Cranioplasty Using Titanium Mesh After Skull Tumor Resection in Five Dogs.

OBJECTIVE: To describe the clinical details, surgery, postoperative imaging, and short to mid-term outcome after cranioplasty with titanium mesh in dogs with large skull tumors. STUDY DESIGN: Case series. ANIMALS: Client-owned dogs with skull tumors (n=5). METHODS: All tumors were removed via craniectomy and a sheet of titanium mesh was contoured to reconstruct the calvarial defect and sutured to surrounding musculature. RESULTS: Four dogs had multilobular tumors of bone and 1 dog had a soft tissue sarcoma invading the cranial vault. Neurologic examination was unchanged or improved postoperative, a good cosmetic appearance was achieved, and no complications were noted at 2 weeks postoperative. Late postoperative computed tomography (CT) in 2 dogs and magnetic resonance (MR) imaging in 1 dog confirmed the presence of the titanium mesh without migration. There was no interference of the mesh with image interpretation and definitive radiation therapy was pursued in 1 dog without complication. Late follow-up reported 2 dogs euthanatized; at 44 weeks postoperative due to tumor re-growth; at 12 weeks postoperative for hemoabdomen, respectively. One dog drowned at 40 weeks postoperative, 1 dog was lost to follow-up, and 1 dog is alive at 83 weeks postoperative free of clinical signs. CONCLUSIONS: Titanium mesh is suitable for cranioplasty based on its strength, biocompatibility, and excellent handling characteristics. It does not interfere with acquisition or interpretation of CT or MR images, thereby allowing postoperative imaging for ongoing assessment.

CLINICAL AND MAGNETIC RESONANCE IMAGING FEATURES OF IDIOPATHIC OCULOMOTOR NEUROPATHY IN 14 DOGS.

Ophthalmoplegia/ophthalmoparesis (internal, external, or both) has been reported in dogs secondary to neoplasia affecting the oculomotor nerve and is usually given a poor prognosis. The purpose of this retrospective study was to describe the clinical findings, magnetic resonance imaging (MRI) findings, management, outcome, and follow-up in a group of canine cases with idiopathic oculomotor neuropathy. Inclusion criteria included cases with ophthalmoplegia/ophthalmoparesis (internal, external or both) as sole neuroophthalmologic signs, complete ophthalmic and neurologic examination, head MRI, and a minimum follow-up period of 1 year. Dogs with progressive neurological signs not related to oculomotor neuropathy were excluded. Fourteen cases met the inclusion criteria. All cases were unilaterally affected. Magnetic resonance imaging showed equivocal enlargement of the oculomotor nerve in three cases, mild enlargement in five, and marked enlargement in six. Contrast enhancement was present in 12 cases, being marked in six. When present, the contrast enhancement was focal in eight cases and diffuse in four. The median follow-up time was 25 months. External ophthalmoparesis improved in seven cases, five cases under no treatment and two under systemic corticosteroid therapy. The clinical signs in the other seven cases remained unchanged. Idiopathic oculomotor neuropathy should be included as a differential diagnosis in dogs presenting with unilateral ophthalmoplegia/ophthalmoparesis (internal, external, or both) with the absence of other neurologic and ophthalmic signs, and with the MRI findings restricted to the oculomotor nerve. Idiopathic oculomotor neuropathy has a good prognosis as the clinical signs do not deteriorate and they can improve without treatment.

IMAGING DIAGNOSIS - UNILATERAL TRIGEMINAL NEURITIS MIMICKING PERIPHERAL NERVE SHEATH TUMOR IN A HORSE.

A 16-year old Warmblood gelding presented with a nonhealing corneal ulcer and absent corneal sensation in the left eye. A lesion affecting the maxillary and ophthalmic branches of the left trigeminal nerve was suspected. Magnetic resonance (MR) imaging identified marked thickening of the ophthalmic and maxillary branches of the left trigeminal nerve. The nerve was iso- to hypointense on T1-weighted and T2-weighted images with heterogeneous enhancement. A peripheral nerve sheath tumor was suspected, however granulomatous neuritis was histopathologically confirmed. These inflammatory changes can result in severe nerve enlargement and should be considered with MR findings suggestive of peripheral nerve sheath tumor.

The cutaneous trunci muscle reflex: a predictor of recovery in dogs with acute thoracolumbar myelopathies caused by intervertebral disc extrusions.

OBJECTIVE: To determine whether changes in the cutaneous trunci muscle (CTM) reflex are an early predictor of outcome in dogs with severe acute thoracolumbar intervertebral disc extrusion (IVDE). STUDY DESIGN: Multicenter prospective cohort study. ANIMALS: Dogs (n = 36) with acute IVDE causing paraplegia, loss of nociception in pelvic limbs and tail, and an abnormal CTM reflex postoperatively. METHODS: The caudal border of the CTM reflex was established 24 hours after surgery and at discharge, and was reported as moving cranially, caudally, or staying static. Dogs were re-evaluated at 12-20 weeks and at 7-36 months postoperatively. Outcome was classified as improved or unimproved, successful or unsuccessful, and ascending myelomalacia or not, and compared with early movement of the CTM reflex by construction of contingency tables and performing a Fisher's exact test. RESULTS: By discharge (mean, 4.7 days; SD = 2.10), CTM reflex progression was caudal in 19 dogs, static in 11, and cranial in 6. Five of 6 dogs with cranial movement developed ascending myelomalacia (P < .0001). Seventeen of 19 dogs with caudal movement showed an improvement by 12-20 weeks (P = .0046) and none developed ascending myelomalacia (P = .0013). CONCLUSIONS: Postoperative changes of the caudal border of the CTM reflex are an early indicator of outcome in dogs with severe acute IVDE. Cranial movement of the CTM reflex is significantly associated with the development of ascending myelomalacia. Caudal movement is significantly associated with improvement, but not associated with a long-term successful outcome.

Quantitative analysis of Chiari-like malformation and syringomyelia in the Griffon Bruxellois dog.

This study aimed to develop a system of quantitative analysis of canine Chiari-like malformation and syringomyelia on variable quality MRI. We made a series of measurements from magnetic resonance DICOM images from Griffon Bruxellois dogs with and without Chiari-like malformation and syringomyelia and identified several significant variables. We found that in the Griffon Bruxellois dog, Chiari-like malformation is characterized by an apparent shortening of the entire cranial base and possibly by increased proximity of the atlas to the occiput. As a compensatory change, there appears to be an increased height of the rostral cranial cavity with lengthening of the dorsal cranial vault and considerable reorganization of the brain parenchyma including ventral deviation of the olfactory bulbs and rostral invagination of the cerebellum under the occipital lobes.

Quantitative trait loci (QTL) study identifies novel genomic regions associated to Chiari-like malformation in Griffon Bruxellois dogs.

Chiari-like malformation (CM) is a developmental abnormality of the craniocervical junction that is common in the Griffon Bruxellois (GB) breed with an estimated prevalence of 65%. This disease is characterized by overcrowding of the neural parenchyma at the craniocervical junction and disturbance of cerebrospinal fluid (CSF) flow. The most common clinical sign is pain either as a direct consequence of CM or neuropathic pain as a consequence of secondary syringomyelia. The etiology of CM remains unknown but genetic factors play an important role. To investigate the genetic complexity of the disease, a quantitative trait locus (QTL) approach was adopted. A total of 14 quantitative skull and atlas measurements were taken and were tested for association to CM. Six traits were found to be associated to CM and were subjected to a whole-genome association study using the Illumina canine high density bead chip in 74 GB dogs (50 affected and 24 controls). Linear and mixed regression analyses identified associated single nucleotide polymorphisms (SNPs) on 5 Canis Familiaris Autosomes (CFAs): CFA2, CFA9, CFA12, CFA14 and CFA24. A reconstructed haplotype of 0.53 Mb on CFA2 strongly associated to the height of the cranial fossa (diameter F) and an haplotype of 2.5 Mb on CFA14 associated to both the height of the rostral part of the caudal cranial fossa (AE) and the height of the brain (FG) were significantly associated to CM after 10 000 permutations strengthening their candidacy for this disease (P = 0.0421, P = 0.0094 respectively). The CFA2 QTL harbours the Sall-1 gene which is an excellent candidate since its orthologue in humans is mutated in Townes-Brocks syndrome which has previously been associated to Chiari malformation I. Our study demonstrates the implication of multiple traits in the etiology of CM and has successfully identified two new QTL associated to CM and a potential candidate gene.