Study of clinicodemographic profile of acute central nervous system infection in children and its correlation with neuroimaging

INTRODUCTION

Infection of the central nervous system (CNS) is the most common cause of fever associated with signs and symptoms of CNS disease in children. Viral infections of the CNS are much more common than bacterial infections, which, in turn, are more common than fungal and parasitic infections.

Radiology and pathology are inseparable at the time of understanding the phenomenon causing nervous system infections. There are a wide range of neuroimaging findings in CNS infections, often with considerable overlap, which makes determination of a specific diagnosis difficult. Correlation with laboratory tests, particularly cerebrospinal fluid (CSF) analysis, is considered to be essential in establishing a definitive diagnosis.¹

Most patients with CNS infection have similar clinical manifestations. Common symptoms include headache, nausea, vomiting, anorexia, restlessness, altered state of consciousness, and irritability; most of these symptoms are nonspecific.² Common signs of CNS infection, in addition to fever, include photophobia, neck pain and rigidity, obtundation, stupor, coma, seizures, and focal neurologic deficits. The severity and constellation of signs are determined by the specific pathogen, the host, and the area of the CNS affected.² Infection of the CNS may be diffuse or focal. Meningitis and encephalitis are examples of diffuse infection. Meningitis implies primary involvement of the meninges, whereas encephalitis indicates brain parenchymal involvement. Because these anatomic boundaries are often not distinct, many patients have evidence of both meningeal and parenchymal involvement and should be considered to have meningoencephalitis. Brain abscess is the best example of a focal infection of the CNS.³

The diagnosis of diffuse CNS infections depends on examination of CSF obtained by lumbar puncture (LP). Though CSF remains the gold standard for diagnosis of acute CNS infection, role of neuroimaging cannot be denied. Few Indian studies are available which delineate the efficacy and accuracy of neuroimaging in management of patient with acute CNS infection. The present study aims to study the utility of neuroimaging in diagnosis of acute CNS infection and the neuroimaging patterns found in different CNS infection.

METHODS

Study type

This is prospective observational study in children (1 month–12 years old) who presented with CNS infection.

Study place

Ward and pediatric intensive care unit (PICU) of tertiary care hospital- Shardaben General Hospital affiliated to Smt. NHL Medical College, Ahmedabad, Gujarat.

Study period

The period of the study was from June 2020 to November 2021.

Selection criteria

The given inclusion and exclusion criteria was used to select the study subjects.

Inclusion criteria

All children between age of 1 month to 12 years admitted in ward and PICU of tertiary care centre were diagnosed as having CNS infection based on clinical and neuroimaging findings. Neuroimaging was done in all suspected cases of CNS infection.

Exclusion criteria

Patient expired within 24 hour of admission. Those patients who are clinically suspected for acute CNS infection but not affordable for neuro-imaging.

Method

The cases of acute CNS infection were classified based on standard case definition and standard protocol.

Clinical and imaging – computed tomography/magnetic resonance imaging (CT/MRI scan) database review of diagnosed patients having CNS infection based on neuroimaging findings was done.

Detailed history and examination of these children was carried out.

Data was collected in form of detailed proforma with CNS examination as per the design.

Necessary investigation like MRI, lumbar puncture done and patients were managed appropriately according the standard protocol.

Modality of neuroimaging defined based on protocol.

Requested neuro-imaging was done with prior explanation of the radiological investigation and informed written consent of the patient/relatives.

CT was performed on Philips ingenuity core 128 multiline unit with axial, coronal and sagittal reconstructions of desired thickness of acquired data. Contrast enhanced computed tomography (CECT) scans were performed after bolus injection of low osmolalaity non-ionic iodinated contrast material (iohexol 300 mg/ml, dose: 1 ml/kg).

MRI scans were performed on 1.5T GE signa HDe 8 channel unit with acquisition of spin echo T1W, T2W, T2 FLAIR, SWI in desired planes and axial EPI- DWI and ADC maps.

CE MRI was done post IV gadolinium (dose 0.1 mmol/kg) injection with acquisition of TIW scans in three orthogonal planes. Imaging findings were evaluated and tabulated and correlated with the clinical findings and pathological findings (wherever available) subsequently.

Data was entered and appropriate statistical software-statistical package for the social sciences (SPSS) applied.

Ethical consideration

Informed consent was taken in vernacular language.

RESULTS

Total 58 cases of less than 12 years old children were suspected to have CNS infection in study period at a tertiary care center.

In this study, among the 58 cases, fever was present in 45 (77.58%), Altered sensorium in 18 (31.03%), seizures in 50 (86.20%), vomiting was present in 17 (29.31%), headache in 9 (15.51%) and cough-cold in 8 (13.79%) cases. out of 50 cases with seizures 60% had status epilepticus. 34 (58.62%) cases had signs of meningeal irritation while in 24 (41.37%) cases signs were absent. Around half of the patient had meningeal signs because both meningitis and encephalitis are included as part of spectrum of acute CNS infection.

In this study on distributing patients based on clinical and pathological findings, viral infection 14 (24.13%) was most common, followed by acute bacterial/ pyogenic infection 11 (18.96%), tubercular infection 16 (27.5%), dengue encephalitis in 5 (8.62%), enteric encephalitis 3 (5.13%), TB spine and HSE, COVID encephalitis in 1 (1.72%).

Among the 30 cases with abnormal neuroimaging 3 (10%) showed pyogenic meningitis. In CNS TB: tubercular meningitis present in 7 (23.23%) patient, tuberculoma in 4 (13.13%), TBM and tuberculoma in 3 (10%).

Viral meningitis in 4 (13.3%), HSE in 1 (3.3%), COVID encephalitis in 1(3.3%), ADEM in 4 (13.3%) while 2 patients (6.66%) were found to have brain abscess.

Clinically diagnosed was confirmed in 51.72% (30 case) and was wrong in 48.27% (28 case). There was significant statistical correlation between abnormal neuroimaging findings and etiology of CNS infections. Correlation is significantly more in case of Tuberculous meningitis as compared to pyogenic meningitis (p<0.05).

Correlation was 100% in ADEM, brain abscess, tuberculoma, TB spine, HSV followed by TBM 77.77% and followed by pyogenic meningitis (27.27%) and viral encephalitis (26.66%).

Sensitivity was highest in TBM and lower in case of pyogenic meningitis and viral encephalitis, which was comparable to other study.

DISCUSSION

This was prospective observational study in children (1 month–12 year old) who presented with CNS infection. This study included 58 children in the age group of 1 month–12 years with a clinical picture suggestive of CNS infection.

Acute CNS infection found to be more prevalent in 1 month to 1 year group (27.58%), followed by 5 to 8 year (24.13%), 1 to <3 year (22.41%), >8 year (20.68%), and 3-5 year (5.17%). The results are comparable with study done at Ananthapuri Hospital and Research Institute, Thiruvananthapuram, India between 2008 and 2020 where 16 patient in the infant (1 month-1 year old) group (25.80%) and 27 patient (43.54%) in the age group 1-5 year.⁴

Among the 58 cases, fever was present in 45 (77.58%), Altered sensorium in 18 (31.03%), seizures in 50 (86.20%), vomiting was present in 17 (29.31%). Thus, fever, altered sensorium and seizures, which is considered to be the triad of symptoms in acute CNS infections, was present in most of the cases.⁵ This study was compared with the “clinico-etiological correlation with the neuroimaging study” in Dhiraj Hospital, Vadodra. Fever was the most common presenting symptom and was present in all patients followed by convulsion (73.77%), altered sensorium (36.07%), vomiting (31.15%), irritability 17 (27.87%) and headache (18%) respectively.^6,9

Out of 50 cases with seizure, 60% had status epilepticus. 34 (58.62%) cases had signs of meningeal irritation. The results are comparable with study done at Ananthapuri Hospital and Research Institute, Thiruvananthapuram, India between 2008 and 2020 were out of 24 patient, 14 patients (58.33%) presented with status epilepticus, and it is the most common symptom.^4,8,12

Distributing patients based on clinical and pathological findings, viral infection (24.13%) was most common followed by acute bacterial/pyogenic infection (18.96%), tubercular infection 16 (27.5%), dengue encephalitis in (8.62%), TB spine and HSE in (1.72%). This study compared with the imaging of CNS Infections with clinic-pathological correlation, done at Western Uttar Pradesh where tubercular infection (TBM) was most common (41.2%) followed by acute bacterial/ pyogenic infection (36.2%) and viral infection (22.5%).^7,10 Thus, commonest CNS infection encountered in the present study was viral meningitis followed by pyogenic meningitis which was closely followed by gynogenic meningitis.

Out of 58 patient 28 (48.2%) patients had normal neuroimaging study and 30 (51.7%) had abnormal neuroimaging study. Among the cases with abnormal neuroimaging 3 (10%) showed pyogenic meningitis, TBM was present in 7 (23.23%) patients, tuberculoma in 4 (13.13%), TBM and tuberculoma in 3 (10%), viral meningitis in 4 (13.3%), HSE in 1 (3.3%), COVID encephalitis in 1 (3.3%), ADEM in 4 (13.3%) while 2 patients (6.66%) were found to have brain abscess. Thus, out of the patients with abnormal neuroimaging in the present study, maximum number of patients was of CNS tuberculosis, followed by viral meningitis and ADEM. Pyogenic meningitis was found in around 1/10^th of the patients.

Clinico-neuroimaging correlation was seen in ADEM, brain abscess (100%), and followed by CNS TB (77.77%), pyogenic meningitis (27.27%), viral meningoencephalitis (26.66%). Thus neuroimaging remain modality of choice for diagnosis of ADEM, brain abscess, TB spine, tuberculoma, HSE. This fact is confirmed in the study .Also correlation was significantly more in TBM as compared to pyogenic meningitis.

Limitation of study

Since this is an observational study, comparison groups are not taken further analytical studies would be more valuable to draw more specific conclusion.

CONCLUSION

It was found that neuro-imaging was accurate in early diagnosis and categorization of CNS infections with high sensitivity in CNS tuberculosis.

Recommendations

In patients presenting with CNS infection, familiarity of various imaging patterns in CNS infections is of key importance to pediatricians and radiologists in timely diagnosis thereby reduce irrational over use of antibiotic and antiviral medication, morbidity and mortality of the potential threatening disease.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: The study was approved by the Institutional Ethics Committee

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