Clinical and metabolic correlates of cerebral calcifications in Sturge-Weber syndrome

Abstract

Aim: To evaluate clinical and metabolic correlates of cerebral calcifications in children with Sturge-Weber syndrome (SWS).

Method: Fifteen children (11 females, four males; age range 7mo-9y, mean 4y 1mo) with unilateral SWS underwent baseline and follow-up magnetic resonance imaging (MRI) with susceptibility weighted imaging (SWI), glucose metabolism positron emission tomography (PET), and neurocognitive assessment (mean follow-up 1y 8mo). Calcified brain volumes measured on SWI were correlated with areas of abnormal glucose metabolism, seizure variables, and cognitive function (IQ).

Results: Ten children had brain calcification at baseline and 11 at follow-up. Mean calcified brain volume increased from 1.69 to 2.47cm³ (p=0.003) in these children; the rate of interval calcified volume increase was associated with early onset of epilepsy (Spearman's rho [r_s ]=-0.63, p=0.036). Calcified brain regions showed a variable degree of glucose hypometabolism with the metabolic abnormalities often extending to non-calcified cerebral lobes. Larger calcified brain volumes at baseline were associated with longer duration of epilepsy (r_s =0.69, p=0.004) and lower outcome IQ (r_s =-0.53, p=0.042).

Interpretation: Brain calcifications are common and progress faster in children with SWS with early epilepsy onset, and are associated with a variable degree of hypometabolism, which is typically more extensive than the calcified area. Higher calcified brain volumes may indicate a risk for poorer neurocognitive outcome.

Figure 1

Demonstration of brain calcification on computed tomography (CT) and susceptibility weighted imaging (SWI; both magnitude and phase images are shown). The images are from a 4-year-old female (patient #10) with extensive right hemispheric involvement. Both computed tomography and SWI detected calcification in the lateral frontal and temporo-parieto-occipital cortex.

Figure 2

Enlarged MRI (susceptibility weighted imaging, SWI) magnitude and phase images at baseline and follow-up in a 21-month-old male (patient #3) with right posterior hemispheric involvement and minimal calcification at baseline. SWI showed progressive calcification in the right parietal and temporal lobe (arrows), with calcified brain volume increasing on follow-up images at age 3 years; this patient also had a second follow-up MRI at age 13 years, demonstrating further progression in the calcified area.

Figure 3

Co-registered axial susceptibility weighted imaging (SWI) phase and 2-deoxy-2-[¹⁸F]fluoro-D-glucose positron emission tomography (FDG-PET) image planes from three Sturge–Weber syndrome (SWS) patients. (A) Patient #9 had left parietal (along with temporo-occipital, not shown) calcification (white arrows). The left parietal cortex showed moderate hypometabolism on PET (green area, red arrow), while the non-calcified frontal cortex showed mild hypometabolism (red arrowhead) compared with the contralateral unaffected side. (B) Left temporo-occipital and also frontal calcifications (white arrows) in patient #14. While the left temporo-occipital cortex (along with the left thalamus) showed severe hypometabolism (blue area, red arrow), the calcified frontal cortex showed largely preserved glucose metabolism, except for a mild decrease in the posterior frontal region (red arrowhead). (C) Patient #15 had no evidence of calcification on SWI, while PET showed moderate (green area) to severe (blue area) hypometabolism (red arrows) in the right temporo-occipital (and also parietal, not shown) cortex.