Ganglioglioma and intractable epilepsy: Clinical and neurophysiologic features and predictors of outcome after surgery

Purpose: To review the clinical, neurophysiologic, and radiological data of patients with ganglioglioma who had undergone evaluation and surgery in our Epilepsy Program. Methods: The medical and neurophysiologic records of 38 patients with intractable epilepsy and ganglioglioma were reviewed. Data underwent statistical analysis. Results: There were 28 temporal and 10 extratemporal resections, with a mean age at seizure onset of 10.5 years and mean age at surgery of 22 years. Five tumor resections performed earlier were recorded. Twenty-nine patients had auras and 20 had secondarily generalized seizures. All 28 patients with temporal tumor had complex partial seizures. Preoperative MRI demonstrated the tumor in 36 of 36 patients: 17 of 29 demonstrated gadolinium enhancement, and 17 of 36 had mass effect. Scalp interictal sharp waves were present in 32 patients, and in 15 they were multiregional. In two patients, scalp EEG seizure onset was from the hemisphere contralateral to the tumor. Postoperatively, 79% of patients (30 of 38) were seizure-free (Engel's class I) at 6 months, 72% at 1 year (26 of 36), and 63%, at 2 years (20 of 32). Excellent outcome was associated with a lower age at operation (p = 0.008), shorter duration of epilepsy (p = < 0.01), absence of generalized seizures (p = < 0.01), and no epileptiform discharges on a postoperative EEG (p = 0.01). Conclusions: Good surgical outcome is expected in patients with ganglioglioma despite years of medically resistant seizures, Good outcome may be achieved despite EEG findings that may conflict with tumor location, and is more likely when surgery is performed relatively soon after epilepsy onset.