Pediatric intractable epilepsy: a functional neuroimaging diagnostic challenge

This study was conducted on 39 children with intractable epilepsy. All were subjected to thorough clinical examination, EEG, MRI and interictal brain SPECT. Ictal SPECT was performed only in 13 patients. The patients were divided according to the clinical semiology of seizures into group A with generalized intractable epilepsy and group B with partial intractable epilepsy. For the whole group, the diagnostic and localizing values were 76.9% and 30.7% for EEG, 56.4% and 46.2% for MRI as well as 69.2% and 43.6% for interictal SPECT. The localizing value was higher for group B in all diagnostic modalities [75% for both MRI and interictal SPECT]. Ictal SPECT was performed for 13 patients only, it had the highest diagnostic and localizing values. It was diagnostic and localizing in seven patients in group B who performed ictal SPECT

Serum parathormone level as a predictor of sensitivity of preoperative Tc99M MIBI parathyroid scintigraphy in primary hyperparathyroidism

The diagnosis of primary hyperparathyroidism is made by the finding of elevated serum calcium [Ca] and intact parathormone [iPTH] levels. Tc99m MIBI scintigraphy represents the most suitable non invasive technique for preoperative localization of overfunctioning parathyroid tissue with a mean sensitivity of 91% and a range of 55-100%. The scan sensitivity was reported to decrease for small adenomas with lower serum Ca and iPTH levels. The aim of the current study was to verify the possibility of the use of serum level of iPTH as a predictor of sensitivity of preoperative Tc99m M1131 parathyroid scintigraphy in primary hyperparathyroidism and the feasibility to apply this for selection of patients who are going to get the utmost benefit from the scan according to iPTH serum level if we are going to take cost effectiveness into consideration. 98 patients with biochemically established primary hyperparathyroidism were enrolled retrospectively in the current study all were subjected to preoperative Tc99m MIBI parathyroid scintigraphy. All underwent surgery with histopathologically proven parathyroid pathology. The mean age of our patients was 56 years, with females representing 67%of study population. Eighty nine patients [90.8%] had parathyroid adenoma and the remaining 9 patients [9.2%] had parathyroid hyperplasia. The mean value of iPTH level for the whole group was 688pg/ ml; with a mean elevation above upper normal limit of 7.4 folds. The overall scan sensitivity was 59.2%. Seventeen patients were asymptomatic, they had significantly lower values of serum Ca and iPTH levels and scan sensitivity [29.4%] compared to the symptomatic group, the latter had scan sensitivity of 65.4%. According to degree of elevation of serum iPTH level, patients were divided into 4 main groups, group I with elevation less than 3 folds, group 2 [between 3 and 6 folds], group 3 [between 6 and 9 folds] and group 4 [more than 9 folds]. The mean value of serum iPTH level for patients" groups was I 17.6pg/ml, 374.7 pg/mI, 631.4 pg/mI and 1621.2 pg/mI with Tc99m MIBI scan sensitivity of 16.7%. 37.5%, 78,9% and 96.8% respectively. There is a statistically significant difference between all groups as regards both iPTH serum level and scan sensitivity. On addition of patients of group 1 and 2 together [48 patients with less than 6 folds elevation of iPTH level], the mean value of iPTH was 246pg/ml with scan sensitivity of 27%. These figures were significantly lower than those found for 50 patients of groups 3 and 4 together with iPTH serum level more than 6 folds [I 126pg/ml and 90% respectively]. It is concluded that asymptomatic patients with primary hyperparathyroidism had significantly lower levels of serum Ca and iPTH levels and lower Tc99m MIBI scan sensitivity compared to symptomatic group. Also we can conclude that serum iPTH level can be successfully employed to predict sensitivity of preoperative Tc99m MIBI scintigraphy. The degree of hormonal elevation is directly proportional to scan sensitivity with lowest value [16.7%] for less than 3 folds elevation, increasing to 37.5%, 78,9% and 96.8% for elevation from 3 to 6 folds, 6 to 9 folds and above 9 folds respectively. If we take cost effectiveness into consideration, it is advisable to perform Tc99m MIBI scan for patients with primary hyperparathyroidism in whom serum iPTH level is more than 6 folds elevation above upper normal limit, with scan sensitivity of 90% compared to 27% for those with lower hormonal level