Exploration of rich-club reorganization in facial synkinesis: insights from structural and functional brain network analysis.

Facial palsy therapies based on cortical plasticity are in development, but facial synkinesis progress is limited. Studying neural plasticity characteristics, especially network organization and its constitutive elements (nodes/edges), is the key to overcome the bottleneck. We studied 55 participants (33 facial synkinesis patients, 22 healthy controls) with clinical assessments, functional magnetic resonance imaging (fMRI), and diffusion tensor imaging (DTI). We analyzed rich-club organization and metrics of structural brain networks (rich-club coefficients, strength, degree, density, and efficiency). Functional brain network metrics, including functional connectivity and its coupling with the structural network, were also computed. Patients displayed reduced strength and density of rich-club nodes and edges, as well as decreased global efficiency. All nodes exhibited decreased nodal efficiency in patients. Patients had significantly increased functional connectivity and decreased structural-functional coupling strength in rich-club nodes, rich-club edges, and feeder edges. Our study indicates that facial synkinesis patients have weakened structural connections but enhanced functional transmission from rich-club nodes. The loss of connections and efficiency in structural network may trigger compensatory increases in functional connectivity of rich-club nodes. Two potential biomarkers, rich-club edge density and structural-functional coupling strength, may serve as indicators of disease outcome. These findings provide valuable insights into synkinesis mechanisms and offer potential targets for cortical intervention.

Perineal and foot muscle synkinesis following trauma to the sacrum in an adult male - A case of motor root ephaptic transmission?

Ephaptic transmission has been proven as an alternative to chemical synaptic neural transmission and occurs in pathological situations, such as epilepsy and demyelination. Hereby, we report the case of an adult male that in 2012 was involved in a low-speed motorcycle accident with sacrum impact that from day three onwards reported unwanted penile movement when performing hallux and toe plantar flexion of the right foot. Urologic studies and perineal MRI were unremarkable but sacral MRI showed a significantly stenotic canal at the S1-S2 level while EMG displayed chronic moderate right S2 radiculopathy. Nine years later the patient underwent surgical decompression of the sacral canal with complete resolution of the synkinesis. We hypothesize ephaptic transmission between adjacent motor nerve fibres at the S2 sacral nerve root to be the likely mechanism explaining this phenomenon.

Oculo-zygomatic nerve transfer for facial synkinesis: An anatomical feasibility study.

BACKGROUND: Patients with severe oro-ocular synkinesis often present with concomitant inefficient smile excursion on the affected site. In theory, oculo-zygomatic nerve transfer may decrease synkinesis and improve smile by redirecting nerve fibers to their target muscle. The aim of this study was to explore the feasibility of nerve transfer in human cadavers between a caudal branch innervating the orbicularis oculi to a cephalad branch innervating the zygomaticus major muscles. METHODS: Eighteen hemi-faces were dissected. Reach for direct coaptation of a caudal nerve branch innervating the orbicularis oculi muscle to a cephalad nerve branch innervating the zygomaticus major muscle was assessed. Measurements included total number of nerve branches as well as maximum dissection length. Nerve samples were taken from both branches at the site of coaptation and histomorphometric analysis for axonal count was performed. RESULTS: The number of sub-branches to the orbicularis oculi muscle was 3.1 ± 1.0 and to the zygomaticus major muscle 4.7 ± 1.2. The maximal length of dissection of the caudal nerve branch to the orbicularis oculi muscle was 28.3 ± 7.3 mm and for the cranial nerve branch to the zygomaticus major muscle 23.8 ± 6.5 mm. Transection and tension-free coaptation was possible in all cases but one. The average myelinated fiber counts per mm2 was of 5,173 ± 2,293 for the caudal orbicularis oculi branch and 5,256 ± 1,774 for the cephalad zygomaticus major branch. CONCLUSION: Oculo-zygomatic nerve transfer is an anatomically feasible procedure. The clinical value of this procedure, however, remains to be proven.

Trochlear-oculomotor synkinesis: another congenital cranial dysinnervation disorder? / Sincinesia troclear-oculomotora: outro distúrbio congênito de denervação craniana?

ABSTRACT This report documents an unusual phenomenon. A 6-year-old girl with trochlear-oculomotor synkinesis presented with superior oblique and palpebral levator co-contraction. The literature was reviewed and the possibility of classifying this entity as a congenital cranial dysinnervation disorder was speculated.

RESUMO Este relato descreve um fenômeno incomum. Uma menina de 6 anos com sincinesia troclear-oculomotora apresentou co-contração do oblíquo superior e do levantador da pálpebra. A literatura foi revisada e especulou-se a possibilidade de classificar essa desordem como um distúrbio da congenital cranial dysinnervation disorder.

Trochlear-oculomotor synkinesis: another congenital cranial dysinnervation disorder?

This report documents an unusual phenomenon. A 6-year-old girl with trochlear-oculomotor synkinesis presented with superior oblique and palpebral levator co-contraction. The literature was reviewed and the possibility of classifying this entity as a congenital cranial dysinnervation disorder was speculated.

Experimental studies on the recovery processes from severe facial palsy and the development of its sequelae.

OBJECTIVE: To experimentally elucidate the pathogenesis of inappropriate co-contraction of facially innervated muscles after severe facial palsy. METHODS: Twenty-two guinea pigs with severe facial palsy induced by the interruption of the petrosal artery were used to follow up behavioral facial movement, including the degree of facial palsy and abnormal hyperkinetic facial movement of synkinesis and mass contracture. At the end of the follow-up, the evoked facial compound muscle action potential (evoked FCMP) and antidromically evoked facial nerve response (AFNR) were examined in a few typical cases with complete recovery and with incomplete recovery accompanied by synkinesis. After the follow-up, all animals were sacrificed for morphological studies, which consisted of a light-microscopic study (by Luxol fast blue and hematoxylin and eosin staining or toluidine blue staining) and/or an electron-microscopic study. RESULTS: The initial sign of recovery was mass contracture or spasm. This condition continued for 2 weeks or more. As voluntary facial movement recovered, the mass contracture became unnoticeable. It could not be distinguished when the so-called synkinesis developed. Synkinesis usually developed during the recovery process from severe to moderate palsy, and synkinesis persisted or progressed once it appeared. Histologically, unmyelinated fibers were intermingled with myelinated fibers in an early stage of recovery with mass contracture. In the late stage with the development of synkinesis, however, such an intermingling of unmyelinated and myelinated axons was not observed. In this stage, axons became well myelinated, but they were irregular in shape in cases with synkinesis. Especially, axons irregularly ran at the level of the G1 (at the region of the second genu) segment, and bifurcated axons were sporadically found. The axon count had a tendency to increase toward the periphery. AFNR was not detected, although evoked FCMP could be clearly detected in cases with synkinesis. CONCLUSION: Misguidance of regenerated axons is an important cause of facial synkinesis in the ischemia-induced facial palsy model. Ephaptic transmission between unmyelinated and myelinated axons is also likely to be responsible for mass contracture manifested in the early stage of the recovery process.

Concurrence of multiple types of eyelid synkinesia in a patient with congenital anomalies.

We report the case of a 5-year-old boy with multiple congenital anomalies, including ptosis, polydactyly, ventricular septal defect, epilepsy, and intellectual deficits. The patient presented with synkinetic eyelid movements accompanying jaw and ocular movements, including Marcus-Gunn phenomenon (eyelid elevation at mouth opening) in the right eye, inverse Marcus-Gunn phenomenon (aggravation of ptosis at mouth opening) in the left eye, and unilateral eyelid elevation on each side during ipsilateral abduction. This suggests that the different types of synkinesia may represent a common etiology of aberrant innervations and/or reflex phenomena of the cranial nerves caused by a specific genetic defect.

Hemifacial spasm and reinnervation synkinesias: long-term treatment with either Botox or Dysport.

Botulinum toxin is considered the treatment of choice for hemifacial spasm (HFS) and reinnervation synkinesias (RS). We present 133 patients with HFS (n = 97) and RS (n = 36) who have been treated with either Botox (n = 78) or Dysport (n = 55) exclusively for 6 years (range 2-12 years). The Botox dose was 21 +/- 8 MU, the Dysport dose 46 +/- 22 MU. The therapeutic effect started after 7.1 +/- 2.3 days and lasted for 12.5 +/- 3.9 weeks. It was stable throughout the observation period in 85% of all patients. Adverse effects occurred in 5.4% of injection series. No patient terminated treatment because of unsatisfactory results. Secondary therapy failure did not occur. With an effective conversion ratio of Botox:Dysport = 1:2.56 there were no differences between both drugs with respect to therapeutic efficacy and adverse effects thus confirming the hypothesis that there may not be intrinsic differences between both products.