5.2  Skull Base Fractures/Meningeal

Injuries

Nearly 5–20% of all cranio-cerebral injuries (CCIs) are associated with skull base fractures (Dietz 1970a, b; Loew et al. 1984; Ommaya 1985; Founier 2007).

Depending on the trauma mechanism, one can distinguish open and closed cranio-cerebral traumas. If the dura mater is intact, the injury is defined as a closed or “covered” injury. If there is a laceration of the meninges or the sinus system, one speaks of an open brain lesion. An open brain lesion, caused by penetration or by tearing of the meninges, results in a liquor fistula (Schaller 2003).

5.2.1  Frequency

The literature states that in 3–11% of the anterior skull base fractures there are additional meningeal lesions with subsequent loss of cerebro-spinal fluid (CSF leakage) (Boenninghaus 1971; Ommaya 1985; Dagi and George 1988; Schmidek and Sweet 1988; Schroth et al. 1998, 2004).

The collateral swelling can obliterate an existing dura laceration in skull base injuries. In this case, a primary loss of cerebro-spinal fluid is clinically nondetectable (Ernst et al. 2004). One can overlook the loss of cerebro-spinal fluid due to traumatic obliteration by blood clots, bone fragments or by trapped brain tissues (Dietz1970a,b;Strohecker1984;ProbstandTomaschett 1990).

With 18% vs 86% there is statistical evidence for a striking discrepancy between the immediately clinically evident meningeal injuries and the intraoperatively detected actual meningeal lacerations (Dietz 1970a, b; Strohecker 1984; Dietrich et al. 1993; Kral et al. 1997 (96% -intraoperative). Considering the fact that patients with serious cranio-cerebral trauma are often admitted when intubated, it is very difficult to clinically detect a cerebro-spinal leakage in the emergency room.

5.2.2  Localization

A disruption of the meningeal tissues is most likely in the anterior cranial fossa where the dura is rigidly fixed to the cribriform plate, in the posterior wall of the frontal­ sinus and the posterior part of the roof of the ethmoid bone.

The meningeal tissues are also very vulnerable at the rigid dura attachment at the top of the sphenoid sinus and at the temporal part of the roof of the orbit (Kretschmer 1978; Ernst et al. 2004).

Isolated skull base fractures in combination with dural injuries occur most often in the region of the ethmoid and cribriform plate, followed by fractures of the orbital roof and the posterior wall of the frontal sinus (Probst 1986; Probst and Tomaschett 1990; Kocks 1993).

Depending on the severity and the extension of the cranial injury, multiple dura disruptions can occur.

Localization of skull base fractures in cerebro-cranial trauma (Probst 1986)

5.3  Midface: Skull Base Fractures

A statistical survey from craniofacial trauma centers presents extensive evidence of combined midface and skull base fractures depending on the severity and extension of the injury (Hausamen and Schmidseder 1975; O Brian and Reade 1984; Jacobs 1984; Manson et al. 1987; Brachvogel et al. 1991; Schilli and Joss 1991; Wahlmann and Wagner 1991; Haug et al. 1992; Denneke et al. 1992; Hardt et al. 1990; Raveh et al. 1992; Schroeder 1993; Weerda 1995; Hausamen and Schmelzeisen 1996; Koch and Lehnhardt 2000; Joos et al. 2001; Mc Mahon et al. 2003).

• Skull base fracture diastasis in craniofacial fractures

Vajda et al. (1987) provided CT data on bone diastasis in different craniofacial fractures with dural injuries. They observed a diastasis of more than 6 mm in high midface/skull fractures (ESCHER type I) and a diastasis of less than 5 mm in central (cribriform plate, posterior ethmoid) midface fractures (ESCHER type II). In ESCHER type III fractures with disruption of the midface from the skull base, there was a median diastasis of 4.8 mm. In all combined midface and frontal skull base fractures, a mean bone dislocation of 5.7 mm, with a range of 3.2–12.8 mm, was found.

• Skull base fracture frequency in craniofacial fractures

The number of skull base fractures associated with complex midface fractures is significantly higher in