A 37‐Year‐Old Woman With Left Sensomotor Seizure

Clinical History

A 37‐year‐old female from Brazil complained of paresthesia and cramping in the left calf. She also reported a transient loss of strength in the left arm. Neurological examination revealed paresthesia on the entire left hemicorpus. No clinical abnormality was noted on physical examination, including breast and lymph node examination. During hospitalization, she presented sensomotor seizure of the left arm and leg. Cerebral MRI showed a rolandic right lesion of postcentral gyrus with FLAIR hypersignal (Figure 1A), heterogeneous enhancement and edema around the lesion (Figure 1A and B). Laboratory tests, including blood cell count and CSF puncture, did not find any abnormality. A cerebral biopsy was done.

Figure 1.

 

Pathological Findings

The cerebral parenchyma showed several inflammatory lesions with an epithelioid granuloma and gigantocellular cells surrounding a foreign body. After PAS staining (Figure 1c), these foreign bodies appeared unstained; they were Ziehl‐Neelsen positive (Figure 1d). What is your diagnosis?

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 was continued by email, 1 year later she did not have any clinical symptoms.

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 4 and the disease is endemic in 74 countries (mostly tropical) 3. In France, a recent outbreak of urogenital schistosomiasis in Corsica renewed interest for this helminthiasis, demonstrating that it could emerge outside tropical areas 1. However neurological involvement is uncommon and probably under diagnosed, as it is frequently confounded with a tumor process 3. 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 4. Indeed S. mansoni eggs are larger than S. japonicum's and present a protruding spine so that they less likely progress onto the brain 2.

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 3. 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 3, 4, 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) 3, 4. 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 3. 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 3, 4. 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 caused by S. mansoni result in digestive damages, mainly hepatic fibrosis. Neurological involvement varies from 1% to 5% in endemic population reports 4. 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.