Stimulating the Brain in Epilepsy

Anli Liu MD MAAssistant Professor of Neurology

NYU FACES 2013 Epilepsy ConferenceMay 5, 2013

Background: An Unmet Need

• About 2/3 of patients with epilepsy will achieve seizure control with medications

• Despite the introduction of 14 new anti-epileptic medications since 1993, there is still a huge need for patients with drug-resistant epilepsy (DRE)

• Seizure surgery is the best option for DRE patients and offers the best chance for seizure freedom.

• However, some patients are not eligible for seizure surgeryBergey, 2013

Background: Neurostimulation

Neurostimulation options for patients with poorly controlled partial-onset epilepsy

Recent completion of well-designed large clinical

Trials

Advances in brain stimulation and

hardware technology

Background: Neurostimulation

While counterintuitive, delivering an excitatory stimulation during a seizure canDisrupt the seizure and prevent its spread. Mechanism not understood.

Background: Neurostimulation

Potential benefits:• Absent or minimal side effect profile• No teratogenicity• Distinct mechanism of action• Can occur automatically and as a supplementary treatment

Background: Partial vs. Generalized Epilepsy

Partial Epilepsy• Seizure starts from one side • Most adult-onset epilepsy• 50% have seizure control with medications

Generalized Epilepsy• Seizure starts from both sides • Most childhood and adolescent onset • Primary generalized w 80% seizure control

Background: Neurostimulation

While stimulating the brain in epilepsy seems counterintuitive, these therapies could

potentially be an excellent treatment option for patients with partial onset seizures who

are not candidates for surgery.

Neurostimulation

Invasive Non-invasive

• Vagal Nerve Stimulation (FDA 1997)

• Deep Brain Stimulation (Thalamus) (Appr. Europe and Canada 2012)

• Responsive Neurostimulation (RNS) (FDA approval pending)

• Transcranial Magnetic Stimulation (TMS)

• Transcranial Current Stimulation (TCS)

Larger, multicenter controlled trialsFDA approval granted or pending

Smaller, pilot studiesApplications in epilepsy, cognition,Psychiatry, and many other neuroLogic disorders.

Invasive Neurostimulation• Vagal Nerve

Stimulation (VNS)• Deep Brain

Stimulation (thalamus)

• Responsive Neurostimulation (RNS)

A vagal nerve stimulator

Vagal Nerve Stimulation• First FDA approved device for

epilepsy and treatment refractory depression (1997)

• The most prevalent neurostimulation method (60,000 patients in US)

• Programmed to have constant modulation, and a magnet rescue setting

• Trials demonstrate between 25-50% of patients had a reduction of >50% of seizure frequency; few become seizure free.*

• Very safe. Side effects of hoarseness and cough.

Vagus Nerve Stimulation

Leads are wrapped around the vagus nerve in the neck. Through an unknown Mechanism, can decrease the frequency of seizures in partial onset epilepsy.

Fridley Neurosurg Focus 2012

Deep Brain Stimulation (DBS)

Deep Brain Stimulation (DBS) has been FDA approved for Parkinson’sDisease and Esssential Tremor and is now investigated for epilepsy

Deep Brain Stimulation (DBS) of the Anterior Thalamus

DBS delivers continuous low-level stimulation

The anterior thalamus has widespread connectionsAnd is an attractive target.

Patients can have multiple seizure onset zones

DBS Thalamus

• A multicenter controlled trial (SANTE, Fisher 2010) of patients with poorly controlled partial epilepsy*

40% decrease in seizure frequency after 3 months44% decrease for temporal lobe epilepsy56% decrease by 2 years13% were seizure free for at least 6 months

• Safe: no significant bleeding or death.• Side effects: Sensory changes (18%), transient

memory impairment and depression• Approved in Europe and Canada, but not in US.

Responsive Neuro Stimulation(RNS, Neuropace)• Depth electrodes Are placed into or nearThe seizure focus andConnected to a Neurostimulator Implanted into thePatient’s skull.

• Continuous EEG Is recorded by implantedcomputer

• When a seizure is Detected, electricalStimulation is deliveredAnd stops the seizure fromspreading

Fridley Neurosurg Focus 2012

Responsive Nerve Stimulation (RNS)• Large controlled trial

(Morell,2011) with drug resistant partial onset epilepsy showed a 38% seizure reduction

• Progressive improvement over time: 50% reduction at 2 years.

• Improvement in quality of life, Verbal ability, and memory• Retention 90% at 3 years,

reflecting good side effect profile• Major risks: infection and

bleeding• Waiting FDA approval

A patient with temporal lobe

epilepsy and RNS device.

Bergey 2013

Summary: Invasive Neurostimulation

PROS

• Could be an excellent therapy for patients with partial onset seizures who are not candidates for surgery.

• Good efficacy (25-40% seizure Reduction) with improved benefit over time

• Good safety profile

• May spare from side effects from epilepsy medications

CONS

• Range from slightly invasive (VNS) to invasive (anterior thalamic and RNS) neurosurgical procedures

• Risks are bleeding and infection

• Optimal stimulation parameters not proven

• Number of seizure free patients is very low, partly because of patients enrolled in studies

Non-invasive stimulation

Transcranial Magnetic Stimulation (TMS)

Transcranial Current Stimulation (TCS)

Why the excitement?

We can stimulate a superficial area to activate Deeper and widespread networks

To produce temporary and long-lasting effects

• Depression (FDA cleared)• Parkinsons Disease• Stroke• Pain• Epilepsy• Schizophrenia• Autism• Tinnitus• Alzheimer’s Disease• Tourette’s syndrome• Ataxia

Many Treatment Applications in Neuropsychiatric Disorders

Research with noninvasive stimulation is rapidly growing (71)

Transcranial Magnetic Stimulation (TMS)

TMS uses an alternating magnetic field to produce a secondary current in the underlying brain tissue

TMS-guidance with MRI Brain

Co-registration of the TMS wand with the patient’s MRI Brain increases precision.Useful for presurgical planning.

TMS for Epilepsy• As seizures arise from areas of hyperexcitability, we apply low-frequency

TMS to suppress this activity

• Since 2002, a few controlled trials published showing mixed results:No significant effect Significant Decrease in Sz frequencyTheodore (2002)* Fregni (2005)Joo (2007) Fregni (2006)*Cantello (2007) Santiago (2008)

Sun (2012)

• Mix of findings due to mixed patients and protocols

• Meta-analysis of low-frequency rTMS (Hsu 2011) shows modest reduction in seizure frequency

Seizure Reduction after rTMS (Bae 2007)

Suggestion of TMS benefit persisting between 2 to 8 weeks after stimulation.

TMS Batwing (H) Coil: Stimulating Deep Targets

• Batwing Coil increases Depth of Penetration, up to 6 cm

• Currently a Pilot Study of Deep TMS in Patients with Temporal Lobe Epilepsy (Rotenberg)

TMS Safety

• Rare reports of seizure (1.4%) Bae 2007• Most seizures typical in character and duration• No reported instances of status epilepticus• Safety guidelines are now published

Transcranial Direct Current Stimulation (tDCS)

• Application of a weak direct current (1-2 mA) to scalp• Modulation of brain activity, can enhance or suppress

tCS advantages

• Easy to use

• Low cost

• Non-invasive

• Painless

• Long lasting effects

• Few mild side effects (itching, tingling, headache, burning sensation and discomfort limited to the scalp site)

• Safe: no reports of seizures

Safety in tDCS

Brunoni 2011

tDCS for Epilepsy

Fregni (2006): RCT of single 20 minute session of over cortical malformation showed trend toward reduction in seizure frequency

Potentially good for patients with partial onset epilepsy with a seizure focus that is near the surface

HD-tDCS for Ongoing Focal Seizures(Alex Rotenberg, MD PhD, CHB/Harvard)

•Targeted direct current stimulation may produce a more potent effect.

Summary: Non-Invasive Neurostimulation

PROS

• Could be an excellent therapy for patients with partial onset seizures where seizure focus is superficial.

• Noninvasive

• Safe

• May spare from side effects from epilepsy medications

• May eventually be a portable, inexpensive office or home treatment

CONS

• Current research is early with mixed results

• Treatments will likely need to be repeated

• Optimal stimulation parameters not proven

Research at NYU Comprehensive Epilepsy Center

• Efficacy of TDCS for Working Memory Dysfunction and Depression in Patients with Temporal Lobe Epilepsy (now recruiting)

• TCS during Sleep to Improve Cognition in Epilepsy

Research Question

In patients with temporal lobe epilepsy (TLE), what is the efficacy of transcranial direct current stimulation (tDCS) on:•Working Memory Dysfunction?•Depression?•Seizure Frequency?•Interictal Discharges/EEG?

Study Design

A double-blinded, randomized, sham-controlled trial of tDCS on patients diagnosed with temporal lobe epilepsy

Outcomes: • Verbal and visuospatial working memory tests• Mood questionnaires• Seizure frequency• Interictal discharge frequency

Study Design

• Participation involves 8 visits (1-3 hrs)• Subjects undergo memory and mood testing, 20 minutes of EEG at baseline• Five (5) sessions of real of sham tDCS• Repeat testing and EEG• Followup at 2 and 4 weeks

Compensated $50 a visit.

Summary: Neurostimulation

Invasive Non-invasive

• Vagal Nerve Stimulation (FDA 1997)

• Anterior Thalamic Stimulation (Appr. Europe and Canada 2012)

• Responsive Neurostimulation (RNS) (FDA approval pending)

• Transcranial Magnetic Stimulation (TMS)

• Transcranial Current Stimulation (TCS)

Larger, multicenter controlled trialsFDA approval granted or pending

Smaller, pilot studiesApplications in epilepsy, cognition,Psychiatry, and many other neuroLogic disorders.

Summary: Neurostimulation

While stimulating the brain in epilepsy seems counterintuitive, these therapies could

potentially be an excellent treatment option for patients with partial onset seizures who

are not candidates for surgery.

Summary: Neurostimulation

Discuss your eligibility for neurostimulation with your epilepsy doctor.

Supporting research is important:Find out how you can get involved!

ReferencesBergey G., Neurostimulation in the Treatment of Epilepsy, Experimental Neurology, epub 2013Fridley et al. Brain Stimulation for the Treatment of Epilepsy, Neurosurg Focus 32 (3) E 13, 2012.Morrell MJ. Responsive Cortical Stimulation for the Treatment of Medically Intractable Partial Epilepsy, Neurology 2011.