Correspondence

Evagination of Taenia solium in the Fourth Ventricle

N Engl J Med 1996; 335:753-754September 5, 1996

Article

To the Editor:

Cysticerci of Taenia solium (parasites of the subclass Cestoda) evaginate in vitro1,2 and in the human eye,3,4 where the scolex, the anterior end of the organism, protrudes and reinvaginates and may change from a subretinal to a vitreous location.4 We report on a patient with an evaginated cysticercus in the fourth ventricle of the brain, discovered by magnetic resonance imaging (MRI) fortuitously performed precisely when the cysticercus evaginated. The cyst, its evaginated scolex, and minimal inflammation were seen in the ventricle (Figure 1Figure 1T₁-Weighted MRI Scan of the Brain of a 34-year-old Woman.).

The patient was a 34-year-old woman who had had dizziness, nausea, and slight vertigo for two months. She had no signs or symptoms of intracranial hypertension. She had bilateral first-degree nystagmus (extreme end-gaze physiologic nystagmus associated with vertical nystagmus). A neuro-otologic analysis showing nystagmus, with a lack of suppression on ocular fixation, demonstrated the presence of a central lesion. The MRI scan showed a single lesion and no supratentorial hydrocephalus. A posterior fossa craniectomy was performed. A living cysticercus, with a thin vesicle filled with crystal-clear fluid and an invaginated scolex, was removed. Histopathological analysis confirmed that the organism was a T. solium cysticercus. Dexamethasone (8 mg three times a day for five days) was administered postoperatively. The patient's symptoms remitted.

Cysticerci of T. solium evaginate only after ingestion by humans. We are unaware of evaginated cysticerci in swine muscle, neurosurgical specimens, or brain parenchyma,5 where they are surrounded by a host capsule. An in vitro study suggests that evagination is associated with the absence of a host capsule.2 Parasites in eyes and in ventricles of the brain, where there is no capsule, may protrude and invaginate repeatedly in search of an appropriate place to anchor, whereas no evagination may occur when an inflammatory capsule surrounds the cysticercus.

Ana Flisser, D.Sc.
Universidad Nacional Autónoma de México, Mexico, D.F. 04510, Mexico

Ignacio Madrazo, M.D., D.Sc.
Centro Médico Nacional Siglo XXI, Mexico, D.F. 14050, Mexico

5 References

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   Ostrosky L, Correa D, Faradji R, Garcia H, Flisser A. Taenia solium: inhibition of spontaneous evagination of cysticerci by the host inflammatory capsule. Int J Parasitol 1991;21:603-604
   CrossRef | Web of Science | Medline

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   Cardenas F, Quiroz H, Meza A, Plancarte A, Dalma A, Flisser A. Cisticercosis intraocular. In: Flisser A, Malagon F, eds. Cisticercosis humana y porcina: su conocimiento e investigación en México. Mexico City, Mexico: Consejo Nacional de Ciencia y Tecnologia, 1989:69-75.
   

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   Puig Solanes M. Consideraciones clinico-patológicas acerca de la cisticercosis intraocular: cisticerco viable y cisticerco en involución. Arch Soc Española Oftalmol 1974;34:341-64.
   

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   Rabiela-Cervantes MT, Rivas-Hernández A, Castillo-Medina S, de-María Cancino F. Anatomopathological aspects of human brain cysticercosis. In: Flisser A, Willms K, Laclette JP, Larralde C, Ridaura C, Beltrán F, eds. Cysticercosis: present state of knowledge and perspectives. New York: Academic Press, 1982:179-200.
   

Citing Articles (2)

Citing Articles

1. 1

   Ana Flisser, Philip S. Craig. 2010. Larval Cestodes. .
   CrossRef

2. 2

   José E. H. Pittella. (1997) Neurocysticercosis. Brain Pathology 7:1, 681-693
   CrossRef