Fraser McConnell

Association of clinical and magnetic resonance imaging findings with outcome in dogs with presumptive acute noncompressive nucleus pulposus extrusion: 42 cases (2000–2007)

OBJECTIVE To assess associations of severity of neurologic signs (neurologic score), involvement of an intumescence, and findings of magnetic resonance imaging (MRI) with interval to recovery and outcome in dogs with presumptive acute noncompressive nucleus pulposus extrusions. DESIGN Retrospective case series. ANIMALS 42 dogs with presumptive acute noncompressive nucleus pulposus extrusions. PROCEDURES Medical records and magnetic resonance (MR) images of dogs evaluated from 2000 through 2007 were reviewed. Inclusion criteria were acute onset of nonprogressive myelopathy following trauma or strenuous exercise, MRI of the spine performed within 7 days after onset, MRI findings consistent with acute noncompressive nucleus pulposus extrusions, and complete medical records and follow-up. RESULTS Clinical neuroanatomic localization of lesions was to the C1-C5 (n = 6), C6-T2 (6), T3-L3 (28), and L4-S3 (2) spinal cord segments. Median neurologic score was 3.5. Median duration of follow-up was 804 days (range, 3 to 2,134 days) after onset of neurologic signs. Outcome was successful in 28 (67%) dogs and unsuccessful in 14 (33%) dogs. Severity of neurologic signs, extent of the intramedullary hyperintensity on sagittal and transverse T2-weighted MR images, and detection of intramedullary hypointensity on GRE images were all associated with outcome on univariate analysis. Results of multivariate analysis suggested that maximal cross-sectional area of the intramedullary hyperintensity on transverse T2-weighted MR images was the best predictor of outcome. CONCLUSIONS AND CLINICAL IMPORTANCE Clinical and MRI findings can help predict outcome in dogs with acute noncompressive nucleus pulposus extrusions.

Association of clinical and magnetic resonance imaging findings with outcome in dogs suspected to have ischemic myelopathy: 50 cases (2000-2006).

OBJECTIVE To determine whether clinical signs or magnetic resonance imaging findings were associated with outcome in dogs with presumptive ischemic myelopathy. DESIGN Retrospective case series. ANIMALS 50 dogs. PROCEDURES Medical records and magnetic resonance images were reviewed. A neurologic score from 1 (normal) to 5 (most severe degree of dysfunction) was assigned on the basis of neurologic signs at the time of initial examination. Follow-up information was obtained from the medical records and by means of a telephone questionnaire completed by owners and referring veterinarians. RESULTS Median neurologic score at the time of initial examination was 3 (range, 2 to 5). Median follow-up time was 584 days (range, 4 to 2,090 days). Neurologic score at the time of initial examination and extent of the lesion seen on magnetic resonance images (quantified as the lesion length-to-vertebral length ratio and as the percentage cross-sectional area of the lesion) were significantly associated with outcome. Sensitivity of using a lesion length-to-vertebral length ratio > 2.0 or a percentage cross-sectional area of the lesion > or = 67% to predict an unsuccessful outcome was 100%. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that severity of neurologic signs at the time of initial examination and extent of the lesions seen on magnetic resonance images were associated with outcome in dogs with ischemic myelopathy.

The potential role of MRI in veterinary clinical cardiology.

Over the last decade, magnetic resonance imaging (MRI) has become established as a useful referral diagnostic method in veterinary medicine that is widely used in small animal brain and spinal diseases, aural, nasal and orbital disorders, planning soft tissue surgery, oncology and small animal and equine orthopaedics. The use of MRI in these disciplines has grown due to its unparalleled capability to image soft tissue structures. This has been exploited in human cardiology where, despite the inherent difficulties in imaging a moving, contractile structure, cardiac MRI (CMRI) has become the optimal technique for the morphological assessment and quantification of ventricular function. Both CMRI hardware and software systems have developed rapidly in the last 10 years but although several preliminary veterinary CMRI studies have been reported, the techniques growth has been limited and is currently used primarily in clinical research. A review of published studies is presented with a description of CMRI technology and the potential of CMRI is discussed along with some of the reasons for its limited usage.

MAGNETIC RESONANCE IMAGING FEATURES OF DISCOSPONDYLITIS IN DOGS

The diagnosis of discospondylitis is based mainly on diagnostic imaging and laboratory results. Herein, we describe the magnetic resonance imaging (MRI) findings in 13 dogs with confirmed discospondylitis. In total there were 17 sites of discospondylitis. Eleven (81.1%) of the dogs had spinal pain for >3 weeks and a variable degree of neurologic signs. Two dogs had spinal pain and ataxia for 4 days. Radiographs were available in nine of the dogs. In MR images there was always involvement of two adjacent vertebral endplates and the associated disk. The involved endplates and adjacent marrow were T1-hypointense with hyperintensity in short tau inversion recovery (STIR) images in all dogs, and all dogs also had contrast enhancement of endplates and paravertebral tissues. The intervertebral disks were hyperintense in T2W and STIR images and characterized by contrast enhancement in 15 sites (88.2%). Endplate erosion was present in 15 sites (88.2%) and was associated with T2-hypointense bone marrow adjacent to it. In two sites (11.8%) endplate erosion was not MR images or radiographically. The vertebral bone marrow in these sites was T2-hyperintense. Epidural extension was conspicuous in postcontrast images at 15 sites (88.2%). Spinal cord compression was present at 15 sites (88.2%), and all affected dogs had neurologic signs. Subluxation was present in two sites (11.8%). MRI shows characteristic features of discospondylitis, and it allows the recognition of the exact location and extension (to the epidural space and paravertebral soft tissues) of the infection. Furthermore, MRI increases lesion conspicuity in early discospondylitis that may not be visualized by radiography.

CLINICAL, MORPHOLOGIC, AND MORPHOMETRIC FEATURES OF CRANIAL THORACIC SPINAL STENOSIS IN LARGE AND GIANT BREED DOGS

The clinical, morphologic, and morphometric features of cranial thoracic spinal stenosis were investigated in large and giant breed dogs. Seventy-nine magnetic resonance imaging studies of the cranial thoracic spine were assessed. Twenty-six were retrieved retrospectively and 53 were acquired prospectively using the same inclusion criteria. Images were evaluated using a modified compression scale as: no osseous stenosis (grade 0), osseous stenosis without spinal cord compression (grade 1), and osseous stenosis with spinal cord compression (grade 2). Morphometric analysis was performed and compared to the subjective grading system. Grades 1 and 2 cranial thoracic spinal stenosis were identified on 24 imaging studies in 23 dogs. Sixteen of 23 dogs had a conformation typified by Molosser breeds and 21/23 were male. The most common sites of stenosis were T2-3 and T3-4. The articular process joints were enlarged with abnormal oblique orientation. Stenosis was dorsolateral, lateralized, or dorsoventral. Concurrent osseous cervical spondylomyelopathy was recognized in six dogs and other neurologic disease in five dogs. Cranial thoracic spinal stenosis was the only finding in 12 dogs. In 9 of these 12 dogs (all grade 2) neurolocalization was to the T3-L3 spinal segment. The median age of these dogs was 9.5 months. In the remaining three dogs neurologic signs were not present. Stenosis ratios were of limited benefit in detecting stenotic sites. Grade 2 cranial thoracic spinal stenosis causing direct spinal cord compression may lead to neurologic signs, however milder stenosis (grade 1) is likely to be subclinical or incidental.

Clinical Features, Imaging Characteristics, and Long-term Outcome of Dogs with Cranial Meningocele or Meningoencephalocele

Background The term meningoencephalocele (MEC) describes a herniation of cerebral tissue and meninges through a defect in the cranium, whereas a meningocele (MC) is a herniation of the meninges alone. Hypothesis/Objectives To describe the clinical features, magnetic resonance imaging (MRI) characteristics, and outcomes of dogs with cranial MC and MEC. Animals Twenty‐two client‐owned dogs diagnosed with cranial MC or MEC. Methods Multicentric retrospective descriptive study. Clinical records of 13 institutions were reviewed. Signalment, clinical history, neurologic findings and MRI characteristics as well as treatment and outcome were recorded and evaluated. Results Most affected dogs were presented at a young age (median, 6.5 months; range, 1 month – 8 years). The most common presenting complaints were seizures and behavioral abnormalities. Intranasal MEC was more common than parietal MC. Magnetic resonance imaging identified meningeal enhancement of the protruded tissue in 77% of the cases. Porencephaly was seen in all cases with parietal MC. Cerebrospinal fluid (CSF) analysis identified mild abnormalities in 4 of 11 cases. Surgery was not performed in any affected dog. Seventeen patients were treated medically, and seizures were adequately controlled with anti‐epileptic drugs in 10 dogs. Dogs with intranasal MEC and mild neurologic signs had a fair prognosis with medical treatment. Conclusion and clinical importance Although uncommon, MC and MEC should be considered as a differential diagnosis in young dogs presenting with seizures or alterations in behavior. Medical treatment is a valid option with a fair prognosis when the neurologic signs are mild.

Cervical intervertebral foraminal disc extrusion in dogs: clinical presentation, MRI characteristics and outcome after medical management

The aim of the present study was to retrospectively evaluate the clinical signs, MRI characteristics, interobserver agreement and outcome after medical treatment in dogs affected by cervical intervertebral foraminal disc extrusion (CIFDE). The medical records of three referral institutions were searched for dogs diagnosed with CIFDE between 2010 and 2012. Thirteen dogs were identified with CIFDE; affected dogs often had a normal neurological examination, with cervical hyperaesthesia and lameness as the most common clinical signs. On MRI, sagittal images showed no evidence of compression of the spinal cord; CIFDE could be identified only on transverse sections in all cases. An excellent interobserver agreement was found in the localisation of the affected intervertebral disc space, and a substantial agreement was found on the detection of CIFDE versus foraminal stenosis caused by overgrowing articular processes. All but two dogs recovered completely, and they were considered free of clinical signs without analgesia within a median of 7.5 weeks (range: 2–20) after medical management was started. The remaining two dogs were surgically treated followed by complete recovery. In view of our findings, the importance of a thorough MRI investigation in dogs presenting with cervical hyperaesthesia as the sole clinical sign should be highlighted.

MRI, CT and histopathological findings in a cat with hypovitaminosis A

An adult, male, domestic longhair cat was evaluated for chronic progressive visual impairment and lethargy. Neurological abnormalities localised to the cerebellum/central vestibular system, and optic chiasm/retinas and/or optic nerves were present on clinical examination. MRI and CT studies showed diffuse hyperostosis with thickening of the calvarium and tentorium cerebelli causing compression and distortion of the brain. Biochemical testing showed low plasma retinol levels at 0.1 μmol/l (0.86–2.2). Postmortem examination showed reduction in volume of the frontal lobes secondary to diffuse skull hyperostosis. Microscopically, there were mild white matter spongiosis affecting the corona radiata and optic nerves and multiple small plaque-like thickening of the meninges. This is the first case report to provide a comprehensive clinical, diagnostic imaging and pathological details of hypovitaminosis A in a cat.

Focal cortical dysplasia resulting in seizures in an adult dog

A two-year-old, neutered male, old English sheepdog was presented for further investigation of generalised tonic-clonic seizures. MRI of the brain revealed cortical grey matter thickening, grey-white matter blurring and malformation of the prorean and precruciate gyrus and absence of the presylvian sulcus. These findings are consistent with congenital focal cortical dysplasia; although the histopathological findings have been previously described in dogs, the MRI findings have not yet been reported in the veterinary literature. Phenobarbitone was added at the time of diagnosis with levetiracetam being added after 12 months due to worsening seizure frequency. Cortical dysplasia, although uncommon, should be considered as a differential diagnosis in an adult dog with generalised seizures.

Fundamentals in diagnostic imaging: Introduction to the BSAVA Manual of Canine and Feline Radiography and Radiology

The new edition of the BSAVA Manual of Canine and Feline Radiography and Radiology focuses on the basic principles of radiology to present a systematic approach to interpretation.