- On the two lateral projections, which were made at slightly different degrees of obliquity, the ventral margin of the basisphenoid-basioccipital bones is focally markedly discontinuous, as characterized by the presence of a sharply marginated fracture, associated with the presence of a well-defined and fusiform osseous fragment. Poorly defined dorsal extension of the fracture into the calvarial vault is considered likely (yellow outline).
- Evaluation of the surrounding soft tissues is limited due to superimposition; however, thickening of the soft tissues in the dorsal pharyngeal wall is suspected.
- Within the guttural pouches, there is a homogeneous increase in soft tissue opacity.
Conclusions:
- Acute and traumatic comminuted basisphenoid-basioccipital fracture with probable intra-calvarial extension. An avulsion fracture at the insertion of the flexor muscles at the base of the skull (e.g. rectus capitis ventralis major, rectus capitis ventralis minor and longus capitis ventralis).
- Retropharyngeal soft tissue swelling (e.g. hemorrhage and/or edema) and guttural pouch fluid accumulation (likely hemorrhage).
Computed Tomography:
- As seen on the radiographs, there is a comminuted fracture involving the basisphenoid bone. An additional segmental fracture is identified in the right ventral caudal calvarium at the level of the jugular process. Medial to the petrous temporal bone on the left, a well-defined and severely comminuted fracture is identified. Immediately adjacent to this, there is gas dissection into the calvarium.
- A nondisplaced fracture line is seen in the ventral left cranial vault at the level of the temporomandibular joint.
- Soft tissue attenuating material fills the left tympanic bulla as well as the medial compartment of the left guttural pouch.
- There is severe soft tissue swelling in the region between the medial guttural pouches.
- There is also a large accumulation of subdural hemorrhage in the left cranial vault, which compresses the left cerebrum.
- Multiple irregular ill defined foci of hemorrhage are identified within the left cerebrum.
- Hemorrhage is also identified in the left caudal maxillary sinus and accumulated in the dependent portion of the right frontal sinus.
Magnetic Resonance Imaging:
A little bit more…
- Basilar skull fracture are most often secondary to rearing and flipping over backwards, with a subsequent direct impact on the poll of the head (Vitale et al.).
- More prevalent in young horses (less compliant) (Vitale et al.).
- Hyperextension of the head leads to contraction of the flexor muscles at the base of the skull (e.g. rectus capitis ventralis major, rectus capitis ventralis minor and longus capitis ventralis), resulting in possible fracture with or without displacement of fragments of the basisphenoid and basioccipital bones (Vitale et al., Ramirez et al., Beccati et al.).
- Clinical signs are variable and may include cranial nerve deficits, ataxia, seizure or reluctance to move head (Ramirez et al., Beccati et al.).
- Identification of basisphenoid-basioccipital fracture may be difficult with radiographs in the absence of displaced fragment. Computed tomography is preferred and allows for a better evaluation of the fracture extent (Vitale et al.).
- Prognosis depends on the extent of the fracture. A guarded prognosis is reported with more severe fractures, especially in the presence of neurological signs (Ramirez et al., Beccati et al.).
References:
- Vitale V, Gascón E, Corradini I, Armengou L, Jose‐Cunilleras E. Basisphenoid bone fracture in two juvenile horses with different clinical presentation. Veterinary Record Case Reports. 2021 Sep;9(3):e141.
- Ramirez III O, Jorgensen JS, Thrall DE. Imaging basilar skull fractures in the horse: a review. Veterinary Radiology & Ultrasound. 1998 Sep;39(5):391-5.
- Beccati F, Angeli G, Secco I, Contini A, Gialletti R, Pepe M. Comminuted basilar skull fracture in a colt: Use of computed tomography to aid the diagnosis. Equine Veterinary Education. 2011 Jul;23(7):327-32.
