Cerebral Toxoplasmosis1

8/10/2019 Cerebral Toxoplasmosis1

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Cerebral toxoplasmosisDr Henry Knipe and Dr Praveen Jha et al.

Cerebral toxoplasmosis is an opportunistic infection which typically affects patients with HIV / AIDS , and is the ost co on cause of cere!ral a!scess in these patients " .#on$enitalto%oplas osis is discussed separately.

EpidemiologyToxoplasma gondii is found u!i&uitously and anti!odies to the or$anis can !e identified in '()of all hu ans. *he rate varies $reatly fro population to population and has a wide reportedprevalence+ fro " -() . In ost cases, the infection is asy pto atic. However, ini unoco pro ised patients especially those with HIV / AIDS0, infection can !eco eesta!lished. #ere!ral to%oplas osis is found in 1( '2) of autopsies on patients with HIV /

AIDS .*he infection typically occurs once the #D23 count has dropped to !elow 1(( cells / '," .

Clinical presentationIn i unoco petent patients, acute encephalitis is e%tre ely rare. 4ven in thei unoco pro ised sy pto s are typically va$ue and indolent. Develop ent of newneurolo$ical sy pto s in these patients should raise hi$h suspicion of cere!ral to%oplas osis.

PathologyToxoplasma gondii is an intracellular parasite that infects !irds and a als. It5s definitive hostis the cat and other Felidae species. 4%cretion of oocytes in its faecal content followed !yhu an conta inated uncoo6ed consu ption can lead to hu an infection. In i unoco petentindividuals, it pri arily causes a su!clinical or asy pto atic infection. In i unoco pro isedindividuals e.$. AIDS patients0, to%oplas osis is the ost co on cause of a !rain a!scess .Patholo$ically, parenchy al to%oplas a lesions have three distinct 7ones+

a central avascular 7one of coa$ulative necrosis an inter ediate vascular 7one containin$ nu erous or$anis s an outer ost 7one of encysted or$anis s+ toxoplasma lesions do not have capsule

Radiographic features*ypically cere!ral to%oplas osis anifest as ultiple lesions, with a predilection for the !asal$an$lia and cortico edullary 8unction 2.

CT*ypically, cere!ral to%oplas osis appears as ultiple hypodense re$ions predo inantly in the!asal $an$lia and at the cortico edullary 8unction. However, they ay !e seen in the posteriorfossa. Si7e is varia!le, fro less than 1 c to ore than ' c , and there ay !e associatedass effect.

enhance ent followin$ ad inistration of contrast there is nodular or rin$ enhance entwhich is typically thin and s ooth

dou!le dose delayed scan ay show a central fillin$ on delayed scans calcification seen in treated cases9 ay !e dot li6e or thic6 and 5chun6y5
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MRI T1 ay !e difficult to identify, !ut are typically iso intense or hypo intense T2 o intensity is varia!le, fro hyper intense to iso intense :

hyper intense thou$ht to represent necrotisin$ encephalitis

iso intense thou$ht to represent or$anisin$ a!scess 2o lesions are surrounded !y perilesional oede a T1 C+ !d" lesions often de onstrate rin$ enhance ent or nodular enhance ent MR spectroscopyo increased lactate 2

o increased lipidso reduced #ho, #r and ;AAo Increased lipid lactate pea6 is characteristic, however choline pea6 also ay !e

seen in few cases.

Treatment and prognosisIn $eneral, !iopsy is not re&uired and treat ent is initiated and follow up i a$in$ perfor ed.*he e%ception to this rule are patients who have atypical i a$in$ features e.$. sin$le lesion0 orwho are serone$ative for Toxoplasma gondii " .*reat ent consists of sulfadia7ine with pyri etha ine " .

#ifferential diagnosis4, #hian$ ?= et al. @adiolo$ic patholo$ic correlation. #ere!ral

to%oplas osis and ly pho a in AIDS. AJ;@ A J ;euroradiol. 1-- 91" 0+ 1" '"'. AJ;@ A J ;euroradiol citation0 Pu! ed citation

:. @a sey @


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. Kornien6o V;, Pronin I;. Dia$nostic ;euroradiolo$y. Sprin$er Verla$. :((-0ISC;+' 2(B " :'. @ead it at


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incu!ation period or period !etween infection and the start of the diseaseran$es fro several days to onths.

Anyone can !e infected !y T. gondii , !ut usually only those individuals

with wea6ened i une syste s i unoco pro ised0 developsy pto s of the disease. ?or the , to%oplas osis can !e severe,de!ilitatin$, and fatal. I unoco pro ised individuals at ris6 includethose with AIDS , cancer, or other chronic illnesses.

*here is no person to person trans ission, e%cept fro an infectedother to her child in the wo !. Appro%i ately si% out of 1,((( wo encontract to%oplas osis durin$ pre$nancy . ;early half of these aternalinfections are passed on to the fetus. Known as con$enitalto%oplas osis, this for of the disease is ac&uired at !irth !yappro%i ately ','(( infants in the nited States every year. *he ris6 offetal infection is esti ated to !e !etween one in 1,((( to one in 1(,(((.In children !orn with to%oplas osis, sy pto s ay !e severe and&uic6ly fatal, or ay not appear until several onths or even years after!irth.

Causes and symptoms

Healthy individuals do not usually display sy pto s. Ehen sy pto sdo occur, they are usually ild, rese !lin$ infectious ononucleosis ,and include the followin$+

enlar$ed ly ph nodes uscle pains

inter ittent fever

$eneral sic6 feelin$

*he distinction is ade !etween ac&uired to%oplas osis, in which anindividual !eco es infected, and neonatal con$enital to%oplas osis, inwhich a fetus is !orn with the infection !ecause the other !eca einfected durin$ pre$nancy. If a fetus !eco es infected early inpre$nancy, the disease can cause the fetus to spontaneously a!ort, !e
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still!orn. If full ter , the infant ay die in infancy or suffer fro centralnervous syste lesions. If the other !eco es infected in the last threeonths of pre$nancy, however, the pro$nosis is $ood and the !a!y aynot even display any sy pto s.In adults, if the infection continues for an e%tended period of ti e,chronic to%oplas osis can cause an infla ation of the eyes calledretinochoroiditis, which can lead to !lindness, severe yellowin$ of thes6in and whites of the eyes 8aundice 0, easy !ruisin$, and convulsions.

Adults with wea6ened i une syste s have a hi$h ris6 of developin$cere!ral to%oplas osis, includin$ infla ation of the !rainencephalitis 0, one sided wea6ness or nu !ness, ood and personality

chan$es, vision distur!ances, uscle spas s, and severe headaches. If untreated, cere!ral to%oplas osis can lead to co a and death . *hisfor of encephalitis is the second ost co on AIDS related nervoussyste infection that ta6es advanta$e of a person5s wea6ened i unesyste opportunistic infection0.

#iagnosis

A dia$nosis of to%oplas osis is ade !ased on clinical si$ns andsupportin$ la!oratory results, includin$ visuali7ation of the proto7oa in!ody tissue or isolation in ani als and !lood tests. =a!oratory tests forto%oplas osis are desi$ned to detect increased a ounts of a protein oranti!ody produced in response to infection with the to%oplas osisor$anis . Anti!ody levels can !e elevated for years, however, withoutactive disease.

Treatment

>ost individuals who contract to%oplas osis do not re&uire treat ent

!ecause their i une syste s are a!le to control the disease.Sy pto s are not usually present. >ild sy pto s ay !e relieved !yta6in$ over the counter edications, such as aceta inophen *ylenol0and i!uprofen >otrin, Advil0. Sore throat lo7en$es and rest ay alsoease the sy pto s.
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Althou$h the treat ent of wo en infected with to%oplas osis durin$pre$nancy is controversial, ost physicians feel that treat ent is

8ustified. *rans ission of to%oplas osis fro the other to the fetusay !e prevented if the other ta6es the anti!iotic spira ycin. =ater in apre$nancy, if the fetus has contracted the disease, treat ent with theanti!iotic pyri etha ine Darapri , ?ansidar0 or sulfona ides ay !eeffective. Ca!ies !orn with to%oplas osis who show sy pto s of thedisease ay !e treated with pyri etha ine, the sulfa dru$ sulfadia7ine>icrosulfon0, and folinic acid an active for of folic acid 0.

AIDS patients who have not !een infected ay !e $iven a dru$ called*>P/S>G Cactri or Septra0 to prevent to%oplas osis infection. *o

treat cases of to%oplas osis in i unoco pro ised AIDS patients, aco !ination of pyri etha ine and a sulfa !ased dru$, eithersulfadia7ine or clinda ycin #leocin0, have !een used to$ether and can!e effective in treatin$ this disease. Fther anti!iotic co !inations anddosin$ schedules are still !ein$ investi$ated. Physicians have reportedsuccess in alleviatin$ sy pto s !y usin$ tri ethopri sulfa etho%a7oleProlopri or *ri pe%0 or dapsone DDS0 plus pyri etha ine. *hesedru$s can produce side effects, such as aller$ic reaction, itchin$ ,

rashes9, and nausea and patients ust !e onitored closely.
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Cerebral Toxoplasmosis1