Presentation
Medically refractory partial epilepsy referable to the right frontal lobe.
Patient Data
Multiple cortical and subcortical T2 hyperintense lesions, the largest in the right frontal lobe are present. There are no enhancing lesions and no subependymal masses or foci of calcification. No new parenchymal abnormality. No diffusion restriction. No hydrocephalus.
Conclusion
Despite the absence of subependymal nodules, features are characteristic of tuberous sclerosis.
The patient went on to have surface electrodes implanted to confirm location of epilepogenic foci.
A subdural grid has been inserted overlying the right frontal lobe as well as a single strip of electrodes in the interhemispheric fissure. An extra-axial hematoma is present displacing the grid and resulting in mild midline shift. Allowing for streak artefact, there is no evidence of intraxial hemorrhage or infarction.
After recording confirmed epilepogenic activity from the frontal lobe, the patient returned to the operating room for removal of the electrodes and resection of the relevant tubers / regions.
MACROSCOPIC DESCRIPTION:
- "Opercular polar": Two fragments of cortex and white matter up to 10mm and 8mm. A separate wedge of cortex and white matter measuring 10x10x8mm.
- "Frontal Polar": Fragments of cortex and white matter up to 10mm and a separate wedge of cortex and white matter 20x10x5mm.
- "Frontal parasagittal": A wedge shaped piece of cerebral cortex and white matter measuring 15x10x22mm.
MICROSCOPIC DESCRIPTION:
Sections of each of the three specimens show similar features of distortion of white matter and cortical architecture by a disorganized arrangement of astrocytes mixed with TS cells typical of tubers in Tuberous Sclerosis. The TS cells have enlarged vesicular nuclei with conspicuous nucleoli and a large amount of eosinophilic cytoplasm with coarse peripheral processes. The TS cells show strong cytoplasmic immunostaining for GFAP and nestin and weak staining for synaptophysin. There is also strong cytoplasmic staining and moderate nuclear staining for p16. There of loss of normal cortical laminar architecture. Moderate numbers of enlarged dysmorphic neurons are also noted. No balloon neurons are identified. There is reduced myelin within the lesions. No features of a glial or neuronal tumor are seen.
FINAL DIAGNOSIS: Tubers consistent with tuberous sclerosis.
Case Discussion
Although the most widely recognized feature of tuberous sclerosis is the presence of calcified subependymal nodules, present in the majority of cases, the appearance on MRI FLAIR is actually more characteristic the presence of multiple cortical and subcortical tubers.