Bone dehiscences of medial orbital wall on computed tomography and assessment of terminological errors in literature

The objective of this study is to investigate the position and frequency of dehiscences in the medial orbital wall and to reveal that dehiscences and orbital adipose tissue hernias are distinct entities.

Two hundred-thirty medial orbital walls of 115 patients with a preliminary diagnosis of headache and sinusitis but without active ethmoidal sinusitis were examined by computer tomography in the axial plane. Two separate radiologists assessed continuity of the medial orbital wall and orbital fat tissue herniation in ethmoid cells. The medial orbital wall was divided into four quadrants and the dehiscence distribution was evaluated.

Bone defects were detected in 71 (30.9%) patients in 230 orbital medial wall reviews of 115 patients (59 males, 56 females). Eight (3.5%) of these cases (4 male, 4 female) had herniation of the orbital adipose tissue into the ethmoid sinus. Of the 108 dehiscences, 47 were localised in the posterior upper quadrant. A statistically significant difference was found in the dehiscence distribution according to the quadrants. No significant relationship was found among age, gender, side of dehiscence and frequency of dehiscence.

Dehiscences in the posterior upper quadrant are more common in the medial orbital wall. Although bone dehiscences in the medial orbital wall and the herniation of the orbital fat tissue are two different entities, they are used interchangeably in most of the literature and in radiological reporting.