Apport de l’IRM dans le syndrome de Stilling-Duane : résultats préliminaires

MRI evaluation of cranial nerve abnormalities and extraocular muscle fibrosis in duane retraction syndrome and congenital extraocular muscle fibrosis

PURPOSE

To investigate the alterations in extraocular muscles (EOMs) by magnetic resonance imaging (MRI) among patients diagnosed with Duane retraction yndrome (DRS) and congenital fibrosis of the extraocular muscles (CFEOM), who present with various cranial nerve anomalies in an attempt to enhance the clinical diagnostic process.

METHODS

A case-control study was conducted to evaluate 27 patients with DRS and 14 patients with CFEOM. All patients underwent MRI scans of the brainstem and orbital examination. Neurodevelopmental assessments were conducted through MRI, and maximum cross-sectional area and volumes of EOMs were obtained. Three types of models were constructed using machine learning decision tree algorithms based on EOMs to predict disease diagnosis, cranial nerve abnormalities, and clinical subtypes.

RESULTS

Patients with bilateral CN VI abnormalities had smaller volumes of LR, MR, and IR muscles compared to those with unilateral involvement (P < 0.05). Similarly, patients with CFEOM and unilateral third cranial nerve abnormalities had a smaller maximum cross-section of the affected eye's SR compared to the contralateral eye (P < 0.05). In patients with both CN III and CN VI abnormalities, the volume of SR was smaller than in patients with CN III abnormalities alone (P < 0.05). The prediction model using EOMs volume showed a diagnostic precision of 82.5% for clinical cases and 60.1% for predicting cranial nerve abnormalities. Nonetheless, the precision for identifying clinical subtypes was relatively modest, at only 41.7%.

CONCLUSION

The distinctive volumetric alterations in EOMs among individuals exhibiting distinct cranial nerve anomalies associated with DRS or CFEOM provide valuable diagnostic insights into to Congenital Cranial Neurodevelopmental Disorders (CCDDs). MRI analysis of EOMs should thus be regarded as a crucial diagnostic modality.

Imaging of congenital cranial dysinnervation disorders: What radiologist wants to know?

We aim to review the imaging features of congenital cranial dysinnervation disorders. Characteristic imaging findings can define subtypes of these disorders through assessment of cranial nerves, extraocular muscles, orbital, and brain abnormalities. Duane retraction syndrome shows absent or hypoplasic 6th cranial nerve and preserved extraocular muscles (EOM). Mobius syndrome shows absent 7th and 6th cranial nerves, absence of facial colliculus, flattening of the dorsal aspect of the pons, hypoplasia of the pons and medulla, and flattening of the 4th ventricular floor. Congenital fibrosis of the extraocular muscles reveals unilateral or bilateral hypoplasia or aplasia of the 3rd cranial nerve, atrophy of superior rectus and levator palpebrae superioris muscles, and atrophy of the brainstem and cerebellar hemispheres. Horizontal gaze palsy and progressive scoliosis show characteristic split pons sign, butterfly medulla, absent facial colliculi, and spinal scoliosis. HOXA1 Mutations show a bilateral absence of 6th cranial nerves with the underdeveloped inner ear. Pontine Cap Tegmental Dysplasia shows ventral pontine hypoplasia, dorsal tegmental projection into the 4th ventricle, and variable cranial nerve deficits.

Duane type I retraction syndrome associated with Wyburn-Mason syndrome

PURPOSE

Our aim is to report the co-existence of Duane's retraction syndrome and Wyburn-Mason syndrome, a rare condition characterized by arteriovenous malformations (AVMs) in the central nervous system and retina.

METHODS

An 11-year-old boy was referred for evaluation of strabismus present since birth. On examination his uncorrected visual acuity was 6/6 in each eye, with small angle left eye esotropia in the primary position, ipsilateral face turn, abduction deficit, lid fissure narrowing in adduction and widening in abduction; plus typical features of left-sided type I Duane syndrome were present. The left fundus demonstrated localized, well-compensated, markedly convoluted, dilated and tortuous retinal vessels and venous congenital retinal macrovessel, which traverse the macular region. The right fundus was unremarkable. In order to elucidate if this retinal vascular malformation is associated with similar lesions in the orbit, paranasal sinuses and/or brain, magnetic resonance imaging (MRI) was performed, followed by digital subtraction angiography of the brain vessels.

RESULTS

Clinical features of retinal disease (typical retinal vascular malformation) and brain imaging studies have led to the diagnosis of Wyburn-Mason syndrome. Digital subtraction angiography of the brain revealed an AVM of 30 mm maximal diameter in the left occipital lobe.

CONCLUSIONS

Intracranial AVM might have affected the normal vascular development during the second month of gestation, causing involutional changes of the sixth nerve and resulted in Duane's syndrome by "steal phenomenon." Retinal AVM may point to concomitant intracranial AVMs, thus warranting neurological assessment. Patients with AVM of the retina should be examined early with brain and orbital neuroimaging to rule out cerebral AVMs.

Imaging findings in congenital cranial dysinnervation disorders

In 2002, the term congenital cranial dysinnervation disorders (CCDDs) was proposed to group heterogeneous syndromes with congenital abnormalities of ocular muscle and facial innervations. The concept of neurogenic etiology has been supported by discovery of genes that are essential to the normal development of brainstem, cranial nerves, and their axonal connections. The CCDDs include Duane retraction syndrome, congenital fibrosis of the extraocular muscles, Möbius syndrome, horizontal gaze palsy with progressive scoliosis, the human homeobox-related disorders, pontine cap tegmental dysplasia, and an expanding list. The purpose of this review was to update the imaging features, as well as clinical and genetic information, regarding cases of CCDDs.