Clinical Characteristics

Most of the clinical manifestations of cysticercosis occur when the central nervous system (CNS) is affected. The presence of cysticercus in the CNS can incite a mild or extensive host response, almost always triggered by death of the cyst and resultant inflammatory reaction. Extraparenchymal lesions (ventricular, subarachnoid, spinal, and mixed) have a poorer prognosis than parenchymal lesions. Symptoms depend on the size, number, and location of lesions and include headaches, jacksonian epileptic seizures, focal neurological deficit, loss of vision, mental disturbances, and neuropsychiatric problems produced by brain parenchymal mass effect, reactive edema, and glial scarring. Meningitis, hydrocephalus, ischemic cerebrovascular disease, cerebellar ataxia, spinal cord compression, and transient paralytic episodes can occur at times.

In parenchymal-type cysticercosis, some affected individuals may remain asymptomatic. On the other hand, infection of the brain can be so overwhelming that death occurs from fulminating disease within a week of onset of symptoms and closely resembles an acute encephalitis.

The cysts can present as cerebral tumors (Fig. 7.10 B), with clinical signs varying according to their location. Apart from intermittent raised intracranial pressure from cysts within the ventricular system, those affecting the meninges over the base of the brain can also raise the intracranial pressure by obstruction to the flow of CSF.

Imaging Diagnosis

The possibility of neurocysticercosis should be remembered in every patient with recent onset of epilepsy or other unexpected cerebral symptomatology. Residence in, or travel to, an endemic area 3 or more years previously should alert physicians to this possibility. About 10% of patients known to have cysticercosis will show one or more cerebral calcifications on routine radiographs of the skull (Figs. 7.15, 7.16). Over 75%, and in some series nearly 100%, will have calcifications in muscles or elsewhere in the soft tissues; however, failure to demonstrate calcified soft tissue cysticerci does not exclude cerebral cysticercosis because it is possible to have parasites in only one organ. Intracranial cysticerci calcify later and much less often than those in the muscles and soft tissues. In the brain, they occasionally show calcium deposition in their investing capsules; there may be an area of radiolucency inside and, in the very center, a tiny calcified scolex may sometimes be seen on careful inspection (Fig. 7.15).

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Fig. 7.15. (A) Cysticercus of T. solium in the brain. (Courtesy of Dr. Herman Zaiman, Valley City, North Dakota) (B) Posteroanterior view and (C) right lateral view of the skull reveal a solitary calcified cysticercus in the right frontal lobe of a patient from Colombia. Note the typical 2-mm calcification representing the scolex within a central radiolucency surrounded by a partially calcified sphere 1 cm in diameter, which is the body of the encysted larva. (D) Anteroposterior Townes' view of the skull reveals a solitary calcified cysticercus in the left cerebral hemisphere of a 3-year-old Colombian girl with mongolism and a history suggestive of convulsions. Note again the target-like appearance of the calcification with a central density (scolex) surrounded by a lucent area and finally a ring of calcification around the outside of the cysticercus cyst (arrow). (B-D courtesy of Dr. William Thomas, McLean)

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Fig. 7.16. (A) Cerebral cysticercosis in an 11-year-old Colombian girl with a history of grand mal seizures. There are numerous 2- to 4 mm calcifications scattered throughout the brain compatible with, but not diagnostic of, cysticercosis since several other diseases such as tuberculosis may give similar calcifications. (B) Autopsy specimen of the brain of another patient with fatal cerebral cysticercosis showing multiple cysticerci of varying size and shape in the cortex and ventricular walls of the brain. In the brain, cysticerci are thin-walled cysts, each of which is filled with clear fluid and contains a scolex.