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Listeria Brainstem Encephalitis in Small Ruminants: Correlation of Magnetic Resonance Imaging and Histopathology.
No full textListeria Brainstem Encephalitis in Small Ruminants: Correlation of Magnetic Resonance Imaging and Histopathology
Christina Stahl1, Anna Oevermann2, Daniela Gorgas1
1Clinical Radiology, Department of Clinical Veterinary Medicine, Vetsuisse-Faculty, University of Bern, Switzerland
2Neurocenter, Department of Clinical Research and Veterinary Public Health, Vetsuisse-Faculty, University of Bern, Switzerland
Abstract
Brainstem encephalitis is an intriguing form of Listeria monocytogenes central nervous system (CNS) infection in humans and ruminants and has a high fatality rate. However, intra vitam diagnosis remains difficult in both species (1, 2). We performed MRI of affected small ruminants, in which Listeria brainstem encephalitis is a common CNS disease, and correlated MRI features with histopathology in order to define MRI criteria for the diagnosis of listeria brainstem encephalitis.
Fifteen small ruminants (nine sheep, six goats) with listeriosis underwent MRI examination of the brain using a 0.3 T system (five animals) and 1.0 T system (ten animals) including T2w, FLAIR and T1w sequences pre and post Gadolinium administration. Listeria brainstem encephalitis was confirmed by histopathology, and histopathological changes were correlated to MRI features.
On MRI, lesions were best visualized in T2-weighted sequences. In all animals they were characterized by asymmetric increased signal intensity in the rhombencephalon in T2w and FLAIR sequences. The lesions showed a variable pattern and distribution, ranging from patchy with ill defined borders to diffusely affecting the entire cross-sectional area of the brainstem. Few animals had lesions in the diencephalon (three animals), whilst histopathologically detectable lesions commonly extended to the diencephalon and involved cranial nerve roots (twelve animals). The lesions were iso- to mildly hypointens in T1w sequence. Mild to moderate patchy or ring-like contrast uptake was observed in the rhombencephalon of five animals (one sheep, four goats), which showed vascular damage and perivascular fibrin accumulation on light microscopy.
In the brainstem, the asymmetric T2-hyperintense lesions observed by MRI correlated well with the inflammatory infiltrates observed in histopathology (3). However, lesions in the diencephalon, cranial nerves and meninges of rostral brain areas were rarely detected by MRI, indicating that MRI underestimates involvement of the rostral brain and brain associated structures. Contrary to reported human cases of neurolisteriosis (4), contrast uptake was an inconsistent finding occurring in the rhombencephalon of only five animals.
References
1. Armstrong RW, Fung PC. Brainstem encephalitis (rhombencephalitis) due to Listeria monocytogenes: case report and review. Clin Infect Dis. 1993;16(5):689-702. Review.
2. Oevermann A, Botteron C, Seuberlich T, Nicolier A, Friess M, Doherr MG, et al. Neuropathological survey of fallen stock: active surveillance reveals high prevalence of encephalitic listeriosis in small ruminants. Vet Microbiol. 2008 Aug 25;130(3-4):320-9.
3. Antal EA, Loberg EM, Dietrichs E, Maehlen J. Neuropathological findings in 9 cases of listeria monocytogenes brain stem encephalitis. Brain Pathol. 2005;15(3):187-91.
4. Reynaud L, Graf M, Gentile I, Cerini R, Ciampi R, Noce S, et al. A rare case of brainstem encephalitis by Listeria monocytogenes with isolated mesencephalic localization. Case report and review. Diagn Microbiol Infect Dis. 2007;58(1):121-3
EXPERIMENTAL ASSESSMENT OF IMAGING MEASUREMENTS TO DIAGNOSE ATLANTOAXIAL INSTABILITY ON COMPUTED TOMOGRAPHY IMAGES
No full text
Metabolic profiling of listeria rhombencephalitis in small ruminants by 1 H high-resolution magic angle spinning NMR spectroscopy
No full textListeria rhombencephalitis is caused by infection with Listeria monocytogenes and is associated with a high mortality rate in humans and ruminants. Little is known about the metabolic changes associated with neurolisteriosis in particular and infectious central nervous system (CNS) diseases in general. The purpose of our study was to investigate the metabolic changes associated with listeria rhombencephalitis in small ruminants (goats and sheep) as a model for inflammatory CNS disease by 1 H high-resolution magic angle spinning nuclear magnetic resonance (1 H HR-MAS NMR) spectroscopy of brain biopsies obtained from the brainstem and thalamus. Statistical analysis revealed distinct differences in the metabolic profile of brainstem biopsies, the primary location of listeria rhombencephalitis with moderate or severe inflammatory changes. N-Acetylaspartate (NAA), N-acetylaspartylglutamate, choline, myo-inositol and scyllo-inositol were decreased, and glycine, phosphocholine, taurine and lactate were increased, in the diseased group (n = 13) in comparison with the control group (n = 12). In the thalamus, which showed no or only mild inflammatory changes in the majority of animals, no statistically significant metabolic changes were observed. However, trends for metabolic alterations were partly the same as those found in the brainstem, including NAA, choline and lactate. This may be an indicator of metabolic changes occurring in the early stages of the disease. Therefore, further research with a larger number of animals is needed to evaluate the presence of subtle metabolic changes associated with mild inflammatory changes in the thalamus. In conclusion, 1 H HR-MAS NMR investigation of listeria rhombencephalitis identified brain metabolite changes, offering new insights into the disease pathophysiology
Use of contrast-enhanced fluid-attenuated inversion recovery sequence to detect brain lesions in dogs and cats.
No full textBACKGROUND
The diagnostic value of a contrast-enhanced T2-weighted FLAIR sequence (ceFLAIR) in brain imaging is unclear.
HYPOTHESIS/OBJECTIVES
That the number of brain lesions detected with ceFLAIR would be no greater than the sum of lesions detected with nFLAIR and ceT1W sequence.
ANIMALS
One hundred and twenty-nine animals (108 dogs and 21 cats) undergoing magnetic resonance imaging (MRI) of the head between July 2010 and October 2011 were included in the study.
METHODS
A transverse ceFLAIR was added to a standard brain MRI protocol. Presence and number of lesions were determined based on all available MRI sequences by 3 examiners in consensus and lesion visibility was evaluated for nFLAIR, ceFLAIR, and ceT1W sequences.
RESULTS
Eighty-three lesions (58 intra-axial and 25 extra-axial) were identified in 51 patients. Five lesions were detected with nFLAIR alone, 2 with ceT1W alone, and 1 with ceFLAIR alone. Significantly higher numbers of lesions were detected using ceFLAIR than nFLAIR (76 versus 67 lesions; P = 0.04), in particular for lesions also detected with ceT1W images (53 versus 40; P =.01). There was no significant difference between the number of lesions detected with combined nFLAIR and ceT1W sequences compared to those detected with ceFLAIR (82 versus 76; P =.25).
CONCLUSION AND CLINICAL IMPORTANCE
Use of ceFLAIR as a complementary sequence to nFLAIR and ceT1W sequences did not improve the detection of brain lesions and cannot be recommended as part of a routine brain MRI protocol in dogs and cats with suspected brain lesions
1High-Resolution Magic-Angle-Spinning NMR Spectroscopy to Determine Phosphate Sugars in Biological Tissues and Cell Cultures.
No full textCervical Intervertebral Disk to Vertebral Body Ratios of Different Dog Breeds Based on Sagittal Magnetic Resonance Imaging.
Full text linkTo establish sagittal area and length reference values and ratios between apparently normal canine cervical vertebrae and intervertebral disks using magnetic resonance imaging. Retrospective evaluation of cervical vertebral column magnetic resonance imaging studies of 44 dogs representing 5 different breeds (Labrador Retriever, = 10; French Bulldog, = 10; Great Dane, = 9; Chihuahua, = 10; Dachshund, = 5). Mid-sagittal measurements of vertebral body and disk areas were obtained from C3 through C7 vertebrae and C2/C3 through C6/C7 intervertebral disks. Disk to vertebra area ratios were calculated and compared among dog breeds. Additionally, sagittal vertebral body and disk length measurements were obtained and disk to vertebra length ratios calculated. Inter and intra observer variability was assessed. There were significant differences for disk to vertebral body area and length ratios between evaluated dog breeds and cervical vertebral locations ( < 0.001). Mean area ratio of Chihuahuas was significantly larger than all other breeds, while results from Dachshunds were only significantly different than Chihuahuas and Labrador Retrievers. Mean area ratios were statistically different between the cranial and caudal cervical vertebral locations. Regarding length ratios, results from Chihuahuas were significantly different than all breeds except Dachshunds. Mean length ratios were statistically different between all cervical locations, except C2/C3 compared to C3/C4. Intra- and interobserver variability was very good to excellent. There are significant differences in area and length ratios between dog breeds. Differences also exist in area and length ratios between the cranial and caudal cervical vertebral column. These differences may play a role in the development of vertebral column diseases including intervertebral disk disease
Biomechanical Evaluation of the Stabilizing Function of Three Atlantoaxial Implants Under Shear Loading: A Canine Cadaveric Study
No full textOBJECTIVE:
To compare the biomechanical properties of a ventral transarticular lag screw fixation technique, a new dorsal atlantoaxial instability (AAI) clamp, and a new ventral AAI hook plate under sagittal shear loading after transection of the ligaments of the atlantoaxial joint.
STUDY DESIGN:
Cadaveric biomechanical study.
ANIMALS:
Canine cadavers (n = 10).
MATERIALS AND METHODS:
The occipitoatlantoaxial region of Beagles euthanatized for reasons unrelated to the study was prepared leaving only ligamentous structures and the joint capsules between the first 2 cervical vertebrae (C1 and C2). The atlanto-occipital joints were stabilized with 2 transarticular diverging positive threaded K-wires. The occipital bone and the caudal end of C2 were embedded in polymethylmethacrylate and loaded in shear to a force of 50 Newtons. The range of motion (ROM) and neutral zone (NZ) of the atlantoaxial joint were determined after 3 loading cycles with atlantoaxial ligaments intact, after ligament transection, and after fixation with each implant. The testing order of implants was randomly assigned. The implants tested last were subjected to failure testing.
RESULTS:
All stabilization procedures decreased the ROM and NZ of the atlantoaxial joint compared to transected ligament specimens. Only stabilization with transarticular lag screws and ventral plates produced a significant reduction of ROM compare to intact specimens.
CONCLUSION:
Fixation with transarticular lag screws and a ventral hook plate was biomechanically similar and provided more rigidity compared to dorsal clamp fixation. Further load cycling to failure tests and clinical studies are required before making clinical recommendations
Magnetic Resonance Imaging Finding in Small Ruminants with Brain Disease.
No full textBrain disease is an important cause of neurologic deficits in small ruminants, however few MRI features have been described. The aim of this retrospective, case series study was to describe MRI characteristics in a group of small ruminants with confirmed brain disease. A total of nine small ruminants (six sheep and three goats) met inclusion criteria. All had neurologic disorders localized to the brain and histopathologic confirmation. In animals with toxic-metabolic diseases, there were bilaterally symmetric MRI lesions affecting either the gray matter (one animal with polioencephalomalacia) or the white matter (two animals with enterotoxemia). In animals with suppurative inflammation, asymmetric focal brainstem lesions were present (two animals with listeric encephalitis), or lesions typical of an intra-axial (one animal) or dural abscess (one animal), respectively. No MRI lesions were detected in one animal with suspected viral cerebellitis and one animal with parasitic migration tracts. No neoplastic or vascular lesions were identified in this case series. Findings from the current study supported the use of MRI for diagnosing brain diseases in small ruminants
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