#3 Responsive Neurostimulator for Intractable Epilepsy

Overview

Epilepsy is a neurological condition that produces seizures—brief disturbances in the normal electrical functions of the brain—that affect various mental and physical functions. Seizures happen when clusters of nerve cells in the brain signal abnormally, which may briefly alter a person’s consciousness or movements. When a person has two or more unprovoked seizures, he or she is considered to have epilepsy.

According to the Institute of Medicine, epilepsy affects as many as 2.8 million Americans, while the ailment affects 65 million people worldwide, and after migraine, stroke, and Alzheimer’s disease it’s the fourth most common neurological disorder in this country. Its prevalence is greater than cerebral palsy, multiple sclerosis, autism spectrum disorder, and Parkinson’s disease combined.

Medications and other treatments help many people of all ages who live with epilepsy, but in spite of their medication regimen more than one million people continue to have seizures that can severely limit or curtail many of their life’s experiences. About 30% of Americans have intractable epilepsy, which is a seizure disorder in which a patient’s seizures fail to come under control with treatment.

Also called “uncontrolled” or “refractory,” intractable epilepsy interferes with a patient’s quality of life and can destroy life as well. Sudden Unexpected Death in Epilepsy, or SUDEP, is a serious concern. SUDEP is a non-accidental death in a person with epilepsy, who was otherwise in a usual state of health. In people with frequent epileptic seizures that are poorly controlled with medications, the death rate is approximately 1 in 150 per year.
 People who are not seizure-free need to be careful about possible accidents during a seizure. Those with intractable epilepsy need to take caution while in water, near busy streets or railway platforms, and they’re often required to surrender their driver’s license.

Epilepsy surgery is a possibility for some with intractable epilepsy, but many cannot have it due to the risks or because it’s unlikely to be helpful. There is now another option.

An implanted neurological device that can significantly reduce the frequcncy of epileptic seizures gained the unanimous backing of an FDA neurological device advisory panel in 2013.

 Surgically implanted under the skin of the skull, the device, which is smaller than a cellphone, records electrocorticographic (ECog) patterns through leads containing electrodes that are placed at the patient’s seizure focus within the brain or else they rest on the brain surface where seizures are known to start. When detection thresholds are met, the device delivers short electrical pulses to interrupt the triggers before any seizure symptoms can occur.

After reviewing ECoG recordings, physicians can assess the relationship between the detections of the device and reported seizures, and then non-invasively customize the system’s electrical impulses as needed for that patient.

At long last, there appears to be a workable solution for people who suffer the out-of-control bursts of electrical energy in the brain. With more than 15 years of development and testing and three clinical trials, the pivotal clinical study reported a 40% reduction in seizure frequency in the treatment group compared to a 17% reduction in the sham-stimulation control group. Long-term results demonstrated sustained improvements in seizure frequency, with average frequency reductions of 44% and 53% at one and two years post-implant, respectively.

 

Where Are They Now

Long term study results confirmed the device’s efficacy, with a 66% reduction in seizure frequency 6 years post-implant and caused a surge in first-time implantations at multiple hospitals throughout the nation. A more recent study completed in April 2016 reports a median percentage reduction of seizures of 70%. This device is projected to play an important part in the $6.2 billion dollar neuromodulation market.

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