Single small enhancing CT lesion in Thai patients with acute symptomatic seizures: a clinico-radiological study.

OBJECTIVE: To identify the frequency of single small enhancing CT lesion cases (SSECTL) in a provincial hospital in Thailand and verify a set of clinico-radiological criteria for the diagnosis of benign SSECTL.
METHODS: All patients who fulfilled the following criteria were recruited: acute symptomatic focal seizures with or without secondary generalization; minimal or no neurological deficit; no evidence of raised intracranial pressure; no evidence of systemic disease; CT scan showing SSECTL of < 20 mm diameter. After recruitment, patients received antiepileptic drugs and other symptomatic treatment. A CT scan of the brain was repeated every 2 weeks until the lesion had significantly resolved, which was defined as a 50% decrease in size. A CT scan was then taken every 4 weeks until the lesion had completely disappeared or turned into a calcified spot. The data from all other patients presenting with seizures and solitary enhancing lesion on the CT scan who did not fulfil the inclusion criteria were also reviewed.
RESULTS: 972 patients with seizure disorder were recruited. 110 patients (11.3%) presented with seizure and solitary enhancing lesion on the CT scan, 22 of whom (20%) fulfilled the inclusion criteria. 20 of the 22 patients had SSECTL with a spontaneous resolution: 14 (70%) within 4 weeks and 18 (90%) within 8 weeks. Two patients had a progressive course. One patient with a solitary enhancing CT lesion > 20 mm had spontaneous resolution. 87 patients had another diagnoses. The diagnostic criteria for benign SSECTL were 95.23% sensitive, 97.75% specific, had a positive predictive value of 90.91% and a negative predictive value of 98.86%.
CONCLUSION: SSECTL is not uncommon in our provincial hospital. The clinico-radiological criteria proposed by Rajshekhar (1991) are valid and reliable in predicting a benign outcome. CT follow-up within the first 4 weeks is critical.