Future treatment options for facial nerve palsy: a review on electrical stimulation devices for the orbicularis oculi muscle.

Facial nerve palsy can cause diminished eyelid closure (lagophthalmos). This occurs due to functional deficits of the orbicularis oculi muscle, potentially leading to sight-threatening complications due to corneal exposure. Current management options range from frequent lubrication with eye drops, to the use of moisture chambers and surgery. However, achieving functional restoration may not always be possible. Recent efforts have been directed towards the support of orbicularis oculi muscle function through electrical stimulation. Electrical stimulation of the orbicularis oculi muscle has been demonstrated as feasible in human subjects. This article offers a comprehensive review of electrical stimulation parameters necessary to achieve full functionality and a natural-looking eye blink in human subjects. At present, readily available portable electrical stimulation devices remain unavailable. This review lays the foundation for advancing knowledge from laboratory research to clinical practice, with the ultimate objective of developing a portable electrical stimulation device. Further research is essential to enhance our understanding of electrical stimulation, establish safety standards, determine optimal current settings, and investigate potential side effects.

Sutureless transconjunctival insertion of eyelid gold weight.

OBJECTIVE: Surgical intervention for paralytic lagophthalmos has been gold weight implant through supratarsal crease incision for decades. The aim of this study is to propose a modified novel minimally invasive approach that can be described as sutureless and transconjunctival placement of eyelid weights. METHOD: Unilateral eyelid gold weights were implanted in six patients due to paralytic lagophthalmos secondary to peripheral facial nerve palsy. The patients were followed for an average of 6 months. RESULTS: Functional and aesthetically desired results were obtained in all six patients with suture-free transconjunctival placement of the eyelid weight. The patients did not experience any discomfort and avoided the burden of suture removal after the surgery. No complications developed in six patients during the postoperative period. CONCLUSION: Sutureless transconjunctival insertion of eyelid weight without external incision and suturing is practical, relatively easy and fast to perform. It preserves attachment of the levator muscle to the tarsus and presents functional results similar to conventional method. Fixing the implant with sutures to the tarsal plate is not needed. Sutureless of this method avoids external wound care, burden of suture removal for both surgeons and patients, and hence, suture related complications are eliminated.

Influence of epinephrine contained in local anesthetics on upper eyelid height in transconjunctival blepharoptosis surgery.

PURPOSE: To examine the influence of epinephrine contained in local anesthetic on upper eyelid height in transconjunctival aponeurotic repair for aponeurotic blepharoptosis. METHODS: This retrospective study included 164 eyelids from 94 patients with aponeurotic blepharoptosis. Patients were divided according to the use of local anesthetic with (group A, n = 108) or without 1:100000 epinephrine (group B, n = 56). Margin reflex distance-1 (MRD-1) was measured before and after local anesthesia, and before, during, and 3 months after surgery. Change in MRD-1a (∆MRD-1a) was calculated by subtracting the postanesthetic MRD-1 value from the preanesthetic value, and we defined ∆MRD-1b by subtracting the postoperative 3-month MRD-1 value from the intraoperative value. RESULTS: ∆MRD-1a was positive in group A (0.57 ± 0.63 mm) and negative in group B (- 0.50 ± 0.45 mm; p < 0.001). Postoperative MRD-1 decreased significantly from intraoperative MRD-1 in group A (P < 0.001), although there was no significant difference between intraoperative and postoperative MRD-1 in group B (p = 0.255). The magnitude of ∆MRD-1b in group A (- 0.86 ± 0.63) was larger than that in group B (- 0.23 ± 0.26; p < 0.001). CONCLUSIONS: Epinephrine stimulates Müller's muscle during surgery, which leads to postoperative upper eyelid droop after the disappearance of the epinephrine effect. Using local anesthetics without epinephrine may allow more accurate estimation of postoperative eyelid height in transconjunctival aponeurotic repair.

A hybrid technique to address exposure keratopathy secondary to facial nerve paresis: A combination of a lateral tarsorrhaphy and lateral wedge resection.

PURPOSE: To present the results of treating combined lower eyelid laxity, retraction and midface descent secondary to facial nerve weakness with a hybrid surgical procedure. MATERIALS AND METHODS: A retrospective analysis of patients from January 2015 to January 2017 who underwent a hybrid surgical technique for the treatment of corneal exposure secondary to facial nerve paresis with a single surgeon was performed. Age, gender, and presence of exposure symptoms were recorded pre-operatively. Outcomes assessed included improvement of lower eyelid laxity and position, operative complications, and post-operative symptomatic relief. RESULTS: A total of 11 patients underwent unilateral eyelid surgery. All patients had symptomatic relief and good functional outcomes defined as improvement in eyelid laxity, lower eyelid position, and objective corneal exposure. No cases required reoperation during an average follow up of 174.5 days. CONCLUSIONS: Combining portions of a tarsorrhaphy and lateral wedge resection technique is a simple and effective procedure to improve lower eyelid position and limit corneal exposure secondary to facial nerve paresis.

Eyelid reanimation using crossface nerve graft: Relationship between surgical outcome and preoperative paralysis duration.

BACKGROUND: To reanimate the mimetic muscles, crossface nerve graft (CFNG) is an effective surgical option. However, muscle atrophy after facial paralysis may influence the surgical result. We analyzed the relationship between surgical result and preoperative paralysis duration. METHODS: We performed CFNG on 15 patients. The sural nerve was transferred between the affected and nonaffected sides of the zygomatic branch. Eyelid function and eyelid lid were evaluated using the modified House-Brackmann scale. The effects of age, sex, cause of facial paralysis, graft nerve length, and preoperative paralysis duration were evaluated. RESULTS: The mean follow up period was 9.3 ± 3.3 (range 4-14) years. Eyelid closure was excellent in four patients, good in six, fair in one, and poor in four. Statistically, no significant difference was observed between those patients with excellent or good outcomes and fair or poor outcomes regarding age (40.9 ± 11.0 years vs. 22.6 ± 20.8; P = .067), sex (male/female = 2/8 vs. 3/2; P = .250), cause (tumor/trauma = 10/0 vs. 3/2; P = .095), and length of nerve graft (14.4 ± 0.8 cm vs. 13.8 ± 1.6 cm; P = .375). The average preoperative paralysis duration in the excellent/good patients was significantly shorter than that in the fair/poor patients (P = .005). All eight cases with preoperative paralysis of less than 6 months showed a marked excellent/good result. Two of the seven patients with preoperative paralysis was 6 months or longer marked fair/poor result. (P = .007). CONCLUSIONS: To achieve successful results with CFNG, surgery should be performed within 6 months of the onset of paralysis.

Location of the Septoaponeurosis Junction Relative to the Tarsal Plate in Upper Eyelids.

The aim of this study was to measure the location of the septoaponeurosis junction relative to the tarsal plate in the upper eyelids of Koreans through a histologic study.Thirty-four upper eyelids from 34 Korean adult cadavers (mean age, 77.8 years) were used. Sagittal sections on the midpupillary line were made, and 10-µm-thick sections were prepared and stained with hematoxylin-eosin and Masson trichrome. Under a magnifying loupe with a scale, the height of the tarsal plate (HTP), thickness of the tarsal plate (TTP), distance from the lid margin to the septoaponeurosis junction (MJD), and distance from the upper border of the tarsal plate to the septoaponeurosis junction (TJD) were measured.The mean HTP was 8.09 ±â€Š1.68 mm (range: 4.0-0.8 mm). The mean TTP was 1.52 ±â€Š1.56 mm (range: 0.8-3.0 mm). The mean MJD was 9.18 ±â€Š2.69 mm (range: 2.5-13.0 mm). The mean TJD was 1.1 ±â€Š2.6 mm (range: -5.5-7.0 mm). In 25 (73.5%) of the 34 eyelids, the SAJ (1.1 ±â€Š2.6 mm) was above the upper border of the tarsal plate (UTP); however, in 9 (26.5%) of the 34 eyelids, below the UTP. The greater the HTP, the greater the MJD was (y=0.620x+4.166, P = 0.024 [linear regression analysis]). However, there was no significant correlation between the HTP and TJD (P = 0.155 [correlation analysis]).The results of this study provide a useful guide for performing operations involving the orbital septum and levator aponeurosis.

Sensory Innervation of the Upper Eyelid.

The aim of this study was to elucidate the sensory territory of the trigeminal nerve on the upper eyelid.Eight hemifaces from Korean cadavers were dissected. The frontal nerve (FN), supraorbital nerve (SON), supratrochlear nerve (STN), infratrochlear nerve (ITN), and lacrimal nerve (LN) were traced.The terminal branches to the eyelid margin of FN were distributed between 1/6 and 2/5 of the palpebral fissure width lateral to the medial canthus and 1/6 of the eyebrow height from eyelid margin. The SON was distributed between 2/5 and 9/10 of the eye width lateral to the medial canthus, at 1/3 of the eyebrow height. The STN was distributed between -1/4 and -1/5 of the eye width medial to the medial canthus, at 1/5 of the eyebrow height. The ITN was distributed at -1/4 and 1/10 of the eye width medial to the medial canthus, and at 1/5 of the eyebrow height. The LN was distributed between approximately 3/5 and 13/10 of the eye width lateral to the medial canthus, and at 1/4 of the eyebrow height. The main branches of FN and SON ran deep to the orbicularis from the supraorbital notch to the upper border of the tarsal plate. In the pretarsal area, they were between the orbicularis and tarsal plate. The STN and ITN were between the orbicularis and the skin. The LN was observed between the orbicularis and the tarsal plate.Upper eyelid was mainly supplied by SON and FN. The medial extremity was supplied by STN and ITN, and the lateral extremity by LN.

Anatomy of the Corrugator Muscle.

The aim of this article is to systematically review the anatomy and action of the corrugator muscle. PubMed and Scopus were searched using the terms "corrugator" AND "anatomy." Among the 60 full texts from the 145 relevant abstracts, 34 articles without sufficient content were excluded and 4 articles drawn from the reference lists were added. Among the 30 articles analyzed (721 hemifaces), 28% classified by oblique head and transverse head, and 72% did not. Corrugator originated mostly from the medial supraorbital rim (45%), followed by the medial frontal bone (31%), the medial infraorbital rim (17%), and the upper nasal process (7%). Corrugator extended through the frontalis and orbicularis oculi (41%), only the frontalis (41%), or only the orbicularis oculi (18%). Corrugator ran superolaterally (59%), or laterally (41%). Corrugators inserted mostly to the middle of the eyebrow (57%), or the medial half of the eyebrow (36%), but also to the glabella region (7%). The length of the corrugator ranged 38 to 53 mm. The transverse head (23.38 mm) was longer than the oblique head (19.75 mm). Corrugator was thicker at the medial canthus than at the midpupillary line. Corrugator was innervated by the temporal branch of the facial nerve (66%), the zygomatic branch (17%), or the angular nerve (zygomatic branch and buccal branch, 17%). Supraorbital nerve (60%) or supratrochlear nerve (40%) penetrated the corrugator. The action was depressing, pulling the eyebrow medially (91%), or with medial eyebrow elevation and lateral eyebrow depression (9%). Surgeons must keep this anatomy in mind during surgical procedures.

Previously undescribed palpebral branch from the infraorbital canal: Application to surgery of the eyelid and treatment of orbital floor fractures.

The sensory innervation of the inferior eyelid is mainly derived from the inferior palpebral branch (IPb) of the infraorbital nerve (ION). This study aimed to investigate another, to our knowledge, previously unknown branch, and elucidate its location and distribution. Twelve sides from seven fresh frozen cadaveric Caucasian heads were used in this study. The specimens were derived from two male and four female adult cadavers age. The diameter of the IPb of the ION (D1) and branch arising from the upper wall of the infraorbital canal (D2), and distance between the branching points of this branch and the anterior border of the orbit floor (L1) was measured. A branch to the lower eyelid was found arising from the infraorbital canal on the majority of sides. D1 ranged from 0.4 to 1.1 mm. The branch arising from the upper wall of the infraorbital canal was found 10 sides (83%). D2 ranged 0.6 to 1.0 mm. L1 ranged from 10.2 to 19.8 mm. All of the branches arising from the upper wall of the infraorbital canal (10 sides) primarily innervated to the inferior eyelid. We suggest this branch should be named the "posterior IPb" of the ION. Knowledge of this branch might decrease sensory loss following invasive procedures of the lower orbit. Clin. Anat. 30:835-838, 2017. © 2017Wiley Periodicals, Inc.

Relating cerebellar purkinje cell activity to the timing and amplitude of conditioned eyelid responses.

How Purkinje cell (PC) activity may be altered by learning is central to theories of the cerebellum. Pavlovian eyelid conditioning, because of how directly it engages the cerebellum, has helped reveal many aspects of cerebellar learning and the underlying mechanisms. Theories of cerebellar learning assert that climbing fiber inputs control plasticity at synapses onto PCs, and thus PCs control the expression of learned responses. We tested this assertion by recording 184 eyelid PCs and 240 non-eyelid PCs during the expression of conditioned eyelid responses (CRs) in well trained rabbits. By contrasting the responses of eyelid and non-eyelid PCs and by contrasting the responses of eyelid PCs under conditions that produce differently timed CRs, we test the hypothesis that learning-related changes in eyelid PCs contribute to the learning and adaptive timing of the CRs. We used a variety of analyses to test the quantitative relationships between eyelid PC responses and the kinematic properties of the eyelid CRs. We find that the timing of eyelid PC responses varies systematically with the timing of the behavioral CRs and that there are differences in the magnitude of eyelid PC responses between larger-CR, smaller-CR, and non-CR trials. However, eyelid PC activity does not encode any single kinematic property of the behavioral CRs at a fixed time lag, nor does it linearly encode CR amplitude. Even so, the results are consistent with the hypothesis that learning-dependent changes in PC activity contribute to the adaptively timed expression of conditioned eyelid responses.

The effect of different low-frequency filters on concentric needle jitter in stimulated orbicularis oculi.

INTRODUCTION: Our objective was to compare the effect of different low-frequency filters on jitter parameters when stimulating the orbicularis oculi. METHODS: Ten healthy volunteers were studied. Jitter was expressed as the mean consecutive difference (MCD). The low filter settings compared were 1, 2, and 3 kHz. RESULTS: No significant difference in mean MCD or outliers was found with the different filter settings. No significant difference in mean MCD was seen when the number of potentials analyzed was reduced. CONCLUSION: Different low-frequency settings do not influence the mean MCD when using a peak detection system. Muscle Nerve 54: 317-319, 2016.

Emerging Points of the Supraorbital and Supratrochlear Nerves in the Supraorbital Margin With Reference to the Lacrimal Caruncle: Implications for Regional Nerve Block in Upper Eyelid and Dermatologic Surgery.

BACKGROUND: Blocking the supraorbital nerve (SON) and supratrochlear nerve (STN) by injecting anesthetic distal to the surgical site has the advantage in upper eyelid surgery that avoids obscuring the surgical landmarks and compromising the levator function. OBJECTIVE: To identify the emerging points of the SON and STN in the supraorbital margin with reference to the lacrimal caruncle. METHODS: Forty-nine orbits from 27 embalmed Korean cadavers were dissected. The lacrimal caruncle and facial midline were used as landmarks. The emerging points of the SON and STN in the supraorbital margin were determined. RESULTS: The emerging points of the SON and STN were, respectively, located at 3.0 mm lateral and 3.3 mm medial to the vertical line through the apex of the lacrimal caruncle along the supraorbital margin. The horizontal distances from the facial midline to the emerging points of the SON and STN were 22.8 and 15.2 mm, respectively. CONCLUSION: The optimum sites for achieving SON and STN block are, respectively, located approximately 3 mm lateral and 3 mm medial to the vertical line through the apex of lacrimal caruncle along the supraorbital margin. This knowledge will help the surgeon achieve an easy and accurate approach for regional nerve block.

The effective stimulating pulse for restoration of blink function in unilateral facial nerve paralysis rabbits, verified by a simple FES system.

The trains of 200 ms biphasic square pulses with the width of 9 ms delivered at 50 Hz were found to be the most suitable and effective mean as stimulation in FES system of restoring the blink function in unilateral facial nerve paralysis rabbit model. FES system is a reliable tool for these patients. Facial paralysis affects thousands of people every year. Many will have long term facial difficulties and the loss of the ability to blink the eye, which can lead to potential loss of the eye. Although many treatments exist, no one approach corrects all the deficits associated with the loss of orbicularis oculi function. FES is a means of providing movement in paralysed muscles to assist with practical activities and one possible way of restoring blink and other functions in these patients. Although some previous researches had investigated the effect of simple FES system on restoration of paralyzed facial muscles, there is still controversy about the appropriate details of the most effective stimulating pulses, such as the frequency, wave pattern and pulse width. Our aim is to find out the parameters of the most appropriate and effective stimulatin verify it by a simple FES system. 24 healthy adult male New Zealand white rabbits were accepted the surgery of right side facial nerve main trunk transaction under general anesthesia as the unilateral facial nerve paralysis models. The platinum tungsten alloy electrodes were implanted in orbicularis oculi muscle. The parameters of stimulus pulses were set to a 200 ms biphasic pulse with different waveforms (square, sine and triangle), different frequencies (25, 50, 100 Hz) and different widths from 1 to 9 ms. Next, we set up a simple FES system to verify the previous results as the stimulus signal. We observed the movement of the both sides of eyelid when eye blink induced by different kinds of pulses. In all animals, the three kinds of waveforms pulse with frequency of 25 Hz could not evoke the smooth blink movement. But the pulses with frequency of 50 and 100 Hz can achieve this effect. The voltage threshold of the square pulse was lower than that of the sine pulse and triangle pulse. With the increase of pulse width from 1 to 9 ms, the voltage threshold decreased gradually. The voltage threshold of the pulse with frequency of 100 Hz was obviously lower than that of 50 Hz. But the amount of total charge of the stimulation pulse of 100 Hz was significantly more than that of 50 Hz. In addition, when the FES system was turned on, the eye blink on the affected side with the stimulation pulses that were set by the previous step results was successfully aroused by the blink movement as a trigger on the contralateral.

Post-septal upper eyelid loading for treatment of exposure keratopathy secondary to non-cicatricial lagophthalmos.

Exposure keratopathy may result in ocular surface dryness, pain, corneal ulceration and loss of vision. Upper eyelid loading is an effective surgical treatment for paralytic lagophthalmos but has been criticised for complications of implant exposure and poor cosmesis. We therefore reviewed the safety and efficacy of our technique of upper eyelid post-septal loading for exposure keratopathy in this context. A retrospective case notes analysis was undertaken of 38 patients who had upper eyelid loading, all with post-septal weight placement, for correction of lagophthalmos. Patient demographics, indications for surgery, outcomes and complications were analysed. The mean age of all patients was 59.6 years. Exposure keratopathy was secondary to facial nerve paralysis in all but two patients, with tumor excision being the commonest underlying aetiology (63.8%). The mean implant weight used was 1.4 grams. Pre-operatively, all 38 patients had ocular discomfort despite maximal use of lubricating eye drops but post-operatively, 29 patients (76.3%) were comfortable without any such drops. Mean lagophthalmos on blink and gentle closure improved from 7.42mm and 5.47mm pre-operatively to 2.18mm and 1.18mm post-operatively (p < 0.001). Similarly, before surgery all patients had some corneal staining but after surgery 37 patients (97.4%) had none. The gold weight was removed in four patients (10.5%), due to chronic inflammation in three and due to mild astigmatism in one. No patient had exposure of the weight and one patient had a ptosis repair 6 months after surgery. Upper eyelid loading was effective in reducing both signs and symptoms of exposure keratopathy related to lagophthalmos in our series. Patients were very satisfied with the surgical outcome and complications related to exposure and cosmesis were very rare.

Infratrochlear neuralgia.

INTRODUCTION: The infratrochlear nerve supplies the medial aspect of the upper eyelid, the superolateral aspect of the nose and the lacrimal caruncle. This nerve may contribute to the pain stemming from the trochlea, but infratrochlear neuralgia has not been identified as a specific cause of pain. METHODS: Over a 10-year period we have been recruiting patients with pain in the internal angle of the orbit that did not show features of trochlear pain. RESULTS: Seven patients (six female, one male; mean age, 46.1 ± 18.9) presented with pain in the territory of the infratrochlear nerve. The pain appeared in the internal angle of the orbit and upper eyelid (n = 3), the superolateral aspect of the nose (n = 3), or the lacrimal caruncle (n = 1). All patients had a paroxysmal pain, with the attacks lasting five to 30 seconds. Pain attacks were mostly spontaneous, but two patients had triggers. Between attacks, all patients had local allodynia. Pain did not increase with vertical eye movements. Six patients were treated with gabapentin with complete response, and one patient experienced long-lasting relief with an anesthetic blockade of the infratrochlear nerve. CONCLUSION: Infratrochlear neuralgia should be considered as a possible cause of pain in the internal angle of the orbit.

Transient traumatic isolated neurogenic ptosis after a mild head trauma: a case report.

BACKGROUND: Transient traumatic isolated neurogenic ptosis (TTINP) is a sporadically reported rare entity. However, to the best of our knowledge, nearly all the reported cases are either secondary to direct periorbital trauma or surgery. We would like to report on a case of TTINP with countre-coup injury of the periorbital region. CASE PRESENTATION: A 49-year-old female slipped and fell down while walking. She was hospitalized with a moderate headache and undisturbed mental state. The patient recalled that the force bearing point was her occipital region. Physical examination and computed tomography (CT) on admission showed right isolated ptosis and mild contusion and laceration in the bilateral frontal cortex. Further radiological investigation revealed nothing remarkable except for a fracture of the superior portion of the right medial orbital wall. She was managed conservatively and recovered completely in two months. CONCLUSION: TTINP might manifest as a unique entity with a relatively mild, reversible, and non-devastating injury to the terminal branch of the oculomotor nerve and for which perhaps no special treatment is needed. The proposed mechanism is injury of the terminal branch of the superior division of the oculomotor nerve.

Anatomy of the Anterior Deep Temporal Nerve: Implications for Neurotization in Blinking Restoration in Facial Paralysis.

Facial paralysis can lead to dysfunctions in eyelid closure, which is called lagophthalmos. A number of surgical procedures, both dynamic and static, have been described to restore the innervation of the orbicularis oculi muscle that closes the eyelids. This cadaver-based anatomical study aimed to evaluate the anatomy of the anterior, middle, and posterior deep temporal nerves; nerves to the temporalis muscle; and their availability for direct muscle neurotization of the orbicularis oculi. A total of 10 hemisectioned head specimens from 5 adult cadavers (2 men and 3 women) were used in this study. The adequacy of the length of the anterior deep temporal nerve was assessed for direct neorotization of the orbicularis oculi muscle. The mean distances between the originating point of the deep temporal nerves from the mandibular nerve in the infratemporal fossa and their terminal entry points into the muscle were 46.4 (42-51 mm), 42.2 (38-46 mm), and 33.4 mm (26-40 mm) for the anterior, middle and posterior branches of the nerves, respectively. We conclude that the anterior deep temporal nerve is a versatile nerve that can be used for direct muscle neurotization, nerve transfer, and babysitter procedures in selective blinking restoration. Before proceeding with any further clinical use, an anatomical study should be performed with fresh specimens from cadavers.

[Management of oculo-palpebral consequences in facial paralysis]. / Prise en charge des atteintes orbito-palpébrales secondaires à une paralysie faciale.

Facial paralysis prognostic depends on eye lesion. In this pathology, lacrymal and palpebral functions will be modified: bad eye closure and leak of tears secretions. It can leads to corneal complications from keratitis to corneal abcedation and visual dysfonction. This chapter details different procedures and their indications to avoid this kind of complications.

Trigeminal high-frequency stimulation produces short- and long-term modification of reflex blink gain.

Reflex blinks provide a model system for investigating motor learning in normal and pathological states. We investigated whether high-frequency stimulation (HFS) of the supraorbital branch of the trigeminal nerve before the R2 blink component (HFS-B) decreases reflex blink gain in alert rats. As with humans (Mao JB, Evinger C. J Neurosci 21: RC151, 2001), HFS-B significantly reduced blink size in the first hour after treatment for rats. Repeated days of HFS-B treatment produced long-term depression of blink circuits. Blink gain decreased exponentially across days, indicating a long-term depression of blink circuits. Additionally, the HFS-B protocol became more effective at depressing blink amplitude across days of treatment. This depression was not habituation, because neither long- nor short-term blink changes occurred when HFS was presented after the R2. To investigate whether gain modifications produced by HFS-B involved cerebellar networks, we trained rats in a delay eyelid conditioning paradigm using HFS-B as the unconditioned stimulus and a tone as the conditioned stimulus. As HFS-B depresses blink circuits and delay conditioning enhances blink circuit activity, occlusion should occur if they share neural networks. Rats acquiring robust eyelid conditioning did not exhibit decreases in blink gain, whereas rats developing low levels of eyelid conditioning exhibited weak, short-term reductions in blink gain. These results suggested that delay eyelid conditioning and long-term HFS-B utilize some of the same cerebellar circuits. The ability of repeated HFS-B treatment to depress trigeminal blink circuit activity long term implied that it may be a useful protocol to reduce hyperexcitable blink circuits that underlie diseases like benign essential blepharospasm.