Abstract
This chapter, reviews the basics for children undergoing epilepsy surgery. The authors discuss the incidence and types of seizures as well as various modalities for seizure suppression (e.g. ketogenic diet, vagal nerve stimulation). The chapter presents the surgical approaches to epilepsy surgery, MRI mapping followed by laser ablation and electrocorticography with mapping followed by surgical excision. The anesthetic implications related to these complex patients are presented.
A nine-month-old boy born at 39 weeks of gestation was noted to have “seizure like” activity at three weeks of age and was found to have a hypothalamic hamartoma.
His current vital signs are: blood pressure 90/52 mmHg; heart rate 116/min; respiratory rate 24; SpO2 100% on room air. Weight is 8.6 kg. The patient is taking levetiracetam.
What Is the Incidence of Seizures in the Pediatric Population?
In 2015, 1.2% of the total US population had active epilepsy; this includes about 470,000 children. About 0.6% of children aged 0–17 years have active epilepsy, such that an elementary school with 500 students would have 3 children with epilepsy.
What Are the Treatment Options for Subcortical Epilepsy?
Treatment includes medical therapy and is usually the first option including: antiepilepsy drugs (AEDs), and maintenance of a ketogenic diet. Surgical options vary greatly from implantation of a vagal nerve stimulator to gamma knife radiosurgery, stereotactic thermoablation (radiofrequency or laser, with or without MR thermography), transcallosal interforniceal resection, transventricular endoscopic resection, or pterional (orbitozygomatic) resection.
What Is the Incidence of Hypothalamic Hamartoma?
Hypothalamic hamartomas (HH) are relatively rare. HH with epilepsy occurs in 1 of 200,000 children. A small number of patients with HH only have precocious puberty and are much less likely to have cognitive disabilities. Males appear to have a slightly higher risk than females (approximately 1.3:1) for HH with epilepsy. There are no identified maternal risk factors for developing HH, and there are no known geographical or ethnic concentrations.
How Is a Ketogenic Diet Employed in Epilepsy Patients?
Originally developed in the 1920s for control of seizures prior to development of AEDs, the ketogenic diet has made a resurgence when seizures are refractory to medical treatment. It consists of a high fat and low protein and carbohydrate diet to produce ketosis. The mechanism of action in treating seizures is highly multifactorial but centers around reduced neuronal firing and activation and can have a profound effect on seizure frequency.
What Is a Vagal Nerve Stimulator?
Vagal nerve stimulators (VNS) have been used as an adjunct to treat intractable epilepsy in children. The exact mechanism of action remains unknown but may be related to changes in regional blood flow during stimulation. Most vagal nerve stimulators are MRI compatible and each institution should have protocols involving the pre- and postinterrogation of these devices in relation to the MRI. At Texas Children’s Hospital, the VNS is turned off immediately prior to the MRI and restarted on completion of the scan.
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