Advances in facial reanimation

Pediatric Facial Reanimation

Pediatric facial palsy is rare but severely debilitating and results in profound functional, developmental, psychosocial, and esthetic consequences. Identifying the specific cause of the palsy is important in directing the treatment course. The most common etiologies of pediatric facial palsy are distinct from those of adults. Facial reanimation interventions are targeted to address the zones of the face, with oral/smile rehabilitation the most common region requiring intervention in pediatric patients. Gracilis microneurovascular free tissue transfer is safe and highly effective in the pediatric population, providing significant functional, psychosocial, and esthetic benefits.

Advances in Facial Reanimation

Facial nerve paralysis is a debilitating clinical entity that presents as a complete or incomplete loss of facial nerve function. The etiology of facial nerve palsy and sequelae varies tremendously. The most common cause of facial paralysis is Bell's palsy, followed by malignant or benign tumors, iatrogenic insults, trauma, virus-associated paralysis, and congenital etiologies.

Long-Term Outcomes of the Electrically Unresponsive, Anatomically Intact Facial Nerve Following Vestibular Schwannoma Surgery

Objective The study aimed to determine long-term outcomes in patients with intraoperative electrical conduction block in an anatomically intact facial nerve (FN).

Methods Single center retrospective review of prospectively collected database of all vestibular schwannoma surgeries between January 1, 2008 and August 25, 2015. Operative notes were reviewed and patients with anatomically intact FNs, but complete conduction block at the end of surgery were included for analysis.

Results In total, 371 patients had vestibular schwannoma surgery of which 18 met inclusion criteria. Mean follow-up was 34.28 months and average tumor size was 28.00 mm. Seventeen patients had House-Brackmann Grade VI facial palsy immediately postoperatively and one patient was grade V. At 1 year, three patients remained grade VI (17%), two improved to grade V (11%), seven to grade IV (39%), six to grade III (33%), and one patient to grade II (6%). On extended follow-up, five patients (28%) had additional 1 to 2 score improvement in facial function. Subset analysis revealed no correlation of tumor size, vascularity, adherence to nerve, operative approach, extent of resection, splaying of FN, and recurrent tumor or sporadic tumors to the extent of FN recovery.

Conclusion Intraoperative conduction block does not condemn a patient to permanent FN palsy. There is potential for a degree of recovery comparable with those undergoing nerve grafting. Our data do not clearly support a policy of same-surgery or early-postoperative primary nerve grafting in the event of a complete conduction block, and instead we favor monitoring for recovery in an anatomically intact nerve.

Facial Reanimation by Modified Intraoral Temporalis Tendon Transfer With Ancillary Procedures

ABSTRACT

Facial nerve palsy is an exceedingly debilitating condition, incapacitating functional and aesthetic facets of the face. Orthodromic transfer of temporalis muscle is an easy and predictable technique which offers early animation of oral commissure and lower face. A retrospective chart review of 6 patients of facial palsy treated with orthodromic temporalis tendon transfer for facial reanimation is presented. The technique consisted of intra-oral coronoidectomy followed by attachment of fascia lata grafts from the coronoid to the commissure, the upper and lower lips via small cutaneous incisions. Contraction of the temporalis, pulls the fascia lata extensions thereby reanimating the lower face. 4 male and 2 female patients with an age range of 25 to 49 years were treated. Simultaneous fat grafting (2 patients), depressor labi inferioris muscle resection (2 patients) and wedge excision of nasolabial fold (2 patients) was done as ancillary procedures. Post-operative smile evaluation was carried out using the Terzis and Noah facial grading system. Patients were asked to smile with and without biting, and photographs and video were taken. The results were graded from 1 to 5 based on a 5-point scale (ie, poor, fair, moderate, good, and excellent) by an independent observer. The results were excellent in 1 patient (Terzis grading 5/5) and good in the remaining 5 patients (Terzis grading 4/5). Excursion of the oral commissure ranged from 6 to 10 mm. Our experience indicates that temporalis tendon transfer for facial reanimation has a short learning curve and provides early predictable outcome without significant complications. This single-stage, day-care procedure can be easily incorporated by maxillofacial surgeons to expand their surgical spectrum.

Masseter nerve-based facial palsy reconstruction

Facial paralysis is a devastating disease, the treatment of which is challenging. The use of the masseteric nerve in facial reanimation has become increasingly popular and has been applied to an expanded range of clinical scenarios. However, appropriate selection of the motor nerve and reanimation method is vital for successful facial reanimation. In this literature review on facial reanimation and the masseter nerve, we summarize and compare various reanimation methods using the masseter nerve. The masseter nerve can be used for direct coaptation with the paralyzed facial nerve for temporary motor input during cross-facial nerve graft regeneration and for double innervation with the contralateral facial nerve. The masseter nerve is favorable because of its proximity to the facial nerve, limited donor site morbidity, and rapid functional recovery. Masseter nerve transfer usually leads to improved symmetry and oral commissure excursion due to robust motor input. However, the lack of a spontaneous, effortless smile is a significant concern with the use of the masseter nerve. A thorough understanding of the advantages and disadvantages of the use of the masseter nerve, along with careful patient selection, can expand its use in clinical scenarios and improve the outcomes of facial reanimation surgery.

Perforating foreign body causing incomplete facial paralysis

Facial nerve trauma is a common cause of facial paralysis; both blunt and penetrating forces may compromise the facial nerve. A comprehensive primary and secondary survey is essential for diagnosis and treatment of the injury. Here we report on a young patient who sustained a quad bike accident, leading to an perforating injuries of the face from a bough, causing facial paralysis.

Microsurgical Reconstruction of the Smile: A Critical Analysis of Outcomes

BACKGROUND

Facial paralysis is a significant problem with functional, psychological, and esthetic consequences. Free muscle transfer for reanimation of the smile has been established as the preferred reconstructive method. However, little has been reported on the complications after this procedure. We sought to perform a critical analysis of these complications and their ultimate outcomes.

METHODS

A retrospective review was performed on consecutive patients undergoing microsurgical reconstruction of the smile by the senior author from 2013 through 2017. Patient demographics including age, race, body mass index, and medical comorbidities were recorded. The cause of facial palsy and type of microsurgical reconstruction were assessed. Patient outcomes including complications and management of the complication were analyzed. All statistical analyses were performed using nonparametric analyses.

RESULTS

We identified 17 patients who underwent microsurgical reconstruction of the smile, with 1 patient undergoing bilateral procedures, for a total of 18 microsurgical smile reanimation procedures performed. Sixteen of these were 1-stage reconstructions with the coaptation of the nerve to the masseter, whereas 2 were 2-stage reconstructions using cross-facial nerve grafts. The gracilis muscle was used as the donor muscle in all cases. The patients had a median age of 26.5 and a median follow-up of 1.04 years from surgery. There were no major early complications observed in our cohort. Eight (44.4%) reanimations developed a minor complication that required subsequent reoperation. The reoperations were performed at a median of 0.97 years after the microsurgical procedure. The most common indication for reoperation was lateral retraction of the insertion of the transplanted muscle, which occurred in 5 (62.5%) patients. One patient underwent surgical exploration for an abrupt loss of transplanted muscle function after trauma to the cheek. Another patient had less than expected transplanted muscle activity at 1 year postoperatively and underwent exploration of the cross-facial nerve graft and a neurorrhaphy revision. Lastly, 1 patient developed significant rhytids over the transplanted muscle secondary to tethering of the skin to the underlying muscle. This patient underwent 2 subsequent revisions, with placement of acellular dermal matrix between the muscle and skin and fat grafting. All patients had functional animation of the transplanted muscle postoperatively.

CONCLUSIONS

Complications occurred in 44.4% of patients undergoing microsurgical reanimation of the smile. Most complications were minor in nature and were readily addressed with advancement of the transplanted muscle. All patients in our series had muscle function after the muscle transplantation.

Treatment for ophthalmic paralysis: functional and aesthetic optimization

Facial nerve palsy has an effect on a person's well-being functionally and psychologically. Therefore, comprehensive patient management is essential. One of the most common uncomfortable and potentially debilitating features is associated with the incapacity for eye closure. Restoration of eye closure is a key consideration during the surgical management of facial palsy. In this article, we introduce simple surgical methods-which are relatively easy to learn and involve the upper and lower eyelids-for achieving eye closure. Correcting upper eyelid function involves facilitating the component of eye closure that is in the same direction as gravity and is, therefore, less complicated and favorable outcomes than correction of lower lid. Aesthetic aspects should be considered to correct the asymmetry caused by facial palsy. Lower eyelid function involves a force that opposes gravity for eye closure, which makes correction of lower eyelid ectropion more challenging than surgery for the upper eyelid, particularly in terms of effecting a sustained correction. Initially, proper ophthalmic evaluation is required, including identifying the chronicity and severity of ectropion. Also, it is important to determine whether or not lateral canthoplasty is necessary. The lateral tarsal strip procedure is commonly used for lower lid correction. However, effective lower lid correction can be achieved with better cosmesis when extensive supporting techniques are applied, including those involving cheek tissue.

Facial Paralysis Discussion and Debate

This article examines 6 questions about facial paralysis answered by 3 experts in their field of facial plastic surgery. The topics covered include routine assessment, neuromuscular training, nonsurgical management, and the future of this field. All the authors answered these questions in a "How I do it" manner to provide the reader with a true understanding of their thoughts and techniques. This article provides a practical resource to all physicians and practitioners treating patients with facial paralysis on some of the most common questions and issues.

Objective Outcomes of Minimally Invasive Temporalis Tendon Transfer for Prolonged Complete Facial Paralysis

OBJECTIVES

We describe an approach to reanimation of complete, prolonged facial paralysis using minimally invasive temporalis tendon transfer (MIT3) by the melolabial or transoral approach. Objective outcome measures are evaluated based on symmetry, and grading of preoperative/post-operative results and the scar at the melolabial fold.

STUDY DESIGN

Retrospective cohort study.

METHODS

Twenty-five patients undergoing the MIT3 technique were studied. Photographic analysis was used to determine the percentage of difference between the 2 sides (symmetry). Using the Delphi method to achieve consensus, a panel of experts graded pre/post-operative photos using the Terzis' Facial Grading System and a 1 to 10 Likert-type scale and the melolabial scar using the Beausang Scar Scale.

RESULTS

Percentage of difference (symmetry) with smiling improved from 18.6% ± 1.5% (mean ± standard error of the mean [SEM]) preoperatively to 5.0 ± 0.9% (mean ± SEM) post-operatively. Expert grading by the Terzis system showed improvement post-operatively (mean 3.7/5; median 3.6/5) versus preoperatively (mean 1.5/5; median 1.2/5). Perceived improvement was also largely favourable (mean 8.1/10; median 8.0/10). Melolabial scar grading was favourable in terms of colour (mean 1.53/4), surface character (mean 1.05/2), contour (mean 1.60/4), and distortion (mean 1.74/4).

CONCLUSIONS

The MIT3 technique offers immediate, predictable, and symmetrical return of smile function. Objective symmetry analysis and favourable expert grading of both pre-/post-operative photographs and the scar at the melolabial fold demonstrate applicability for facial reanimation in patients where other procedures have failed, or when a direct return to function is desired. Both the melolabial approach and transoral approach were found to be acceptable and effective, although applicability varies.

Outcome of a graduated minimally invasive facial reanimation in patients with facial paralysis

Peripheral paralysis of the facial nerve is the most frequent of all cranial nerve disorders. Despite advances in facial surgery, the functional and aesthetic reconstruction of a paralyzed face remains a challenge. Graduated minimally invasive facial reanimation is based on a modular principle. According to the patients' needs, precondition, and expectations, the following modules can be performed: temporalis muscle transposition and facelift, nasal valve suspension, endoscopic brow lift, and eyelid reconstruction. Applying a concept of a graduated minimally invasive facial reanimation may help minimize surgical trauma and reduce morbidity. Twenty patients underwent a graduated minimally invasive facial reanimation. A retrospective chart review was performed with a follow-up examination between 1 and 8 months after surgery. The FACEgram software was used to calculate pre- and postoperative eyelid closure, the level of brows, nasal, and philtral symmetry as well as oral commissure position at rest and oral commissure excursion with smile. As a patient-oriented outcome parameter, the Glasgow Benefit Inventory questionnaire was applied. There was a statistically significant improvement in the postoperative score of eyelid closure, brow asymmetry, nasal asymmetry, philtral asymmetry as well as oral commissure symmetry at rest (p < 0.05). Smile evaluation revealed no significant change of oral commissure excursion. The mean Glasgow Benefit Inventory score indicated substantial improvement in patients' overall quality of life. If a primary facial nerve repair or microneurovascular tissue transfer cannot be applied, graduated minimally invasive facial reanimation is a promising option to restore facial function and symmetry at rest.

Facial Palsy, a Disorder Belonging to Influential Neurological Dynasty: Review of Literature

Facial paralysis is one of the common problem leading to facial deformation. Bell's palsy (BP) is defined as a lower motor neuron palsy of acute onset and idiopathic origin. BP is regarded as a benign common neurological disorder of unknown cause. It has an acute onset and is almost always a mononeuritis. The facial nerve is a mixed cranial nerve with a predominant motor component, which supplies all muscles concerned with unilateral facial expression. Knowledge of its course is vital for anatomic localization and clinical correlation. BP accounts for approximately 72% of facial palsies. Almost a century later, the management and etiology of BP is still a subject of controversy. Here, we present a review of literature on this neurologically significant entity.

Open and endovascular repair of aneurysms affecting the distal extracranial internal carotid artery: case series

Objective:

Three cases of internal carotid artery aneurysm affecting the distal cervical segment were retrospectively reviewed.

Methods:

Two patients underwent open surgical repair requiring petrous segment exposure for bypass of the affected segment using a Fisch type A lateral skull base approach. The third patient underwent endovascular stenting.

Results:

There were no cerebrovascular complications post-operatively. Both open repair patients experienced temporary lower cranial nerve palsies. One required facial nerve grafting. All patients had patent grafts at follow up. The stent graft patient had a small endoleak at six months.

Conclusion:

Endovascular and open approaches both have advantages and disadvantages. Treatment needs to be tailored to the lesion and the patient. An open surgical approach is difficult but well established. Endovascular treatment of these lesions is a relatively recent technique, and new cases need to be continually reported with a view to attaining long-term data.

Overview of Facial Plastic Surgery and Current Developments

Facial plastic surgery is a multidisciplinary specialty largely driven by otolaryngology but includes oral maxillary surgery, dermatology, ophthalmology, and plastic surgery. It encompasses both reconstructive and cosmetic components. The scope of practice for facial plastic surgeons in the United States may include rhinoplasty, browlifts, blepharoplasty, facelifts, microvascular reconstruction of the head and neck, craniomaxillofacial trauma reconstruction, and correction of defects in the face after skin cancer resection. Facial plastic surgery also encompasses the use of injectable fillers, neural modulators (e.g., BOTOX Cosmetic, Allergan Pharmaceuticals, Westport, Ireland), lasers, and other devices aimed at rejuvenating skin. Facial plastic surgery is a constantly evolving field with continuing innovative advances in surgical techniques and cosmetic adjunctive technologies. This article aims to give an overview of the various procedures that encompass the field of facial plastic surgery and to highlight the recent advances and trends in procedures and surgical techniques.

Facial nerve trauma: evaluation and considerations in management

The management of facial paralysis continues to evolve. Understanding the facial nerve anatomy and the different methods of evaluating the degree of facial nerve injury are crucial for successful management. When the facial nerve is transected, direct coaptation leads to the best outcome, followed by interpositional nerve grafting. In cases where motor end plates are still intact but a primary repair or graft is not feasible, a nerve transfer should be employed. When complete muscle atrophy has occurred, regional muscle transfer or free flap reconstruction is an option. When dynamic reanimation cannot be undertaken, static procedures offer some benefit. Adjunctive tools such as botulinum toxin injection and biofeedback can be helpful. Several new treatment modalities lie on the horizon which hold potential to alter the current treatment algorithm.

Facial reanimation utilizing combined orthodromic temporalis muscle flap and end-to-side cross-face nerve grafts

BACKGROUND

Individuals with facial paralysis of 6 months or more without evidence of clinical or electromyographic improvement have been successfully reanimated utilizing an orthodromic temporalis transfer in conjunction with end-to-side cross-face nerve grafts. The temporalis muscle insertion is released from the coronoid process of the mandible and sutured to a fascia lata graft that is secured distally to the commissure and paralyzed hemilip. The orthodromic transfer of the temporalis muscle overcomes the concave temporal deformity and zygomatic fullness produced by the turning down of the central third of the muscle (Gillies procedure) while yielding stronger muscle contraction and a more symmetric smile. The muscle flap is combined with cross-face sural nerve grafts utilizing end-to-side neurorrhaphies to import myelinated motor fibers to the paralyzed muscles of facial expression in the midface and perioral region. Cross-face nerve grafting provides the potential for true spontaneous facial motion. We feel that the synergy created by the combination of techniques can perhaps produce a more symmetrical and synchronized smile than either procedure in isolation.

METHODS

Nineteen patients underwent an orthodromic temporalis muscle flap in conjunction with cross-face (buccal-buccal with end-to-side neurorrhaphy) nerve grafts. To evaluate the symmetry of the smile, we measured the length of the two hemilips (normal and affected) using the CorelDRAW X3 software. Measurements were obtained in the pre- and postoperative period and compared for symmetry.

RESULTS

There was significant improvement in smile symmetry in 89.5 % of patients.

CONCLUSION

Orthodromic temporalis muscle transfer in conjunction with cross face nerve grafts creates a synergistic effect frequently producing an aesthetic, symmetric smile.

LEVEL OF EVIDENCE V

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors at www.springer.com/00266 .

Facial reanimation of patients with neurofibromatosis type 2

BACKGROUND

Neurofibromatosis type 2 (NF2) is a tumor suppressor syndrome defined by bilateral vestibular schwannomas. Facial paralysis, from either tumor growth or surgical intervention, is a devastating complication of this disorder and can contribute to disfigurement and corneal keratopathy. Historically, physicians have not attempted to treat facial paralysis in these patients.

OBJECTIVE

To review our clinical experience with free gracilis muscle transfer for the purpose of facial reanimation in patients with NF2.

METHODS

Five patients with NF2 and complete unilateral facial paralysis were referred to the facial nerve center at our institution. Charts and operative reports were reviewed; treatment details and functional outcomes are reported.

RESULTS

Patients were treated between 2006 and 2009. Three patients were men and 2 were women. The age of presentation of debilitating facial paralysis ranged from 12 to 50 years. All patients were treated with a single-stage free gracilis muscle transfer for smile reanimation. Each obturator nerve of the gracilis was coapted to the masseteric branch of the trigeminal nerve. Measurement of oral commissure excursions at rest and with smile preoperatively and postoperatively revealed an improved and nearly symmetric smile in all cases.

CONCLUSION

Management of facial paralysis is often times overlooked when defining a care plan for NF2 patients who typically have multiple brain and spine tumors. The paralyzed smile may be treated successfully with single-stage free gracilis muscle transfer in the motivated patient.

The pedicled masseter muscle transfer for smile reconstruction in facial paralysis: repositioning the origin and insertion

BACKGROUND

The pedicled masseter muscle transfer (PMMT) is introduced as a new reconstructive option for dynamic smile restoration in patients with facial paralysis. The masseter muscle is detached from both its origin and insertion and transferred to a new position to imitate the function of the native zygomaticus major muscle.

METHODS

Part one of this study consisted of cadaveric dissections of 4 heads (eight sides) in order to determine whether the masseter muscle could be (a) pedicled solely by its dominant neurovascular bundle and (b) repositioned directly over the native zygomaticus major. The second part of the study consisted of clinical assessments in three patients in order to confirm the applicability of this muscle transfer. Commissure excursion and vector of contraction following PMMT were compared to the non-paralyzed side.

RESULTS

In all eight sides, the masseter muscles were successfully isolated on their pedicle and transposed on top of and in-line with the ipsilateral zygomaticus major. The mean length of the masseter and its angle from Frankfurt's horizontal line after transposition compared favorably to the native zygomaticus major muscle. In the clinical cases, the mean commissure movements of the paralyzed and normal sides were 7 mm and 12 mm respectively. The mean angles of commissural movement for the paralyzed and normal sides were 62° and 59° respectively.

CONCLUSIONS

The PMMT can be used as a dynamic reconstruction for patients with permanent facial paralysis. As we gain experience with the PMMT, it may be possible to use it as a first-line option for patients not eligible for free micro-neurovascular reconstruction.

Myoelectric signals of levator palpebrae superioris as a trigger for FES to restore the paralyzed eyelid

Some closed loop FES systems have been designed to restore the blinking function of facial paralysis patients. All of them used myoelectric signal of orbicularis oculi at the normal side as the trigger to stimulate the paralyzed side. They were limited to the one side facial paralysis. Here we proposed that the myoelectric signal of levator palpebrae superioris could be used as the trigger to stimulate the paralyzed orbicularis oculi. Because the levator palpebrae superioris and the innervating nerve are intact, the myoelectric signal of the paralyzed side still could be used as the trigger. It will be more acceptable for the patients and have the potential to resolve the bilateral facial paralysis.

Nerve-muscle-endplate band grafting: a new technique for muscle reinnervation

BACKGROUND

Because currently existing reinnervation methods result in poor functional recovery, there is a great need to develop new treatment strategies.

OBJECTIVE

To investigate the efficacy of our recently developed nerve-muscle-endplate band grafting (NMEG) technique for muscle reinnervation.

METHODS

Twenty-five adult rats were used. Sternohyoid (SH) and sternomastoid (SM) muscles served as donor and recipient muscle, respectively. Neural organization of the SH and SM muscles and surgical feasibility of the NMEG technique were determined. An NMEG contained a muscle block, a nerve branch with nerve terminals, and a motor endplate band with numerous neuromuscular junctions. After a 3-month recovery period, the degree of functional recovery was evaluated with a maximal tetanic force measurement. Retrograde horseradish peroxidase tracing was used to track the origin of the motor innervation of the reinnervated muscles. The reinnervated muscles were examined morphohistologically and immunohistochemically to assess the extent of axonal regeneration.

RESULTS

Nerve supply patterns and locations of the motor endplate bands in the SH and SM muscles were documented. The results demonstrated that the reinnervated SM muscles gained motor control from the SH motoneurons. The NMEG technique yielded extensive axonal regeneration and significant recovery of SM muscle force-generating capacity (67% of control). The mean wet weight of the NMEG-reinnervated muscles (87% of control) was greater than that of the denervated SM muscles (36% of control).

CONCLUSION

The NMEG technique resulted in successful muscle reinnervation and functional recovery. This technique holds promise in the treatment of muscle paralysis.

Reconstruction of the paralyzed face

Facial nerve paralysis can be difficult to treat because it presents a variety of functional, aesthetic, and psychosocial challenges. The goals of treatment include facial symmetry at rest, corneal protection, oral competence, restoration of voluntary and spontaneous facial movements, and minimal synkinesis. A multitude of static and dynamic procedures have been used to achieve these goals. Facial nerve reapproximation or interpositional grafting is associated with the best end results. The results of dynamic procedures are generally better than those of static procedures. Optimal reconstruction of the paralyzed face usually requires multiple surgeries with both types of procedures. Patients must be extensively counseled regarding expected results before they embark on what is an oftentimes lengthy reconstructive process. In this article, we discuss the anatomy of the facial nerve, the etiologic factors associated with facial nerve paralysis, the evaluation of the patient with facial paralysis, and the various surgical options for static and dynamic reconstruction of the paralyzed face. We also review the literature.

Subdivision of the sural nerve: step towards individual facial reanimation

Long term facial paralysis is a serious affliction and upsetting for the patient. Dynamic facial reanimation has become the treatment of choice. Various techniques that use different donor muscles have been developed since the first functional muscle transplant for facial paralysis more than 30 years ago. The concept of using a single muscle was refined into the use of dividable muscle slips such as serratus muscle or separate muscular subunits to avoid the resulting mass movements. Because the results are still not satisfactory, efforts were put into also dividing the donor nerve transplant into corresponding subunits to create a continuous line of individual action. Twenty human cadaveric sural nerves were successfully dissected into three completely separate subunits, transecting the interfascicular bridges. This anatomical study gives the potential to allow an independent triple innervation of three separate serratus anterior muscle slips, so decreasing further the mass movement after facial reanimation.

Learning course adjustments during arm movements with reversed sensitivity derivatives

BACKGROUND

To learn, a motor system needs to know its sensitivity derivatives, which quantify how its neural commands affect motor error. But are these derivatives themselves learned, or are they known solely innately? Here we test a recent theory that the brain's estimates of sensitivity derivatives are revisable based on sensory feedback. In its simplest form, the theory says that each control system has a single, adjustable estimate of its sensitivity derivatives which affects all aspects of its task, e.g. if you learn to reach to mirror-reversed targets then your revised estimate should reverse not only your initial aiming but also your online course adjustments when the target jumps in mid-movement.

METHODS

Human subjects bent a joystick to move a cursor to a target on a computer screen, but the cursor's motion was reversed relative to the joystick's. The target jumped once during each movement. Subjects had up to 4000 trials to practice aiming and responding to target jumps.

RESULTS

All subjects learned to reverse both initial aiming and course adjustments.

CONCLUSIONS

Our study confirms that sensitivity derivatives can be relearned. It is consistent with the idea of a single, all-purpose estimate of those derivatives; and it suggests that the estimate is a function of context, as one would expect given that the true sensitivity derivatives may vary with the state of the controlled system, the target, and the motor commands.

Facial nerve palsy: providing eye comfort and cosmesis

Development of facial nerve palsy (FNP) may lead to dramatic change in the patient's facial function, expression, and emotions. The ophthalmologist may play an important role in the initial evaluation, and the long-term management of patients with new-onset of FNP. In patients with expected temporary facial weakness, no efforts should be wasted to ensure proper corneal protection. Patients with permanent functional deficit may require combination of surgical procedures tailored to the patient's clinical findings that may require good eye comfort and cosmesis.