The syndrome of seizures in association with single small enhancing CT lesions (SSELs)

Neurocysticercosis is an important cause of seizures in developing countries. Most patients with neurocysticercosis have multiple intra-cranial cystic or calcified lesions. The syndrome of seizures in association with single, small enhancing CT/MRI lesions (SSELs) accounts for about 10% of epilepsy patients seen at major neurological centres in India. The clinical features of this syndrome and possible factors responsible for its etio-pathogenesis have been reviewed. In a large study on such patients, seizures were partial with or without secondarily generalized in 86% and majority (97%) of patients was treated with a single AED. Significant resolution of the CT/MRI scan lesion was noted within 6 months in 53% cases while only on anti-epileptic drugs. Two-thirds of patients had no seizures while on single AED and additional 18% had no seizures even after AEDs were withdrawn. A family history of seizures was noted in 21% probands and 60% of affected sibs had syndromic concordance with probands. HLA class II genomic typing was done to identify the role of hereditary factors in the etiopathogenesis of this syndrome. There was a positive association of HLA DRB1*13 (Pc= 0.036) with this syndrome. Seizures in association with single, small enhancing CT/MRI lesions (SSELs) seems to be a “benign localization related epileptic syndrome” expressed in a subset of Indians genetically predisposed to seizures. This syndrome may be an example of “multi-factorial inheritance” with one gene predisposing to seizures while the other gene may be responsible for susceptibility to an environmental agent like cysticercosis. Epilepsy has always been recognized as a disease and a large number of controversies in regards to every aspect of the disease have been prevailing since the days of ancient civilizations. Detailed accounts of the disease are available throughout the human history. Many concepts about the disease have changed over the centuries with advancements in the understanding of different aspect of epilepsy. The basic clinical fundamental remains true even today that the disease is characterized by ‘recurrent unprovoked seizures’. While India has continued to share with the rest of the world most of the important aspects of common neurological diseases, it has always been believed that certain factors may be peculiar to or influencing the incidence of epilepsy in India. Peri-natal insult, infections and infestations of the central nervous system being common in any developing country including India could be responsible for the belief that epilepsy may be more common among populations living in developing countries. The Indian Council of Medical Research (ICMR) in early seventies decided to undertake a multicentric prospective study on ‘epidemiology of epilepsy’, keeping all these factors in mind and recognizing the diverse socio-cultural and environmental milieu of Indian population. The final report of the ICMR study was published in 1989 and contains voluminous data on 3,439 epilepsy patients seen in 5 different centres across the country. The ICMR study report contains some very interesting data that has been meticulously collected, most of the important features of the disease were in accordance to those reported from other countries.1 Long before the ICMR report was ultimately published, a very interesting epileptic syndrome first came to the attention of neurologists in India in the late seventies and early eighties. This was mainly as a result of the addition of CT scanning to the diagnostic kit for patients with epilepsy. Address correspondence to: Prof. Satish Jain, MD; DM, Epileptologist, Sir Ganga Ram Hospital & Director – Indian Epilepsy Centre. A-258, Defence Colony, New Delhi 110 024 (India). Phone: 91-11-2433 3331, 91-11-2433 5214, Fax: 91-112433 3330, Email: [email protected]. Neurology Asia December 2004 4 The CT scan revealed some very unusual and interesting abnormalities in some epileptic patients from India who are otherwise absolutely normal. It can be assumed with a fair degree of certainty that these abnormalities must have existed in such patients even before the introduction of CT scanning in India. The so called ‘Disappearing CT Lesions or Single, Small, Enhancing Lesions’ are now accepted to be a common finding in a large number of epileptic patients from India. The entire Indian literature on this subject including the series presented by many authors in the Annual Conferences of the Neurological Society of India (NSI) till the end of 1988 was reviewed and published.2 Most of the patients with this epileptic syndrome are young and have a few partial with or without secondarily generalized seizures. Occasionally they may even have evanescent post-ictal focal neurological deficits. The CT scans usually shows a small subcortical contrast enhancing hyperdense disc or ring lesion surrounded by a large zone of low attenuation. The CT scan appearance returns to normal or almost normal (complete or nearly complete resolution) within a few weeks without any specific therapy except anti-epileptic drugs (AEDs) to control seizures (figure 1).