Large Cerebral Abscess in a Patient of Tetralogy of Fallot

Abstract

Brain abscess is a rare but dangerous suppurative infection. Incidence of congenital heart disease varies from 5% to 18.7%. Despite the improvement in imaging modalities, medical management with newer antibiotics and surgical management, mortality is quite high. We hereby present a case of large brain abscess in a patient of tetralogy of Fallot which was successfully treated by drainage of pus through burr hole and intravenous antibiotics.

INTRODUCTION

A brain abscess is an intraparenchymal accumulation of pus, with its prevalence in the general population ranging from 1% to 2% of all intracranial space-occupying lesions in developed nations, to 8% in underdeveloped nations, and from 5% to 18.7% in cases of congenital heart disease.[1] Despite the lack of adequate documentation about the prevalence of brain abscesses in India, research published in Indian literature has shown that the incidence of brain abscess is much more that seen in developed countries.[2,3,4,5] Brain abscesses are two to three times more prevalent in males than in women. Although infrequent, they may be deadly and are linked to significant morbidity, particularly impacting those in their 40 s.[6]

The infection originates from the spread of surrounding “nonneuronal tissue, haematogenous seeding, or direct penetration into the brain. Predisposing factors are congenital heart disease with right-to-left shunt, middle ear infections, mastoid, paranasal sinuses, orbit, face, as well as scalp, penetrating skull injuries, comminuted skull fractures, intracranial surgeries such as the insertion of ventricular-peritoneal shunts,” dural sinusitis, as well as abnormal immune functions.

Primary predisposing factors include prolonged hypoxia leading to polycythaemia and hyper viscosity, as well as compromised host immunity. In impoverished nations, postponement of surgical intervention for tetralogy of fallot (TOF) increases the likelihood of children experiencing detrimental neurological consequences, including brain abscesses.[6] Infective endocarditis as well as brain abscesses have been rare manifestations of TOF. The ideal age for elective repair of TOF, based on mortality and physical results, is from 3 to 11 months.[7] Timely identification and intervention for TOF may avert complications like brain abscess, ventriculitis, obstructive hydrocephalus, and other coagulation disorders that may jeopardize anesthesia and surgical procedures in TOF patients.[8]

“Here we present a case of a large brain abscess in a patient” of TOF, which was successfully treated by a multidisciplinary approach.

CASE REPORT

An 18-year-old male presented to our hospital with complaints of high-grade continuous fever associated with mild headache, not responding to medications for 2 months. Thereafter, he also developed a gradually progressive weakness on the left side of the body within 1 month. These clinical features were not associated with ear discharge, abnormal movements, or loss of consciousness.

The patient was a diagnosed case of TOF and had typical complaints of episodes of bluish discoloration of skin and mucous membrane following crying since 1 week after birth, along with the history of cyanotic spells and squatting.

On examination, cyanosis was present on the lips, tip of the nose, tongue, fingers, and toes, along with grade 3 clubbing present in the fingers and toes. The child had a toxic look, but the rest of the vitals were stable. On cardiovascular system examination, a systolic thrill was palpable at the left parasternal border in the 3^rd and 4^th intercostal spaces, and a mild right parasternal heave was also palpable over the precordium. On auscultation in the pulmonary area, S2 was single and loud, with a harsh ejection systolic murmur of high pitch present in the left 3^rd and 4^th parasternal, best heard in the sitting and leaning forward position. On central nervous system examination, he was conscious, oriented to time, place as well as person with normal cranial nerves examination. On motor examination, power was 3/5 on the left side of the body, while on the right side, power was normal, and plantar reflex was extensor on the left side.

Investigations revealed hemoglobin 22.3 g/dl, total leukocyte count 15000/mm³ (P₈₄, L₁₆), platelet count 2.21 lacs/mm³, and hematocrit 70.7%. The arterial blood gas analysis showed a partial pressure of oxygen 58 mmHg, with a percentage oxygen saturation of 87% and pH-7.31. Echocardiography suggested situs solitus with a large subaortic ventricular septal defect, with over-riding of the aorta with infundibular pulmonary stenosis. The aortic and pulmonary valves were normal without any patent ductus arteriosus. Computed tomography head showed a well-defined ring-enhancing lesion in the right oparietal region [Figure 1]. Magnetic resonance imaging of the brain showed well-defined, peripherally enhancing thick-walled cystic lesion with surrounding moderate peripheral edema in the right high fronto-parietal region, suggestive of a brain abscess [Figure 2]. Pus was drained by burr hole under general anesthesia with proper antibiotic coverage by neurosurgeons. Pus culture was sterile, probably due to prior antibiotic coverage.

Figure 1.

Computed tomography head showing a well-defined ring-enhancing lesion in the right front parietal region

Figure 2.

T2 Weighted MRI brain showing a hyperintense lesion with a thin hypo-intense wall ([a] Axial and [b] Coronal) and mild surrounding edema with moderate mass effect. The lesion showed peripheral rim enhancement on postcontrast T1-weighted image (c)

The patient was kept on intravenous antibiotics with ceftriaxone 2 g 12 hourly and metronidazole 500 mg 8 hourly for 6 weeks. In follow-up patient shows complete improvement in his headache and weakness, and computed tomography head showed regression in the size of the abscess [Figure 3].

Figure 3.

Postoperative computed tomography head showing regression of the size of the abscess

DISCUSSION

TOF is the predominant cyanotic congenital cardiac anomaly in infancy. Cerebral abscesses in congenital heart disease cases are documented in early literature; nevertheless, the correlation between the two disorders was not definitively established until Ballet (1880) demonstrated that, in some instances of congenital heart disease, mortality resulted from rupture of a cerebral abscess.

In cyanotic congenital heart disease patients, venous to arterial shunts within the heart allow recirculation of poorly oxygenated venous blood to the systemic circulation. This condition causes hypoxia in systemic circulation as well as body tissues, like “the brain.” Hypoxia of the brain can cause the formation of necrotic areas, which are predisposed to infection. In addition to that, hypoxia also causes polycythemia. The increased blood viscosity leads to a reduction of cerebral blood flow rate, and thus worsens the brain necrosis.[9,10]

The formation of brain abscess in Tetralogy patients has also been influenced by the exposure of the brain to bacteremia. First, the bacteremia can result from the bypassing of the pulmonary circulation system, because the system has a filtering effect on bacteria by phagocytosis. Secondly, the heart disease itself becomes a predisposition to the formation of vegetation on heart valves. If bacteremia occurs, the bacteria will harbor on the vegetations. This, in turn, becomes an effective vegetative embolus that joins the systemic circulation. If this embolus reaches the necrotic area in the brain, the development of a brain abscess can occur. It is suggested that 2 conditions have been necessary for brain abscess formation: (1) intermittent bacteremia, as well as (2) focal encephalomalacia.[11] Patients having TOF might therefore be susceptible to focal encephalomalacia due to their severe hypoxia as well as increased viscosity associated with polycythemia and iron deficiency.[12]

In cyanotic congenital heart disease patients, the brain abscess often occurs at the interface of grey and white matter. The predominant involvement of these regions is due to their reduced perfusion resulting from chronic severe hypoxia and elevated blood viscosity seen in individuals with cyanotic heart disease. The species involved include Streptococcus milleri, Staphylococcus aureus, Streptococcus spp., as well as Haemophilus spp.[1]

Management techniques include both medicinal and surgical methodologies. Small, deep-seated abscesses measuring <2 cm and instances with concurrent meningitis are often treated medically. Surgery is warranted when an abscess has been multiloculated, exceeds 2 cm in diameter, contains gas, is situated in the posterior fossa, or is recognised as a fungal abscess. Infectious conditions, such as mastoiditis, sinusitis, or a periorbital abscess, may need surgical drainage. Surgery not only acquires pus for precise bacteriological identification but also reduces the quantity of infections, necrotic tissue, most critically alleviates mass effect along with intracranial pressure.

The antibiotic regimen must be meticulously chosen depending on the bacteria recovered from blood or cerebrospinal fluid. Antibiotics such as first-generation cephalosporins, aminoglycosides, and tetracyclines are unsuccessful in treating brain abscesses due to their inability to penetrate the blood-brain barrier.[13] The standard empirical antibiotic therapy for brain abscesses includes cefotaxime or ceftriaxone, along with nitroimidazole antibiotics (metronidazole and tinidazole), which should be adjusted depending on the susceptibility profile of the identified organism. The recommended treatment length for a brain abscess has been 6–8 weeks.[8]

Freehand aspiration, stereotactic aspiration, endoscopic aspiration, as well as craniotomy with excision, have been surgical techniques employed in brain abscess management. Selection of treatment depends upon patient’s condition, the available procedures, as well as surgeon’s expertise. Aspiration is the optimal therapy for brain abscesses; it was straightforward as well as may be performed through burr hole, even in severely sick patients at any stage of abscess. The only contraindication for aspiration has been coagulopathy. Furthermore, aspiration may be conducted repeatedly.

The postoperative mortality rate for brain abscess remains above 40%, and survivors may experience significant neurological impairments because of tentacular extensions of the capsule into adjacent oedematous white matter, potentially resulting in extensive cerebral tissue damage.[14]

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.