Cerebral seizures of probable orbitofrontal origin

Area of Science:

• Neurology
• Epileptology
• Neurophysiology

Background:

• Temporal lobe epilepsy is a common focal epilepsy.
• Orbitofrontal cortex epilepsy is less understood and often misdiagnosed.
• Identifying the ictal onset zone is crucial for epilepsy management.

Purpose of the Study:

• To investigate focal ictal onset in the orbitofrontal cortex in patients with presumed temporal lobe epilepsy.
• To characterize the clinical and electrographic features of orbitofrontal epilepsy.
• To explore the relationship between orbitofrontal and temporo-limbic structures in epilepsy.

Main Methods:

• Analysis of four patients with implanted electrodes or electrocorticography (ECoG) showing orbitofrontal ictal onset.
• Review of eight additional literature cases of possible orbitofrontal epilepsy.
• Correlation of electrographic findings with clinical seizure semiology.
• Examination of scalp electroencephalograms (EEGs).

Main Results:

• Definite focal ictal onset in the orbitofrontal cortex was identified in four patients.
• Automatisms occurred with orbitofrontal activation without temporal lobe spread in three cases.
• Literature review revealed two subgroups: psychomotor seizures and loss of consciousness with generalized convulsions.
• Scalp EEGs showed bifrontal or anterior quadrant discharges, sometimes with temporal involvement.

Conclusions:

• The orbitofrontal cortex can be a focal ictal onset zone, mimicking temporal lobe epilepsy.
• A posterior orbitofrontal and temporo-limbic relationship may support autonomous epileptogenic zones.
• Understanding orbitofrontal epilepsy is essential for accurate diagnosis and treatment.