Pneumocephalus after Orbital Decompression Surgery for Thyroid Eye Disease

Implications of the olfactory fossa anatomy in intracranial complications of inferomedial orbital decompression

Two patients with thyroid eye disease underwent inferomedial orbital decompression complicated by a cerebrospinal fluid (CSF) leak. One of the cases developed a postoperative pneumocephalus resolved with conservative measures. In the second case, the CSF leak was managed intraoperatively. In both patients, a computed tomography (CT) scan revealed a pronounced slope of the lateral lamella of the cribriform plate, forming an obtuse angle with its lateral bony extension. When this anatomical disposition of the olfactory fossa (OF) is present, the course of the anterior ethmoidal artery (AEA) is usually embedded in the skull base, and its foramen should not be taken as the upper limit of the transconjunctival ethmoidectomy. The shape and relative height of the olfactory fossa and fovea ethmoidalis, and the course of the AEA should always be assessed before transconjunctival medial decompressions.

Position of the anterior ethmoidal foramen and trauma to the cranial base during transconjunctival medial orbital decompression: a systematic literature review

PURPOSE

To review the literature on the location of the anterior ethmoidal foramen (AEF) and trauma during transconjunctival medial wall decompression.

METHODS

A comprehensive literature search was conducted using the PubMed, Embase, and Scopus databases, combining the terms "olfactory fossa" and "fovea ethmoidalis" with "trauma," "cerebrospinal fluid leak," "pneumocephalus," "orbital decompression," and "anterior ethmoidal artery" (AEA). All cases of cranial base trauma during medial orbital decompression and the anatomical studies on the location of the AEF and the course of the AEA were reviewed.

RESULTS

Ninety-four articles were identified, of which 37 were related to the AEF, 41 reported the course of the AEA, and 16 to reported cases of cranial base trauma. Out of these cases, 10 were related to transconjunctival medial orbital decompression, affecting 11 patients. Most AEFs are situated at the frontoethmoidal suture, but up to 38.15% of AEFs are located above the suture on the frontal bone. Most AEFs are adjacent to the roof of the ethmoidal sinus. The distance of the AEF to the cranial base increases in the presence of supraorbital ethmoidal cells (SOEC).

CONCLUSIONS

The position of the AEF is variable and should not be considered a safe landmark for all patients.

Delayed Cerebrospinal Fluid Leaks Complicating Endoscopic Orbital Surgeries

OBJECTIVE

To report cerebrospinal fluid leak as an uncommon but noteworthy delayed complication after endoscopic orbital surgeries and to describe its incidence, mechanism, prevention, diagnosis, and management.

METHODS

Case series of 3 patients who underwent endoscopic orbital surgery in the Department of Ophthalmology, Shanghai Ninth People's Hospital affiliated to Shanghai JiaoTong University School of Medicine from January 2003 to December 2020. A review of the literature was also conducted.

RESULTS

Three cases of delayed cerebrospinal fluid leaks occurred 10 years, 3 months, and 4 months after endoscopic orbital surgeries, respectively, were reviewed and reported. Two patients developed cerebrospinal fluid leaks after surgical repair of orbital blowout fractures with titanium mesh and porous polyethylene (Medpor), respectively, and 1 patient developed cerebrospinal fluid leak after transantral optic canal decompression. In the first case, head computed tomography (CT) cisternography and magnetic resonance imaging confirmed the site of the leak that required surgical repair. In the second case, a coronal CT showed that the implanted titanium mesh was tightly against the cribriform plate, which might cause defect of skull base and dura. In the third case, orbital CT identified a dehiscence on the sphenoidal wall as the leak site, which was repaired in a secondary endoscopic surgery.

CONCLUSIONS

A cerebrospinal fluid leak, as an uncommon but noteworthy complication, can occur as delayed as 10 more years after surgery. For patients with specific anatomic characteristics, such as Kero type III, surgeons should perform meticulous preoperative evaluation and intraoperative procedures to prevent this complication.