Bilateral congenital absence of the abducens nerve

An Update on "Reverse Vaccinology": The Pathway from Genomes and Epitope Predictions to Tailored, Recombinant Vaccines

In this chapter, we review the computational approaches that have led to a new generation of vaccines in recent years. There are many alternative routes to develop vaccines based on the concept of reverse vaccinology. They all follow the same basic principles-mining available genome and proteome information for antigen candidates, and recombinantly expressing them for vaccine production. Some of the same principles have been used successfully for cancer therapy approaches. In this review, we focus on infectious diseases, describing the general workflow from bioinformatic predictions of antigens and epitopes down to examples where such predictions have been used successfully for vaccine development.

Association of lateral rectus muscle volume and ocular motility with the abducens nerve in Duane's retraction syndrome

PURPOSE

To investigate the relationship between ocular motility and lateral rectus (LR) muscle volume according to the presence or absence of the abducens nerve in patients with Duane's retraction syndrome (DRS) using high-resolution magnetic resonance imaging (MRI).

METHODS

A total of 54 unilateral DRS patients were divided into two groups according to high-resolution MRI findings: DRS without an abducens nerve on the affected side (absent CN6 group, n = 45) and DRS with symmetric abducens nerves on both sides (present CN6 group, n = 9). Ocular motility was measured by image analysis based on nine gaze photographs. LR volume was measured on T2-weighted coronal MRI of the orbit, and the ratio of paretic/normal side (P/N) LR volume was investigated. Association of the abducens nerve with various parameters including ocular motility, LR volume, and ratios of P/N LR volume were determined.

RESULTS

LR volume was smaller in the affected eye than the non-affected eye in both groups. In the present CN6 group, abducens nerve diameter and the ratio of P/N LR volume showed a positive correlation. A smaller LR volume and more limitation of abduction in the affected eye were predictive of an absent abducens nerve in DRS.

CONCLUSIONS

LR muscle hypoplasia was apparent in the affected eye of DRS patients. Abducens nerve diameter positively correlated with the ratio of P/N LR volume in the present CN6 group. Graphical abstract.

Congenital sixth nerve palsy with associated anomalies

Congenital abduction deficit is most likely due to Duane's retraction syndrome as congenital abducens nerve palsy is very rare. We report two cases of infantile abduction deficit due to sixth nerve palsy associated with other anomalies to highlight the importance of including neuroimaging in the evaluation of an infant presenting with a limitation of abduction.

Cervico-Oculo-Acoustic Syndrome in a Male with Consanguineous Parents

Background:

The cervico-oculo-acoustic syndrome comprises Klippel-Feil anomaly, sensorineural deafness and Duane's retraction syndrome. Polygenic, autosomal dominant, and X-linked inheritance have been hypothesized. The disorder has rarely been reported in males.

Case Report:

A 42-year-old male, born of consanguineous parents, presented with Duane's syndrome, mixed hearing loss, C2-C3 fusion, neck stiffness, and right facial palsy. A variety of cardiac, neurological and urogenital anomalies occurred in his relatives. The electro-oculographic studies showed impaired abduction and adduction of the right eye and impaired abduction of the left eye. Vergence, vertical eye movements and peripheral vestibular responses were normal. Somatosensory evoked potentials showed absence of the N13 peak and brainstem auditory evoked potentials bilateral delay of the I-III interpeak latencies.

Conclusions:

Consanguinity of the patient's parents, not previously reported, suggests autosomal recessive inheritance, but autosomal dominant inheritance is indicated by the family history. The pattern of the oculomotor deficit is consistent with bilateral dysplasia of the abducens nuclei with preserved internuclear neurons in the right abducens nucleus. Neurophysiological investigations revealed lower brainstem and cervical cord involvement.

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.

Development of the human abducens nucleus: a morphometric study

BACKGROUND

The abducens nucleus directly innervates the lateral rectus muscle and plays a role in controlling conjugate horizontal eye movements. Although the neuronal cytoarchitecture of the abducens nucleus has been extensively investigated in various species of vertebrates, few studies have been undertaken in humans, especially in fetuses or neonates.

DESIGN/SUBJECTS

We examined 12 human brains from preterm infants aged 20-43 postmenstrual weeks to document the histology and morphometry of the abducens nucleus. The brain was processed into celloidin-embedded serial sections stained with the Klüver-Barrera and other conventional methods.

RESULTS

The nucleus was identified as a mass of cells as early as 20 weeks. Its neurons were clearly distinguished from glial cells due to droplet-like, clear nuclei containing prominent nucleoli and surrounded by a basophilic perikaryon. Neurons of various sizes and shapes were intermingled within the nucleus, although larger neurons were located towards the center of the nucleus. Immature granular or reticular Nissl bodies were seen at 20-21 weeks. Tigroid, coarse Nissl bodies appeared around 28-29 weeks in larger neurons, although in smaller neurons Nissl bodies were dispersed or concentrated peripherally. Morphometric results were: (1) the nuclear volume exponentially increased with age between 20 and 43 weeks; (2) the histograms of neuronal profile areas showed a non-normal distribution trailing toward the right and widening with age; (3) the geometric average of neuronal profile areas increased linearly with age.

CONCLUSION

Our study suggests that the human abducens nucleus enlarges more quickly toward the end of gestation, and comprises heterogeneous groups of neurons.

Isolated sixth cranial nerve aplasia visualized with Fast Imaging Employing Steady-State Acquisition (FIESTA) MRI

An otherwise healthy 12-month-old girl presented for evaluation of reduced abduction of the left eye detected at 6 months of age. The remainder of the examination was unremarkable. A special MRI sequence-fast imaging employing steady-state acquisition (FIESTA)-visualized the right but not the left sixth nerve cisternal segment. This is the first reported use of the MRI FIESTA sequence to diagnose aplasia of the sixth cranial nerve.

Magnetic resonance imaging in Duane's retraction syndrome

PURPOSE

The aim of this study was to visualize the subarachnoid portion of the nervus abducens by magnetic resonance imaging and to analyze whether aplasia of the nervus abducens is an etiologic factor in Duane's retraction syndrome.

METHODS

We performed thin-sectioned magnetic resonance imaging across the brainstem level in 8 cases (11 eyes) that were clinically diagnosed as Duane's retraction syndrome. The same test was applied to 8 healthy control subjects to verify the accuracy of this technique.

RESULTS

The nervus abducens on the affected side could not be observed in 6 (54.5%) of 11 eyes (8 cases) that were clinically diagnosed as having Duane's retraction syndrome. The nervus abducens was observed in 15 (94%) of 16 eyes that were screened as the control group.

CONCLUSIONS

The results showed that aplasia of the nervus abducens, although an important etiologic factor, is not the only factor responsible for the diagnosis of Duane's retraction syndrome.

Absence of the abducens nerve in Duane syndrome verified by magnetic resonance imaging

PURPOSE

To demonstrate that currently available magnetic resonance imaging techniques may verify the absence of the abducens nerve in Duane syndrome.

METHODS

We performed magnetic resonance imaging in a 36-year-old woman with left Duane syndrome, type 1, using spoiled gradient recalled acquisition in the steady state to obtain high-resolution T1-weighted images through the abducens nerve in its subarachnoid segment. Scans were obtained in the axial plane from the medulla to the midbrain and then reformatted along the plane of the abducens nerve.

RESULT

Unilateral absence of the left abducens nerve was verified using magnetic resonance imaging.

CONCLUSION

The absence of the abducens nerve in Duane syndrome can be verified by modern magnetic resonance imaging techniques.

Bilateral abducens nerve lesions in unilateral type 3 Duane's retraction syndrome

Images

Duane's retraction syndrome

Duane's retraction syndrome (DRS) has been a recognized clinical entity for nearly a century. It is a clinically well described ocular disorder consisting of retraction of the globe with narrowing of the lid fissure in attempted adduction, frequent abduction deficiency with variable limitation to adduction, and upshoot and/or downshoot of the affected eye on adduction. Among strabismus patients the incidence of DRS is probably not more than 5%. Most cases are sporadic, but familial cases have been estimated at 10% by most authors. Numerous theories concerning the etiology and pathogenesis of DRS have been proposed, including agenesis of the abducens nucleus, but the majority of investigators concur that the characteristic findings are best explained by a paradoxical innervation of the lateral rectus muscle, which subsequently causes a cocontraction of the horizontal rectus muscles. The frequent association of DRS with other congenital anomalies suggests a teratogenic event occurring between the fourth to eighth week of gestation as an etiological factor. In this review historical aspects and theories of the syndrome are studied and statistical data are compiled and analyzed. Clinical features, differential diagnoses and variants of the syndrome are examined. Testing and treatment objectives are discussed.

Möbius and Möbius-like syndromes (TTV-OFM, OMLH)

There exists a spectrum of syndromes characterized by cranial nerve palsies, limb anomalies, and craniofacial malformations. Criteria based on type and severity of limb anomaly or presence or absence of cranial nerve palsy may alter the syndrome nomenclature due to a selection bias but do not appear to benefit syndrome delineation to any extent. Patients with seventh nerve palsy and abduction weakness are usually diagnosed as having Möbius syndrome by ophthalmologists. The observed ocular motility findings range from primarily abduction deficiencies to patients who have a Duane or gaze palsy pattern of horizontal movements. Some cases previously described as "sixth nerve and partial third" may better fall into one of the latter groups, since an isolated adduction deficit as a manifestation of third nerve involvement is rare. The presence of clinical appearance of Duane syndrome in these Möbius-type patients raises the possibility of abnormal innervation of the lateral rectus as an explanation of some patterns of motility observed.