PEDIATRIC/CRANIOFACIAL The Outcomes of Dynamic Procedures for Blink Restoration in Pediatric Facial Paralysis (original) (raw)
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Evidence for Facial Nerve–Independent Mechanisms of Blinking in the Rat
Investigative Opthalmology & Visual Science, 2010
PURPOSE. The rat facial nerve (CN VII) controls the orbicularis oculi (OO) muscle, which contracts to close the palpebral fissure during blinking. It was recently observed that rats are able to achieve nearly complete eye closure shortly after CN VII lesion, and hypothesized that the retractor bulbi (RB) muscle assumes an important compensatory role after CN VII lesion. This study was undertaken to determine the maintenance of rat corneal health and eye closure capability after lesion of the OO, RB, or both. METHODS. Twenty-two rats underwent RB transection; 12 of them had undergone complete unilateral CN VII transection (OO denervation) 15 weeks earlier. Corneal appearance and ability to blink in response to a corneal air puff was monitored weekly for 9 weeks. An additional 13 rats received CN VII transection and were video recorded (1000 frames/s) during elicited blinks at days 1, 3, 5/6, and 11 after surgery. RESULTS. Rats achieved nearly full or full eye closure after OO paralysis or RB myotomy, respectively. Ninety-two percent of rats maintained good corneal health after OO denervation over 9 weeks, consistent with compensatory eyelid movement served by the RB muscles. In contrast, only 40% of rats with loss of RB function alone and only 17% of rats with concurrent OO and RB paralysis were able to maintain corneal health by week 3. CONCLUSIONS. Like other small mammals, the rat RB musculature can support nearly complete eye closure when CN VII is lesioned, and must be carefully considered when using blink as a functional recovery parameter of facial nerve lesion. (Invest
Clinical Neurophysiology, 2001
Objectives: Patients with peripheral facial palsy (PFP) may present with transient hyperkinetic movement disorders in the side contralateral to the paralysis. One possible cause of such enhanced motor activity is sensitization of re¯ex responses to afferent inputs from the unprotected cornea. We hypothesized that if this sensitization occurs, the size of the orbicularis oculi (OOc) responses induced by afferents from the ophthalmic branch of the paralyzed side would be larger than those induced by afferents from the contralateral side.
Transcutaneous trigeminal nerve stimulation modulates the hand blink reflex
Scientific Reports
The hand-blink reflex (HBR) is a subcortical response, elicited by the electrical stimulation of the median nerve, whose magnitude is specifically modulated according to the spatial properties of the defensive peripersonal space (DPPS) of the face. For these reasons, the HBR is commonly used as a model to assess the DPPS of the face. Little is known on the effects induced by the activation of cutaneous afferents from the face on the DPPS of the face. Therefore, we tested the effect of non-painful transcutaneous trigeminal nerve stimulation (TNS) on the amplitude of the HBR. Fifteen healthy participants underwent HBR recording before and after 20 min of sham- and real-TNS delivered bilaterally to the infraorbital nerve in two separate sessions. The HBR was recorded bilaterally from the orbicularis oculi muscles, following non-painful median nerve stimulation at the wrist. The HBR amplitude was assessed in the “hand‐far” and “hand‐near” conditions, relative to the hand position in res...
Physiologic and anatomic basis for contralateral R1 in blink reflex
Muscle & Nerve, 1988
We studied the rate of appearance and mechanism of contralateral R, responses in normal subjects. Contralateral R, could be produced by facilitating maneuvers such as a gentle contraction of the orbicularis oculi and conditioning stimulus of the median nerve. In addition, changing the position of the stimulating anode to the midline evoked these responses that were abolished by blocking the contralateral supraorbital nerve, confirming its peripheral origin. We conclude that crossed trigeminofacial pathways probably exist in normal subjects, but in some instances contralateral peripheral trigeminal ophthalmic sensory fibers may be stimulated, giving rise to a contralateral R, response.
Multichannel orbicularis oculi stimulation to restore eye-blink function in facial paralysis
Microsurgery, 2001
Facial paralysis due to facial nerve injury results in the loss of function of the muscles of the hemiface. The most serious complication in extreme cases is the loss of vision. In this study, we compared the effectiveness of single- and multiple-channel electrical stimulation to restore a complete and cosmetically acceptable eye blink. We established bilateral orbicularis oculi muscle (OOM) paralysis in eight dogs; the OOM of one side was directly stimulated using single-channel electrical stimulation and the opposite side was stimulated using multi-channel electrical stimulation. The changes in the palpebral fissure and complete palpebral closure were measured. The difference in current intensities between the multi-channel and single-channel simulation groups was significant, while only multi-channel stimulation produced complete eyelid closure. The latest electronic stimulation circuitry with high-quality implantable electrodes will make it possible to regulate precisely OOM contractions and thus generate complete and cosmetically acceptable eye-blink motion in patients with facial paralysis. © 2001 Wiley-Liss, Inc. MICROSURGERY 21:264–270 2001
Pain Research and Management, 2021
Trigeminal neuralgia is often misdiagnosed at initial presentation due to close connotation with dental pain and is often over diagnosed for the very same reasons leading to numerous unnecessary surgical procedures such as peripheral neurectomy and alcohol injections, while the actual cause may remain elusive for decades. Evaluation of the neurosensory system may disclose the correct anatomical location of the etiology. The neurological examination may be clouded by the sensory deficits subsequent to previous peripheral surgical procedures. The corneal and blink reflexes are integral measures of the trigeminal and facial neurosensory assessment, and their abnormal function may facilitate the identification of intrinsic disease of the brain stem. These reflexes can be employed to discover pathological lesions including intracranial space-occupying trigeminal, lateral medullary, cerebral hemispheric lesions, and degenerative diseases of the central nervous system. Dental surgeons and ...
Aging of the trigeminal blink system
Experimental Brain Research, 2001
This study characterizes trigeminal blinks in normal human subjects between 20 and 80 years of age, 60-year-old Parkinson's disease patients, and young and old guinea pigs. In normal humans over 60 years of age, lid-closing duration, and the excitability and latency of the trigeminal reflex blink increase significantly relative to younger subjects. Aged guinea pigs appear to display similar increases in reflex blink duration and latency. Reflex blink amplitude, however, does not change consistently with age. For subjects less than 70 years of age, a unilateral trigeminal stimulus evokes a 37% larger blink in the eyelid ipsilateral to the stimulus than in the contralateral eyelid, but 70-year-olds exhibit blinks of equal amplitude. In all cases, blink duration is identical for the two eyelids. If normal, age-related loss of dopamine neurons explains these trigeminal blink modifications, then Parkinson's disease should exaggerate age-related changes in these blink parameters. Preliminary data show that Parkinson's disease increases blink duration and excitability relative to age-matched control subjects. Thus, it seems likely that normal, age-related loss of dopamine neurons accounts for increases in trigeminal blink excitability and duration. A previously uncharacterized type of trigeminally evoked blink appears after age 40 in humans and in aged guinea pigs. In subjects less than 40 years old, a single trigeminal stimulus elicits a single reflex blink. In subjects over age 40, however, a single stimulus frequently evokes a reflex blink and additional blinks that occur at a fixed interval relative to the preceding blink. These "blink oscillations" may arise from oscillatory processes within trigeminal reflex blink circuits. The presence of exaggerated blink oscillations in subjects with dry eye and benign essential blepharospasm suggests that an alteration of blink oscillation mechanisms plays a critical role in these disorders.
Neural Organization of Eyelid Responses
b lr' I t' rJ _t t i A blink is a fast narrowing of the palpebral fissure, involving the activity of the orbicularis oculi muscle and, ., in fhose species-with a nictitating membrane, of the re-tractor bulbi motor system and most extraocular eye muscles. Reflex blinks can be triggered by stimuli of different sensory modalities (trigeminal, visual, acoustic, and vestibular). Blinks are not exclusively related to cor-neal protection and wetting, but are also associated with some stages of visual processing and with the complex motor displays involved in the expression of emot¡onal states. Lid movements also accompany eye displacements , as during vertical eye saccades and fixations. Moreover, eyelid movements can be easily evoked using classical conditioning procedures. l-e Because of the technical facilities available for the quantitative evoking and recording of nictitating membrane and/or eyelid movements,3 this motor system has become an excellent experimental model for the study of learned motor responses. [n addition, available relevant information on this motor system can be used as a very useful tool for the understanding of the different patholo-gies related to facial kinematics and expression in humans. We describe the biomechanical constraints involved in this motor systeme-tl and the functional properties of facial motoneurons innervating the orbicularis oculi muscle.¡2 We also introduce some recent findings regarding the involvement of higher premotor centers in the genesis and control of classically conditioned eyelid responses.lFl5 Biomechanical Properties of Eyelid Movements The eyelid motor system is load-free and has a negligible mass; that is, it has a very low inertial damping. Furthermore, orbicularis oculi motoneurons receive no feedback proprioceptive signals from the eyelid, other than those coming from the Outaneous receptors.l¡ During alert cognitive states, lid position is determined from eye position signals.present in the levator palpebrae su-perioris muscle, functionally integrated in the vertical extraocular motor system. The lack of a true stretch re-flexll has important functional implications in the gen-esis and cof¡trol of fácial expressions, as these are generated from internal emotional states and cannot be easily disrupted by the conscious, voluntary motor systenl Recent studies from our groupe shongly suggest that a-20 Hz oscillator underlies eyelid responses and plays a noticeable role in the acquisition of new eyelid motor abilities, such as classically conditioned blinks. This os-cillator is susceptible to being modulated by the cenúal nervous system to modify the velocity of a given quantum (i.e., a single wave) of movement, as well as the total number of waves released. Thus, learned eyelid responses could be rhe result of the discharge ofthe oscil-lator, as a function of the temporal-spatial needs of the involved motor task. Moreover, this putative oscillator seems to be dependent on animal (and eyelid) weight, because there is an inverse logarithmic relationship between oscillation frequency and body weight (see Fig. l).8 These data suggest that eyelid biomechanics are. tuned to the lid's weight and to its viscoelastic properties. The same inverse logarithmic relationship (slope,-0.25) was established years agos between heart rate and body mass for mammals. These oscillatory properties of motor systems are attained at early stages of development. Thus, facial motor units have to tune to the mass and viscoelastic properties of the innervated facial muscle. After development, mo-toneurons are apparently unable to adapt to the oscilla-tory needs of muscles reinnervated de novo, at least in mammals. For example, we have shown in cats that, after successful hypoglossal-facial anastomosis, hypoglossal motoneurons are unable to readapt their motor programs and oscillatory properties to the kinetic needs of the eyelid motor system (see Fig. 2¡.r0 Indeed, the oscillatory properties of a given set of motoneurons depend on the kinetics of active conductances present in their mem-s-?3
Electrically Induced Blink Reflex and Facial Motor Nerve Stimulation in Beagles
Journal of Veterinary Internal Medicine, 2000
Electrophysiologic assessment of the blink reflex test and the muscle-evoked potentials evoked by stimulation of the facial nerve were performed in 15 healthy adult Beagles before and after supraorbital (trigeminal) and facial anesthetic nerve blocks performed by lidocaine injections. Unilateral electrical stimulation of the supraorbital nerve elicited 2 ipsilateral (R 1 and R 2 ) and a contralateral (R c ) reflex muscle potential in orbicularis oculi muscles. Electrical stimulation of the facial nerve elicited 2 muscle potentials (a direct response [D] and a reflex faciofacial response [RF]) in the ipsilateral orbicularis oculi muscle. Anesthetic block of the left supraorbital nerve resulted in bilateral lack of responses upon left supraorbital nerve stimulation, but normal responses in right and left orbicularis oculi muscles upon right supraorbital stimulation. Right facial anesthetic block produced lack of responses in the right orbicularis oculi muscle regardless the side of supraorbital nerve stimulation. Results of this study demonstrate that the blink reflex can be electrically elicited and assessed in dogs. Reference values for the blink reflex responses and for the muscle potentials evoked by direct facial nerve stimulation in dogs are provided. The potential usefulness of the electrically elicited blink reflex test in the diagnosis of peripheral facial and trigeminal dysfunction in dogs was demonstrated.