A 32-year-old woman from rural India presents with recurrent generalized tonic-clonic seizures over the past 3 years. MRI brain shows a cystic lesion with eccentric nodule in the left parietal lobe. What is the most common cause of epilepsy in this patient?

Explanation

## Most Common Cause of Epilepsy in India **Key Point:** Neurocysticercosis is the most common cause of acquired epilepsy in endemic regions, particularly in India, Latin America, and sub-Saharan Africa. ### Epidemiology and Pathophysiology Neurocysticercosis results from infection with *Taenia solium* (pork tapeworm). The disease has four stages: 1. **Vesicular stage** (1–5 years): Live cysts in brain parenchyma; minimal inflammation 2. **Colloidal stage**: Cyst degeneration; maximal inflammation and seizure risk 3. **Nodular stage**: Cyst calcification; chronic inflammation 4. **Nodular-calcified stage**: Fibrosis and gliosis Seizures occur in 70–90% of patients with parenchymal cysts, most commonly during the colloidal and nodular stages when inflammation is greatest. ### Clinical Presentation **High-Yield:** The classic MRI finding is an **eccentric nodule within a cyst** (scolex), which is pathognomonic for neurocysticercosis. | Feature | Neurocysticercosis | |---------|--------------------| | **Most common presentation** | Generalized tonic-clonic seizures (60–70%) | | **MRI hallmark** | Cyst with eccentric nodule (scolex) | | **Epidemiology** | Most common cause of epilepsy in endemic areas | | **Risk factor** | Consumption of undercooked pork, poor sanitation | | **Treatment** | Anticonvulsants + anthelmintics (albendazole/praziquantel) | ### Differential Diagnosis Context - **Arteriovenous malformation**: More common in developed countries; presents with focal neurological deficits or hemorrhage - **Brain tumour**: Less common; typically presents with progressive focal deficits and raised intracranial pressure - **Hippocampal sclerosis**: Most common cause of focal epilepsy in developed nations; associated with febrile seizures in childhood **Clinical Pearl:** In an Indian patient with seizures and a cystic lesion on imaging, neurocysticercosis must be ruled out first. Serological tests (ELISA for *Taenia solium* antibodies) and CSF examination support diagnosis. **Warning:** Do not confuse the eccentric nodule (scolex) with a tumour nodule — the former is characteristic of neurocysticercosis and indicates a parasitic cyst, not malignancy.