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TREATMENTMeningitis acquired in the community in the non-immunocompromised host is most often caused byH. influenzae , meningococci or streptococci. It should beremembered that meningococci are becoming increasinglyresistant to sulphonamides and H. influenzae to ampicillin.Benzylpenicillin can be used to initiate treatment inmeningococcal and pneumococcal infections and whengram-negative organisms are responsible for meningitis inschool going or older subjects. Chloramphenicol shouldbe used in H. influenzae infections or when gram-negativeorganisms are causative in children below five.

Many physicians prefer to combine chloramphenicol(100 rug/kg/day) with either penicillin (150 mglkglday) orampicillin (200 rug/kg/day) as the first line of treatment.These drugs are preferably given intravenously, althoughthe intramuscular route can also be used. Chloramphenicolcrosses the blood-brain barrier readily. Rarely, intrathecaladministration of antibiotics is justified if deteriorationcontinues despite use of appropriate antimicrobials givenin adequate doses. Meningitis complicating a neurosurgicalprocedure is usually caused by gram-negative bacilli orStaphylococcus aureus. Treatment with an amino-glycoside (gentamycin, tobramycin) preferably givenintrathecally, combined with a penicillinase-resistantpenicillin (nafcillin), is appropriate. Cephalosporins suchas cefotaxime and ceftazimide are very effective againstgram-negative bacilli and should be used when the diseaseis caused by chloramphenicol-resistant organisms. Otherpromising drugs include the quinolones. Table IV lists thedoses of some drugs used in meningitis.

Therapy should be continued for at least 10 to 14 days.By this time the patient has usually been afebrile for 3 to 4days and is totally asymptomatic. A repeat lumbar punctureis not essential to determine whether therapy can be stop-ped as quite often the CSF does show raised cells andproteins for several weeks after clinical recovery.

Recurrent meningitis is often seen with compound skullfractures or congenital malformations such as dermal

Surgical management of bacterialmeningitis

Although antimicrobial therapy is the mainstay of manage-ment of bacterial meningitis, surgical intervention issometimes necessary for the indications given in Table I.

COMPLICATIONS OF MENINGITIS

HydrocephalusThis is probably the commonest indication for operationin a patient with bacterial meningitis. Ventricular enlarge-

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TABLE IV. Antibiotic dosages for bacterial meningitis

Antibiotic Adults ChildrenTotal Interval Total Interval(per day) (hours) (per day) (hours)

Ampicillin 12g 4 2~300mglkg 6Carbenicillin 30--40g 4-6 4~SOOmglkg 4

Nafcillin 12-18g 4 IS~200mglkg 4-6

PenicillinG 2~24 x 10" 2-4 2~30x 10' 4-6units units

Cefotaxime 12g 4 IS~200 mglkg 4-6

Ceftazimide 6g 8 1~ISOmglkg 8Cefuroxime 4.S-9g 8 2~240mglkg 6

Chloramphenicol 4g 6 lOOmglkg 6

AmikacinIntravenous ISmglkg 8--12 IS mglkg 8--12Intraventricular 20-30 mg 24 4-Smg 24

GentamicinIntravenous Smglkg 8 5--7mglkg 8Intraventricular 8--\()mg 24 2-2.Smg 24

sinuses or neuroenteric cysts. These patients require earlysurgical repair of the communication between theneuroaxis and the exterior soon after the meningitis hasbeen eradicated with appropriate antimicrobial drugs.

An occasional patient with bacterial meningitisdevelops marked brain swelling. In such instances,intravenous mannitol (0.25 to 5.0 glkg) given over half anhour may be life saving. If seizures develop, these shouldhe treated with diazepam (5 to 10 mg intravenously) orwith phenytoin. Sedation should be avoided because ofthe risk of aspiration pneumonia.

P. P.ASHOKP. D. Hinduja National Hospital

Bombay 4(}()()J6India

TABLE I. Indications for surgery in bacterial meningitis

Complications of meningitis\. Hydrocephalus2. Subdural effusion/empyema3. Rarer complications

a. Brain abscessb. Optochiasmatic

arachnoiditis

Closure of fistulaeI. CSF rhinorrhoea/otorrhoea2. Dermal sinuses

a. Lumbosacralb. Occipital

Eradication of focus of infectionI. Otitis media2. Paranasal sinusitis3. Miscellaneous

a. Cranial osteomyelitisb. Pulmonaryc. Cardiac

MiscellaneousI. Removal of foreign bodies

a. Shunt tubesb. Cranioplasty platesc. Dural substitutes

EVERYDA Y PRACTICE

ment in these patients is because of obstruction to thecerebrospinal fluid (CSF) pathways by exudates aroundthe 4th ventricular outlets (the foramina of Magendie andLuschka) in the basal cisterns, and in the aqueduct ofSylvius. Nearly all patients with tuberculous meningitiswho have survived the first 4 to 6 weeks of their illness andabout 65% of patients with pyogenic meningitis develophydrocephalus which is demonstrable on computerizedtomography (CT) (Fig. 1). However, only a few patientsdevelop hydrocephalus-related symptoms which requiresurgical intervention.

FIG I. CT scan showinghydrocephalus followingtuberculous meningitis

Hydrocephalus may produce symptoms either duringthe acute phase of meningitis or after many weeks ormonths. It should be suspected in these patients if there issymptomatic and clinical deterioration despite adequateand appropriate antimicrobial therapy. In late onset hydro-cephalus, the patient usually has progressive worsening ofheadache, blurring of vision and diplopia-symptoms ofraised intracranial tension. A CT scan of the head is theinvestigation of choice. If CT scan facilities are not avail-able, we have to rely on less sensitive investigations suchas ventriculography or carotid angiography.

Pyogenic meningitis: Acute onset hydrocephalus is rarein patients with pyogenic meningitis. If it occurs, repeatedventricular taps or an external ventricular drainage

FIG2. Ventriculo-peritoneal shunt

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(EVD) are often adequate. EVD is performed by placinga ventricular catheter in the lateral ventricle (most oftenthe right frontal horn) and draining the CSF into a sterileclosed system outside the body. This should be performedunder strict aseptic conditions by a trained surgeon. Thesedrains should not be left in place for more than 24 to 48hours because of the risk of infection. In late onsethydrocephalus, also a rare complication, a ventriculo-peritoneal (VP) shunt (Fig. 2) is effective and is therecommended treatment.

Uncommonly, multi loculated hydrocephalus developsin children with pyogenic meningitis and ventriculitis. Inthis form of hydrocephalus, adhesions develop betweenthe ventricular walls causing the CSF to accumulate inmultiple non-communicating cavities. In these patients asimple shunt will not decompress the ventricular systemand surgical or endoscopic division of the adhesions isnecessary.

Tuberculous meningitis: In tuberculous meningitis theresults of shunt surgery are dependent on the neurologicalstatus of the patient at the time of operation. Patientsin Medical Research Council (MRC) stages I and II(Table II) who develop hydrocephalus should have theprocedure done early. Patients in MRC stage III, i.e.those who are comatose and decerebrate or decorticate,usually have a poor prognosis in spite of shunt surgery.The complications of shunts (Table III) in these patientsare higher and their mortality approaches 50%. EVD mayhelp identify such patients who will benefit from surgery.If patients in stage III improve to stage II or I followingEVD, then shunt surgery is likely to be beneficial. It isimportant to remember that in stage III, factors otherthan hydrocephalus, such as arteritis and encephalitis, areresponsible for the altered sensorium. Shunts may there-fore not produce clinical improvement.

TABLEII. MRC staging of tuberculous meningitis

Stage I. Non-specific symptoms. Minimal signs of meningitis.

Stage II. Conditions between stage I and III.

Stage III. Extremely ill. Deeply stuporous or comatose with gross paresis.

TABLEIII. Complications of CSF shunts

I. Shunt obstruction2. Shunt infection3. Subdural collections4. Shunt nephritis (mainly with ventriculoatrial shunts)5. Peritoneal cyst with ventriculoperitoneal shunts

6. Perforation of a viscous7. Shunt dependency8. Intracerebral or intraventricular haemorrhage during surgery.

Subdural effusions and empyemaSubdural effusions usually occur following H. influenzaeor pneumococcal meningitis and are usually seen in childrenbelow two. This complication should be suspected if thechild remains febrile and toxic in spite of 72 hours of

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FIG 3. Subdural tap through anterior fontanelle

adequate antibacterial treatment, and if he vomits anddevelops seizures and focal neurological signs.

A subdural tap, using a special needle with a stylet, per-formed through the edge of an open anterior fontanelle(Fig. 3) may be both diagnostic and therapeutic. Repeatedtaps may be required. Injury to the cerebral vessels or thebrain can occur especially if there is no effusion and forthis reason the needle should not be pushed too deeplyunder the dura. The fluid is sterile in about 90% ofpatients. Surgery in the form of craniotomy and excisionof the subdural membrane, or a subdural-peritoneal shunt,may be required in the very rare instances where repeatedtaps fail to clear the effusion or if the patient remainssymptomatic.

It is common in adults who present with fever, seizures,focal neurological deficits and a CSF containing an excessof cells. This rare complication of meningitis can be lethal.Drainage of the pus through burr-holes or a craniotomy isnecessary but diagnosis should first be confirmed byeither an Echo or a cr scan.

Rare complicationsBrain abscess occurs only rarely following meningitis.

Aspiration of the abscess through a burr-hole or drainagefollowing craniotomy is the recommended treatment.

Optochiasmatic arachnoiditis is a complication of tuber-culous meningitis. In patients whose vision deterioratesin spite of steroid therapy, craniotomy and release ofadhesions is sometimes performed. However, this is notalways associated with good results because arachnoiditiscauses ischaemic damage to the optic nerves.

CLOSURE OF FISTULAERecurrent meningitis may indicate the existence of acommunication between the central nervous system andthe exterior. Several kinds of communications exist.

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CSF otorhinorrhoea (Dural fistulae)The communication between the subarachnoid space andthe paranasal sinuses or middle ear usually follows a basalskull fracture or surgery in that region; occasionally it maynot be preceded by trauma. In 5% to 10% of patientsthere is no overt CSF leak. In these patients pneumococciare the commonest causative organisms of meningitis.

In patients with otorhinorrhoea, the leaking fluid isclear, watery and not sticky and a sugar value of >0.3 gILin the leaking fluid confirms the diagnosis. X-ray of theskull may reveal a basal fracture, an opaque paranasal sinusor intracranial air (Fig. 4). However. the fistula site is bestdetected by performing a cr scan of the head includingthe sinuses, after injection of a water soluble contrastagent (metrizamide or iohexol) via a lumbar puncture.Surgery through either the intra- or extracranial route isrequired to close the fistula.

FIG 4. CT scan showing intra-cranial air in a patientwith a dural fistula

Dermal sinusesThis should be suspected if coliform organisms are iso-lated in the CSF or the patient has recurrent meningitis.Detection of a dermal sinus in the lumbosacral area or inthe region of the occiput requires careful clinical examina-tion. The hair on the occipital region should be shaved toenable adequate examination. Investigations such asplain X-rays of the skull or myelography may be requiredbefore surgical intervention. These investigations willalso help diagnose congenital turnours that are frequentlyassociated with sinuses. If a tumour is present, it shouldbe excised along with the whole sinus tract, to preventrecurrent meningitis and neurological deficits. It is impor-tant to distinguish lumbosacral dermal sinuses from pilo-nidal sinuses (Fig. 5). The latter are situated in the natalcleft, have many openings and contain hair.

ERADICATION OF A FOCUS OF INFECTIONSurgery may be required to eradicate a focus of infectionwhich is responsible for meningitis. The infection mayspread contiguously (e.g. from the ear, paranasal sinuses)or haematogenously (e.g. from the lungs or heart).

EVERYDA Y PRACTICE

FIG 5a. Lumbosacral sinus FIG 5b. Pilonidal sinus

FOREIGN BODIESMeningitis which occurs because of the presence offoreign bodies after injury (such as wood splinters and oldcompound depressed skull fractures) is difficult to cureunless the foreign body is removed. Another common causeof meningitis due to a foreign body is shunt infectionwhere the organisms (usually Staphylococcus aureus orStaphylococcus epidermidisi colonize the walls of theshunt tube. Parenteral and intrathecal antibiotic therapyare usually not adequate and shunt removal is oftennecessary.

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DISEASES MASQUERADING AS MENINGITIS

Brain abscessIn patients with chronic suppurative otitis media(CSOM), a brain abscess may produce no localizing orlateralizing signs and the patient complains of non-specific symptoms such as headache and vomiting. Such aclinical picture can easily be mistaken for meningitis. Alumbar puncture in such a setting can lead to disastrousconsequences because the raised intracranial pressureassociated with abscesses frequently leads to uncal ortonsillar herniation and may result in the death of thepatient if excess CSF is withdrawn from the lumbar theca.Hence all patients with CSOM and suspected intracranialcomplications should undergo funduscopy for papilloedemafollowed by a cr scan of the head to exclude a brainabscess. If cr scan facilities are not available, cerebralangiography or ventriculography can be performed.These latter investigations are. however, only useful indetecting large abscesses.

TurnOUTS

Leakage of the contents of congenital tumours such ascraniopharyngiomas and epidermoid or dermoid cysts canbe confused with bacterial meningitis. Recurrent attacksof aseptic meningitis with a sterile CSF. focal neurologicalsigns and a high index of suspicion will usually point to thecorrect diagnosis.

V. RAJSHEKHARChristian Medical Col/ege

Vel/ore 632004India