Focal Cortical–Subcortical Calcifications (FCSCs) and Epilepsy in the Indian Subcontinent

Summary: Purpose: A focal cortical–subcortical calcification (FCSC) is a common finding on computed tomography (CT) in individuals with focal or generalized seizures in the Indian subcontinent. We sought to determine the relation of FCSCs to epilepsy by comparing the lobe of seizure origin by electro-clinical and CT evaluations and to study the nature and severity of epilepsy associated with FCSCs. Methods: The relation of these FCSCs to epilepsy/seizures was studied in 40 patients, seen for the first time to the neurology outpatient department of a tertiary care hospital. An attempt was made to classify seizures and determine their lobe of origin based on clinical–electroencephalographic (EEG) criteria of the International League Against Epilepsy (ILAE). The clinical lobe of origin was compared with the location of the FCSC on CT scan. In addition, records of the CT unit of the same hospital were reviewed retrospecitvely, to identify cases with an FCSC and their referral diagnoses. Results: Thirty-one (77.5%) patients with FCSCs were considered to have localization-related epilepsy (frontal lobe epilepsy, 20; temporal lobe epilepsy, three; parietal lobe epilepsy, one; occipital lobe epilepsy, three; and definitely localization related but having ambiguous localization features, four) based on ictal semiology and EEG studies. Other ILAE categories in the cohort included epilepsy without unequivocal focal or generalized features (four patients; 10%), isolated seizures (one patient; 2.5%), juvenile absence epilepsy (one patient; 2.5%), and insufficient data to classify epilepsy (three patients; 7.5%). Radiologic sites for FCSCs included frontal (20; 50%), temporal (six; 15%), parietal (seven; 17.5%), and occipital (seven; 17.5%). Electroclinical and radiologic data were congruent in localizing and lateralizing seizures in 22 (55%) patients. The FCSC was truly incidental in one patient with juvenile absence epilepsy. Discordance between the clinical and radiologic localizations was noted in five (12.5%) instances. Magnetic resonance imaging (MRI) did not reveal additional lesions corresponding to lobes of origin as determined by electroclinical analysis. Discordance was surmised to be a result of seizure spread from a silent region to symptomatic cortex. In 12 (30%) patients, electroclinical and radiologic congruence could not be ascertained because ictal descriptions were either inadequate or ambiguous, and EEG findings were noncontributory. Review of 4,452 CT scans of brain performed in the CT unit revealed 29 (0.65%) cases with FCSCs in individuals with nonseizure disorders, that could be labeled as incidental. Conclusions: An FCSC is an important radiologic finding in localization-related epilepsy in the Indian subcontinent. The severity of epilepsy ranges from asymptomatic cases to daily seizures.