ondarily sti .

clinical disorder whose clinical definition has evolved in

■ Neuromuscular features may vary between orbits

the recent literature. Minimum criteria include congeni-

of the same patient, and among patients with

tal facial palsy with impairment of ocular abduction

6

identical genetic CCDDs.

[54–56]. The wide clinical spectrum and multiple areas

■ High-resolution imaging of EOMs and their

of brainstem involvement in patients with Moebius syn-

peripheral innervation can be clinically valuable

drome have led to its early conceptualization as a devel-

for strabismus management in CCDDs.

opmental disorder of the brainstem, rather than an

isolated cranial nerve developmental disorder [56].

However, Moebius syndrome may present with total

facial paralysis and complete external ophthalmoplegia,

where MRI demonstrates a normal brainstem and suba-

6.6.5 Moebius Syndrome

rachnoid portions of motor cranial nerves innervating

Moebius syndrome typically presents as a sporadic trait

the orbit, but marked hypoplasia of the deep portions of

with

congenital facial (CN7) palsy and abduction

the EOMs.