Research & Current Literature
March 2011
List compiled by Robin Lindsay, M.D.
Bloch, O., M. E. Sughrue, et al. (2011). "Factors associated with preservation of facial nerve function after surgical resection of vestibular schwannoma." J Neurooncol 102(2): 281-286.
Avoidance of facial nerve palsy is one of the major goals of vestibular schwannoma (VS) microsurgery. In this study, we examined the significance of previously implicated prognostic factors (age, tumor size, the extent of resection and the surgical approach) on post-operative facial nerve function. We selected all VS patients from prospectively collected database (1984-2009) who underwent microsurgical resection as their initial treatment for histopathologically confirmed VS. The effect of variables such as surgical approach, tumor size, patient age and extent of resection on rates facial nerve dysfunction after surgery, were analyzed using multivariate logistic regression. Patients with preoperative facial nerve dysfunction (House-Brackman [HB] score 3 or higher) were excluded, and HB grade of 1 or 2 at the last follow-up visit was defined as "facial nerve preservation." A total of 624 VS patients were included in this study. Multivariate logistic regression analysis found that only pre-operative tumor size significantly predicted poorer facial nerve outcome for patients followed-up for >/=6 and >/=12 months (OR 1.27, 95% CI 1.09-1.49, p < 0.01; OR 1.35, 95% CI 1.10-1.67, P < 0.01, respectively). We found no significant relationship between facial nerve function and age, extent of resection, surgical approach, or tumor size (when extent of resection and surgical approach were included in the regression analysis). Because facial nerve palsy is a debilitating and psychologically devastating condition for the patient, we suggest altering surgical aggressiveness in patients with unfavorable tumor anatomy, particularly in cases with large tumors where overaggressive resection might subject the patient to unwarranted risk. Residual disease can be followed and controlled with radiosurgery if interval growth is noted.
Bosco, D., M. Plastino, et al. (2011). "Bell's palsy: a manifestation of prediabetes?" Acta Neurol Scand 123(1): 68-72.
BACKGROUND: Idiopathic peripheral facial nerve palsy or Bell's palsy (BP) is the most common cause of facial nerve palsy. OBJECTIVE: To evaluate the role of glucose metabolism abnormalities in BP. METHODS: We identified 148 patients with unilateral BP and 128 control subjects. In all we evaluated glucose level at fasting and after a 2-h oral glucose tolerance test (2h-OGTT). In addition we determined insulin resistance (IR), by HOMA-index. Patients and controls were divided in to two groups, according to their Body Mass Index (BMI). RESULTS: Following a 2h-OGTT, the prevalence of glucose metabolism abnormalities was significantly higher in patients with BP than in controls (P < 0.001). Impaired glucose tolerance (IGT) was found in 57 (38%) patients and in 23 (18%) controls, while a new-diagnosed DM (NDDM) was found in 29 (19%) patients and in 8 (6%) controls. The IR was significantly increased only in BP patients with BMI >/= 24.9 (P = 0.005). BMI, waist circumference, blood pressure, tryglicerides, serum lipid, drugs use were not significantly different between patients and controls. CONCLUSIONS: In this study we found that prediabetes is frequently associated with facial palsy. We propose to perform a 2h-OGTT in patients with peripheral facial palsy and normal fasting glycaemia. HOMA-index should be evaluated in obese facial palsy patients.
Burmeister, H. P., P. A. Baltzer, et al. (2011). "Evaluation of the early phase of Bell's palsy using 3 T MRI." Eur Arch Otorhinolaryngol.
This prospective study on Bell's palsy investigated the value of 3 T MRI as a diagnostic tool to evaluate pathophysiological changes (i.e. edema) of facial nerve segments and the possibility to differentiate patients with high risk for incomplete recovery from patients who recover completely within 3 days after symptoms onset. For this institutional review board approved investigation, thirty patients (14 male, 16 female, mean age 44 years) with Bell's palsy underwent pre and postcontrast 3 T MRI of the cerebellopontine angle. T1-weighted imaging was performed (TR 20.0 ms, TE 2.46 ms, isotropic voxel size: 0.6 mm). Region-of-interest measurements were performed on the healthy and paralyzed side. To obtain normalized values, signal intensity increase percentage (SIIP) values were divided by contralateral results of the healthy side. Signal intensity measurements of examined nerve segments were compared using Wilcoxon and Mann-Whitney U tests and correlated to clinical findings categorized by the House-Brackmann score. The lesion side showed significantly higher signal intensities in the premeatal segment before and after contrast agent administration (P < 0.001). SIIP was highest in the premeatal segment compared to the geniculate ganglion (P < 0.001). Correlation analyses revealed no association between signal intensity measurements, clinical findings or early recovery rates after 3 months (P > 0.05). According to our results, early palsy-associated pathophysiological changes in the facial nerve premeatal segment might also be related to accumulation of proteins and not exclusively to edema. However, contrast agent enhancement quantification was not suitable as a diagnostic tool to distinguish different prognostic groups.
Ch'ng, S., B. G. Ashford, et al. (2011). "Reconstruction of Post-Radical Parotidectomy Defects." Plast Reconstr Surg.
BACKGROUND: Radical parotidectomy presents a unique combination of reconstructive challenges. The high visibility of the region and the specialized structures involved create an inter-dependence between aesthetics and function. This paper describes our surgical concepts and experience in post-radical parotidectomy reconstruction. METHODS: The various components of reconstruction following radical parotidetomy including contour restoration, skin coverage, mandible reconstruction and facial reanimation are reviewed. We discuss our methods of choice and specific technical refinements.Twenty-one (M:F=17:4, median age 75 years) post-radical parotidectomy reconstruction cases performed from July 2006 - May 2010 were identified. Information on patient demographics, etiology, reconstruction technique, surgical complications, postoperative adjuvant radiotherapy and survival was culled. RESULTS: The most common indication for radical parotidectomy was metastatic cutaneous squamous cell carcinoma, followed by carcinoma ex pleomorphic adenoma and direct extension from primary cutaneous malignancy. Our standard approach in reconstruction was a combination of anterolateral thigh free flap and cervicofacial rotation advancement flap, repair of the facial nerve with nerve to vastus lateralis segmental interpositional graft, gold weight loading of the upper eyelid, lateral canthopexy, temporalis and digastric muscle transfers and a delayed brow lift. Surgical complications include under-correction of facial reanimation, gold weight extrusion, wound breakdown and infections. 17 (81%) patients received adjuvant radiotherapy (range 50-66G to the primary site, 40-60G to the neck). CONCLUSION: Radical parotidectomy is a morbid procedure that is sometimes necessary for oncologic control. However, with sound principles and attention to detail in reconstruction, quality of life can be greatly improved.
Dauer, D. J., Z. Huang, et al. (2011). "Age and facial nerve axotomy-induced T cell trafficking: relation to microglial and motor neuron status." Brain Behav Immun 25(1): 77-82.
Following peripheral axotomy of the facial nerve in mice, T lymphocytes cross the blood-brain-barrier (BBB) into the central nervous system (CNS), where they home to the neuronal cell bodies of origin in the facial motor nucleus (FMN) and act in concert with microglial cells to support the injured motor neurons. Several lines of evidence suggested normal aging may alter the injury-related responses of T cells, microglia, and motor neurons in this model. In this study, we therefore sought to test the hypothesis that compared to 8-week-old mice (young adult), 52-week-old mice (advanced middle age) would exhibit more neuronal damage and increased T cell trafficking into the injured FMN following facial nerve resection. Comparison of 8- and 52-week-old mice at 7, 14, 21, and 28 days post-resection of the facial nerve, confirmed our hypothesis that age influences the kinetics of CD3(+) T lymphocyte trafficking in the axotomized FMN. The peak T cell response was significantly higher, occurred later, and remained elevated longer in the injured FMN of mice in the 52 week age group. Although the kinetics of motor neuron death (identified by quantifying CD11b(+) perineuronal microglial phagocytic clusters engulfing the dead neurons at 7, 14, 21, and 28 days post-resection) differed between the age groups, motor neuron profile counts at day 28 showed that levels of cumulative motor neuron loss did not differ between the age groups. Compared to 8-week-old mice, however, there was small reduction in the mean cell size of the surviving motor neurons in the 52 week age group. Since T lymphocyte function decreases with normal aging, it will be important to determine if increased T cell trafficking into the injured CNS is a compensatory response to the decreased function of older T cells, and if these and related neuroimmunological changes are more pronounced in mice in the late stages of the life cycle. Elliott, R. M., G. S. Weinstein, et al. (2011). "Reconstruction of Complex Total Parotidectomy Defects Using the Free Anterolateral Thigh Flap: A Classification System and Algorithm." Ann Plast Surg.
BACKGROUND:: Composite defects resulting from total parotidectomy present unique reconstructive challenges. This study reviews our experience using the anterolateral thigh (ALT) flap with adjacent fascia and nerve grafts to reconstruct these defects, and establishes a classification system and treatment algorithm that simplifies reconstruction. METHODS:: Between July 2005 and November 2009, 22 patients underwent total parotidectomy and immediate reconstruction with the extended ALT flap. Of total, 21 patients had concomitant neck dissection. Defects were classified as follows: Type I, significant soft-tissue loss (n = 4); Type II, significant soft-tissue loss with facial nerve excision (n = 2); Type III, significant soft-tissue loss with resection of surrounding bone(s) (n = 5); and Type IV, significant soft-tissue loss, bone resection, and facial nerve excision (n = 11). Reconstruction procedures included free ALT (n = 9); ALT with fascia lata sling (n = 4); ALT with nerve grafting (n = 5); and ALT, fascia lata sling, and nerve grafting (n = 4). Complications, functional outcome, and patient satisfaction were assessed by chart review and prospective surveys. RESULTS:: Fourteen of 22 patients participated in surveys. There was 1 flap loss. Donor site complications included the following: 4 patients (29%) with minor numbness of the lateral thigh skin, and 1 (7%) seroma. There was no leg weakness or infection. Recipient site morbidity included 2 patients (14%) with Frey syndrome, 3 (21%) with delayed wound healing, 5 (36%) with facial numbness, and 5 with mild oral incompetence. Smile asymmetry was present in 7 patients (50%). Ten patients (71%) reported being "very happy" with their appearance. CONCLUSIONS:: The ALT flap, used with adjacent nerve and fascia, offers a versatile option for reconstructing complex parotidectomy defects. The procedure involves minimal donor site morbidity, and results in sound functional outcomes and high degrees of patient satisfaction. Diamond, M., C. T. Wartmann, et al. (2011). "Peripheral facial nerve communications and their clinical implications." Clin Anat 24(1): 10-18.
The facial nerve (CN VII) nerve follows a torturous and complex path from its emergence at the pontomedullary junction to its various destinations. It exhibits a highly variable and complicated branching pattern and forms communications with several other cranial nerves. The facial nerve forms most of these neural intercommunications with branches of all three divisions of the trigeminal nerve (CN V), including branches of the auriculotemporal, buccal, mental, lingual, infraorbital, zygomatic, and ophthalmic nerves. Furthermore, CN VII also communicates with branches of the vestibulocochlear nerve (CN VIII), glossopharyngeal nerve (CN IX), and vagus nerve (CN X) as well as with branches of the cervical plexus such as the great auricular, greater, and lesser occipital, and transverse cervical nerves. This review intends to explore the many communications between the facial nerve and other nerves along its course from the brainstem to its peripheral branches on the human face. Such connections may have importance during clinical examination and surgical procedures of the facial nerve. Knowledge of the anatomy of these neural connections may be particularly important in facial reconstructive surgery, neck dissection, and various nerve transfer procedures as well as for understanding the pathophysiology of various cranial, skull base, and neck disorders. Hagino, K., A. Tsunoda, et al. (2011). "Measurement of the Facial Nerve Caliber in Facial Palsy: Implications for Facial Nerve Decompression." Otol Neurotol.
OBJECTIVES:: The clinical effectiveness of facial nerve decompression remains controversial. To investigate this problem, we observed changes in the facial nerves of patients with and without facial palsy after this procedure. STUDY DESIGN:: Retrospective case review. SETTING:: Tertiary referral center. PATIENTS AND METHODS:: Fifteen cases who underwent opening of the facial canal under total mastoidectomy were enrolled for this study. Among these, 7 patients with Bell's palsy (House-Brackmann grade VI) underwent facial nerve decompression. The remaining 8 patients with temporal bone tumors did not show facial palsy and underwent rerouting or grafting of the facial nerve. After removal of the bone around the facial nerve, various parameters regarding the facial nerve (including the nerve width) were carefully observed, measured, and recorded. These values were subsequently compared using the Student's t test. RESULTS:: After removal of the bony covering, swelling of the facial nerve was observed in all 7 patients with facial palsy, and nerves dilated in diameter by 12% to 32% (mean, 21.0 +/- 6.1%). Injection and exudate also were observed among these patients. Swelling of the facial nerve was not observed in 8 patients without facial palsy before surgery (mean, 0.6 +/- 1.2%). A statistically significant difference was observed between the 2 groups (p < 0.01). CONCLUSION:: In the present study, edema of the facial nerve was not observed in patients without facial palsy. Although the present study has limitations and do not necessarily justify decompression, these different findings suggest that nerve decompression relieves the entrapment of the facial nerve.
Henstrom, D. K., R. W. Lindsay, et al. (2011). "Surgical treatment of the periocular complex and improvement of quality of life in patients with facial paralysis." Arch Facial Plast Surg 13(2): 125-128.
Objective A devastating sequela of facial paralysis is the inability to close the eye. The resulting loss of corneal protection can potentially lead to severe consequences. Eyelid weight placement, lower eyelid suspension, and brow ptosis correction are frequently performed to protect the eye. We sought to measure and report the change in quality of life (QOL) after surgical treatment of the periocular complex, using the validated Facial Clinimetric Evaluation (FaCE) QOL instrument. Methods From March 2009 to May 2010, 49 patients presenting to the Facial Nerve Center with paralytic lagophthalmos requiring intervention were treated with static periocular reanimation. Thirty-seven of the patients completed preoperative and postoperative FaCE surveys. Results Overall QOL, measured by the FaCE instrument, significantly improved following static periocular treatment. Mean FaCE scores increased from 44.1 to 52.7 (P < .001). Patients also reported a significant decrease in the amount of time their eye felt dry, irritated, or scratchy (P < .001). The amount of artificial tears and/or ointment also significantly decreased (P = .03). There were 2 cases of localized cellulitis with 1 eyelid weight extrusion. Conclusions We report the first series of postoperative QOL changes following static periocular treatment for paralytic lagophthalmos. Patients report a notable improvement in periocular comfort and overall QOL.
Lassaletta, L., L. Del Rio, et al. (2011). "Cyclin D1 expression and facial function outcome after vestibular schwannoma surgery." Otol Neurotol 32(1): 136-140.
HYPOTHESIS: The proto-oncogen cyclin D1 has been implicated in the development and behavior of vestibular schwannoma. This study evaluates the association between cyclin D1 expression and other known prognostic factors in facial function outcome 1 year after vestibular schwannoma surgery. METHODS: Sixty-four patients undergoing surgery for vestibular schwannoma were studied. Immunohistochemistry analysis was performed with anticyclin D1 in all cases. Cyclin D1 expression, as well as other demographic, clinical, radiologic, and intraoperative data, was correlated with 1-year postoperative facial function. RESULTS: Good 1-year facial function (Grades 1-2) was achieved in 73% of cases. Cyclin D1 expression was found in 67% of the tumors. Positive cyclin D1 staining was more frequent in patients with Grades 1 to 2 (75%) than in those with Grades 3 to 6 (25%). Other significant variables were tumor volume and facial nerve stimulation after tumor resection. The area under the receiver operating characteristics curve increased when adding cyclin D1 expression to the multivariate model. CONCLUSION: Cyclin D1 expression is associated to facial outcome after vestibular schwannoma surgery. The prognostic value of cyclin D1 expression is independent of tumor size and facial nerve stimulation at the end of surgery. Lauretti, L., M. D'Ercole, et al. (2011). "Facial—hypoglossal nerve end-to-side neurorrhaphy: anatomical study in rats." Acta Neurochir Suppl 108: 221-226.
End-to-side neurorrhaphy (ESN) is presented as a sort of surgical technique for nerve repair that has the aim to obtain a good reinnervation of the recipient nerve and function preservation of the donor nerve. Several problems regarding this technique remain to be solved. Even if ESN could find some indications in particular cases of peripheral nerve surgery, we do not think that this technique can be first choice surgery for repairing a damaged facial nerve because of the complexity of the function of facial muscles and the necessity to offer an adequate number of motoneurons from the donor nerve for reinnervation of the recipient nerve.So, despite some reports about the clinical use of facial-hypoglossal nerve ESN, we studied experimentally such technique in the rat, having as recipient the facial nerve and as donor the hypoglossus. The purpose was to establish the number of motoneurons with which the donor hypoglossal nerve innervates the recipient facial nerve, and to compare the result with that obtained after facial-hypoglossus end-to-end neurorrhaphy (EEN). Beside other interesting findings, the key point of the obtained results was that motoneuron contribution given from the donor hypoglossus to the innervation of the recipient facial nerve was limited in ESN as compared to the classic EEN. Lieberman, D. M., T. A. Jan, et al. (2011). "Effects of corticosteroids on functional recovery and neuron survival after facial nerve injury in mice." Arch Facial Plast Surg 13(2): 117-124.
Objectives To assess the effects of corticosteroid administration on functional recovery and cell survival in the facial motor nucleus (FMN) following crush injury in adult and juvenile mice and to evaluate the relationship between functional recovery and facial motoneuron survival. Methods A prospective blinded analysis of functional recovery and cell survival in the FMN after crush injury in juvenile and adult mice was carried out. All mice underwent a unilateral facial nerve crush injury and received 7 doses of daily injections. Adults received normal saline or low-dose or high-dose corticosteroid treatment. Juveniles received either normal saline or low-dose corticosteroid treatment. Whisker function was monitored to assess functional recovery. Stereologic analysis was performed to determine neuron and glial survival in the FMN following recovery. Results Following facial nerve injury, all adult mice recovered fully, while juvenile mice recovered slower and incompletely. This corresponded to a significantly greater neuron loss in the FMN of juveniles compared with adults. Corticosteroid treatment slowed functional recovery in adult mice. This corresponded with significantly greater neuron loss in the FMN in corticosteroid-treated mice. In juvenile mice, corticosteroid treatment showed a trend, which was significant at several time points, toward a more robust functional recovery compared with controls. Conclusions Corticosteroid treatment slows functional recovery and impairs neuron survival following facial nerve crush injury in adult mice. The degree of motor neuron survival corresponds with functional status. In juvenile mice, crush injury results in overall poor functional recovery and profound cell loss in the FMN. With low-dose corticosteroid treatment, there is a significantly enhanced functional recovery after injury in these mice (P < .05). Prell, J., S. Rampp, et al. (2011). "Botulinum toxin for temporary corneal protection after surgery for vestibular schwannoma." J Neurosurg 114(2): 426-431.
OBJECT: High-grade postoperative facial nerve paresis after surgery for vestibular schwannoma with insufficient eye closure involves a risk for severe ocular complications. When conservative measurements are not sufficient, conventional invasive treatments include tarsorrhaphy and eyelid loading. In this study, injection of botulinum toxin into the levator palpebrae muscle was investigated as an alternative for temporary iatrogenic eye closure. METHODS: Injection of botulinum toxin was indicated by an interdisciplinary decision (neurosurgery and ophthalmology) in patients with a postoperative facial nerve paresis corresponding to a House-Brackmann Grade of IV or greater and documented abnormalities concerning corneal status such as keratopathia or conjunctival redness. Twenty-five IUs of botulinum toxin were injected transcutaneously and transconjunctivally. RESULTS: Six of 11 patients with high-grade paresis showed abnormal corneal findings in the early postoperative period. In 4 of these patients, botulinum toxin was injected; 1 patient declined the treatment, and in 1 patient it was not performed because of contralateral blindness. Temporary eye closure was achieved for 2 to 6 months in all cases. In all cases, facial nerve function had recovered sufficiently in terms of eye closure when the effect of botulinum toxin subsided. CONCLUSION: The application of botulinum toxin for temporary iatrogenic eye closure is an excellent low-risk and temporary alternative to other invasive measures for the treatment of postoperative high-grade facial nerve paresis when the facial nerve is anatomically intact. Pereira, L. M., K. Obara, et al. (2011). "Facial exercise therapy for facial palsy: systematic review and meta-analysis." Clin Rehabil.
The effectiveness of facial exercises therapy for facial palsy has been debated in systematic reviews but its effects are still not totally explained. Objective: To perform a systematic review with meta-analysis to evaluate the effects of facial exercise therapy for facial palsy. Data sources: A search was performed in the following databases: Cochrane Controlled Trials Register Library, Cochrane Disease Group Trials Register, MEDLINE, EMBASE, LILACS, PEDro, Scielo and DARE from 1966 to 2010; the following keywords were used: 'idiopathic facial palsy', 'facial paralysis', 'Bell's palsy', 'physical therapy', 'exercise movement techniques', 'facial exercises', 'mime therapy' 'facial expression', 'massage' and 'randomized controlled trials'. Review methods: The inclusion criteria were studies with facial exercises, associated or not with mirror biofeedback, to treat facial palsy. Results: One hundred and thirty-two studies were found but only six met the inclusion criteria. All the studies were evaluated by two independent reviewers, following the recommendations of Cochrane Collaboration Handbook for assessment of risk of bias (kappa coefficient = 0.8). Only one study presented sufficient data to perform the meta-analysis, and significant improvements in functionality was found for the experimental group (standardized mean difference (SMD) = 13.90; 95% confidence interval (CI) 4.31, 23.49; P = 0.005). Conclusion: Facial exercise therapy is effective for facial palsy for the outcome functionality. Riga, M., G. Kefalidis, et al. (2011). "Increased seroprevalence of Toxoplasma gondii in a population of patients with Bell's palsy: a sceptical interpretation of the results regarding the pathogenesis of facial nerve palsy." Eur Arch Otorhinolaryngol.
Facial nerve oedema and anatomical predisposition to compression within the fallopian tube seem to be the only generally accepted facts in the pathophysiology of Bell's palsy. Several infectious causes have been suggested as possible triggers of this oedema. Most of the suggested pathogens have been associated with facial nerve lesions during latent infections, reinfections or endogenous reactivations. The aim of this study was to investigate the seroprevalence of three such pathogens Toxoplasma gondii, Epstein-Barr virus (EBV) and cytomegalovirus (CMV) in a population of patients with facial nerve palsy. Fifty-six patients with Bell's palsy were included in the study. A group of 25 individuals with similar age and gender distribution was used as control. Seropositivity for T. gondii, EBV viral capsid antigen (VCA) and CMV-specific IgM and IgG antibodies was investigated 2-5 days after the onset of the palsy. Comparisons for both IgM and IgG antibodies against T. gondii attributed significantly higher seroprevalence in the patients' group than in the control group (p = 0.024 and 0.013, respectively). The respective examinations for EBV and CMV attributed no significant results. The roles of EBV and CMV in the pathogenesis of Bell's palsy were not confirmed by this study. However, a significantly higher seroprevalence of IgM- and IgG-specific T. gondii antibodies was detected in patients with Bell's palsy when compared to healthy controls. The possibility that facial nerve palsy might be a late complication of acquired toxoplasmosis may need to be addressed in further studies. Shim, H. J., H. Jung, et al. (2011). "Ramsay Hunt syndrome with multicranial nerve involvement." Acta Otolaryngol 131(2): 210-215.
CONCLUSIONS: Ramsay Hunt syndrome (RHS) with multiple involvement of cranial nerves is more severe and intractable than RHS without such involvement. OBJECTIVES: Typically, RHS involves VII and VIII nerves and unilaterally, and RHS accompanied by multiple cranial neuropathy is very rare. We describe 11 patients who developed RHS with multicranial nerve involvement and we analyzed their clinical characteristics and compared them with those of patients with RHS not accompanied by multiple cranial neuropathy. METHODS: During the period 1995-2009, we treated 339 patients with RHS; of these, 11 patients had concurrent multiple cranial neuropathy. We assessed the clinical characteristics of RHS patients with and without multiple cranial neuropathy. RESULTS: The mean age of the 11 patients with multiple cranial neuropathy (6 men, 5 women) was 49.2 +/- 19.4 years, although 7 were aged 50 years or older. Eight patients had right-sided and three had left-sided facial paralysis. The initial degree of facial paralysis was House-Brackmann (HB) grade IV in four patients (36.4%) and HB grade V in seven (63.6%). Six patients showed improvement in symptoms, whereas five (45.6%) showed no improvement. The recovery rates from facial paralysis in patients with and without multiple cranial neuropathy were 54.5% and 82.9%, respectively, and the complete recovery rates were 27.3% and 67.7%, respectively
Siemionow, M., B. B. Gharb, et al. (2011). "The face as a sensory organ." Plast Reconstr Surg 127(2): 652-662.
BACKGROUND: The human face is a highly specialized organ for receiving the sensory information from the environment and for its transmission to the cortex. The advent of facial transplantation has shown that excellent reconstruction of disfiguring defects can be achieved; thus, the expectations are now focused on functional recovery of the transplant. So far, restoration of facial sensation has not received the same attention as the recovery of motor function. METHODS: A thorough review of the literature was performed to investigate the current knowledge on the sensory pathways of the human face and their functions to evaluate current methods of sensory assessment and the available data on normal sensation. RESULTS: The presence of Meissner and Ruffini corpuscles, Merkel disks, hair-associated fibers, and intraepidermal free nerve endings was confirmed. Occurrence of extensive cross-communications between trigeminal and facial nerve was substantiated. Two-point discrimination and pressure thresholds represented the most objective measures of facial sensation. Age, sex, and smoker status of the patients were shown to influence normal sensibility values. The most suitable areas for sensory testing based on the tested modality and innervation were inferred. The anatomical course of the nerves and their variations had implications for the harvest of face allografts and repair of the sensory nerves. CONCLUSIONS: This review has illustrated the complexity of sensory pathways of the face and their influence on somatic and visceral responses. In view of the discussed data, during facial transplantation, it is important to consider different mechanisms of restoration of facial sensation. Tomas-Roca, L., A. Perez-Aytes, et al. (2011). "In silico identification of new candidate genes for hereditary congenital facial paresis." Int J Dev Neurosci.
Hereditary congenital facial paresis (HCFP) consists of the paralysis or weakness of facial muscles caused by a maldevelopment of the facial branchiomotor (FBM) nucleus and its nerve. Linkage analyses have related this disorder to two loci, HCFP1 and HCFP2, placed respectively in human chromosomes 3q21.2-q22.1 and 10q21.3-q22.1, but the causative genes are still unknown. In this work we aimed to identify which genes from these loci are expressed in the developing hindbrain and particularly in the FBM nucleus. To this end, we retrieved from the ENSEMBL genomic database the list of these genes as well as their respective mouse orthologs. Subsequently we examined their respective expression patterns in the mouse embryo by using the GenePaint gene expression database. As a result of this screening, we found a new gene (Mgll) from the HCFP1 locus that has strong and specific expression in the developing FBM nucleus. In its turn, the HCFP2 locus appeared as a large gene-desert region, flanked by two genes, Reep3, with specific expression in the FBM nucleus, and Lrrtm3, broadly expressed in the brainstem, including the same nucleus. The concurrence of genomic position and neural expression pattern makes these genes new potential candidates for HCFP.
Valls-Sole, J., C. D. Castillo, et al. (2011). "Clinical consequences of reinnervation disorders after focal peripheral nerve lesions." Clin Neurophysiol 122(2): 219-228.
Axonal regeneration and organ reinnervation are the necessary steps for functional recovery after a nerve lesion. However, these processes are frequently accompanied by collateral events that may not be beneficial, such as: (1) Uncontrolled branching of growing axons at the lesion site. (2) Misdirection of axons and target organ reinnervation errors, (3) Enhancement of excitability of the parent neuron, and (4) Compensatory activity in non-damaged nerves. Each one of those possible problems or a combination of them can be the underlying pathophysiological mechanism for some clinical conditions seen as a consequence of a nerve lesion. Reinnervation-related motor disorders are more likely to occur with lesions affecting nerves which innervate muscles with antagonistic functions, such as the facial, the laryngeal and the ulnar nerves. Motor disorders are better demonstrated than sensory disturbances, which might follow similar patterns. In some instances, the available examination methods give only scarce evidence for the positive diagnosis of reinnervation-related disorders in humans and the diagnosis of such condition can only be based on clinical observation. Whatever the lesion, though, the restitution of complex functions such as fine motor control and sensory discrimination would require not only a successful regeneration process but also a central nervous system reorganization in order to integrate the newly formed peripheral nerve structure into the prepared motor programs and sensory patterns.
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