3.12\ Osteoplastic Flap with Frontal Sinus Obliteration

3.12.1\ Discussion

The osteoplastic flap is an option for treating chronic frontal sinusitis refractory to endoscopic surgery, mucopyocele, extensive fractures that obstruct the drainage pathways, and following resection of large tumors in the frontal recess region. The procedure consists of performing an osteotomy in the coronal plane to open the frontal sinus (Fig. 3.37). Typically, the sinus mucosa is removed and the frontal recess is packed with fat graft or other material, and the bone flap is then returned to its original position. Complications of the osteoplastic flap frontal sinus obliteration include retained secretions (Fig. 3.38); ­mucoceles (Fig. 3.39), which can result in mass effect upon the brain or orbital

(Fig. 3.41). While CT is useful for delineating the condition of the osteoplastic flap and associated hardware, MRI is useful for further characteriz-

ing the contents of the appearance of the surgical bed on MRI varies based on the contents as follows:

Central

High T2-weighted signal intensity, no enhancement: Secretions or fat

High T2-weighted signal intensity, enhancement: Granulation tissue or inflammation

Low T2-weighted signal intensity, no enhancement: Fibrosis or secretions

Low T2-weighted signal intensity, enhancement: Granulation or scar tissue

Peripheral

High T2-weighted signal intensity, no enhancement: Mucosa or fluid

High T2-weighted signal intensity, enhancement: Mucosa or granulation tissue

Low T2-weighted signal intensity, no enhancement: Fibrosis

Low T2-weighted signal intensity, enhancement: Granulation tissue and neovascularity

Fig. 3.38  Osteoplastic flap with retained secretions. Axial fat-suppressed T2-weighted (a), T1-weighted (b), and fat-suppressed post-contrast T1-weighted (c) MRI

images show extensive non-enhancing material within the frontal sinuses beneath the osteoplastic flap, as well as enhancing mucosa (arrow)

Fig. 3.40  Extruded packing material and inflammatory debris. The patient presented with forehead swelling after osteoplastic flap surgery. Axial CT image (a) shows a fragment of fat packing in the frontal subgaleal space (arrow) surrounded by soft tissue material. Sagittal

T1-weighted MRI (b) shows that the soft tissue (arrow) in the subgaleal space indeed communicates with the residual frontal sinus through the osteotomy. The soft tissue represents a mucocele with chronic inflammatory debris