Pediatric emergency medicine trisk 0590 0590
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The action of a muscle may also be impaired by restriction. The muscle can
become infiltrated with substances that might restrict its action or cause fibrosis.
Children with hyperthyroid eye disease (e.g., Graves) can have enlarged, tight eye
muscles, which along with infiltrate to the periorbital fat, contribute to proptosis.
An eyeball may be restricted in its movements by tumors or infection in and
around the globe. Orbital tumors, cellulitis, or abscesses that cause restriction
may be associated with proptosis or a displacement of the entire eyeball, either
vertically or horizontally. With blunt trauma to the eyeball, the globe may be
translocated posteriorly, causing increased intraorbital pressure that may result in
a “blowout” fracture of the bony orbital wall. When an orbital wall fracture
occurs, the muscle or surrounding tissues that run along that wall may become
entrapped within that fracture, tethering the eyeball so the eye cannot look in the
direction opposite the fracture. Children with orbital floor or medial orbital wall
fractures are prone to entrapment of the inferior or medial rectus muscles,
respectively. This may not be noticeable until eye movements are attempted. For
example, fractures of the orbital floor may entrap the inferior rectus muscle,
tethering the eye downward and thereby restricting upgaze ( Fig. 28.4 ). Less
commonly, the eye may have a limitation of movement in the direction of the
fracture. Orbital wall fractures may also be associated with enophthalmos, in
which the eye appears to be sunken in the orbit, or proptosis caused by retroorbital hemorrhage. All patients with orbital fractures must receive a complete
ophthalmic examination to rule out accompanying ocular injury. The most
common fracture involves the inferior and/or medial walls of the orbit. The lateral
wall is rarely fractured. Fracture of the superior wall (orbital roof) is particularly
worrisome because it may allow communication between the orbit and the
subfrontal intracranial space.
