Skull conditions

Question 1

Hydrocephalus

Answer 1

Abnormal CSF accumulation in the cerebral ventricular system, associated with an elevated intracranial pressure and variable neurological signs.
No sex predilection, commonly seen in small breed, toy dogs and brachycephalic breeds. It is an autosomal recessive trait in Siamese cats.
May include a large dome shaped cranium, open fontanelles, visual and auditory defects, uncoordinated gait. Radiographically, an enlarged cranium with cortical thinning, decreased calvarium and convolutions are seen along with open fontanelles and suture lines.

Question 2

Occipital dyplasia

Answer 2

Is a congenital abnormality of the formation of the occipital bones of the cranium, which manifests as an underdeveloped occipital bone leading to a dorsoventrally enlarged foramen magnum. In patients with this condtion a fibrous tissue membrane that covers the caudal surface of the cerebellum replaces the normal occipital bone.
No sex predilection, common in small/toy breeds. Majority of animals are asymptomatic. Radiographically, enlargement and dorsal extension of the foramen magnum (keyhole shape). Occipital condyle dysplasia which may show atlanto-occipital subluxation

Question 3

Hyperparathyroidism

Answer 3

Primary hyperparathyroidism: tumour of the parathyroid gland that results in excessive production of parathyroid hormone, leads to hypercalcaemia and subsequently bone resorption.
Secondary hyperparathyroidism: Renal and nutritional causes alterations in calcium and phosphorus homeostasis subsequent bone resorption.
Radiographic findings:
- Early lesion is loss of lamina dura
- Demineralisation of the mandible and maxilla
- Floating appearance of teeth
- Fibrious osteodystrophy may lead to thickening of affected portion of skull.

Question 4

Craniomandibular osteopathy

Answer 4

No sex predilection, clinical signs often observed at 3-8 mths of age, in terrier breeds. CMO is a benign, proliferative, non-neoplastic disorder affecting bones of the cranium and mandibles, occasionally produces a periosteal reaction on long bones. Self limiting and changes slow at 7-8mths of age. Clinical signs include mandibular swelling, drooling, difficulty eating, fever and pain upon opening the mouth.
Radiographic findings: irregular mineralisation opacity (may appead palisading) periosteal new bone involving the mandibles (often near angular process), temporal bone (petrous portion and tympanic bullae), usually bilateral changes. Ankylosis of the temporomandibular joint may occur.

Question 5

Skull fractures

Answer 5

Usually a result of blunt trauma, with mandibular and maxillary fractures the most common. Central nervous system involvement may occur as a result of a fracture or as a result of brain contusion, extradural haemorrhage, or a subchondral haemorrhage.
Radiographic findings:
- Soft tissue swelling, gas (pneumocephalus), foreign objects
- Subcutaneous emphysema if nasal cavity or frontal sinus involved.
- Abnormal radiolucent line in and displacements of osseous structures

Question 6

Rhinitis

Answer 6

Non-destructive (Left image): Rhinitis: Infection, foreign body, nasopharangeal polyps, allergies, coagulopathies. Webbed appearance.

Destructive (Right image): Fungal infections, neoplasia, chronic foreign bodies. Radiolucence.

Question 7

Periodontal disease

Answer 7

Most common disease along with periodontal abscess in small dogs and cats.
Radiographic findings:
- Early widening of periodontal space
- Tooth loss with bone resorption and lamina dura loss
- Osteomyelitis, pathological fractures

Question 8

Periapical infection

Answer 8

Tooth root abscess have a typical radiographic appearance of lysis around the tooth root and destruction of alveolar bone.
Radiographic findings
- Lysis of alveolar bone
- Irregularity of tooth root
- Loss of lamina dura
- Sclerosis near apex.