Martin Konar

Influence of intervertebral disc fenestration at the herniation site in association with hemilaminectomy on recurrence in chondrodystrophic dogs with thoracolumbar disc disease: a prospective MRI study.

OBJECTIVE To describe the influence of fenestration at the disc herniation site on recurrence in thoracolumbar disc disease of chondrodystrophoid dogs. STUDY DESIGN Prospective clinical study. ANIMALS Chondrodystrophic dogs (n=19). METHODS Dogs were divided into 2 groups: group 1 (9 dogs) had thoracolumbar disc extrusion (Hansen type I) treated by hemilaminectomy and concomitant fenestration of the affected intervertebral disc and group 2 (10 dogs) had hemilaminectomy without fenestration. All dogs had 3 magnetic resonance imaging (MRI) examinations: preoperatively, immediately postoperatively to assess removal of herniated disc material, and again 6 weeks after surgery. RESULTS There were 13 male and 6 female dogs; mean age, 7.1 years. Thoracolumbar disc herniation was confirmed with MRI. Immediate post surgical MRI revealed that the herniated disc removal was complete in all but 1 dog and that fenestration did not lead to complete removal of nucleus pulposus within the intervertebral disc space. On the 3rd MRI examination, none of the group 1 dogs had further disc material herniation at the fenestrated site. Six of the 10 group 2 dogs had a recurrence of herniation leading to clinical signs in 3 dogs (pain in 2 dogs, paresis in 1 dog). CONCLUSION In thoracolumbar disc herniation, fenestration of the affected intervertebral disc space prevents further extrusion of disc material. CLINICAL RELEVANCE Fenestration reduces the risk of early recurrence of disc herniation and associated postoperative complications.

PROS AND CONS OF LOW-FIELD MAGNETIC RESONANCE IMAGING IN VETERINARY PRACTICE

Low-field (LF) (0.2-0.4T) magnetic resonance (MR) imaging predominates in veterinary practice. Advantages of LF MR include reduced costs, better patient access, and greater safety. High quality examinations can be achieved using appropriate protocols and investing more scanning time than with high-field (HF) systems. The main disadvantage of LF MR is the reduced signal to noise ratio compared with HF systems. LF MR protocols for small animal brain and spine imaging are described.

Ventral Intraspinal Cysts Associated with the Intervertebral Disc: Magnetic Resonance Imaging Observations in Seven Dogs

Objective— To report clinical and diagnostic imaging features, and outcome after surgical treatment of ventral intraspinal cysts in dogs. Study Design— Retrospective study. Animals— Dogs (n=7) with ventral intraspinal cysts. Methods— Clinical signs, magnetic resonance imaging (MRI) findings and surgical findings of 7 dogs and histologic findings (1 dog) with intraspinal cysts associated with the intervertebral disc were reviewed. Results— Ventral intraspinal cyst is characterized by: (1) clinical signs indistinguishable from those of typical disc herniation; (2) an extradural, round to oval, mass lesion with low T1 and high T2 signal intensity on MRI, compatible with a liquid-containing cyst; (3) cyst is in close proximity to the intervertebral disc; and (4) MRI signs of disc degeneration. Although the exact cause is unknown, underlying minor disc injury may predispose to cyst formation. Conclusion— Intraspinal cysts have clinical signs identical to those of disc herniation. Given the close proximity of the cyst to the corresponding disc and the similarity of MRI findings to discal cysts in humans, we propose the term “canine discal cyst” to describe this observation. Clinical Relevance— Discal cysts should be considered in the differential choices for cystic extradural compressing lesions.

Multiple meningiomas: Clinical, radiological, surgical, and pathological findings with outcome in four cats

The present report describes the clinical signs, magnetic resonance imaging (MRI) findings, surgical procedure, pathological findings and follow-up in four cats with multiple meningiomas; three castrated male and one spayed female domestic shorthair indoor cats, ranging in age from 11 to 14 years. In three of four cats, clinical signs at presentation were suggestive of a focal lesion. Three cats had two meningiomas and one had four meningiomas. Most of the tumours were supratentorial, one arose from the tentorium and one was infratentorial. The duration of presenting signs before surgery ranged from 10 days to 11 months. Postoperative MRI revealed complete gross tumour removal in three cases. In one cat with two cranial fossa meningiomas, subtotal excision with a small basal remnant (2×2 mm) of the ventral part of one meningioma lying on the floor of the skull, was observed. Based on histopathological architecture, six tumours revealed features of a transitional subtype meningioma, and four of a meningotheliomatous meningioma. In each cat, the multiple meningiomas were all assigned to the same histopathological group. The preoperative presenting signs had resolved by the follow-up examinations 4 weeks after surgery in two cats. Long-term follow-up evaluation revealed that surgically-induced or exacerbated neurological deficits in two cats had completely or almost completely resolved within 8 weeks of surgery. All patients are still alive 12 to 21 months after surgery and no clinical signs of recurrence could be detected at that time.

Accuracy of the withdrawal reflex for localization of the site of cervical disk herniation in dogs: 35 cases (2004-2007)

OBJECTIVE To evaluate the accuracy of neurologic examination versus magnetic resonance imaging (MRI) in localization of cervical disk herniation and evaluate the usefulness of withdrawal reflex testing in dogs. DESIGN Retrospective case series. ANIMALS 35 client-owned dogs with a single-level cervical disk herniation as determined via MRI. PROCEDURES 1 of 2 board-certified neurologists performed a complete neurologic examination in each dog. Clinical signs of a cervical lesion included evidence of neck pain and tetraparesis. The withdrawal reflex was used for neuroanatomic localization (C1-C5 or C6-T2). Agreement between results of neurologic and MRI examinations was determined. RESULTS Agreement between neurologic and MRI diagnoses was 65.8%. In 11 dogs in which the lesion was clinically localized to the C6-T2 segment on the basis of a decreased withdrawal reflex in the forelimbs, MRI revealed an isolated C1-C5 disk lesion. In 1 dog, in which the lesion was suspected to be at the C1-C5 level, MRI revealed a C6-T2 lesion. Cranial cervical lesions were significantly associated with an incorrect neurologic diagnosis regarding site of the lesion. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that the withdrawal reflex in dogs with cervical disk herniation is not reliable for determining the affected site and that a decreased withdrawal reflex does not always indicate a lesion from C6 to T2.

Cerebellar Ependymal Cyst in a Dog

An 11-week-old, male, Staffordshire Bull Terrier had a history of generalized ataxia and falling since birth. The neurologic findings suggested a localization in the cerebellum. Magnetic resonance imaging of the brain was performed. In all sequences the area of the cerebellum was almost replaced by fluid isointense to cerebrospinal fluid. A complete necropsy was performed after euthanasia. Histologically, the lesion was characterized by extensive loss of cerebellar tissue in both hemispheres and vermis. Toward the surface of the cerebellar defect, the cavity was confined by ruptured and folded membranes consisting of a layer of glial fibrillary acidic (GFAP)-positive glial cells covered multifocally by epithelial cells. Some of these cells bore apical cilia and were cytokeratin and GFAP negative, supporting their ependymal origin. The histopathologic features of our case are consistent with the diagnosis of an ependymal cyst. Its glial and ependymal nature as demonstrated by histopathologic and immunohistochemical examination differs from arachnoid cysts, which have also been reported in dogs. The origin of these cysts remains controversial, but it has been suggested that they develop during embryogenesis subsequent to sequestration of developing neuroectoderm. We speculate that the cyst could have been the result of a pre- or perinatal, possibly traumatic, insult because hemorrhage, and tissue destruction had occurred. To our knowledge, this is the first description of an ependymal cyst in the veterinary literature.

MAGNETIC RESONANCE IMAGING FEATURES OF SINONASAL DISORDERS IN HORSES

Diseases of paranasal sinuses and nasal passages in horses can be a diagnostic challenge because of the complex anatomy of the head and limitations of many diagnostic modalities. Our hypothesis was that magnetic resonance (MR) imaging would provide excellent anatomical detail and soft tissue resolution, and would be accurate in the diagnosis of diseases of the paranasal sinuses and nasal passages in horses. Fourteen horses were imaged. Inclusion criteria were lesions located to the sinuses or nasal passages that underwent MR imaging and subsequent surgical intervention and/or histopathologic examination. A low field, 0.3 tesla open magnet was used. Sequences in the standard protocol were fast spin echo T2 sagittal and transverse, spin echo T1 transverse, short-tau inversion recovery (STIR) dorsal, gradient echo 3D T1 MPR dorsal (plain and contrast enhanced), spin echo T1 fatsat (contrast enhanced). Mean scan time to complete the examination was 53 min (range 39-99 min). Lesions identified were primary or secondary sinusitis (six horses), paranasal sinus cyst (four horses), progressive ethmoid hematoma (two horses), and neoplasia (two horses). The most useful sequences were fast spin echo T2 transverse and sagittal, STIR dorsal and FE3D MPR (survey and contrast enhanced). Fluid accumulation, mucosal thickening, presence of encapsulated contents, bone deformation, and thickening were common findings observed in MR imaging. In selected horses, magnetic resonance imaging is a useful tool in diagnosing lesions of the paranasal sinuses and nasal passages.

Laser-Doppler measurements of spinal cord blood flow changes during hemilaminectomy in chondrodystrophic dogs with disk extrusion.

OBJECTIVES (1) To assess spinal cord blood flow (SCBF) during surgical treatment of disk extrusion in dogs and (2) to investigate associations between SCBF, clinical signs, presurgical MRI images, and 24-hour surgical outcome. STUDY DESIGN Cohort study. ANIMALS Chondrodystrophic dogs with thoracolumbar disk extrusion (n=12). METHODS Diagnosis was based on clinical signs and MRI findings, and confirmed at surgery. Regional SCBF was measured intraoperatively by laser-Doppler flowmetry before, immediately after surgical spinal cord decompression, and after 15 minutes of lavaging the lesion. Care was taken to ensure a standardized surgical procedure to minimize factors that could influence measurement readings. RESULTS A significant increase in intraoperative SCBF was found in all dogs (Wilcoxons signed-rank test; P=.05) immediately after spinal cord decompression and after 15 minutes. Changes in SCBF were not associated with duration of clinical signs; initial or 24-hour neurologic status; or degree of spinal cord compression assessed by MRI. CONCLUSION SCBF increases immediately after spinal cord decompression in dogs with disk herniation; however, increased SCBF was not associated with a diminished 24-hour neurologic status. CLINICAL RELEVANCE An increase in SCBF does not appear to be either associated with the degree of spinal cord compression or of a magnitude sufficient to outweigh the benefit of surgical decompression by resulting in clinically relevant changes in 24-hour outcome.

Cerebral extension of steroid‐responsive meningitis arteritis in a boxer

A comatose 30-month-old, entire male boxer was presented because of an acute history of a cluster of three to four seizures. Neurological examination suggested a diffuse to multifocal intracranial lesion. Magnetic resonance tomography revealed symmetrical multifocal to diffuse changes of the cerebral grey matter and ependymal lining with sediment in the lateral ventricles. Haematological examination revealed leucocytosis with neutrophilia. Cerebrospinal fluid examination revealed high protein concentration and polymorphonuclear pleocytosis. Despite antiepileptic treatment, therapy against increased intracranial pressure and antibiosis, the dogs condition continued to deteriorate and he was euthanased. Pathological examination revealed fibrinosuppurative meningo-ependymitis and necrotising arteritis throughout the brain. In addition, chronic inflammation and arterial stenosis was found in the spinal meninges. No infectious agent was found. A diagnosis of steroid-responsive meningitis arteritis was made. The massive extension into the meninges and ventricular system of the forebrain has not been described previously in dogs with steroid-responsive meningitis arteritis and should be considered in the differential diagnosis when an intracranial suppurative infection is suspected.

A Novel Leukoencephalomyelopathy of Leonberger Dogs

Many different degenerative diseases of the canine central nervous system (CNS) have been described involving white matter in various breeds. These include Afghan Hound myelopathy and a similar disease in Kooiker dogs, globoid cell leukodystrophy of various breeds, oligodendroglial dysplasia in Bullmastiffs, cavitating leukodystrophy of Dalmatians, hound ataxia, leukoencephalomyelopathy of Rottweiler dogs, and myelopathies in Jack Russell and Fox Terriers. In the Leonberger dog, no degenerative diseases of the nervous system have been described apart from an inherited polyneuropathy. This report describes the clinical signs, magnetic resonance imaging (MRI) findings, and neuropathology of a novel neurodegenerative disorder affecting the white matter of brain and spinal cord in 2 Leonberger dogs.