Magnetic stimulation coils and ferromagnetic components for reduced surface stimulation and improved treatment depth

Abstract

A TMS device may include treatment coils and ferromagnetic components that are configured to be disposed proximate to corresponding ones of the treatment coils. The treatment coils and ferromagnetic components of the TMS device may cooperatively generate a magnetic field that exhibits one or more characteristics that differ from those of a magnetic field that is generated by the treatment coils alone. For example, the magnetic field may exhibit lower induced electrical stimulation intensity in the cranial nerves, while substantially maintaining a penetration depth into the subject's brain. In another example, the magnetic field may exhibit increased penetration depth into the subject's brain, while substantially maintaining induced electrical stimulation intensity in the cranial nerves. The TMS device may be configured to be adjustable and/or reconfigurable, for instance with respect to the anatomy of a subject (e.g., to the shape of the subject's head).

What is claimed: 
     
         1 . A system for treating or diagnosing a patient, the system comprising:
 a stimulation coil;   an adjustable ferromagnetic component comprising a plurality of segments, the ferromagnetic component defining a first end and a second end;   a control circuit in electrical communication with the stimulation coil and configured to provide current to the stimulation coil to generate a magnetic field in a target anatomy of a human subject;   wherein, when the ferromagnetic component is adjusted such that the first and second ends are moved away from each other, the magnetic field generated by the stimulation coil exhibits lesser focality and increased penetration depth as compared to the focality and penetration depth of the magnetic field created by the stimulation coil when the ferromagnetic component is adjusted such that the first and second ends are moved toward each other.   
     
     
         2 . The system of  claim 1 , wherein the ferromagnetic component further comprises a hinge located between two segments of the ferromagnetic component, the hinge configured to allow the first and second ends of the ferromagnetic component to be moved away from and toward each other. 
     
     
         3 . The system of  claim 1 , wherein the plurality of segments of the ferromagnetic component are releasably attachable to each other; and
 wherein the ferromagnetic component is configured to move the first and second ends away from each other and toward each other by adding or removing, respectively, one or more segments to the ferromagnetic component.   
     
     
         4 . The system of  claim 1 , wherein the stimulation coil comprising a plurality of windings. 
     
     
         5 . The system of  claim 4 , wherein one or more of the plurality of windings are configured to be removed from the stimulation coil. 
     
     
         6 . The system of  claim 4 , wherein the stimulation coil is configured to replace a first winding having a first winding density with a second winding having a second winding density. 
     
     
         7 . The system of  claim 1 , wherein the stimulation coil is configured such that adjusting the ferromagnetic component reduces an air gap between the stimulation coil and the human subject's head. 
     
     
         8 . The system of  claim 1 , wherein the stimulation coil is configured such that the generated magnetic field exhibits a greater intensity in an upper region of the human subject's brain located near a midpoint along the ferromagnetic component as compared to other regions of the human subject's brain. 
     
     
         9 . The system of  claim 1 , wherein the ferromagnetic component is adjustable such that the magnetic field generated by the stimulation coil generates an induced electrical field within the target anatomy of the human subject that comprises a saddle point, the saddle point located proximate to a midpoint of the ferromagnetic component and defining a region within the target anatomy of the human subject where the induced electrical field is below a stimulation threshold of the target anatomy. 
     
     
         10 . The system of  claim 1 , wherein the stimulation coil is configured to generate a magnetic field in a first and second hemisphere of the human subject's brain. 
     
     
         11 . The system of  claim 1 , wherein the ferromagnetic component defines an arc shape. 
     
     
         12 . The system of  claim 1 , wherein the ferromagnetic component is adjustable relative to the human subject. 
     
     
         13 . The system of  claim 1 , wherein the ferromagnetic component comprises powdered ferromagnetic iron particles. 
     
     
         14 . The system of  claim 1 , wherein the ferromagnetic component is freely adjustable. 
     
     
         15 . The system of  claim 1 , wherein the ferromagnetic component is incrementally adjustable. 
     
     
         16 . A transcranial magnetic stimulation (TMS) system for treating or diagnosing a patient, the system comprising:
 a TMS device comprising a treatment coil and an adjustable ferromagnetic component, the ferromagnetic component comprising a first segment and a second segment, the first segment comprising an upper portion and a leg portion, and the second segment comprising an upper portion and a leg portion; and   a control circuit in electrical communication with the TMS device and configured to provide current to the TMS device to generate a magnetic field in a target anatomy of a human subject; and   wherein the first and second leg portions of the ferromagnetic component are configured to be adjustable to adjust a distance between the treatment coil and the target anatomy of the human subject.   
     
     
         17 . The system of  claim 16 , wherein a bottom end of the leg portions of the first and second segments conform to the target anatomy of the human subject. 
     
     
         18 . The system of  claim 16 , wherein at least one of the first and second leg portions are configured to be lengthened and shortened to adjust heat transfer from the stimulation coil and the target anatomy. 
     
     
         19 . The system of  claim 16 , wherein the first and second leg portions of the ferromagnetic component are configured to adjust the distance between the treatment coil and the target anatomy of the human subject so that heat transfer from the treatment coil to the target anatomy of the human subject does not cause a temperature of target anatomy to exceed a predetermined threshold. 
     
     
         20 . The system of  claim 16 , wherein the ferromagnetic component comprises powdered ferromagnetic iron particles.