|Year : 2006 | Volume
| Issue : 4 | Page : 553-558
|Ultrasound evaluation of acute bacterial meningitis and its sequale in infants
D Baruah, N Gogoi, RK Gogoi
Department of Radiology,Assam Medical College and Hospital, Dibrugarh, India
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|Date of Submission||20-Dec-2005|
|Date of Acceptance||10-Aug-2006|
| Abstract|| |
Objective: Ultrasonographic characterization of intracranial pathologies with respect to acute bacterial meningitis and its sequale.
Materials and methods: A prospective study of 70 cases, below 12 months of age within a period of two years, was undertaken to characterize sonographic abnormalities in acute bacterial meningitis and its sequale.
Results: Echogenic sulci, ventriculomegaly and ventriculitis were the findings observed on ultrasonography in cases with acute bacterial meningitis and its sequale.
Conclusion: Infantile transcranial ultrasonography is an useful diagnostic tool for rapid, safe and fairly accurate evaluation of intracranial pathologies in relation to acute bacterial meningitis and its sequale.
Keywords: echogenic sulci, ventriculomegaly, ventriculitis
|How to cite this article:|
Baruah D, Gogoi N, Gogoi R K. Ultrasound evaluation of acute bacterial meningitis and its sequale in infants. Indian J Radiol Imaging 2006;16:553-8
|How to cite this URL:|
Baruah D, Gogoi N, Gogoi R K. Ultrasound evaluation of acute bacterial meningitis and its sequale in infants. Indian J Radiol Imaging [serial online] 2006 [cited 2020 Jul 9];16:553-8. Available from: http://www.ijri.org/text.asp?2006/16/4/553/32267
| Introduction|| |
Meningitis is inflammation of the membranes (Greek: Meninx - a membrane) covering the brain and the spinal cord .
Bacterial meningitis may be defined as an inflammatory response to bacterial infection of the pia-arachnoid and cerebrospinal fluid of subarachnoid space. Since the subarachnoid space is continuous over the brain, spinal cord & optic nerve, infection in this space extends throughout cerebrospinal axis unless there is obstruction of the subarachnoid space .
Infections of the brain, especially meningitis are one of the important cause of morbidity and mortality in infants. A noticeable amount of survivors are left with marked neurological sequale despite adequate treatment.
Early detection of intracranial pathologies and sequale associated with acute bacterial meningitis are of utmost importance for timely intervention.
Among the imaging modalities ultrasound has got its importance due to portability, lower cost, speed, no need for sedation, real-time, multiplanar and most importantly lack of ionizing radiation. It is promising because the presence of open anterior fontanel, a bone free window makes it possible to image the brain and CSF pathways accurately and also depict the normal brain structure in considerable detail .
Aims and objective of the study were ultrasonographic detection of intracranial pathologies with respect to acute bacterial meningitis and its sequale, and correlation with cerebrospinal fluid cytology.
| Materials and Methods|| |
Infants of both sexes below 12 months with clinical suspicion of acute bacterial meningitis and its sequale or cases with cerebrospinal fluid confirmation with open anterior fontanel were selected for the study. A thorough evaluation of all cases selected for study was carried out prior to ultrasonographic examination.
Infants with pre existing neurological abnormality or anatomical cranial malformations were excluded from the study.
70 cases were prospectively studied in the department of Radiology; Assam Medical College and Hospital; Dibrugarh for a period of 2 years (1st June 2002 to 30th May 2004)
Ultrasound equipment used were Siemens Sonoline Adara (3.5MHz probe) and Philips P-600 (3.5 MHz and 7 MHz probes).In the premature infants, a 7.5 MHz transducer is recommended to obtain the highest resolution possible. A 5MHz is necessary to allow adequate sound penetration of a larger infant head .
All the cases were scanned in three planes. On sagittal scanning the centre of the transducer was placed over the anterior fontanel with the scanning plane aligned with the long axis of the head. Transducer is angled first to right and then to left. For coronal scanning transducer was rotated 90 degree so that the scan plane was aligned transversely and beam was angled forward and then backward. .For axial scanning transducer was centered just above ear and beam is angled towards the vault and down towards base of skull. It was then repeated on the other side.
Ultrasonography of cranium was done in all cases within 48 hours of diagnosis and repeat ultrasonography was done on 7th and 14th day or earlier if -fever was persisting beyond 48 hours, persisting seizure, repeat CSF examination showed abnormality and condition of patient was deteriorating.
The anterior fontanel remains open until approximately 2 years of age, but is suitable for scanning only until about 12 to 14 months .
| Results|| |
Among 70 cases maximum numbers of cases were found in the age group of 5 to 12 months. Among all the cases male were 71.4 % (50 among 70) and female were 28.6% (20 among 70).Age and sex distribution is given in the table below (Table 1)
Among bacterial positive cases (31.4% of total cases were bacterial cytology positive in cerebrospinal fluid) maximum cases were of haemophillus influenzae.Group B streptococci were the only isolates in first one moth of age.Sterile and bacterial positive cases are shown in the table below (Table 2)
Echogenic sulci was the commonest ultrasonographic findings in cases with abnormal sonographic picture. Different sonographic findings are correlated according to the positive organisms or sterile culture as shown in the table below (Table 3)
Total cerebrospinal protein was found to be high (>150 mg/dl) in all sonographically abnormal cases and only 20% of sonographically normal normal cases.
| Discussion|| |
Bacterial meningitis is a quite frequently encountered pediatric emergency in this part of country. Though it is common in different parts of the world, its incidence varies from place to place. The clinical diagnosis is confirmed by biochemical analysis, cytological study of CSF and demonstration and isolation of infected organism. In this present prospective study conducted over a period of 24 months, we have analysed various imaging findings associated with acute bacterial meningitis and its sequale along with etiological features of these cases.
The age of the patients included in the present study was 0-1 year age group. The incidence was found to be higher in 5 to 12 months age group (60%). Apart from this age group, the next highest incidence was found in age group of 2-4 months (21.9%) followed by less than 1 month (17.1%).
Out of total of 70 cases, male were 50 (71.4%) and female 20 (28.6%). A male preponderance was seen in our study. Similar high male incidence was also seen in other studies .
In the present study bacteriological evidence was found to 31.4. % of cases. Similar observation of culture positivity was found in studies carried by different workers like Panjarathinam et al (1990) - 28.68% and Vincent et al (1987) - 43%, ,. Among bacterial positive cases most common organism found in present study was H. influenzae (59 %) and second common was N. meningitides (22.7%).
In the present study, 70 cases were taken and among these 42 cases had abnormal (60%) and 28 had normal (40%) sonographic findings.
Similar finding were also put forward by Han BK et al (1985) and Moorthy S et al (1992) [9,10].Following Table-4 compares the present study with different series in regards to normal sonogram.
Echogenic Sulci: Qualitative increase in the brightness and widening of the sulcal echoes due to accumulation of inflammatory exudates in the depth of sulcal fissures is a common finding in meningitis. In our study echogenic sulci was the most commonly found abnormality. Comparison of our study with that of the other studies is shown in the Table-5.
Ventriculomegaly: The mean width of the lateral ventricle in full term infant is 12 mm measured at the level of body of the lateral ventricle . So, ventriculomegaly is considered when lateral ventricle width at the level of the body is exceeded 12 mm.In the present study ventriculomegaly was present in 28.6% of cases. Following Table-6 compares the findings of different authors to that of present study in regards of ventriculomegaly.
The Table-6 shows that the finding of our series is consistent to that of the result of other studies.
Ventriculitis: In the present study the findings of ventriculitis (echogenic septa with ventricular debris) was found in 1 case (1.4%).Ventriculitis often occur in neonate and young infant in bacterial meningitis and significantly increases the mortality and morbidity. Ventricular debris and septa are thought to represent intraventricular inflammatory exudate and partially detached ependymal lining respectively. The increased periventricular echogenecity can be attributed to the sub-ependymal infiltration of inflammatory cells. The ventricular septa may contribute to persistent or recurrent shunt failure or infection. The ventricular band being a solid septum in cystic space is demonstrated clearly on sonogram.
The following Table-7 summarizes the finding in different series regarding ventriculitis.
Infarct: The sonographic features used for recognition of infarction are : absence of arterial pulsation, absence of gyral pattern, altered parenchymal echogenicity and midline shift. It appears that none of these are pathognomic enough to allow confident diagnosis. It appears in our study in 0% cases.
Extraaxial Fluid Collection: In present study it was not found. Han BK et al in 1985 reported in 33.3% which is comparatively higher whereas Chowdhury V et al (1987) and Moorthy et al (1992) it was 7.5% and 1.7% respectively [9, 10, 16].Moorthy et al (1992) attributes the low or absent finding of extraaxial fluid collection in bacterial meningitis to it being masked by poor near field resolution of the transducer used .
Abscess: The percentage of identification and diagnosis of abscess by USG cranium has been very low in different reported series. Moorthy S et al (1992) states that abscess is uncommon in neonate and infantile meningitis and is usually caused by Staphylococcus and virulent gram negative organism . The incidence of Staphylococcal meningitis in our study is nil and this may be reason for non identification of abscess in present study.
Cerebral Edema: It was sonographically diagnosed by effacement of sulci and gyri and by shape of the chink like ventricle. This finding was absent in present study.
It was found from the present study that echogenic sulci, ventriculomegaly and ventriculitis were more commonly associated with H. influenzae meningitis. However, it is evident that neither parenchymal nor ventricular changes in USG findings can be attributed to particular organism.
| Conclusion|| |
Bacterial meningitis is fairly common disease in infancy. The typical features of fever, seizure, refusal to feed, lethargy and irritability with signs of meningeal irritation and of hazy cerebrospinal fluid with low sugar, high protein and polymorphonuclear leucocytosis were observed in most of cases.
Hemophillus influenzae, Streptococcus pneumoniae Neisseria More Details meningitis were major causative organism found in this study. Prior antibiotic therapy could be a major cause of reduced percentage of culture positivity in acute bacterial meningitis,
The duration of illness on presentation, predisposing illness, complication at presentation, cerebrospinal fluid protein and cell count had significant influence on further complications and prognosis in acute bacterial meningitis.
Over the past decade the technique of transfontanalle ultrasonography of the infant brain has clearly emerged as a major application of ultrasonography.
Transfontanalle real time ultrasonography is a rapid, safe, effective, cheaper, noninvasive, portable and easy to repeat and fairely accurate method for evaluating intracranial changes in uncomplicated as well as complicated meningitis. On the basis of sonographic findings, adequate medical treatment can be monitored and surgical intervention can be exhibited.
Infantile transcranial neurosonography in this study has emerged as a very effective diagnostic tool for rapid,safe and fairly accurate evaluation of intracranial pathologies in relation to acute bacterial meningitis and its sequale.Such a kind of evaluation helps in planning and timely intervention of the neonates ensuring their future good health.
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Source of Support: None, Conflict of Interest: None
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5]
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5], [Table - 6], [Table - 7]
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