as discussed above , there is a need in the art for improved tns therapy methods . to satisfy this need in the art , trigeminal neurostimulation ( tns ) techniques using electrodes placed through a template are disclosed . fig1 a illustrates a patient having cutaneous electrodes 10 placed using a template 200 shown in fig2 . to provide efficacious trigeminal neurostimulation therapy without the need for daily medical facility visits , the patient first medially centers template 200 across their forehead . template 200 is constructed with apertures 205 within which the patient ( or a clinician ) applies electrodes 10 . in this fashion , each aperture 205 receives a corresponding electrode 10 . due to the configuration of template 200 , the placed electrodes 10 are then positioned over the supraorbital and / or supratrochlear trunks ( not illustrated ). to ensure the maximum coverage or stimulation of each supraorbital and supratrochlear nerve trunk , the patent may be instructed to align an inferior edge of template 200 just above their orbital arches . the anatomy for these nerve trunks will now be discussed . with reference to fig1 b and 1c , the trigeminal nerve is the largest cranial nerve and has extensive connections with the brainstem and other brain structures . the trigeminal nerve , also named the fifth cranial nerve or “ cn v ,” has three major sensory branches over the face , all of which are bilateral , and highly accessible . the ophthalmic nerve is frequently referred to as the v 1 division and includes the supraorbital and supratrochlear nerves that supply sensory information about pain , temperature , and light touch to the skin of the forehead , the upper eyelid , the anterior part of the nose , and the eye . the v 2 division includes the infraorbital and maxillary nerves . the infraorbital branch supplies sensory information about pain , temperature , and light touch sensation to the lower eyelid , cheek , and upper lip . finally , the v 3 division includes the auriculotemporal , lingual , and inferior alveolar branches of the mandibular nerves . the inferior alveolar branch supplies similar sensory modalities to the skin of the lower face ( e . g . jaw and tongue ) and lips . these branches exit the skull through three groups of foramina or notches , as shown in fig1 b and 1 c . the supraorbital and supratrochlear nerves exit at foramina 1 . in particular , the foramen ( or notch ) for the supratrochlear nerve is approximately 2 . 1 - 2 . 6 cm from the nasal midline ( in adults ), and is located immediately above the orbital ridge that is located below the eyebrow . the supratrochlear foramen is indicated as foramen 1 b . in contrast , the foramen ( or notch ) for the supraorbital nerve is located more laterally from the nasal midline : e . g ., approximately 3 . 2 cm from the nasal midline in adults . this foramen is indicated as foramen 1 a . the infraorbital branch or maxillary nerve exits at foramen 2 , approximately 2 . 4 - 3 . 0 cm from the nasal midline ( in adults ) and the mentalis nerve exits at foramen 3 , approximately 2 . 0 - 2 . 3 cm from the nasal midline ( in adults ). other sensory branches , including the zygomaticofacial , zygomaticoorbital , zygomaticotemporal , and auriculotemporal , arise from other foramina . fibers from the three major branches join together to form the trigeminal ganglion . from there , fibers ascend into the brainstem at the level of the pons to synapse with the main sensory nucleus of the pons , the mesencephalic nucleus of v , and the spinal nucleus and tract of v . pain fibers descend in the spinal nucleus and tract of v , and then ascend to the ventral posterior medial nucleus ( vpm ) of the thalamus , and then project to the cerebral cortex . light touch sensory fibers are large myelinated fibers , which ascend to the ventral posterior lateral ( vpl ) nucleus of the thalamus , and also project to the cerebral cortex . afferent sensory fibers project from the trigeminal nuclei to the thalamus and the cerebral cortex . with regard to a given supraorbital arch ( either the left or right side of the forehead ), the corresponding supraorbital nerve and the adjacent supratrochlear nerve are referred to herein as an “ ophthalmic nerve pair .” in this fashion , the ambiguity that results from referring to just the supraorbital nerve ( or the supratrochlear ) as the “ ophthalmic ” nerve is avoided . referring again to fig2 , in an embodiment in which template 200 is constructed for bilateral stimulation , an electrode 10 will thus be on located above each orbit and over the supraorbital notches / foramina such that a current pulse transmitted between the electrodes 10 will conduct across the supraorbital and supratrochlear nerve fibers as they arise from their respective orbits . moreover , these nerve branches are relatively shallow with regard to the forehead skin surface and thus readily stimulated by electrodes 10 . a pulse generator 15 drives electrodes 10 through a common cable 20 that bifurcates into individual leads 24 for driving electrodes 10 . it is important that a patient be able to correctly position each electrode 10 so that the appropriate nerves are stimulated without the risks of current penetration to the brain . because a patient can readily position template 200 medially on their forehead using a landmark such as their nasal midline , the patient needs no knowledge of anatomy in that regard yet they are positioning the template 200 in an advantageous location for tns therapy . studies have shown that tns carried out with properly - placed electrodes are significantly more efficacious than the use of conventional vns . yet tns is far less invasive , has much fewer risks , and considerably lower cost than vns . referring back to fig1 a and 1b , suppose that there is an electrode 10 over or lateral to each supraorbital nerve . a current driven through one of the contacts into the remaining electrode will thus pass across not only the supraorbital nerves but also across the supratrochlear nerves . one can see that each supraorbital nerve arises from its foramen just medially to the center of each supraorbital ridge . referring again to fig1 a , cutaneous tns excitation is thus readily achieved by lay people in that template 200 is readily centered on the forehead such that each aperture 205 is positioned over the corresponding ophthalmic nerve pair . the width of each electrode 10 may be such that it is greater than the expected spacing between the supraorbital nerve and the supratrochlear nerve in a given ophthalmic nerve pair . this is quite advantageous as compared to prior art tns approaches in which individual contacts were positioned by palpating for the supraorbital notch or foramen and attaching an electrode over or above the foramen . such an individual contact placement is problematic in that a lay person may not attach the contacts properly , which may result in excessive current exposure such that the brain itself receives appreciable currents . but with template 200 , the lay person may readily center its midline with the nasal midline . since the apertures 205 are positioned apart so that an electrode 10 placed within the aperture stimulates the underlying ophthalmic nerve pair , the problems and dangers of prior art individual electrode application are avoided . as seen in fig2 , template 200 may include a midline alignment feature on either of its longitudinal borders to assist in the alignment of template 200 with the nasal midline . for example , a midline alignment feature such as a convex angle 210 ( e . g ., an angle of 168 degrees ) may be defined by the bottom and top longitudinal edges of template 200 . alternatively , only one of the bottom or top edges of template 200 may include such an alignment feature . apertures 205 are separated by approximately 14 mm . given the chevron shaping resulting from convex angles 210 , each aperture 205 narrows by 12 degrees from a medial edge of a 27 mm to a lateral edge of 20 mm ( with regard to the template midline ) over a width of 31 . 5 mm . the lateral edge of each aperture 205 is thus 38 . 5 mm from the nasal midline . such an aperture spacing assures that each aperture 205 is positioned over an ophthalmic nerve pair so that an electrode placed within aperture 205 will then stimulate both the supraorbital nerve and the supraorbital nerve in the corresponding ophthalmic nerve pair for the vast bulk of the adult population . but some adults will require even a greater aperture / electrode width such as 34 mm to assure that the supraorbital nerves receive adequate stimulation . it will be appreciated that many alternative embodiments exist for template 200 with regard to inclusion of suitable apertures and midline alignment features . template 200 is quite advantageous in that a lay person may readily center it about their nasal midline . since the apertures 205 are spaced apart so that each aperture is positioned over an ophthalmic nerve pair on opposing sides of the forehead , a lay person may readily apply cutaneous electrodes through apertures 205 such that the applied electrodes are properly positioned over the ophthalmic nerves without requiring clinical expertise . referring again to fig1 a , once a patient or clinician has placed template 200 appropriately on the forehead and applied the electrodes 10 within apertures 205 , template 200 may then be removed so that tns therapy may ensue . in various embodiments , the stimulation is delivered at a specific pulse width or range of pulse widths ( or pulse duration ). the stimulation can be set to deliver pulse widths in any range within a lower limit of about 10 microseconds and an upper limit of about 3 seconds . in various embodiments , the stimulation can be set to deliver pulse widths in the range greater than and / or less than one or more of 50 μs , 60 μs , 70 μs , 80 μs , 90 μs , 100 μs , 125 μs , 150 μs , 175 μs , 200 μs , 225 μs , 250 μs , up to 500 μs . those of skill in the art will recognized that one or more of the above times can be used as a border of a range of pulse widths in some embodiments , the stimulation amplitude is delivered as a voltage or current controlled stimulation . in other embodiments it can be delivered as a capacitive discharge . in various embodiments , the current amplitude can be in any range within a lower limit of about 300 μa and an upper limit of about 30 ma - 35 ma , depending on the surface area of the electrodes , inter - electrode distance , the branch ( es ) stimulated , and the modeling data as described above . in various embodiments , the amplitude can be in a range greater than and / or less than one or more of 50 μa , 75 μa , 100 μa , 125 μa , 150 μa , 175 μa , 200 μa , 225 μa , 250 μa , 275 μa , 300 μa , 325 μa , 350 μa , 375 μa , 400 μa , 425 μa , 450 μa , 475 μa , 500 μa , 525 μa , 550 μa , 575 μa , 600 μa , 625 μa , 650 μa , 675 μa , 700 μa , 725 μa , 850 μa , 875 μa , 900 μa , 925 μa , 950 μa , 975 μa , 1 ma , 2 ma , 3 ma , 4 ma , 5 ma , 6 ma , 7 ma , 8 ma , 9 ma , 10 ma , 11ma , 12 ma , 13 ma , 14 ma , 15 ma , 16 ma , 17 ma , 18 ma , 19 ma and 20 ma . those of skill in the art will recognize that one or more of the above amplitudes can be used as a border of a range of amplitudes . in various embodiments , the stimulation can be delivered at one or more frequencies , or within a range of frequencies . the stimulation can be set to be delivered at frequencies in any range within an upper limit of about 500 hz and a lower limit of about 10 hz . in various embodiments , the stimulation can be set to be delivered at frequencies less than , and / or greater than one or more of 50 hz , 45 hz , 40 hz , 35 hz , 30 hz , 25 hz , 20 hz , 15 hz , or 10 hz . in various embodiments , the stimulation can be set to be delivered at frequencies greater than , and / or less than , one or more of 20hz , 30hz , 40hz , 50 hz , 60 hz , 70 hz , 80 hz , 90 hz , 100 hz , 125 hz , 150 hz , up to 300 hz . those of skill in the art will recognize that one or more of the above frequencies can be used as a border of a range of frequencies . in various embodiments , the stimulation is delivered at a specific duty cycle or range of duty cycles within a range from 100 % down to about 5 %. the duty cycle is defined with regard to a duty cycle period . in each duty cycle period , the current is pulsed during an on portion of the duty cycle period and not pulsed during a remaining off portion of each duty cycle period . the ratio of the on portion to the duty cycle period defines the duty cycle . for example , if the on portion is one half of the duty cycle period , the duty cycle would be 50 %. in various embodiments , the stimulation can be set to be delivered at a duty cycle in the range greater than and / or less than one or more of 5 %, 10 %, 15 %, 20 %, 25 %, 30 %, 35 %, 40 %, 45 %, 50 %, 55 %, 60 %, 65 %, 70 %, 75 %, 80 %, 85 %, 90 %, 95 %, or 100 %. the period used to define the duty cycle may be 60 seconds such that a 50 % duty cycle would comprise 30 seconds of pulsing and 30 seconds of quiescence in each duty cycle period . in some embodiments , to ensure preservation of the nerve , a duty cycle of 10 % to 50 % may be preferable . in some embodiments , duty cycles up to 100 % may be useful in particular circumstances . those of skill in the art will recognize that one or more of the above percentages can be used as a border of a range of duty cycles .
a template is provided that includes two apertures spaced apart by the expected spacing between a pair of ophthalmic nerves on a patient &# 39 ; s forehead . the template may thus be advantageously used to apply cutaneous electrodes to a patient &# 39 ; s forehead for trigeminal nerve stimulation without clinical training .