Single photon emission computed tomography (SPECT) in neurocysticercosis

RESUMO

Neurocysticercosis (NC) is a parasitic infectious disease caused by Taenia solium eggs that set in the brain. Its incidence is increasing both in the developing and the developed world, as a result of low economical and hygiene levels and immigration, respectively. Clinical manifestation of disease varies from no symptoms to epilepsy, increased intra-cranial pressure, arachnoiditis and dementia. In order to evaluate function (perfusion) of affected brains, we studied 40 patients (21 females and 19 males, 19-71 yo) by means of SPECT (ECD, ethyl cysteinate dimer, labelled with 99mTc) and with and without contrast CT. SPECT studies were all abnormal. No difference was noted between active and inactive disease. Two SPECT patterns were noted: a) several areas of focally reduced uptake, resulting from coalescent and big lesions and large destruction of brain tissue (small, isolated and symmetric cysts seen in CT were missed by SPECT); b) diffuse atrophy with reduction of the tracer uptake, associated with ventricle dilatation, corresponding to the cases where ventricular NC was important. Interestingly, we noted diffuse hypoperfusion, with the scintigraphic pattern of atrophy in 5 cases of massive parenchymal infection; in such cases, CT signs of atrophy were clearly less prominent. The first scintigraphic aspect can be explained by the destruction of large areas of brain, which produces focal absence of perfusion; generalised vasculitis and the destruction of large portions of brain tissue could explain the difference noted between the SPECT and the CT aspects in the 5 cases of massive parenchimal infection, and this may be interesting for prognosis. Dilatation of ventricles and Sylvian fissures were interestingly prominent in SPECT. SPECT may be of great value to evaluate brain perfusion in NC