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|Year : 2022 | Volume
| Issue : 2 | Page : 760-763
Unusual Magnetic Resonance Imaging Features of Scrub Typhus Encephalitis
Shailendra S Naik, Mayurnath R Bedadala, Manik Sharma, Himanshu Sethi
Department of Radiodiagnosis, Mahatma Gandhi Medical College and Research Institute, Puducherry, India
|Date of Submission||06-May-2021|
|Date of Decision||06-Dec-2021|
|Date of Acceptance||28-Jan-2022|
|Date of Web Publication||3-May-2022|
Dr. Mayurnath R Bedadala
Department of Radiodiagnosis, Mahatma Gandhi Medical College and Research Institute, Puducherry
Source of Support: None, Conflict of Interest: None
Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi. The diagnosis of scrub typhus relies on the patient's history of exposure, clinical manifestations, and results of serological tests. Our patient had a history of altered sensorium, inability to walk, and macular rashes predominantly distributed over the chest and bilateral upper limbs. Post serological testing, the patient was referred to the radiology department for MRI brain. Radiologically, MRI being a superior modality helps in the evaluation of lesions in depth, helping to simplify the diagnosis of meningitis, scrub typhus encephalitis, and other related conditions. Various findings have been described in scrub typhus encephalitis in MR brain imaging, and our case shows an unusual finding in brain imaging.
Keywords: Direct immunofluorescence assay, meningoencephalitis, MRI, scrub typhus, Weil–Felix test
Key Message: In patients presenting with features of meningoencephalitis/encephalopathy, along with MRI brain showing micro-hemorrhages and white matter abnormalities, scrub typhus should always be ruled out as prompt administration of antibiotics is the only known management to cure scrub typhus.
|How to cite this article:|
Naik SS, Bedadala MR, Sharma M, Sethi H. Unusual Magnetic Resonance Imaging Features of Scrub Typhus Encephalitis. Neurol India 2022;70:760-3
Scrub typhus was originally reported in the foothills of the Himalayan region and has now spread to other parts of the nation in recent years. The southern part of India, especially Tamil Nadu and Puducherry, has witnessed an increase in the zoonotic illness in the past ten years.,, Orientia tsutsugamushi, an obligate intracellular gram-negative bacterium, is maintained by transovarian transmission in trombiculid mites with rats as their intermediate hosts. Humans get infected when they come in contact with mite-infested scrub vegetation, especially during the monsoons. ELISA remains the investigation of choice for diagnosis of scrub typhus, but due to high costs, long result time, and low availability, other tests such as Weil–Felix can also be used. Patients present with symptoms such as headache, myalgia, fever, and cough with a primary papule (caused by the bite of chigger). Patients are also known to develop serious complications such as acute respiratory distress syndrome, pneumonitis, meningoencephalitis, deafness, perivasculitis, and myocarditis. Although meningoencephalitis is seen in two-thirds of the patients with scrub typhus, there is scarce literature describing MRI findings in such patients. We report here a patient who had an unusual presentation of scrub typhus encephalitis.
| » Case Report|| |
A 38-year-old diabetic male presented with complaints of inability to walk and altered sensorium for 2 weeks along with complaints of inability to speak, decrease food intake, and macular rashes predominantly distributed over the chest and bilateral upper limbs. Considering macular rashes and fever, the patient was provisionally diagnosed with chickenpox, for which he was referred to our institute for further evaluation. Upon admission to the casualty, the patient developed an episode of GTCS that lasted for 5 min and was associated with tongue bite and urinary incontinence. Lumbar puncture along with several other tests was performed for further analysis of new manifested CNS symptoms that revealed typical bacterial meningitis. His CSF was clear and on analysis, glucose- 116 mg/dL, protein- 400 mg/dL, lymphocytes- 50 cells/mm3, and chloride- 115 mEq/L were found. No pus cells were present. CSF findings were suggestive of meningitis. Card test for Scrub typhus turned out to be positive, following which the patient was referred to the department of radiodiagnosis to evaluate the extent of CNS involvement. CT brain was done. which revealed no significant findings [Figure 1].
MRI brain was performed on a 1.5-T PHILLIPS ACHIEVA scanner, which revealed multifocal T2/FLAIR hyperintense areas in the left frontal cortex, right high parietal lobe, right high frontal cortex, right centrum semiovale, and left insular and peri-insular cortex [Figure 2]. On gradient refocused images, some areas in the left insular cortex showed blooming [Figure 3]. Diffusion restriction and corresponding areas of signal drop were noted on DWI and ADC imaging, respectively [Figure 4]. On post-contrast imaging, the lesion showed no evidence of enhancement [Figure 5].
|Figure 2: (a) and (c) T2/FLAIR axial sections show hyperintensity in the left frontal cortex (white and yellow arrows correspondingly). (b) and (d) T2/FLAIR axial sections show hyperintensity in the right corona radiata (blue and red arrows correspondingly)|
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|Figure 3: (a) T1 axial section shows a heterogenous, predominantly hypointense lesion in the left frontal cortex (red arrow). (b) On gradient refocused image, blooming is noted within the lesion (black arrow)|
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|Figure 4: The T2/FLAIR lesions previously described show (a and b) diffusion restriction on DWI (green and yellow arrows) and (c and d) corresponding signal drop on ADC mapping. (Purple and red arrows)|
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|Figure 5: Post-contrast imaging shows no evidence of enhancement of the abovementioned lesions|
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MR imaging features were suggestive of encephalitis, and no meningeal enhancement was seen to suggest imaging features of meningitis.
ELISA sample was sent, which later turned out to be positive for scrub typhus. The patient was started on multiple antibiotics such as meropenem, polymyxin B, and linezolid for approximately 3 weeks. The patient responded to the treatment well and was later discharged in good condition.
| » Discussion|| |
Scrub typhus affects all humans irrespective of any specific age or sex predilection. The incubation period is around 6–21 days, and headache, myalgia, fever, cough, and gastric upset which later undergoes necrosis and forms black eschar are among the common symptoms experienced among the affected individuals. Maculopapular rashes are known cutaneous manifestations associated with scrub typhus. The illness is generally mild and self-limiting but can prove fatal in about 30% of cases if left untreated.
Diagnosis is generally based on a combination of clinical setting, laboratory investigations, and serology, out of which serology holds the superiority when it comes to diagnosis. ELISA remains the investigation of choice for diagnosis of scrub typhus, but due to high costs, long result time, and low availability, other tests can also be used. Weil–Felix test, which is based on the principle of detecting cross antibodies on Proteus Mirabilus OX-K, is one of the oldest tests and is still used widely because of its reliability and high specificity. Other tests such as indirect fluorescent assay, PCR, blood investigations, CSF sampling, and radiological investigations are also used.
As mentioned before, meningoencephalitis can be seen in two-thirds of scrub typhus patients. These patients present with a variety of clinical features such as headache, altered sensorium, focal weakness, and neck stiffness. Very rarely, patients presenting with Guillain–Barre syndrome has also been observed.
The role of radiology is limited to only respiratory and neurological complications. Although clinical features of meningoencephalitis are commonly described in the majority of scrub typhus patients, MRI brain findings are rarely discussed. There are very few case reports in the English literature that describe these findings; thus, many radiologists today are not familiar with them. The most commonly described findings are T2/FLAIR white matter lesions, predominantly noted in the subcortical, periventricular and deep white matter areas., Sood et al. reported microhemorrhages detected on diffusion restriction and susceptibility-weighted imaging.
When a patient presents with features of meningoencephalitis/encephalopathy, along with MRI brain showing microhemorrhages and white matter abnormalities, scrub typhus should be part of differential diagnosis. Imaging findings can be confusing with features of stroke and brain tumors; however, clinical presentation and pattern of involvement of brain parenchyma is different in other differentials. ADC values in stroke depend on the age of ischemia and in brain tumors depend on the membranous disruption of cells by higher tumor grades; however, in cases of encephalitis, cortical diffusion restrictions with low ADC values and microhemorrhages can be seen. Early diagnosis of scrub typhus is a must for the patients' wellbeing as prompt administration of antibiotics is the only known management to cure scrub typhus.
For treatment of scrub encephalitis, doxycycline is the antibiotic of choice. Chloramphenicol, azithromycin, and rifampicin are other antibiotics used for the treatment of scrub typhus, and treatment and imaging protocols are almost similar in all parts of the world depending upon the presentation and clinical features.
| » Conclusion|| |
Scrub typhus is still prevalent in most of the country and can present with varied symptoms and presentations. When presented with features of encephalopathy, MRI brain is the most common imaging preferred. Treating physicians and radiologists should be familiar with the imaging findings, which can vary from patient to patient. Our case described one such finding where prompt diagnosis and treatment was helpful to the patient.
Declaration of patient consent
Full and detailed consent from the patient/guardian has been taken. The patient's identity has been adequately anonymized. If anything related to the patient's identity is shown, adequate consent has been taken from the patient/relative/guardian. The journal will not be responsible for any medico-legal issues arising out of issues related to patient's identity or any other issues arising from the public display of the video.”
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]