Medical Policy: 07.01.71
Original Effective Date: January 2016
Reviewed: January 2017
Revised: January 2017
Benefit determinations are based on the applicable contract language in effect at the time the services were rendered. Exclusions, limitations or exceptions may apply. Benefits may vary based on contract, and individual member benefits must be verified. Wellmark determines medical necessity only if the benefit exists and no contract exclusions are applicable. This medical policy may not apply to FEP. Benefits are determined by the Federal Employee Program.
This Medical Policy document describes the status of medical technology at the time the document was developed. Since that time, new technology may have emerged or new medical literature may have been published. This Medical Policy will be reviewed regularly and be updated as scientific and medical literature becomes available.
Responsive neurostimulation (RNS) for the treatment of partial epilepsy involves the use of 1 or more implantable electrode leads that serve as both a seizure detection and neurostimulation function. The device is programmed using a proprietary algorithm to recognize seizure patterns from electrocorticography output (an electroencephalogram made with electrodes that are in direct contact with the brain) and to deliver electrical stimulation with the goal of terminating a seizure before onset.
Neurostimulation devices are classified as one of two types: chronic programmed stimulation devices that administer stimulation at regular preprogrammed intervals (continuous or intermittent) and responsive neurostimulation (RNS) devices that deliver stimulation directly to the brain at the seizure focus only in response to device-detected, abnormal electrical brain activity. The chronic programmed stimulation methods available for treating epilepsy include vagus nerve stimulation (VNS). Responsive neurostimulation is intended to reduce seizures in patients diagnosed with partial onset of seizures, that are refractory to medical therapy and are not candidates for surgical resection.
There are two broad categories of seizures: focal (or partial) and generalized. Focal (partial) seizures involve only a portion of the brain, typically part of one lobe of one hemisphere. A focal (partial) seizure can be associated with impairment of consciousness or awareness (previously called complex partial seizure) or no impairment of consciousness (previously called simple partial seizures). A focal (partial) seizure can evolve over seconds into a tonic-clonic convulsion, also referred to as a secondary generalized seizure.
Focal (partial) seizures without impairment of consciousness can present in a variety of ways; however, within an individual patient, the seizures are usually stereotyped. Common focal seizures that do not alter awareness include both visible manifestations, such as jerking of a limb as well as subjective experiences perceived only by the patient, such as epigastric discomfort, fear, or an unpleasant smell. Such subject feelings are commonly referred to as auras. These seizures may be immediately followed by altered consciousness or awareness; this is usually manifested by a clouding of consciousness, staring, and repetitive motor behaviors, termed automatisms, such as swallowing, chewing or lip smacking. After such a seizure, the patient may experience confusion, fatigue, and throbbing headache. Individuals with altered awareness often have no recollection of their seizure, in fact,some patients are completely unware of all of their seizures.
The primary treatment option for epilepsy is drug therapy consisting of one more antiepileptic drugs. However, many cases of epilepsy do not respond adequately to drug therapy. Medically refractory epilepsy is defined as “failure of adequate trials of two tolerated and appropriately chosen and used antiepileptic drug schedules to achieve sustained seizure freedom.” A second or third line option for these patients is surgical resection or transection of the seizure focus, which is considered to be the most effective therapy; however, some patients are not candidates for this type of surgery. Patients may not be candidates for surgery because seizure foci may be unidentifiable or because of overlap with vital areas of the brain. Treatment options are very limited for patients with medically refractory epilepsy who are not candidates for surgical resection. These patients may pursue alternative treatments which includes neurostimulation.
One responsive neurostimulation device, the Neuropace RNS System, is currently approved by FDA and is commercially available in the United States. The system consists of the implant and external components. The implant is the RNS neurostimulator (generator) and leads (tiny wires containing electrodes connected to the target areas of the brain). The neurostimulator is a battery powered microprocessor-controlled generator that is placed within the skull and beneath the scalp. It connects to one or two leads that are either inserted into the brain (depth lead) or placed on the brain surface in the area of the seizure focus (cortical strip lead). The external components include the programmer, remote monitor and magnet. The programmer is a laptop computer installed with a proprietary software program, which clinicians use to retrieve information from the neurstimulator and noninvasively program the neurostimulator through telemetry wand. A laptop computer installed with a proprietary software program and a telemetry wand compose the remote monitor. Using the telemetry wand (by swiping it over the implant site), a patient can transfer information from the neurostimulator to the laptop at home. The magnet allows patients to instruct the neurostimulator to record brain activity when seizure occurs or stop stimulation.
Before device implantation, the patient undergoes seizure localization, which includes video-EEG monitoring and magnetic resonance imaging for detection of epileptogenic lesions. Additional testing may also include EEG with intracranial electrodes, intraoperative or extraoperative stimulation with subdural electrodes, additional imaging studies, and/or neuropsychological testing and intracarotid amytal (Wada) testing. The selection and location of the leads are based on the location of seizure foci. Cortical strip leads are recommended for seizure on the cortical surface, while the depth leads are recommended for seizure foci beneath the cortical surface. The neurosurgeon performs a scalp incision and then drills two to four holes in the skull to allow for lead placement. The surgeon typically implants the depth leads using specialized localization tools and planning software and implants the cortical strip leads on the brain surface under the dura. After securing the leads the surgeon removes the area of skull that conforms precisely to the neurostimulator (craniotomy) to accommodate the neurostimulator. The neurostimulator rests in a frame above the dura and does not touch the brain. After connecting the leads to the neurostimulator, the surgeon programs the neurostimulator for initial use and closes the incision. in the operating room to detect electrocorticographic activity (electroencephalogram made with electrodes that are in direct contact with the brain). Responsive therapy is initially set up using standard parameters (Neuropace recommended initial settings: frequency 200 Hz; pulse width 160 us; burst duration 100 ms; current 1.0 mA) from the electrodes from which electrical activity is detected. Over time, the responsive stimulation settings are adjusted on the basis of electrocorticography data, which are collected by the patient through interrogation of the device with the telemetry wand and transmitted to the data management system.
The patient data management system (PDMS) is a database for storing patient data that clinicians can access through the web. Clinicians and/or patients send data from the programmer or remote monitor to the PDMS regularly. Clinicians may use the PDMS to review a patient’s historical or current information (e.g. programmed settings, detection and stimulation parameters, brain electrical activity recording) and create new stimulation and detection settings. The neurostimulator’s lifetime is 2.0 to 3.5 years with typical use, and the clinicians can use the programmer to monitor battery life.
The development of the RNS system arose out of observations related to the effects of cortical electrical stimulation for seizure location. It has been observed that electrical cortical stimulation can terminate induced and spontaneous electrographic seizure activity. Patients with epilepsy may undergo implantation of subdural monitoring electrodes for the purposes of seizure location, which at times have been used for neurostimulation to identify eloquent brain regions. Epileptiform discharges that occur during stimulation for localization can be stopped by a train of neighboring brief electrical stimulations.
In tandem with the recognition that cortical stimulation may be able to stop epileptiform discharges was the development of fast pre-ictal seizure prediction algorithms. These algorithms involve the interpretation of electrocorticographic data from detection leads over the cortex. The RNS process thus includes electrocorticographic monitoring via cortical electrodes, analysis of data through a proprietary seizure detection algorithm, and delivery of electrical stimulation via both cortical and deep implanted electrodes to attempt to halt a detected epileptiform discharge.
The available literature related to the efficacy of RNS for partial epilepsy consists of 1 industry-sponsored randomized controlled trial (RCT), which was used for the device’s U.S. Food and Drug Administration (FDA) approval, with 2 year follow up available. In addition, there were several case series and case reports. The available RCT is well-designed and well-conducted; it reported that RNS is associated with improvements in mean seizure frequency in patients with refractory partial epilepsy with an absolute difference in change in seizure frequency of about 20% between groups, but noted that the percentage of patients who responded to treatment with at least 50% reduction in seizures did not differ from sham control. Overall, the results suggested a modest reduction in seizure frequency in a subset of patients. The number of adverse events (AEs) reported in the available studies is low. Although the data on AEs is limited by small numbers of patients, and follow-up beyond 2 years has not been reported, patients who are candidates for RNS are generally severely debilitated, and have few other treatment options, so the benefits are likely high relative to the risks. The evidence is sufficient to determine that the technology results in meaningful improvement in the net health outcomes and therefore, RNS may be considered medically necessary in patients with medication refractory partial epilepsy who are not candidates for epilepsy surgery.
November 2013, the NeuroPace RNS system (Neuropace Inc., Mountain View, CA) was approved by the FDA through the premarket approval process for the following indication:
“The RNS System is an adjunctive therapy in reducing the frequency of seizures in individuals 18 years of age or older with partial onset seizures who have undergone diagnostic testing that localized no more than 2 epileptogenic foci, are refractory to two or more antiepileptic medications, and currently have frequent and disabling seizures (motor partial seizures, complex partial seizures and/or secondary generalized seizures). The RNS System has demonstrated safety and effectiveness in patients who average 3 or more disabling seizures per month over the three most recent months (with no month with fewer than two seizures), and has not been evaluated in patients will less frequent seizures.”
Responsive neurostimulation (RNS) may be considered medically necessary for patients with partial epilepsy who meet ALL of the following criteria:
A replacement or revision of a responsive neurostimulation (generator, leads and/or battery) may be considered medically necessary for an individual who meets all of the above criteria and the existing device is no longer under warranty and cannot be repaired.
Responsive neurostimulation (RNS) is considered investigational for all other indications as there is insufficient evidence to support the safety and effectiveness.
To report provider services, use appropriate CPT* codes, Alpha Numeric (HCPCS level 2) codes, Revenue codes and / or diagnosis codes.
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