[Diagnosis and treatment of CNS parasite infection with special reference to parasitic myelitis]

Abstract

The occurrence of visceral larva migrans due to Ascaris suum (A. suum) and Toxocara canis (T. canis) has occasionally been reported in Japan, although parenchymatous involvement of the CNS is extremely rare in A. suum/T. canis visceral larvae migrans. Recently we experienced 7 cases with myelitis caused by visceral larva migrans due to A. suum/T. canis (parasite myelitis). The characteristics of this myelitis are: (1) sensory disturbances (Lhermitte's sign, paresthesia, and hypesthesia) are predominant symptoms, while severe motor weakness is rare, (2) spinal cord lesions on T2-weighted MRI show more extensive lesions compared with mild symptoms, (3) Gadolinium enhancement of spinal cord lesions are limited as compared with spinal cord lesions on T2-weighted MRI lesions, (4) Some cases show the presence of eosinophils in CSF, while others show Th2 deviation in CSF supernatant, and (5) Tests for anti-A. suum/T. canis IgG antibody are strongly positive in serum and CSF. Moreover, 6 percent of 108 consecutive cases with non-compression myelopathy presenting at the Department of Neurology at Kyushu University Hospital from January, 1998 to December, 2002 had parasitic myelitis. Myelitis from visceral larva migrans due to A. suum/T. canis might be overlooked because of its mild neurologic impairment without systemic symptoms, but should be considered as one of the differential diagnoses in non-compression myelopathy.