J Korean Ophthalmol Soc.  2020 Feb;61(2):117-124. 10.3341/jkos.2020.61.2.117.

Clinical Manifestations and Computed Tomography Findings of Trapdoor Type Medial Orbital Wall Blowout Fracture

• Hwang SH
• Park SJ
• Chi M

• KMID: 2470733
• DOI: http://doi.org/10.3341/jkos.2020.61.2.117

Abstract

PURPOSE
To report the clinical manifestations and computed tomography (CT) findings of patients with a trapdoor type medial orbital wall blowout fracture.
METHODS
From March 2009 to October 2016, the clinical records and computed tomography findings of patients who underwent surgical treatment for a trapdoor type medial orbital wall blowout fracture were retrospectively analyzed.
RESULTS
A total of eight patients (six males and two females) were enrolled with a combined mean age of 14.4 years. Clinical manifestations were eyeball movement limitation (abduction and adduction) and ocular motility pain (eight patients, 100%), diplopia (seven patients, 87.5%), and nausea and vomiting (four patients, 50%). On CT, the distance from the orbital apex to the fracture site was an average of 22.0 mm and occurred in the middle position of the entire wall. Two patients had missed rectus completely dislocated into the ethmoid sinus through the fracture gap and six patients had definite involvement in the fracture gap and edema of the medial rectus muscle. The medial rectus muscle cross-sectional area was 47.7 mm² which was edematous compared to the contralateral eye (40.1 mm²). Orbital wall reconstruction was performed an average of 4.1 days after the injury. In all patients with oculocardiac reflex-like nausea and vomiting immediately improved after surgery. Six out of eight patients who had eyeball movement limitations (abduction and adduction) preoperatively showed adduction limitation after surgery. The eyeball movement limitation and diplopia disappeared 11.7 days and 46.7 days after surgery, respectively.
CONCLUSIONS
Patients with trapdoor type medial wall blowout fracture showed characteristic computed tomographic findings and clinical manifestations such as eyeball movement limitation, ocular motility pain, diplopia, and oculocardiac reflex. An understanding of clinical findings and quick surgical treatment are therefore required. The type of eyeball movement limitation was abduction and adduction limitation preoperatively and adduction limitation postoperatively.

Keyword

Computed tomography; Trap-door type medial orbital wall blowout fracture

MeSH Terms

Diplopia
Edema
Ethmoid Sinus
Humans
Male
Nausea
Orbit*
Reflex, Oculocardiac
Retrospective Studies
Vomiting

Figure

• 

  Figure 1 Preoperative computed tomography findings on axial view and measurements. ‘A’ means full length of medial orbital wall, ‘B’ means length from orbital apex to the center of medial wall fracture. ‘C’ indicated virtual full length of medial rectus muscle, and ‘D’ indicated length from the equator to trapped medial rectus muscle. ‘B/A’ shows ratio for comparing fracture site, ‘C/D’ shows ratio for comparing site of trapped muscle.

• 

  Figure 2 Computed tomography findings of left trap-door type medial blowout fracture patient. (A) True missing rectus. (B) Definite trap-door type.

• 

  Figure 3 Schematic configuration of the fracture size on the coronal view of computed tomography. ‘A’ means diagonal length (arrow) at the location of the largest fracture cut, ‘B’ means diagonal width by counting the number of fracture cuts. For example, if the interval between each cut were 2 mm and the number of fracture cuts were 8, the diagonal width would be 14 mm (2 mm × [8-1]).

• 

  Figure 4 Eleven-year-old male patient with left trap-door type medial blowout fracture. (A) A left eyeball movement had limitations on adduction with grade 3 (arrow) and abduction with grade 2 after trauma. (B) An adduction limitation on left eye was still observed (arrow) but abduction limitation was not shown after emergency operation. (C) On postoperative day 19, left eyeball movement was nearly full on both directions. (D) Computed tomography findings after trauma showed ‘true missing rectus’ on his left eye (arrow). (E) Computed tomography after emergency operation showed well-restored medial rectus muscle.

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