Utility of interictal SPECT of rCBF for focal diagnosis of the epileptogenic zone(s)

Abstract

With Single Photon Emission Computed Tomography (SPECT) of regional cerebral bloodflow (rCBF) ictally and interictally, regional changes of rCBF can be detected in many cases with medically intractable complex partial seizures. Interictal SPECT shows abnormal rCBF in the epileptogenic temporal lobe in 40% to 85% of the patients. A critical survey of the methodological problems considering isotopes, scanners, data analysis and patient population is presented here as well as a few semi‐quantitative studies including our own. It is concluded, that SPECT of rCBF is a useful, non‐invasive method of localizing the epileptogenic zone in patients with severe partial focal epilepsy. Ictal SPECT of rCBF has a higher predictive value and is more sensitive than interictal studies for localization of the seizure focus. Interictal SPECT using a high‐resolution system obtains an almost as high frequency of localization of the focus. With low resolution scanners, a minor frequency is observed. Both interictal and ictal SPECT recordings should be obtained for localization of the epileptogenic focus in presurgical cases as interictal hypoperfusion and ictal hyperperfusion demonstrated in the same focal area are highly characteristic of a seizure focus.

Brain perfusion SPECT and EEG findings in Rett syndrome

“…SPECT has been used for localization of epileptic foci in children and in adults with partial epilepsy, and usually there is a good correlation between SPECT findings and the paroxysmal foci seen in EEG (30)(31)(32)(33)(34)(35). Three of our patients had paroxysmal EEG foci located frontally.…”

A case of temporal lobe epilepsy with improvement of clinical symptoms and single photon emission computed tomography findings after treatment with clonazepam

“…Some authors report that SPECT is a useful method to detect localization of the seizure foci. 4–6 Dietrich et al reported that SPECT is more reliable for determining localization of seizure foci than MRI. 5 On the other hand, Jack Jr et al drew the reverse conclusion when comparing SPECT and MRI.…”

“… 1,2 Recently, a number of papers have reported a clinical advantage of SPECT for patients with epilepsy in detecting the localization of seizure foci. 3–6 However, to date, only a few papers have demonstrated alterations of SPECT findings between before and after improvement of clinical features in patients with epilepsy. 7,8 In the present paper, we described a patient with temporal lobe epilepsy showing a marked improvement of clinical symptoms as well as SPECT findings with clonazepam treatment.…”

Avaliação de Pacientes com Epilepsias Parciais Refratárias às Drogas Antiepilépticas

“…Os métodos de neuroimagem funcional como os estudos de SPECT, especialmente aqueles realizados no período crítico (Figura 5) e os estudos de PET, permitem o acesso à fisiologia cerebral, pela avaliação do fluxo sangüíneo e da taxa de metabolismo cerebral, respectivamente. Estudos interictais, em pacientes com epilepsias focais, demonstram uma ou mais regiões de hipometabolismo em 75% a 90% 24 e hipoperfusão regional em 50% a 75% dos pacientes 25 . Neles, a extensão da área de hipometabolismo ou hipofluxo geralmente é maior que a área envolvida pela atividade epileptogênica avaliada pelo EEG.…”