Aberrant Abducent Nerve During Microvascular Decompression for Trigeminal Neuralgiass.

BACKGROUND: Microvascular decompression (MVD) is a commonly performed procedure to treat trigeminal neuralgia and hemifacial spasm. Knowledge of the variable anatomy of the cerebellopontine angle is crucial to avoid injury to cranial nerves. CASE DESCRIPTION: A 76-year-old lady with right V1 (ophthalmic division of the trigeminal nerve) and V2 (maxillary division of the trigeminal nerve) trigeminal neuralgia, refractory to medical treatment, underwent elective MVD. Intraoperatively, a distorted course of the cisternal component of the abducent nerve was noticed, caused by an ectatic anterior inferior cerebellar artery. Careful mobilization of the offending vessel to decompress the trigeminal nerve was carried out; however, abducent nerve decompression was not attempted since its function was not compromised. Facial pain resolved postoperatively without new diplopia. CONCLUSIONS: Careful review of imaging before surgery is recommended in order to preempt such unusual anatomic variations.

Síndrome de Pierre Robin associada à Síndrome de Duane familiar do tipo III / Pierre Robin Syndrome associated with type III familial Duane Retraction Syndrome

Resumo A síndrome de Pierre Robin (PRS) consiste em uma tríade de anomalias caracterizada por micrognatia, glossoptose e fissura de palato, comumente associada com outras síndromes e ocasionalmente com alterações oculares. Na Síndrome de Duane (DRS), há uma falha na inervação do reto lateral pelo VI nervo, com inervação anômala do reto lateral por fibras do III nervo. Ainda que a PRS já tenha sido associada com mais de 50 outras síndromes, não existe na literatura relato de casos de associação com a DRS familiar. Dessa forma, esse trabalho tem por objetivo relatar um caso dessa associação em um paciente de 29 anos com recorrência das síndromes na família.

Abstract The Pierre Robin Syndrome (PRS) consists of a triad of anomalies characterized by micrognathia, glossoptosis and fissure of the palate, usually associated with other syndromes e occasionally associated with ocular variations. In Duane Retraction Syndrome (DRS), there is a failure in the lateral rectus innervation by the VI cranial nerve, with anomalous innervation of the lateral rectus by fibers of the III nerve. Even though PRS has already been associated with more than 50 other syndromes, there is not any report in literature of association with familial DRS. Thus, this work aims to report a case of this association in a 29 years old patient with recurrence of the syndromes in the family.

Bilateral duplication of the abducens nerve - case study.

The abducens nerve is characterized by a long intracranial course and complex topographical relationships. Anatomical knowledge may help to understand both the etiology and clinical symptoms of abducens nerve palsy. Typically, the single trunk of the abducens nerve travels on both sides. However, occasionally different variants of unilateral or bilateral duplications of the abducens nerve may be observed. The presented paper is a detailed anatomical description of bilateral duplication of the abducens nerve, with atypical appearance of the nerve in the cavernous sinus and normal distribution within the lateral rectus muscle on both sides of one cadaver. On the right side both trunks of the abducens nerve fused within the subarachnoid space and pierced the dura mater together. On the left side both trunks of the duplicated abducens nerve pierced the dura mater separately, entered the petrous apex separately and fused just below the petrosphenoidal ligament. Within the cavernous sinus the nerve divided once again into two filaments, which reunited into one trunk a er crossing the horizontal segment of the intracavernous part of internal carotid artery. The orbital segments of the abducens nerve showed a typical course on both sides. Duplication of the abducens nerve is anatomical variation which should be taken into account during diagnostic and surgical procedures performed within the petroclival region and cavernous sinus.

Supernumerary Abducens Nerves: A Comprehensive Review.

BACKGROUND: Branching and/or replication of the abducens nerve is not an uncommon occurrence. Although numerous variations have been documented, the rarest forms are duplicated or triplicated nerves, where multiple nerve roots originate from the brainstem, travel intracranially, and attach to the lateral rectus as separate entities. METHODS: We conducted a systematic literature search on the topic of supernumerary abducens nerve, using PubMed and Google Scholar. RESULTS: After screening, 16 studies were included: 11 cadaveric studies and 6 case reports. CONCLUSIONS: In this paper, we review the literature on variations found, discuss current hypotheses and clinical relevance, and propose future studies. Neurosurgeons should be aware of such nerve variants when viewing imaging or operating in the regions traversed by the abducens nerve.

Estudio clínico, citogenético, molecular y de imagen de los pacientes con síndrome de Moebius del Hospital General 'Dr Manuel Gea González', Ciudad de México / Clinical, cytogenetic, molecular and image study of patients with Mobius syndrome at the General Hospital 'Dr Manuel Gea González', Mexico city

Introducción y Objetivo. El síndrome de Moebius es un trastorno congénito poco frecuente con prevalencia menor del 0.05%, caracterizado por parálisis facial congénita asociada a ausencia de abducción de los ojos por alteraciones del VI y VII nervios craneales, ya sea simétrica o asimétrica. La etiopatogenia cuenta con diferentes hipótesis: genética, vascular y teratógena. Existen pocos reportes en la literatura, y en especial en la latinoamericana, que describan las características clínicas y genéticas de estos pacientes. El presente estudio es el resultado del desarrollo de un equipo multidisciplinario en nuestro centro hospitalario para la descripción del espectro completo de la patología y así poder ofrecer los mejores tratamientos para cada uno de nuestros pacientes. Material y Método. Analizamos 115 pacientes con diagnóstico de síndrome de Moebius en sus 3 presentaciones: Moebius clásico, Moebius incompleto o Moebiuslike. Todos fueron sometidos a exploración física completa por un equipo multidisciplinario formado por ortopedistas, oftalmólogos, otorrinolaringólogos, ortodoncistas, neurólogos, pediatras, genetistas y cirujanos plásticos. Realizamos cariotipos a todos los pacientes para identificar anormalidades estructurales cromosómicas y enviamos muestras al Instituto Nacional de Medicina Genómica (INMeGen) para análisis molecular de cada paciente e identificación de posibles genes involucrados. Resultados. Un total de 52 pacientes (45%) fueron varones y 63 (55%) mujeres. Las manifestaciones clínicas fueron parálisis facial unilateral o bilateral con involucro de la abducción de los ojos en el 100%, asociada con estrabismo en el 62.6%, pie equino varo en el 46.1%, sindactilia simple 15.7%, paladar hendido 17.4%, micrognatia 17.4%, y síndrome de Poland 9.6%, entre otras manifestaciones. El análisis citogenético reportó 114 cariotipos de características estructurales normales y 1 solo caso de translocación recíproca balanceada entre el cromosoma 4 y 10. Dieciséis casos se asociaron a consumo materno de misoprostol en el primer trimestre del embarazo. El análisis molecular no se pudo concretar debido a falta de recursos materiales del INMeGen. Conclusiones. Hasta la fecha, y hasta donde hemos podido comprobar, esta es la cohorte de pacientes con síndrome de Moebius más grande reportada a nivel mundial en un solo centro hospitalario. La variabilidad de las presentaciones clínicas justifica el manejo por un equipo multidisciplinario tanto para el paciente como para los familiares. Este estudio abre las puertas para un campo de investigación mayor que nos pueda llevar a entender mejor la fisiopatología, intentar estableces causalidad y por lo tanto poder ofrecer mejores tratamientos, integrales y reproducibles (AU)

Background and Objective. Möbius syndrome is a rare congenital disease characterized by facial paralysis associated with an absence of abduction of the eyes for abnormalities in VI and VII cranial nerves. The pathogenesis has different hypothesis that include genetic, vascular and teratogenic causes. There are few reports in the literature and especially in Latin America to describe the clinical and genetic characteristics of these patients. The current study is the result of a multidisciplinary team developed in our center to describe the wide spectrum of the disease and offer the best treatment options to each of our patients. Methods. We analyzed 115 patients with the diagnosis of Möbius syndrome in its 3 presentations. All patients underwent a complete clinical examination by a multidisciplinary team formed by orthopedist, ophthalmologist, otolaryngologist, orthodontist, neurologist, plastic surgeon, pediatrician and geneticist. They underwent CTG banded karyotype to identify structural chromosome abnormalities. Results. Fifty two patients (45%) patients were male and 63 (55%) female. Clinical manifestations were found with unilateral or bilateral facial paralysis with VI nerve involvement in 100% of patients, associated with strabismus in 62.6%, 46.1% clubfoot, simple syndactyly 15.7%, 17.4% cleft palate, micrognathia 17.4%, Poland syndrome 9.6%, among others. Cytogenetic analysis showed normal karyotype in 114 patients and a reciprocal translocation between chromosome 4 and 10 in 1 patient. Sixteen cases of reported intake of misoprostol during the first trimester. Conclusions. As far as we know, this study is the largest global cohort reported in a single hospital of patients with Möbius syndrome. Variability of the clinical presentation justifies the management of these patients is a multidisciplinary team. This study opens the door for new studies that allow us to understand the pathophysiology of this disease and its response to different treatments (AU)

Postoperative full abduction in a patient of Duane retraction syndrome without an abducens nerve: a case report.

BACKGROUND: Duane retraction syndrome (DRS) consists of abduction deficit, globe retraction and upshoots or downshoots with adduction. The abducens nerve on the affected side is absent in type 1 DRS. After bilateral medial rectus muscle recession in unilateral type 1 DRS may improve the abduction limitation, but still more than -3 limitation remains. CASE PRESENTATION: A 6-month-old boy presented with esotropia which had been noticed in early infancy. He showed limited abduction, fissure narrowing on attempted adduction and a small upshoot OS. Left abducens nerve was not identified on magnetic resonance imaging compatible with Duane retraction syndrome type 1. He showed full abduction after bilateral medial rectus recession of 6.0 mm at the age of 9 months, and remained orthotropia with full abduction OU 2 years postoperatively. He is my only patient with Duane retraction syndrome who showed full abduction after bilateral medial rectus recession. CONCLUSIONS: A patient with the type 1 Duane retraction syndrome rarely may show full abduction after bilateral medial rectus recession mimicking infantile esotropia.

An unusual variant of the abducens nerve duplication with two nerve trunks merging within the orbit: a case report with comments on developmental background.

This study reports the first case of abducens nerve duplication along its entire intracranial course, ending within the orbit. A distinct abducens nerve duplication reaching the common tendinous ring (annulus of Zinn), as well as another split within the intraconal segment of the nerve have been revealed. Additionally, two groups (superior and inferior) of abducens nerve sub-branches to the lateral rectus muscle were visualised using Sihler's stain. The analysed anatomical variation has never been reported before and it seems to be in the middle of the spectrum between the cases of duplication occurring only within the intracranial segments of the abducens nerve found in the literature and those continuing throughout the whole course of the nerve. Abducens nerve duplication may be treated as a relic of early stages of ontogenesis. Such a variant might result from alternative developmental pathways in which axons of the abducens nerve, specific for a given segment of the lateral rectus muscle, run separately at some stage, instead of forming a single stem.

Bilateral duplication of the abducens nerves: an incidental finding on magnetic resonance imaging.

Although anomaly of the abducens nerve, including duplication, has been reported in anatomical papers, no radiological report exists regarding a duplicated abducens nerve observed on magnetic resonance (MR) imaging. We encountered a case of bilateral duplication of the abducens nerves, which was found incidentally on MR scans from an 11-year-old boy. He did not have any symptoms of eye movement related to abducens nerve abnormality; thus, the duplication was considered to be a normal variant in this patient. Radiologists should be aware that duplication of the abducens nerve may occur and can be diagnosed on MR, particularly when diagnosing symptomatic patients or as a preoperative assessment for microsurgery of the nerve.

Magnetic resonance imaging in congenital Brown syndrome.

AIMS: Our aim was to elucidate the etiology of Brown syndrome by evaluating the trochlea position, morphologic characteristics of the extraocular muscles including superior oblique muscle/tendon complex, and the presence of the cranial nerves (CN) III, IV, and VI using magnetic resonance imaging (MRI) in eight patients with unilateral congenital Brown syndrome and one patient with bilateral congenital Brown syndrome. METHODS: Nine consecutive patients diagnosed with congenital Brown syndrome had a comprehensive ocular examination and MRI for the CN III, CN VI, and the extraocular muscles. Five of the nine patients underwent additional high resolution MRI for CN IV. The distance from the annulus of Zinn to the trochlea was measured. RESULTS: Normal sized CN III, IV, and VI, as well as all extraocular muscles, could be identified bilaterally in all patients with available MRI. The distance from the annulus of Zinn to the trochlea was the same in both eyes. CONCLUSIONS: The findings for our patients, particularly in those who underwent additional high resolution MRI, did not provide evidence of a lack of CN IV as a cause of Brown syndrome.

MRI findings in Duane's ocular retraction syndrome.

AIM: To investigate the innervation pattern of extra-ocular muscles in patients with clinically diagnosed Duane's ocular retraction syndrome (DRS) using magnetic resonance imaging (MRI). MATERIALS AND METHODS: The study population consisted of 11 patients. Six patients had type I DRS (eight eyes), four patients had type II DRS (five eyes) and one patient had inverse DRS. Images were acquired using a Siemens 3 T MRI system. The type of DRS, corresponding innervation findings, and condition of the affected muscles were evaluated by two experienced neuroradiologists in consensus. RESULTS: All patients with clinically diagnosed DRS type I showed absence of the abducens nerve (CN6), hypoplasia of the superior oblique muscle (SOM), and aberrant innervation of lateral rectus muscle (LRM) by an extra branch of oculomotor nerve (CN3). All patients with type II DRS show dual-innervation of the LRM (by CN6 and an aberrant CN3 branch) and hypoplasia of SOM. The single patient with inverse DRS showed hypoplasia of CN3, the medial rectus muscle (MRM), the inferior rectus muscle (IRM), and the inferior oblique muscle (IOM). CONCLUSION: Each type of DRS has characteristic MRI appearances. Therefore, MRI is a useful diagnostic tool for the confirmation and classification of suspected cases of DRS.

Magnetic resonance imaging findings of the abducens nerves in type 1 Duane's retraction syndrome.

PURPOSE: To investigate nervus abducens and extraocular mucles in patients with Type 1 Duane's retraction syndrome using high-definition magnetic resonance imaging. METHODS: The study included 10 patients with Type I Duane's retraction syndrome who underwent magnetic resonance imaging (MRI) of the brain and orbits. RESULTS: Overall, 10 cases were included in the study. There were seven women and three men. The mean age was 5.2 years (1-15 years). MRI of the abducens nerve was performed in all cases. Of the cases, the left eye was involved in eight cases, whereas the right eye was involved in two cases. There was no bilateral eye involvement. Among the 10 patients clinically diagnosed as Type 1 Duane's retraction syndrome, the abducens nerve could not be visualized in eight cases, whereas the nerve was hypoplastic in one case and bilateral abducens nerves were present in one case by MRI. The extraocular muscles were normal in all cases on T2 weighted coronal MRI of the orbits. CONCLUSION: Absence of abducens nerve and normal extraocular muscles was detected in patients with Type 1 Duane's retraction syndrome at the affected side.

Thromboembolism and congenital malformations: from Duane syndrome to thalidomide embryopathy.

OBJECTIVE: To propose a pathophysiologic mechanism to unify a variety of disparate sporadic congenital malformations. METHODS: Inductive and deductive analyses to correlate malformation laterality with asymmetries in thoracic anatomy, critical analysis of malformations with female predominance, and concepts of hydrodynamic pressure gradients in vascular growth were applied to the ensuing development of guiding tissue scaffolds for cellular proliferation, differentiation, and apoptosis. RESULTS: Duane syndrome may develop following a focal vascular insult to the sixth nerve trunk with axonal degeneration, allowing for substitutive innervation from third nerve axons to the lateral rectus muscle. Causative fibrin clots may originate from the venous system and paradoxically migrate through physiological right-to left shunts, or they may arise directly from the heart. Hence, the unilateral, left-sided, and female predominance of Duane syndrome results from the asymmetry in the thoracic anatomy and from thrombosis risk factors. Embolic occlusions may also alter local hemodynamic pressure gradients, leading to the compensatory enlargement and persistence of the fetal vasculature and may dysregulate tissue growth. Within the eye, this results in forms of Peters anomaly, unilateral congenital cataracts, and the morning glory disc anomaly, all in the vascular territory of the carotid arteries that also share a propensity for left-sided involvement in girls. Most aberrant misinnervation phenomena (eg, jaw-winking syndrome, crocodile tear syndrome, Brown syndrome, and congenital fibrosis syndrome) and, by extrapolation, the hypoplasia or dysgenesis of noncephalic anatomical structures (including limbs) may be similarly explained. Such malformations will occur more frequently under thrombogenic conditions, such as those induced by thalidomide. CONCLUSIONS: Fibrin emboli and focal hypoperfusion may explain the development of many sporadic congenital malformations.

Trigemino-abducens synkinesis after lateral orbitotomy.

A 30-year-old man underwent lateral orbitotomy with removal of dermoid cyst in the right orbit. One month after operation, the patient started to experience double vision. He had 25 prism diopters of esotropia in primary gaze with marked limitation of abduction in the right eye. Seven months after the operation, he developed synkinetic movement of the eye when clenching his teeth. He could abduct his right eye while gritting his teeth. This is the fourth reported case of trigemino-abducens synkinesis and the first reported case without brain trauma.

Moebius syndrome and hydrosyringomyelia: description of a new association.

The diagnosis of Moebius syndrome, a rare congenital disorder, is primarily based on congenital facial and abducent nerve palsy. Involvement of other cranial nerves is also common. Occasionally the V, X, XI, and XII cranial nerves are involved, resulting in a difficulty to chew, swallow, and cough, which often leads to respiratory complications. Mental retardation and autism have been reported in some cases. Moebius syndrome can be associated with orofacial anomalies and limb malformations. The authors describe a patient with a confirmed diagnosis of Moebius syndrome associated with hydrosyringomyelia. No case of Moebius syndrome involving primarily the spinal cord has been reported so far. This patient did not present with other factors directly linked to syringomyelia.

Expansion of the CHN1 strabismus phenotype.

PURPOSE: Hyperactivating CHN1 mutations have been described in individuals with Duane retraction syndrome with or without vertical gaze abnormalities. This was a study of five family members with distinctive ocular dysmotility patterns that co-segregated with a novel hyperactivating CHN1 mutation. METHODS: Participating members of a family segregating pleomorphic incomitant strabismus underwent ophthalmic examinations, and several underwent high-resolution magnetic resonance imaging (MRI) of the orbits and brain stem. Participant DNA was extracted and amplified for haplotype analysis encompassing the CHN1 region on chromosome 2q31.1, and mutation analysis of the CHN1 gene, which encodes the Rac-GAP signaling protein α2-chimaerin. In vitro functional studies of the co-inherited mutation were performed, including a Rac-GTP activation assay, quantification of α2-chimaerin translocation, and co-immunoprecipitation. RESULTS: All five clinically affected family members exhibited monocular or binocular supraduction deficits, three in the absence of Duane retraction syndrome. MRI in four affected individuals demonstrated small or absent abducens nerves in all four, small oculomotor nerve in one, and small optic nerves in three. Superior oblique muscle volume was also decreased in three of the individuals, supporting trochlear nerve hypoplasia. Strabismus segregated with the CHN1 locus and affected individuals harbored a c.443A>T CHN1 mutation (p.Y148F). In vitro, this novel mutation behaved similarly to previously reported CHN1 mutations underlying familial Duane syndrome, hyperactivating α2-chimaerin by enhancing its dimerization and membrane association and lowering total intracellular Rac-GTP. CONCLUSIONS: Analysis of the current pedigree expands the phenotypic spectrum of hyperactivating CHN1 mutations to include vertical strabismus and supraduction deficits in the absence of Duane retraction syndrome.