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Intraspinal neurocysticercosis

Intraspinal neurocysticercosis is very rare (less than 1% of patients with neurocysticercosis) and may occur in combination with cerebral infection or separately. Conventional radiographs of the spine do not show any abnormality. Myelography may demonstrate intradural, extramedullary filling defects of different sizes, but more or less spherical in shape. In other patients, there will only be marked irregularity, deformity, or fragmentation of the column of contrast material, secondary to arachnoiditis. Complete obstruction may occur, probably associated with the nonspecific arachnoiditis, similar to basal arachnoiditis in the skull. It is helpful that, in most patients, complement fixing tests on CSF will be positive.

Magnetic resonance imaging is the diagnostic method of choice in patients suspected of having intraspinal cysticercosis. The cysticerci are more commonly found in the subarachnoid space and appear as cystic or lobulated masses, isointense or hyperintense to spinal fluid (Figs. 7.44-7.46). Occasionally, because of its isointensity, the lesion may be difficult to locate, particularly when there is associated inflammatory reaction and arachnoiditis. In these cases, when clinically indicated, myelography and CT postmyelography may complement the MRI study. An intramedullary cysticercus appears as a cystic mass on T1-weighted images, with peripheral enhancement with contrast medium. Mural enhancement and a nodule corresponding to the scolex may also be seen (Fig. 7.47).

Although there are no specific findings in spinal cysticercosis, this possibility should be considered where there are smooth, spherical intradural defects found on myelography, or lobulated or cystic masses on CT or MRI, particularly where the disease is endemic or in those who have been exposed to the possibility of infection.

Fig. 7.44. Intraspinal cysticercosis, lumbar area. Multiple large cystic lesions within the subarachnoid space, isointense to spinal fluid. MRI sagittal plane. (A) T1-weighted and (B) T2-weighted images. (Courtesy of Dr. Alavaro C. Magalhaes).

Fig. 7.45 A,B. Intraspinal cysticercosis, lumbar area. MRI sagittal plane. (A) T1-weighted image identifies a lobulated mass (arrow) in the subarachnoid space, isointense to the conus medullaris. (B) On a T2-weighted gradient-echo image, the mass is slightly hyperintense to spinal fluid. The lesion was demonstrated to move in position on subsequent examinations. (Courtesy of Drs. David Garza Cruz, Olivia Jimenez Flores, and Hugo Arredondo Estrada).

Fig. 7.46. Intraspinal cysticercosis in a Mexican patient. Photograph taken at the time of surgical removal shows a large cysticercus cyst (center) bulging from the spinal canal at the operative site. (Courtesy of Dr. Jorge Ceballos-Labat, Mexico City).

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Fig. 7.47. Intraspinal cysticercosis, proximal cervical area. MRI sagittal plane. (A) T1-weighted image reveals an intramedullary cystic lesion with a scolex within the cyst. (B) T2-weighted postcontrast image shows marked mural enhancement (arrow). (Courtesy of Drs. K.H. Chang, S.Y. Cho, J.R.Hesselink et al. and Neuroimaging Clin North Am, 1991).

Challenges in Treatment

Neurocysticercosis remains a very challenging clinical and socioeconomic problem in endemic areas. Medical treatment using cysticidal drugs, e.g., praziquantel (a pyrazinoisoquinolone compound) and albendazole (a benzimidazole compound), and surgical intervention continue to evolve. Neuroimaging undoubtedly plays an important role in the understanding of the pathophysiology and in the management of this disorder. However, much work remains to be done, particularly in the areas of sanitation and education in the epidemiology of cysticercosis.

Differential Diagnosis

When calcified cysticerci are clearly seen in muscle planes, their oval or ellipsoid shape is unlikely to be mistaken for other calcifications (e.g., granulomas or other parasites such as Sparganum, Armillifer, or Loa loa). When seen "end on," the cysticerci cannot be identified as such. Difficulty occurs in the brain when there is no calcification and the cysts cause a cerebral "mass effect"; in such patients, CT and/or MRI with contrast enhancement will usually suggest the correct etiology.

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