SEEG Improves Epilepsy Surgery Outcomes in Patients with MOGHE

Stereoelectroencephalography (SEEG) adds significant value to neuroimaging and noninvasive electroencephalography (EEG) in identifying the source of seizures in patients with drug-resistant epilepsy caused by mild malformation of cortical development with oligodendroglial hyperplasia (MOGHE), according to a recent study from the Cleveland Clinic. The technique helps to more precisely define the epileptogenic zone, potentially leading to more complete surgical resection and higher rates of seizure freedom.

Understanding MOGHE

First described in 2017, MOGHE is a rare form of focal cortical dysplasia characterized by abnormalities in the white matter of the brain, specifically the presence of heterotopic neurons and an overgrowth of oligodendroglial cells. Unlike other cortical dysplasias, MOGHE often presents with subtle or absent abnormalities on standard brain imaging. Patients typically experience drug-resistant focal epilepsy beginning between the ages of 3 and 5, though the reasons for this are not fully understood.

The Role of SEEG in Diagnosis and Treatment

Accurately pinpointing the epileptogenic zone – the area of the brain responsible for initiating seizures – is crucial for successful epilepsy surgery. However, the subtle imaging features of MOGHE can make this challenging using noninvasive techniques alone. SEEG, an invasive monitoring method involving the implantation of electrodes directly into the brain, offers higher spatial resolution and can help delineate the epileptogenic zone more effectively.

Study Findings

A retrospective analysis conducted at the Cleveland Clinic examined the surgical outcomes of 23 patients with pathologically confirmed MOGHE who underwent epilepsy surgery between 1997 and 2024. Ten of these patients (43%) underwent SEEG evaluation in addition to standard preoperative assessment with scalp video-EEG and neuroimaging.

Results showed that 64% of patients overall achieved seizure freedom at a median follow-up of 3.8 years. Notably, 80% of patients who underwent SEEG achieved seizure freedom, compared to 50% of those who did not. A seizure freedom rate of 90% was observed in patients who underwent SEEG-guided partial lobectomies.

The study also found that MRI findings were abnormal in 83% of patients, but half of these studies were initially reported as normal. Gray-white matter blurring was the most common MRI finding (74%). 65% of patients had generalized findings on interictal EEG.

Implications for Clinical Practice

The findings underscore the potential benefits of SEEG for optimizing surgical planning in patients with MOGHE, particularly when noninvasive imaging results are unclear or subtle. While not every MOGHE patient requires SEEG, the study suggests that relying solely on neuroimaging and noninvasive EEG may be insufficient for accurate presurgical planning.

“The epileptogenic zone in MOGHE often extends beyond MRI-visible lesions, necessitating tailored surgical strategies,” explained Dr. Jean Khoury, epileptologist at Cleveland Clinic and the study’s lead author. “Further studies are needed to identify cases in which the technology would be most beneficial in this setting, because with this form of epilepsy, larger resection usually leads to better outcomes.”

This research highlights the importance of expert neuroradiological review of high-resolution MRI studies in patients suspected of having MOGHE.