Computer simulation of syringomyelia in dogs

Syringomyelia is a pathological condition in which fluid-filled cavities (syringes) form and expand in the spinal cord. Syringomyelia is often linked with obstruction of the craniocervical junction and a Chiari malformation, which is similar in both humans and animals. Some brachycephalic toy breed dogs such as Cavalier King Charles Spaniels (CKCS) are particularly predisposed. The exact mechanism of the formation of syringomyelia is undetermined and consequently with the lack of clinical explanation, engineers and mathematicians have resorted to computer models to identify possible physical mechanisms that can lead to syringes. We developed a computer model of the spinal cavity of a CKCS suffering from a large syrinx. The model was excited at the cranial end to simulate the movement of the cerebrospinal fluid (CSF) and the spinal cord due to the shift of blood volume in the cranium related to the cardiac cycle. To simulate the normal condition, the movement was prescribed to the CSF. To simulate the pathological condition, the movement of CSF was blocked

International Veterinary Epilepsy Task Force recommendations for a veterinary epilepsy-specific MRI protocol

Epilepsy is one of the most common chronic neurological diseases in veterinary practice. Magnetic resonance imaging (MRI) is regarded as an important diagnostic test to reach the diagnosis of idiopathic epilepsy. However, given that the diagnosis requires the exclusion of other differentials for seizures, the parameters for MRI examination should allow the detection of subtle lesions which may not be obvious with existing techniques. In addition, there are several differentials for idiopathic epilepsy in humans, for example some focal cortical dysplasias, which may only apparent with special sequences, imaging planes and/or particular techniques used in performing the MRI scan. As a result, there is a need to standardize MRI examination in veterinary patients with techniques that reliably diagnose subtle lesions, identify post-seizure changes, and which will allow for future identification of underlying causes of seizures not yet apparent in the veterinary literature. There is a need for a standardized veterinary epilepsy-specific MRI protocol which will facilitate more detailed examination of areas susceptible to generating and perpetuating seizures, is cost efficient, simple to perform and can be adapted for both low and high field scanners. Standardisation of imaging will improve clinical communication and uniformity of case definition between research studies. A 6–7 sequence epilepsy-specific MRI protocol for veterinary patients is proposed and further advanced MR and functional imaging is reviewed

MRI characteristics for “phantom” scratching in canine syringomyelia

Background A classic sign of canine syringomyelia (SM) is scratching towards one shoulder. Using magnetic resonance imaging (MRI) we investigate the spinal cord lesion relating to this phenomenon which has characteristics similar to fictive scratch secondary to spinal cord transection. Medical records were searched for Cavalier King Charles spaniels with a clinical and MRI diagnosis of symptomatic SM associated with Chiari-like malformation (CM). The cohort was divided into SM with phantom scratching (19 dogs) and SM but no phantom scratching (18 dogs). MRI files were anonymised, randomised and viewed in EFILM ™. For each transverse image, the maximum perpendicular dimensions of the syrinx in the dorsal spinal cord quadrants were determined. Visual assessment was made as to whether the syrinx extended to the superficial dorsal horn (SDH). Results We showed that phantom scratching appears associated with a large dorsolateral syrinx that extends to the SDH in the C3-C6 spinal cord segments (corresponding to C2-C5 vertebrae). Estimated dorsal quadrant syrinx sizes based on the perpendicular diameters were between 2.5 and 9.5 times larger in dogs with phantom scratching, with the largest mean difference p-value being 0.009. Conclusion SM associated phantom scratching appears associated with MRI findings of a large syrinx extending into the mid cervical SDH. We hypothesise that damage in this region might influence the lumbosacral scratching central pattern generator (CPG). If a scratching SM affected dog does not have a large dorsolateral cervical syrinx with SDH involvement then alternative explanations for scratching should be investigated.</p

Additional file 2: of MRI characteristics for “phantom” scratching in canine syringomyelia

Dataset of syrinx measurements and observations. (XLSX 96 kb

Use of Morphometric Mapping to Characterise Symptomatic Chiari-Like Malformation, Secondary Syringomyelia and Associated Brachycephaly in the Cavalier King Charles Spaniel

<div><p>Objectives</p><p>To characterise the symptomatic phenotype of Chiari-like malformation (CM), secondary syringomyelia (SM) and brachycephaly in the Cavalier King Charles Spaniel using morphometric measurements on mid-sagittal Magnetic Resonance images (MRI) of the brain and craniocervical junction.</p><p>Methods</p><p>This retrospective study, based on a previous quantitative analysis in the Griffon Bruxellois (GB), used 24 measurements taken on 130 T1-weighted MRI of hindbrain and cervical region. Associated brachycephaly was estimated using 26 measurements, including rostral forebrain flattening and olfactory lobe rotation, on 72 T2-weighted MRI of the whole brain. Both study cohorts were divided into three groups; Control, CM pain and SM and their morphometries compared with each other.</p><p>Results</p><p>Fourteen significant traits were identified in the hindbrain study and nine traits in the whole brain study, six of which were similar to the GB and suggest a common aetiology. The Control cohort had the most elliptical brain (p = 0.010), least olfactory bulb rotation (p = 0.003) and a protective angle (p = 0.004) compared to the other groups. The CM pain cohort had the greatest rostral forebrain flattening (p = 0.007), shortest basioccipital (p = 0.019), but a greater distance between the atlas and basioccipital (p = 0.002) which was protective for SM. The SM cohort had two conformation anomalies depending on the severity of craniocervical junction incongruities; i) the proximity of the dens (p <0.001) ii) increased airorhynchy with a smaller, more ventrally rotated olfactory bulb (p <0.001). Both generated ‘concertina’ flexures of the brain and craniocervical junction.</p><p>Conclusion</p><p>Morphometric mapping provides a diagnostic tool for quantifying symptomatic CM, secondary SM and their relationship with brachycephaly. It is hypothesized that CM pain is associated with increased brachycephaly and SM can result from different combinations of abnormalities of the forebrain, caudal fossa and craniocervical junction which compromise the neural parenchyma and impede cerebrospinal fluid flow.</p></div

Study groups with numbers and ages of CKCS in the three study cohorts.

<p>Study groups with numbers and ages of CKCS in the three study cohorts.</p

Additional morphometric measurements taken of the T2w mid-sagittal brain MRI of a CKCS with CM pain.

<p>Key For identity of points a-l see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0170315#pone.0170315.g001" target="_blank">Fig 1</a>. Three ‘best fit’ circles (coloured aqua) and an ellipse (coloured red) that follow the outline shape of the neural parenchyma as closely as possible. Occipital circle (centre f)–as for hindbrain study. Size is determined by the shape of the occipital lobe extending rostroventrally to the baseline labi (basioccipital bone). i Forebrain circle (centre m)—most rostral portion of the forebrain dorsal to the cribriform plate of the ethmoid bone. ii Olfactory circle (centre n)—size is determined by the shape of olfactory bulbs extending beyond the pre-frontal cortex in the mid-sagittal image. iii Cerebral parenchyma ellipse which encompasses the caudal edge of the occipital and rostral edge of the forebrain circle (i.e. the cerebral parenchyma but not including the entire cerebellum or brainstem), its area (mm²) together with its ellipticity ‘E’ (defined as a mathematical relationship between of the largest radius to the smallest radius in the ellipse). Both calculated by Mimics Materialise® software programme. (smaller E values = more spherical, larger E values more elliptical). iv Associated lines (coloured aqua) comprising mf, nf, The olfactory bulb (OB) length and height (product represented. v Five angles (coloured yellow): • top angle—angulation between the frontal and parietal lobes. • bottom angle -angulation between the dorsal OB and the frontal lobe. • OB angle—angulation between the OB and hard palate. • mfn and nfg.</p

Canonical Discriminant Function Coefficients.

<p>Canonical Discriminant Function Coefficients.</p

Four mid-sagittal T2w whole brain MRI exemplars of cohorts Control, CM pain and two conformation cases of SM.

<p>The occipital circle has been standardised in all the images and the baseline labi aligned to facilitate comparison. Colour codes for morphometric ‘signatures’: Blue = Control; Yellow = CM pain; Red/Crimson = SM affected (two cases). Green: all groups = angles 2 and 3 and lines bc and bk. Superimposed- CM pain (yellow) has most extreme range. White: *greatest parenchyma height from skull baseline and is rostral to occipital circle in CM pain and SM affected case 2. x caudal displacement of occipital lobe. white/blue bar drawn at most rostral point of forebrain and olfactory circles indicates angulation of forebrain flattening. The blue bar (Control dog) has been superimposed on the three other group dogs for comparison. CM pain has greatest rostral forebrain flattening; The SM case 2 has the greatest olfactory lobe deviation.Orange: brachycephaly- lines mark the position and relationship of the upper nasal bone and the hard palate. SM case 2 has the greatest brachycephaly with angulation at the nasion and the lower palatine/incisive bones. Aqua: dens. This lies closest to the basioccipital in SM case 1. The different angle of dens in CM pain dog was found to be significant for the study. Black: arrows suggest displacement resulting from craniosynostosis. * indicates deviation (shortening) of occipital bone in CM pain and SM case 2.</p

24 measurements used to map the hindbrain and craniocervical junction on T1w mid-sagittal MRIs of a CKCS without SM.

<p>Key. (a) dorsum of spheno-occipital synchondrosis. (b) basion of basioccipital bone. (c) rostral edge of the dorsal lamina of the atlas. (d) junction between the supraoccipital bone and the occipital crest. (e) most dorsal point of intersection of the cerebellum with the occipital lobe circle. (f) centre of occipital lobe circle placed on the baseline at the level of the basioccipital bone (ab) and extending to encompass the occipital lobes. Diameter of circle = f-diam. (g) point at which the optic nerve deviates into the optic canal. (h) rostral edge of supra-occipital bone. (i) intersection point with ventrally extended line dc with the caudally extended ab baseline (forms angle 3 dib). (j) most rostral aspect of the dens of the axis bone. (k) extended line from point b along the best fit line of the ventral medulla oblongata to where it changes angle to the spinal cord. (l) rostral extension of baseline abi (hence becoming baseline labi). 11 angles measured are (1) lae, (2) fac, (3) dib, (4) fae (5) aeb (6) abd (7) bdi (8) ebd (9) jcb (10) afg (11) dbk. * significant for CM in the Griffon Bruxellois [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0170315#pone.0170315.ref024" target="_blank">24</a>].</p