Schistosomiasis (bilharzia) is a
neglected tropical disease caused by digenetic trematode platyhelminths of the genus Schistosoma.
Neuroschistosomiasis is one of the most severe clinical outcomes associated with schistosome
infection. Neurological complications early during the course of
infection are thought to occur through in situ egg deposition following aberrant migration of adult worms to the brain or spinal cord. The presence of eggs in the CNS induces a cell-mediated Th2-driven periovular granulomatous reaction. The mass effect of thousands of eggs and the large
granulomas concentrated within the brain or spinal cord explain the signs and symptoms of increased intracranial pressure,
myelopathy,
radiculopathy and subsequent clinical sequelae.
Myelopathy (
acute transverse myelitis and subacute myeloradiculopathy) of the lumbosacral region is the most common
neurological manifestation of S. mansoni or S. haematobium
infection, whereas acute
encephalitis of the cortex, subcortical white matter, basal ganglia or internal capsule is typical of S. japonicum
infection. Cerebral complications include
encephalopathy with
headache,
visual impairment,
delirium,
seizures, motor deficits and
ataxia, whereas spinal symptoms include lumbar
pain, lower limb radicular
pain, muscle weakness, sensory loss and bladder dysfunction. The finding of eggs in the stool or a positive serology, provides supportive but not direct evidence of
neuroschistosomiasis. A definitive diagnosis can only be made with histopathological study showing Schistosoma eggs and
granulomas. Schistosomicidal drugs (notably
praziquantel),
steroids and surgery are currently used for the treatment of
neuroschistosomiasis. During the 'acute phase' of the disease,
neuroschistosomiasis is treated with
corticosteroids which are augmented with a course of
praziquantel once female worm ovipositioning commences. Surgery should be reserved for special cases such as in those with evidence of medullary compression and in those who deteriorate despite clinical management.