Surgical strategy for refractory epilepsy secondary to porencephaly: ictal SPECT may obviate the need for intracranial electroencephalography. Patient series

Intraoperative electrocorticography-guided resection of the epileptogenic zone in an unusual porencephalic cyst: case report and literature review

Introduction

Porencephalic cysts resulting from perinatal artery infarctions typically manifest as large cysts accompanied by pre-existing neurological deficits. A small porencephalic cyst without any neurological deficit is a rare cause of medically refractory epilepsy.

Case presentation

A 23-year-old female presented with a history of medically refractory epilepsy secondary to a small right parieto-temporal porencephalic cyst. Despite optimal anti-seizure medications, seizures persisted. Surgical intervention was planned, and intraoperative electrocorticography (ioECoG) was used to delineate the epileptogenic zone (EZ), which was found to be two gyri posterior to the cyst.

Discussion

Very focal ischaemia resulting in a small porencephalic cyst from perinatal artery infarction exhibits a distinct organization of the EZ involving wider area posteriorly indicating involvement of arterial territory distal to the cyst. This contrasts with the typical perilesional EZ observed in other lesional epilepsy causes.

Conclusion

Our findings emphasize the need to consider aetiology during interpretation of ioECoG to better define the electrophysiological border between the normal and epileptogenic brain, aiding in achieving a better surgical outcome.

A Giant Porencephaly: A Rare Etiology of Pediatric Seizures

Pediatric convulsive seizure is common and represents a source of major concern and anxiety for the parents. Seizures can have a broad spectrum of etiologies in children, including metabolic, traumatic, developmental, and infectious causes. Depending on the clinical presentation, laboratory testing and neuroimaging may be indicated in the workup of the first unprovoked afebrile seizure. We present a case of a six-year-old boy who was brought to the emergency department by his mother after an episode of convulsion. She reported that he had jerky repetitive movements of all extremities that lasted around two minutes with spontaneous termination. The child did not have a febrile illness. The mother reported no history of similar episodes. Upon examination, the child appeared alert and conscious. No dysmorphic features were evident. Initial laboratory investigations were within the normal limits. The child underwent magnetic resonance imaging for the brain, which demonstrated a large well-defined extra-axial cystic lesion occupying most of the left hemisphere that is connected to the ventricular system. The lesion had no grey-matter lining and it strictly followed the cerebrospinal fluid in all sequences. Such finding represented the diagnosis of a giant left porencephalic cyst. Porencephaly is an extremely rare neurological anomaly that may present with pediatric seizures. Magnetic resonance imaging is the gold standard modality for the diagnosis of porencephaly. The case demonstrated that porencephaly can have a massive size in a patient with normal psychoneurological development.