INDEX:

Introduction Pg 2

Clinical History Pg 2

Preliminary and Differential Diagnosis Pg 3-5

Figure 1 Pg 3

Figure 2 Pg 4

Figure 3 Pg 4

Interest and Originality Pg 5

Patient management Pg 5-6

Discussion Pg 6-7

Table 1 Pg 7

Conclusion Pg 8

References Pg 9

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INTRODUCTION:

Computerised tomography or CT scanning as it is commonly referred to is a very usefull

tool in aiding patient diagnosis. The topic of this particular case study deals with a

computerised tomography (CT) scan of the brain that looks at the pathology of a brain

abscess. A brain abscess according to Osborn (2004:24) is “a focal pyogenic infection of

the brain parenchyma, typically bacterial, fungal or parasitic”. In this case study the

clinical history of the patient will be discussed as well as how the clinical history relates

to the differential diagnosis made. The case study will also be looking at the steps taken

to reach the final diagnosis of a brain abscess and the management of a brain abscess will

also be discussed.

CLINICAL HISTORY:

Patient X presented to the casualty department of a district hospital. She presented with

pyrexia, headaches and seizures, she was also suffering from confusion and was unable to

speak coherently. She had left sided hemiplegia; “hemiplegia is the paralysis or weakness

of one side of the body” (Oxford Reference Nursing Dictionary, 1994:208). The

hemiplegia is the result of a previous cerebral vascular accident (CVA) or stroke as it is

more commonly referred to. A stroke according to the Oxford reference nursing

dictionary (1994:44) is “a sudden attack of weakness affecting one side of the body

resulting from an interruption to the flow of blood to the brain”. Patient X was human

immune virus (HIV) negative. The casualty medical officer referred patient X to the

radiology department for a CT scan of the brain.

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PRELIMANARY AND DIFFERENTIAL DIAGNOSIS:

The request form of patient X queried a preliminary diagnosis of a new CVA.

The patient was scanned with and without intravenous contrast media. Intravenous

contrast media is used to enhance focal lesions so that more information is obtained to

better aid the diagnosis of the patient (Corr, 2003:21). On the CT scan after the use of

intravenous contrast media there was a large ring enhancing right fronto-pariatial cystic

mass with extensive surrounded oedema. Oedema as described in the Oxford concise

medical dictionary (2003:480) is an “excessive accumulation of fluid in the body tissue”,

in this case the body tissue is the parenchyma of the brain and the fluid is cerebral spinal

fluid (CSF).

FIGURE 1: Demonstrating the ring enhancement (Patient X)

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There is also effacement of the right ventricle with contra lateral hydrocephalus.

Hydrocephalus is “an abnormal increase in the amount of CSF within the ventricles of the

brain” (Oxford Concise Medical Dictionary, 2003:327) There is also marked right to left

midline shift. The bones were normal (Mezzabotta, 2008).

FIGURE 2: Demonstrating contra lateral hydrocephalus (Patient X)

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FIGURE 3: Demonstrates midline shift (Patient X)

In the opinion of the attending radiologist the findings may represent one of these

differential diagnosis a brain abscess, metastases or a primary brain tumour (Mezzabotta,

2008). All of these differential diagnoses are indisstinguisible from each other on CT

scanning. All of them show ring enhancement after intravenous contrast medium and all

of them can have a cystic center (Adam, Dixon, Grainger & Allison, 2008: 1325-1327:

1279-1282).

INTREST AND ORIGINALITY:

Symptoms for a brain abscess may develop suddenly or over a period of weeks. These

symptoms may include headaches, vomiting, seizures, loss of coordination and changes

in mental status (Medline Plus, 2008). A brain abscess can develop from any infection in

the body because it spreads via the blood and lymphatic system.

The following risk factors increase your chances of developing a brain abscess

Right to left heart shunts

Chronic diseases such as cancer

Immunocompromised patients

Immunosuppressants (steroids)

(Medline Plus, 2008.)

PATIENT MANAGEMENT:

Patient X was sent for a chest radiograph. The reason for the chest radiograph was to

check for any infections in the chest or to see if there was a malignant primary tumour in

the chest area. The chest radiograph was clear meaning there was no infections or

tumours visible. Patient X was also referred for an ultrasound scan of the abdomen,

kidneys, uretis and bladder. The ultrasound was done to rule out the possibility of a

primary tumour in these areas. Everything was normal no abnormalities were detected.

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A full white blood cell count (WBC) and erythrocyte sedimentation rate (ESR) was done

and it was found that there was an increased WBC as well as an increased ESR this

indicates that there was an infection present somewhere in the body (Haslett, Chilvers,

Boon, Colledge & Hunter, 2002:1200). Patient X was put on to a high dose broad-

spectrum intravenous antibiotic. The neurosurgical team saw Patient X and they decided

that she should have urgent surgical drainage of the pus to relieve the intracranial

pressure. Literatures support the use of antibiotics if the abscess is small, but for larger

ones surgery is almost always the only solution (Osborn, 2004:26). Mortality rate for

brain abscess is 0% - 30% (Osborn, 2004:26). A brain abscess is a medical emergency

because the pressure inside the skull can become high enough to cause death.

Complications of a brain abscess can be meningitis, epilepsy, and permanent neurological

losses like vision; speech and movement as well as recurrent brain infections (Medline

Plus, 2008). The prognosis for brain abscess is deadly if no treatment is received, with

treatment the death rate drops dramatically. There is also a possibility of long-term

neurological problems after surgery. Patient X was awaiting transfer to a tertiary hospital

for the surgical drainage. Unfortunenatly the patient passed away before she could have

the procedure.

DISCUSSION:

As previously stated there is no definite manner to differentiate between a brain abscess,

metastasis or a primary tumour they all have a similar appearances on CT. They can all

present as a ring-enhancing lesion with a cystic center. A brain abscess was diagnosed on

the CT appearance in conjunction with the symptoms, which were pyrexia, headaches

and confusion. According to Osborn (2004:26) pyrexia, is present in 50% of cases and

headaches the most common symptom are present in 90% of the cases. Confusion is also

one of the symptoms. An increase ESR is present in 75% and increased WBC count in

50% of the cases (Osborn. A, 2004:26) Increased ESR and WBC are usually only present

in the face of an infection. A primary tumour or metastasis was ruled out because they

will usually be asymptomatic meaning that it is highly unlikely that the patient will suffer

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from pyrexia or that their would be so much oedema in either of these cases. These are

usually only present in conjunction with a brain abscess. When the scan was viewed on

the bone window setting the bones appeared normal, metastasis or a primary brain

tumour in a lot of cases affect the bone causing bone erosion (Mezzabotta, 2008). Brain

abscesses in immunocompetant patients are usually the result of bacterial streptococci, or

in about 20% - 40% of patients no organism is identified (Adam, et.al. 2008:1325).

According to Davidson’s principles and practice of medicine (2002:1199), the bacteria

can enter the brain through a penetrating injury, by direct spread from the paranasal

sinuses or a middle ear infection, or by haematogenous spread from septicemia. The site

of abscess formation and the likely causative organism are both related to the source of

the infection (Haslett, et al. 2002:1199)

SITE OF

ABSCESS

SOURCE OF INFECTION

Frontal lobe Paranasal sinuses, Teeth

Temporal lobe Middle ear

Cerebellum Sphenoid sinus

Any site Penetrating trauma

Multiple Metastatic and cryptogenic

Table 1 (Haslett, Et al. 2002:1199)

There are four stages of abscess formation early and late cerebritis and early and late

capsule formation. The appearance of these stages on CT is as follow: cerebritis as an ill

defined low attenuation area, which shows thick ring enhancement. In the capsule

formation stages the abscess has low attenuation centrally, because of the pus or necrotic

debris with thinner ring enhancement surrounded by vasogenic oedema (Adam, et al.

2008:1326). From this information we can conclude that patient X was in the capsule

formation stage because there is an area of low attenuation centrally (refer to fig.1) with

thin ring enhancement surrounded by an area of vasogenic oedema.

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CONCLUSION:

It is important to note that even though CT scanning has made wonderful advances since

it conception it should always only be used as one of the diagnostic steps in aiding

diagnosis of a patient. It should always be used in conjunction with the patient’s clinical

history an additional diagnostic test before any final diagnosis is made. The patient’s

clinical history was used in conjunction with her CT scan and other diagnostic test in a

process of elimination to form a final diagnosis of a brain abscess. The risk factors,

symptoms, management and prognosis of brain abscess have been discussed. From this

case study it can be concluded that no absolute diagnosis can be made from diagnostic

imaging alone.

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REFERENCES:

1) Adam, A., Dixon, A., Grainger, R. & Allison, D. (eds). 2008. Grainger and

Allison’s Diagnostic Radiology: A Textbook for Medical Imaging. 5th ed. vol

2. Edinburgh: Churchill Livingstone.

2) Corr, P. 2003. Pattern Recognition in Diagnostic Imaging. Geneva: World

Health Organization.

3) Haslett, C., Chilvers, E., Boon, N., Colledge, N. & Hunter, J. (eds). 2002.

Davidson’s Principles and Practice of Medicine. 19th ed. Edinburgh: Churchill

Livingstone.

4) Medline Plus. 2008. Medical Encyclopedia: Brain Abscess.

http//www.nlm.gov/medlineplus/ency/article/000783.htm (27 March 2008)

5) Mezzabotta, M. 2008. Interview with radiologist on 26 March 2008, Cape Town.

6) Osborn, A. 2004. Diagnostic Imaging: Brain. Salt Lake City: Amirsys.

7) Oxford Concise Medical Dictionary. 6th ed. 2003. Oxford: Oxford University

Press.

8) Oxford Reference Nursing Dictionary. 2nd ed. 1994. Oxford: Oxford University

Press.

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