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Ann Indian Acad Neurol
Ann Indian Acad Neurol
AIAN
Ann Indian Acad Neurol
Annals of Indian Academy of Neurology
0972-2327
1998-3549
Wolters Kluwer - Medknow India

AIAN-27-443
10.4103/aian.aian_2_24
Letters to the Editor
Cerebral Sparganosis – An Unusual Parasitic Infection Mimicking Cerebral Tuberculosis: Isolation of a Live Plerocercoid Larva of Spirometra mansoni
Rathore Abhishek 1
Padmanabha Hansashree MBBS, MD, DM 1
Mahale Rohan 1
Arora Ankit 2
Goyal Aditi 3
Reddy Jeevika 1
Sipani Mahak 4
Pruthi Nupur 4
Lingaraju T. S. 4
Nagarathna S. 5
Yasha T.C. 3
Saini Jitender 2
Nashi Saraswati 1
Pooja M. 1
Mathuranath P. S. 1
1 Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
2 Department of Neuroimaging and Intervention Radiology, National Institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
3 Department of Neuropathology, National Institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
4 Department of Neurosurgery, National Institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
5 Department of Neuromicrobiology, National Institute of Mental Health and Neurosciences, Bangalore, Karnataka, India
Address for correspondence: Dr. Hansashree Padmanabha, Associate Professor, Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore, Karnataka, India. E-mail: hansa777@gmail.com
Jul-Aug 2024
17 4 2024
27 4 443447
01 1 2024
26 2 2024
09 3 2024
Copyright: © 2024 Annals of Indian Academy of Neurology
2024
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pmcDear Editor,

Sparganosis is a rare but underestimated parasitic disease caused by infestation of the plerocercoid larva of Spirometra tapeworm. Though present worldwide, sparganosis in humans is more commonly reported in China, Japan, and South-East Asia.[1] We report a case of cerebral sparganosis in a young child presenting with focal seizures and multiple intracranial ring-enhancing lesions mimicking tuberculoma.

An 8-year-old girl from South India presented with concerns of fever and recurrent right focal seizures of 3 months duration. Before the symptom onset, the child was developmentally age appropriate with good scholastic performance. Seizures were right focal with impaired awareness, lasting 1–2 min with a frequency of once in 10 days. She had an unremarkable systemic and neurologic examination. The possibility of focal epilepsy secondary to a space-occupying lesion (? infective/neoplastic) was considered. Complete hemogram showed eosinophilia (8.5%), and the erythrocyte sedimentation rate was 21 mm/h. Biochemical profiles were normal. Initial magnetic resonance imaging (MRI) of the brain revealed multiple small, conglomerated, T2-isointense to hyperintense lesions with heterogeneous contrast enhancement in the left hemisphere [Figure 1]. Given the commonality of tuberculosis in the Indian subcontinent and signal characteristics of the lesion (speckled T2 hypointensity coupled with extensive perilesional edema and conglomerate enhancement), intracranial tuberculoma was considered. Cerebrospinal fluid (CSF) analysis showed seven cells (one polymorph and six lymphocytes) with normal protein (32.1 mg/dl), glucose (62 mg/dl), lactate (17.2 mg/dl), and chloride (123 mmol/l). CSF gram staining, bacterial culture, cartridge-based nucleic acid amplification testing, cryptococcal antigen, Brucella polymerase chain reaction (PCR), and fungal PCR were negative. The child was initiated on weight-based antitubercular treatment (ATT; four drugs Isoniazid, Rifampicin, Pyrazinamide and Ethambutol [HRZE] during the intensive phase of ATT for 3 months) with steroids (8 weeks course) along with antiseizure medications and followed up.

Figure 1 Initial MRI. (a and b) Axial and coronal T2-weighted images reveal conglomerated heterogeneous signal intensity lesions in the left parietal lobe with internal specks of T2 hypointensity. (c and d) Diffusion-weighted images with corresponding apparent diffusion coefficient (ADC) maps show no obvious diffusion restriction. (e and f) Multiple punctate foci of blooming are seen on Susceptibility weighted imaging (SWI) images, few of which correspond to calcifications on CT. (g) Postcontrast images reveal heterogeneous avid enhancement within the lesion with internal hypoenhancing areas. (h) No significant elevated perfusion is demonstrated within the lesion in the colored relative cerebral blood volume (r CBV) maps. CT = computed tomography, MRI = magnetic resonance imaging

Neuroimaging after completion of the intensive phase of ATT showed persistence of intracranial lesions. The child was continued on maintenance phase of ATT with three drugs isoniazid, rifampicin and ethambutol (HRE). Third neuroimaging done 15 months after the initiation of ATT showed a new ring-enhancing lesion in the left temporal lobe [Figure 2]. The previous lesion in the left parietal lobe had reduced in size with areas of gliosis. However, susceptibility-weighted imaging at this time point showed elongated, tubular cord-like lesions along the left parietal gyri, akin to the morphology of the organism in retrospect. Given radiologic worsening despite an appropriate dose of ATT, the child underwent an excisional biopsy. A whitish, long, tubular, motile organism resembling a parasite was isolated from the biopsy [Video 1]. Morphologically, the diagnosis of tapeworm infestation was considered, and samples were sent to Mahidol University, Thailand, for serological diagnosis. Stool routine and ultrasound of the abdomen were normal. Serum and CSF samples showed immunoglobulin G4 immunoblotting positivity for sparganosis. Histopathology also confirmed the same [Figure 3]. ATT was stopped, and the child was given a course of praziquantel at 25 mg/kg/day in three divided doses for 7 days. Follow-up MRI done 4 months postoperatively showed resolution of previous lesions with gliosis [Figure 4]. Child’s seizures were controlled, and she was asymptomatic.

Figure 2 Follow-up MRI after 15 months of ATT. (a and b) Axial and coronal T2-weighted images reveal a new similar lesion in the left temporal lobe, which is heterogeneous in signal intensity with surrounding vasogenic edema. (c and d) Axial diffusion-weighted images with ADC maps show mild reduced diffusivity within the lesion. (e and f) Lesion in the left temporal lobe shows irregular heterogeneous enhancement with internal hypoenhancing areas, whereas the lesion in the left parietal lobe is significantly decreased in size with few persisting nodular enhancing areas (white arrowhead in e). (g and h) T2-weighted and CT images showing the lesion in the left parietal lobe has significantly decreased in size with thinning of cortex and punctate calcific foci. ATT = antitubercular treatment, CT = computed tomography, MRI = magnetic resonance imaging

Figure 3 Microphotograph of the H and E-stained section showing histopathology of the bladder wall of the cestode larva (a), with the outermost dense eosinophilic tegument (arrow), tegumental cells beneath it with small nuclei, and smooth muscle merging into loose parenchyma (b) with excretory channels (“*”) which are dilated (inset, b). The smooth muscle is oriented longitudinally (c). The head of the larva shown in (d) does not contain suckers or hooklets. (magnification = scale bar [20 µm]). H and E = hematoxylin and eosin

Figure 4 Follow-up MRI 4 months postoperatively. (a and b) Axial and coronal T2-weighted images demonstrate cortical thinning and atrophy in the left parietal and temporal lobes, inferring gliosis. (c and d) Axial and trace maps of diffusion-weighted imaging show no evident diffusion restriction in the involved areas. (e and f) Susceptibility-weighted images show linear foci of blooming along the gyri in the left parietal and temporal lobes. (g and h) Few punctate enhancing areas are noted in the left parietal and temporal lobes. Also evident are postoperative changes along the left calvaria and the left temporal lobe (white arrowheads). MRI = magnetic resonance imaging

Cerebral sparganosis is a rare parasitic infection caused by infestation of sparganum, that is, plerocercoid larva of Spirometra mansoni.[2] The definitive hosts are dogs and cats, the first intermediate hosts are cyclops, and the second intermediate hosts are frogs, snakes, or rats. Surprisingly, humans are an accidental paratenic host and develop sparganosis by ingestion of the plerocercoid larva in the secondary intermediate host. Humans can acquire infection either by ingestion of raw or inadequately cooked flesh of frogs, snakes, or chickens or by drinking contaminated water from natural resources or by applying the flesh of an infected host as a poultice to an open wound on the eye, skin, or mucosa.[3] If humans acquire infection, they will remain the terminal host and sparganum can live up to 20 years. The proband did not have any history suggesting travel to a foreign country or consumption of the above-mentioned food, and probably might have acquired the infection by drinking water from natural sources.

Sparganum is known for its migrating character; it usually spreads by invading the subcutaneous tissue either into muscles, abdominal cavity, pleura, genitourinary tract, eye, or the spinal canal and can also migrate into the brain. Cerebral infection is the most serious complication with nonspecific clinical manifestations. Diagnosis of cerebral sparganosis is generally made, like in the index case, by open or stereotactic biopsy followed by histopathologic confirmation. Immunopositivity for S. mansoni in both serum and CSF is a useful diagnostic tool with high sensitivity.[45] However, serological testing by enzyme-linked immunosorbent assay is not available in our country and not all lesions are surgically amenable, making the diagnosis of cerebral sparganosis challenging. Often, they can be misdiagnosed as a central nervous system (CNS) neoplasm,[6] CNS tuberculoma,[7] or neurocysticercosis.

Though characteristic neuroimaging findings have been described, imaging findings in isolation would be insufficient to diagnose sparganosis. Imaging reflects different characteristics based on the survival status of sparganum. Twisted or tubular cord-like structures with enhancement mirror the parasite’s morphology. Beaded or ring-shaped enhancements indicate abscess formation, and multiple lesions surrounding the worm body signify the presence of multiple old and new eosinophilic granulomas. Degenerative phases show brain atrophy, widening ventricles, and calcification post-parasite degeneration. Noteworthy signs include migration sign, tunnel sign, and worm body signs, which are crucial for diagnosis and monitoring. Tunnel sign is the most characteristic imaging finding on postcontrast images, which indicates the moving track of the worm; often, it is a late sign predicting poor prognosis.[8] There is no definitive treatment for cerebral sparganosis. Surgical resection of the lesion is considered to be the best.[9] In surgically nonamenable lesions, high-dose praziquantel therapy, with each course consisting of 25–50 mg/kg/day for 7–10 days at regular intervals, has been tried.[10]

Cerebral sparganosis is a rare but important treatable differential for cerebral infective granulomatous lesions which can be commonly mistaken for tuberculomas that are prevalent in India, resulting in greater diagnostic delay. Changes in lesion location and shape on sequential brain imaging, known as migration sign, and path-like changes, known as tunnel sign, can prompt for early surgical biopsy for definitive diagnosis.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Video available on: https://journals.lww.com/annalsofian

Acknowledgement

We would like to acknowledge Dr. Paron Dekumyoy, Ph.D. (paron.dek@mahidol.edu) and Dr. Poom Adisakwattana, Ph.D. (poom.adi@mahidol.edu), Associate Professor, Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Thailand, for performing serological testing for sparganosis.
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