Contributed by Sorya Belaz, MD, Dan Chiforeanu, MD, Jean-Maxime Devaux, Medical Student, Pierre Tattevin, MD, PhD, Florence Robert-Gangneux MD, PhD , and Jean-Pierre Gangneux MD, PhD
FINAL DIAGNOSIS
Cerebral Schistosomiasis Caused by Schistosoma Mansoni
DISCUSSION
Despite the already proven diagnosis, schistosomiasis serology was done to manage follow up. Serology was positive using ELISA and western-blot assays, on blood sample but not on CSF. The treatment combined a corticosteroid therapy for 15 days with Praziquantel 40 mg/kg in one intake. At 2 months follow up, serological results remained unchanged, but clinically the patient had no more seizure, and control MRI showed a decreasing lesion. After that follow up continued by email, one year later she did not have any clinical symptom.
Schistosomiasis is a tropical parasitic disease caused by trematodes of the genus Schistosoma. Prevalence of schistosomiasis in the world is estimated at over 200 million cases (1) and the disease is endemic in 74 countries (mostly tropical) (2). In France, a recent outbreak of urogenital schistosomiasis in Corsica renewed interest for this helminthiasis, demonstrating that it could emerge outside tropical areas (3). However neurological involvement is uncommon and probably under diagnosed, as it is frequently confounded with a tumor process (2). Neuroschistosomiasis symptoms are related to ectopic egg release in the nervous system, following aberrant migration of adult worms to the brain or spinal cord. Whereas S. japonicum eggs are more often found in cerebellum or cerebral cortex, S. mansoni eggs are more often detected in spinal cord (1). Indeed S. mansoni eggs are larger than S. japonicum's and present a protruding spine so that they less likely progress onto the brain (4).
Egg detection in CSF remains extremely rare, so this is not a diagnostic method for any neuroschistosomiasis. In our case, neuroschistosomiasis has not been evoked, despite the geographical origin of the patient and despite the current Corsican outbreak. Patients with cerebral schistosomiasis often present with hypereosinophilia in blood or in CSF. Although eosinophilia was within normal range in this case, it does not exclude diagnosis especially in a chronical infection (2). Histological confirmation was done on the observation of S. mansoni eggs on cerebral biopsy (Ziehl-Neelsen positive). This invasive biopsy could have been avoided, to the profit of serological testing or parasitological examination of stools or rectal biopsy. Even if a positive serology alone does not prove that imaging findings are related to neuroschistosomiasis, it may lead to consider the diagnosis and to start an empiric anthelmintic treatment, which is safer and less invasive than neurological biopsy. While, there is no definitive consensus on treatment scheme (1, 2), praziquantel is the first-choice anthelmintic molecule, and regimens vary from 40 to 60 mg/kg and from a single dose to 6 consecutive days (1 to 3 days for S. mansoni and 3 to 6 days for S. japonicum) (1, 2). Currently, the administration of a single course of therapy is debated because of possible resistance. Moreover, anthelmintic treatment can be ineffective on larva stage and a second dose (similar doses as the first course of treatment) given 15 days after is necessary to eradicate the residual larva (2). In neuroschistosomiasis anthelminthic therapy must be associated with steroids (started prior anthelminthic and continued after); surgical treatment is restricted to complications (medullary compression, hydrocephalus and intracranial hypertension) or for patients who deteriorate despite medical treatment and when definitive diagnosis cannot await (1, 2). After adequate treatment, the prognosis of neuroschistosomiasis is usually good; the most common sequela is epilepsy. On neuroimaging, small calcified lesions can be seen several years after treatment. The classical forms of schistosomiasis due to S. mansoni result in digestive damages, mainly hepatic fibrosis. Neurological involvement varies from 1 to 5% in endemic population reports (1). Given these clinical pictures suggestive of tumor pathology in patients who stayed in schistosomiasis endemic areas, it is essential to discuss the parasitic diagnosis. This can avoid a high-risk surgery aiming mainly at making an appropriate diagnosis, but often useless for the curative treatment of this parasitic disease.
REFERENCES
Contributed by Sorya Belaz, MD, Dan Chiforeanu, MD, Jean-Maxime Devaux, Medical Student, Pierre Tattevin, MD, PhD, Florence Robert-Gangneux MD, PhD , and Jean-Pierre Gangneux MD, PhD
International Society of Neuropathology