Perforation of the Glenoid Fossa into the Middle Cranial Cavity
Pathophysiology of the Complication
The glenoid or mandibular fossa is a depression in the inferior surface of the squamous part of the temporal bone at the base of the zygomatic process, in which the condyle of the mandible rests. The middle cranial fossa lies directly above and contains the temporal lobe.
The thin roof of the glenoid fossa (GF) separates the joint space from the middle cranial fossa (Figs. 4.6 and 4.7). Cadaveric studies, in which the fossa thickness was
Fig. 4.6 TMJ arthroscopy in a cadaver (cranial vault and brain removed), showing the close relationship between the TMJ and the middle cranial fossa and demonstrating the translucency of the thin glenoid fossa after insertion of the arthroscope
Fig. 4.7 Illustrates the thin roof of the glenoid fossa from a sagittal perspective
measured, show a mean thickness of 0.61 mm with a range of 0.2-1.5 mm in normal joints with intact discs and no osteoarthritis [13, 14]. According to radiographic studies, the GF has been shown to have a mean thickness of 1.22 mm (range
0.5-3 mm) on cone beam computed tomography and a mean thickness of 1.46 mm (0.84-3.57 mm) on magnetic resonance imaging, as it also included thickness of cartilage and periosteum as well as bone [13, 15]. It has also been reported that there may be preexisting anatomic defects in the GF .
The intraoperative risk of perforation through the glenoid fossa into the middle cranial fossa is a major concern during both open and arthroscopic surgery. Perforation into the middle cranial fossa has been reported in the literature as a complication of arthroscopic surgery [16-19]. The thin roof of the glenoid fossa can be readily appreciated in a cadaveric specimen undergoing arthroscopy (Fig. 4.6) and with histological specimens (Fig. 4.7).
The risk of injury to the middle cranial fossa contents is rare but has been reported [16, 17, 19-22]. The middle meningeal artery crosses the floor of the middle cranial fossa directly above the roof of the GF, between the bone and the dura. The anterior-posterior distance from the peak height of the glenoid fossa to the middle meningeal artery is on average 2.4 mm (-2 to 8 mm) . Extradural hemorrhage from the middle meningeal artery may occur if the roof of the glenoid fossa is perforated and the artery is injured. Its location within the cranial cavity means that if hemorrhage does occur, it may not be recognized and it is impossible to access from the glenoid fossa. Iatrogenic perforation of the roof of the glenoid fossa can also result in a dural tear and possible exposure of the temporal lobe of the brain resulting in a cerebrospinal fluid (CSF) leak. Arthroscopic irrigation fluid can also enter the middle cranial fossa via a perforation through the roof of the glenoid fossa and may result in symptoms associated with increased intracranial pressure, such as headache, nausea, and vomiting . This can be a difficult to diagnose especially since these symptoms can also be associated with the side effects of general anesthesia (Fig. 4.8).
Fig. 4.8 Postoperative extradural hematoma following TMJ arthroscopy. Note the heterogeneous density of the collection, indicating a combination of blood and irrigation fluid
Sequelae of Perforating into the Middle Cranial Fossa
- • Arthroscopic irrigation fluid enters the cranial cavity (may be extradural or subdural).
- • Bleeding or hemorrhage as a result of injury to the middle meningeal artery.
- • Puncture/tear of the dura mater of the temporal lobe.
- • Cerebrospinal fluid leakage.
- • Extradural or subdural hematoma.
- • Injury to the temporal lobe.