in stained specimens and by culture. This procedure is also proper for practical purposes in order not to overlook sporadic cases of cerebrospinal meningitis, and because the character of the pus organism has some value in prognosis (irrespective of cerebrospinal meningitis).
The pneumocaccus is the most frequent cause of purulent meningitis; it shares, with the less frequently found influenza bacillus, the distinction of causing eases of meningitis appearing in epidemic form in limited areas; indeed it was long counted among the causes of cerebrospinal meningitis. From an anatomic standpoint it is remarkable that the meningitis caused by pneumococei develops especially in the posterior division of the base of the skull, so that many of these cases are described as posterior basilar mening,itis (Frankel, Thurston and others). This individualizes the clinical pieture by the prominence of its basal symp toms, frequently protracted course and comparatively high percentage of recoveries.
Staphylo- and streptococcus meningitis always terminate fatally, if a diffuse process is actually present. It may be briefly noted that this form cannot always be positively difTerentiated during life from the partial form (especially the otogenetie). Some of the few reported cases of recovery from purulent staphylococcus meningitis obviously belong to the type last named; incorrectly diagnosed cases of meningocoecus meningitis (a mistake not always easily avoided) no doubt constitute another portion.
Occasionally, in streptococcic infections, the purulent process is subsidiary to the development of gelatinous serous exudation containing innumerable cocci.
It is worthy of note that the agents enumerated above are not invariably found in pure culture, but often together or with pneumococci.
Quite frequently purulent meningitis is caused by roll bacilli and the bacillus lactis adrogenes (Scherer, Goldrcich and others), which may also constitute the mixed infection in meningoeoccus meningitis (Sac que.pe.e). Furthermore they do not always form pus (Concetti). This form is fatal; a single case of recovery, after lasting four weeks and without sequelm, has been reported by Nobecourt and Pasquier.