Robotic apparatus for targeting and producing deep, focused transcranial magnetic stimulation
Inventors
Schneider, M. Bret • Mishelevich, David J.
Assignees
US Department of Veterans Affairs • Leland Stanford Junior University
Publication Number
US-8845508-B2
Publication Date
2014-09-30
Expiration Date
2024-04-09
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Abstract
Techniques for applying electromagnetic energy to deep, targeted areas without overwhelming other areas are provided. One or more coils are moved relative to a target area and magnetic fields are applied to the target from multiple coil locations. As a result, the aggregate electromagetic energy applied to the target over time is greater than surrounding areas. Additionally, a model for testing and treatment planning is provided.
Core Innovation
The invention provides techniques for applying electromagnetic energy to deep, targeted areas without overwhelming other areas, particularly superficial structures close to the magnetic field generators such as coils. This is achieved by moving one or more coils relative to a target area and applying magnetic fields from multiple coil locations, so that the aggregate electromagnetic energy over a finite time is greater at the target than in interposed regions. The system exploits time-dependent and space-dependent variables of repetitive transcranial magnetic stimulation (rTMS) to effectively focus magnetic fields at depth, stimulating targeted structures precisely while avoiding overstimulation and undesirable effects like seizures.
The problem being solved arises from the limitations of existing transcranial magnetic stimulation techniques and devices that cannot effectively focus magnetic fields at depth due to the rapid diminution of magnetic field strength with distance from the source. Increasing magnetic field intensity to reach deeper structures risks overwhelming superficial brain regions and causing side effects. Previous attempts to use multiple coils simultaneously or static magnet designs were either complex, inflexible, or ineffective in sparing superficial tissue. The invention addresses the need for a robotic, precise manipulation of coil position and electromagnetic field parameters to selectively stimulate deep brain structures without overstimulation of superficial structures.
The invention also includes a treatment planning and testing phantom model that allows users to assess targeting accuracy and local field strength using electrically active physical analogs of neural structures. The system can incorporate stereotactic coordinate data from patient-specific MRI or atlases, and use robotics and software to move coils in orbits or other trajectories around the head, while modulating magnetic field strength and other parameters based on coil position relative to the target and intervening tissue. This dynamic control enables sustained supra-threshold stimulation at the target over time, with sub-threshold exposure elsewhere.
Claims Coverage
The independent claims cover methods of applying electromagnetic energy from multiple coil positions around a subject's head to stimulate a deep brain target without over-stimulating superficial regions, featuring pulse timing, coil positioning, and energy modulation.
Applying electromagnetic energy from multiple coil positions with controlled pulse timing
The method applies first and second pulses or trains of pulses to electromagnetic coils positioned outside the subject's head from different locations. The pulses directed at the head are sub-action potential threshold for peripheral regions, and are temporally separated by intervals that cause the magnetic field energies to add and stimulate neurons at the deep brain target.
Moving and positioning electromagnetic coils relative to the subject's head
The method involves positioning, moving, or rotating multiple electromagnetic coils around the subject's head to control the direction and focus of the magnetic field energy aimed at the deep brain target.
Using trains of pulses applied to coils with controlled timing
Applying trains of pulses from coils, where trains at different coil locations are timed with intervals so that their magnetic field energies add to stimulate the deep brain target without excessive stimulation of surrounding tissue.
Generating sub-threshold magnetic field energy in superficial regions while achieving supra-threshold stimulation at the target
The magnetic field energy from pulses at locations outside the head is maintained at sub-action potential threshold levels for brain regions peripheral to the deep target, thus avoiding overstimulation of superficial cortex during deep brain stimulation.
The claims collectively focus on methods of multi-position coil stimulation with precise timing and positioning to produce deep brain target stimulation while sparing superficial regions, using controlled pulse trains and coil movements.
Stated Advantages
Enables focused electromagnetic energy application to deep brain regions without overwhelming superficial areas.
Allows precise and deliberate stimulation of targeted deep brain structures while avoiding undesirable side effects such as seizures.
Provides flexibility to adjust coil orbit, orientation, and magnetic field parameters to stimulate diverse deep brain locations.
Facilitates objective testing and treatment planning through a phantom model that measures local field strength and targeting accuracy.
Incorporates robotic control and real-time modulation of magnetic field strength based on coil position to maintain effective stimulation at the target.
Documented Applications
Treatment of neuropsychiatric conditions such as major depression using repetitive transcranial magnetic stimulation.
Non-invasive testing and targeted stimulation for movement disorders such as Parkinson's disease.
Locating optimal deep brain stimulation sites for neurosurgical electrode implantation.
Pain relief through stimulation of brain regions such as the septum or anterior cingulate gyrus.
Symptom reduction in Obsessive-Compulsive Disorder by stimulating deep brain areas.
Improvement of memory functions in Alzheimer's disease by stimulation of hippocampal structures.
Magnetic Seizure Therapy for depression, allowing focused seizure induction while minimizing side effects.
Research applications in neuroscience for precise deep brain stimulation and neural function modulation.
Stimulation or suppression of neural activity in extracranial targets such as spinal cord, peripheral nerves, and heart.
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