Behavioral and clinical signs of Chiari-like malformation-associated pain and syringomyelia in Cavalier King Charles spaniels

Genomic analyses in Cavalier King Charles spaniels identify loci associated with clinical signs of Chiari-like malformation and Syringomyelia

BACKGROUND

Chiari-like malformations (CM) and syringomyelia (SM) are common in Cavalier King Charles spaniels (CKCS) leading to variable manifestations of pain and scratch. Inheritance studies suggest a polygenic mode of inheritance and association studies have identified loci associated with the presence of SM on MRI. Given the poor correlation of clinical signs of CMSM with MRI findings, we hypothesized that an association study with clinical signs as the phenotype could reveal new loci of interest. The objectives of this study were to perform genome-wide association studies on CKCS using SM and clinical sign phenotypes of pain and scratch and to use whole genome sequencing (WGS) to identify variants in regions of interest. We collected DNA on 174 CKCS. Owners completed questionnaires to establish the clinical pain and scratch phenotype and magnetic resonance imaging (MRI) was used to identify CM and SM (linear T2 hyperintensity greater than 2 mm in height) in all dogs. Dogs were genotyped using the Axiom K9 HD (710,000 snps) array. GWAS analyses were performed using GEMMA and categorical and quantitative approaches were used to define clinical phenotypes. Whole genome sequencing (WGS) was performed on an Illumina HiSeq 4000 high-throughput sequencing system.

RESULTS

There were no regions associated with SM presence. The presence of signs of pain and scratch was associated with a region on Canis familiaris autosome (CFA) 26 downstream of ZWINT, previously associated with skull changes in CKCS with SM, although genome-wide significance was not reached. Loci were also associated with quantitative pain and scratch scores on CFA 13, 2 and 38. There were 66 variants that segregated with phenotype including 2 missense variants that were predicted to have moderate effects on ZWINT function.

CONCLUSIONS

The identification of a locus on CFA26 using the clinical phenotype of pain and scratch that coincided with a locus identified in a morphological study provides strong support for this as a region of interest.

Cerebrospinal Fluid Concentrations of Calcitonin Gene Related Peptide in Dogs With Chiari-Like Malformation

BACKGROUND

The biomarker Calcitonin Gene-Related Peptide (CGRP) is elevated in human conditions associated with neuropathic pain, but has not yet been studied in Cavalier King Charles Spaniels (CKCS) with Chiari-like malformation (CM).

HYPOTHESIS/OBJECTIVES

Cavalier King Charles Spaniels with clinical signs of CMSM would have higher CSF concentrations of CGRP than asymptomatic CKCS. Our aim was to measure CSF CGRP concentrations in CKCS with and without clinical signs of CMSM.

ANIMALS

Twenty-nine CKCS drawn from research and clinical cases underwent quantification of pain and scratching, a brain and spinal cord MRI, and lumbar CSF collection.

METHODS

This was a prospective study with both normal and clinically affected CKCS recruited. The CSF concentration of CGRP (C-CGRP) was measured using an ELISA assay. Dogs were grouped by the presence of SM, pain, and scratching, and concentrations of C-CGRP were compared between groups using Wilcoxon Rank Sum. The concentration of C-CGRP, pain score, and SM diameter were evaluated using linear regression.

RESULTS

Concentration of C-CGRP was significantly higher in painful dogs (median 116.1, range: 11.6-238.3 pg/mL) as compared to non-painful dogs (median 77.7 pg/mL, range 0-266.2 pg/mL; p = 0.0124). No significant difference in C-CGRP concentration was noted between dogs with (median 99.3, range 0-226.6 pg/mL) and without (median 102.2, range 6.0-266.2 pg/mL) SM (p = 0.305).

CONCLUSIONS AND CLINICAL IMPORTANCE

Cerebrospinal fluid CGRP concentration is elevated in CKCS exhibiting pain regardless of the presence of SM. CGRP might contribute to neuropathic pain in CMSM and could be a target for therapeutic intervention.

Epidemiological Data, Clinical Signs, Therapy and Outcome Evaluation in Dogs with Syringomyelia of Different Etiology

Syringomyelia detected in both animals and humans may cause a variable degree of discomfort and its etiology is commonly unidentified. The aim of this study was to compare the outcome in dogs with those having syringomyelia of different etiology. Dogs with syringomyelia were subdivided into two groups: syringomyelia associated with Chiari-like malformation (S-CLM) (15 dogs) and syringomyelia of other etiology (SOA) (15 dogs). Age onset of S-CLM clinical signs was earlier compared to SOA (mean S-CLM and SOA values: 50.53 and 97.6 months, respectively, p = 0.021). Two neurological dysfunction scoring systems alongside nociception values were lower in SOA compared to S-CLM (mean values for neurological dysfunction scoring system SOA and S-CLM: 5.87 and 4.2, respectively, p = 0.032) (mean values for nociception SOA and S-CLM: 20.97 and 10.03, respectively, p = 0.03). Symptomatic therapy included combinations of corticosteroids, gabapentin (10/15, 66.6%) in S-CLM and NSAID +/- gabapentin (8/15, 53.3% and 9/15, 60%, respectively) in SOA dogs. Eight S-CLM dogs (53.4%) improved with symptomatic therapy and eleven were still alive; however, most SOA dogs (9/15, 73.4%) died/were euthanized by the end of this study. SOA dogs demonstrated more severe neurological signs compared to S-CLM, although the outcome between the two groups was not associated (p = 0.211).

The Effectiveness of Amitriptyline and Gabapentin in Treating Pomeranians with Chiari-like Malformation and/or Syringomyelia

BACKGROUND

Chiari-like malformation (CM) and syringomyelia (SM) are commonly observed disorders in the Pomeranians. Both disorders can lead to pain and diminish quality of life to varying extents. In veterinary medicine, affected dogs are often treated with gabapentin or pregabalin, which contrasts with human medicine, where the tricyclic antidepressants amitriptyline and nortriptyline are the first-choice treatments.

METHODS

affected dogs were treated with either amitriptyline or gabapentin. If a pre-syrinx was present, furosemide was also added. Owners were asked to score the clinical signs they observed (ORCS).

RESULTS

90 Pomeranians were included, of which 62 received amitriptyline and 28 received gabapentin. Adding furosemide did not have an influence on the outcome. A logistic regression analysis with the number of ORCS, duration of ORCS, treatment (amitriptyline or gabapentin), and outcome (responder or non-responder) as the dependent variable revealed that the number of ORCS had an Odds of 1123 (p = 0.03). Duration of the ORCS (Odds 1.027; p = 0.45) and treatment group had a low influence (Odds 1.258; p = 0.65).

CONCLUSIONS

In this study, amitriptyline demonstrated a moderate, though not statistically significant, more favorable effect on CM/SM pain compared to gabapentin. Adding furosemide to either of these two treatments did not influence the outcome. The outcome for dogs affected by CM/SM is not influenced by MRI grading; however, the number of ORCS and a longer duration negatively impact the outcome. A dose of 1 to 2 mg/kg body weight of amitriptyline administered twice daily proved to be more effective in several dogs.

CT- and MRI-based volumetry for Chiari-like malformation and syringomyelia in Pomeranians

Introduction

Volumetric studies in relation to CM/SM have not been reported in Pomeranians. In this study, we aim to (1) report the intermodality agreement between CT- and MRI-based volumetric measurements of the skull and cervical spinal canal, and (2) assess for differences and associations between the volumetric measurements and CM/SM status.

Methods

Pomeranians were included that underwent CT and MRI studies during the period of February 2022-June 2024. Frontal sinus volume (FSV), caudal cranial fossa volume (CCFV), rostral and middle cranial fossa volume (RMCFV), caudal cranial fossa parenchymal volume (CCFPV), rostral and middle cranial fossa parenchymal volume (RMCFPV), cerebellar parenchymal volume (CPV), brain stem parenchymal volume (BSPV), ventricular system volume (VSV), and spinal canal volume between C1-C7 (CSCV) were measured. CCFV to RMCFV volume index (VI) and CCFPV to CCFV (CCFPV%) were calculated. Agreement between MRI- and CT-based quantitative measurements was assessed with intraclass correlation coefficients. Inferential statistical tests including logistic regression modeling were performed to assess for associations between variables and CM/SM status.

Results

For all volumetric assessments that were performed on both CT and MRI, agreement was good or excellent. There were significant differences between SM normal and abnormal dogs for body weight as well as all volumetric parameters except for CCFPV% and RMCFV. Multiple logistic regression showed that a smaller CCFV and larger VSV were associated with SM.

Conclusion

Smaller CCFV and larger VSV are associated with the development of SM in Pomeranians and have increased odds of SM.

A data driven approach for soft tissue biomarker identification linked to Chiari-like malformation and syringomyelia

Canine Chiari-like malformation (CM) is a neuroanatomical condition associated with conformational change of the cranium, craniocervical junction and neuroparenchyma, resulting in pain (Chiari associated pain or CM-P) and the development of syringomyelia (SM). The associated neuro-disability in affected individuals compromises quality of life. CM is characterized by overcrowding of the brain and cervical spinal cord and is predisposed by skull-base shortening and miniaturization with brachycephalic toy dogs overwhelmingly represented. Magnetic resonance imaging (MRI) is conventionally used for diagnosis; however, CM is complex and ubiquitous in some dog breeds so that diagnosis of CM-P relies on a combination of clinical signs, MRI, and elimination of other causes of pain. This research aimed to identify cranial and spinal pathologies and neural morphologies linked to CM-P and SM in dogs using MRI scans and machine learning with the aim of identifying novel data driven biomarkers which could confirm CM-P and identify dogs at risk of developing SM. The methodology identified four regions of interest as having robust discrimination for CM-P, with 89% sensitivity and 76% specificity. A set of morphological features linked to CM-P were identified. Four regions of interest were also identified as having robust discrimination for SM, with 84% sensitivity and 80% specificity. Overall, these findings shed light on the distinct morphologies related to CM-P and SM, offering the potential for more accurate and objective diagnoses in affected dogs using MRI. These results contribute to the further understanding of the complex pathologies associated with CM and SM in brachycephalic toy pure and mixed breed dogs and support the potential utility of data-driven techniques for advancing our knowledge of these debilitating conditions.

Holocord syringomyelia in 18 dogs

Holocord syringomyelia (HSM) is characterized by a continuous spinal cord cavitation along its entire length and is currently poorly documented in dogs. This retrospective multicentric case series investigates the clinical and MRI findings in 18 dogs with HSM. The median age at presentation was 82 months (range 9-108 months) and French Bulldogs were overrepresented (50%). Signs of myelopathy attributed to HSM were detected in 12 dogs (67%), spinal pain/paresthesia/allodynia in eight (44%), and four dogs (22%) had no HSM-associated signs. The most common neuroanatomical localization was C1-C5 spinal cord segments. On MRI, the cranial limit of HSM was at C1 vertebra in seven (39%) and at C2 in 11 dogs (61%). The caudal limit extended to L3 in four dogs (22%), L4 or L5 in six dogs (33%) each, and L6 in two dogs (11%). The conus medullaris terminated at L5 in one dog (6%), L6 in 11 (61%), and L7 in six dogs (33%). Seventeen dogs (94%) exhibited MRI features of Chiari-like and/or other intracranial/cranio-cervical junction malformations. One dog (6%) was treated surgically, 11 (61%) medically, and six (33%) received no treatment. Over a median follow-up of 12 months (range 2-65 months) in 16 dogs, one dog (6%) improved, nine (56%) deteriorated, four (25%) were static, and two (13%) remained free of HSM-associated signs. This is the first study to describe canine HSM, highlighting a possible breed predisposition in French Bulldogs. The frequent occurrence of myelopathy and disease progression underscores the need for further research into the underlying etiopathogenesis, natural disease evolution, and response to therapeutic interventions.

CT-based and manual external skull measurements for Chiari-like malformation and syringomyelia in Pomeranians

Studies in Pomeranians as well as other breeds have looked at clinical signs or external features as predictors of Chiari-like malformation (CM) and syringomyelia (SM). The aim of this study is to describe and analyze morphometric factors of the skull of Pomeranians with and without CM/SM by means of CT as well as manual external measurements. Ninety-two Pomeranians >12 months of age were included that underwent both CT and MRI studies of the head and cervicothoracic vertebral column. Two observers independently reviewed the CT imaging studies and performed quantitative measurements. External measurements were taken from the head of dogs when under general anesthesia using a tape measure and a caliper. Externally measured mandible length was associated with the probability of having SM (p = 0.043). Mandible length was moderately correlated with weight (Pearson correlation coefficient = 0.585, p < 0.001). A cutoff for mandible length of 58 mm yielded a sensitivity of 96% (95% confidence interval 89-100%), meaning dogs in this study population with a mandible length shorter than 58 mm were highly likely to have SM. The measurement of the length of the mandible could help to determine the probability of a Pomeranian having SM, especially when combined with the presence or absence of owner reported clinicals signs as shown in previous studies.

On the utility of cerebrospinal fluid biomarkers in canine neurological disorders

The cerebral biomarkers, neurofilament light chain (NfL), amyloid-β, tau, and neuron specific enolase (NSE) reflect a wide spectrum of neurological damage in the brain and spinal cord. With this study, we aimed to assess whether these biomarkers hold any potential diagnostic value for the three most common canine neurological diseases. Canines suffering from meningoencephalitis of unknown origin (MUO), brain tumors, and selected non-infectious myelopathies were included. For each diagnosis, we analyzed these biomarkers in the cerebrospinal fluid collected via cranial puncture from the cisterna magna. Elevated levels of CSF tau, NfL, and NSE were observed in MUO, with all three biomarkers being intercorrelated. Tau and NSE were increased while amyloid-β was decreased in dogs suffering from tumors. In contrast, no biomarker changes were observed in dogs with myelopathies. Covariates such as age, sex, or castration had minimal impact. CSF biomarkers may reflect molecular changes related to MUO and tumors, but not to non-infectious myelopathies. The combination of NfL, tau, and NSE may represent useful biomarkers for MUO as they reflect the same pathology and are not influenced by age.

Comprehensive comparative study of Chiari-like malformation in veterinary and human medicine

This review aims to enrich our understanding of Chiari-like malformation (CLM) by combining human and veterinary insights, and providing a detailed cross-species overview. CLM is a developmental abnormality characterised by caudal displacement of the hindbrain into the foramen magnum due to an entire brain parenchymal shift caused by insufficient skull volume. This malformation leads to a progressive obstruction at the craniocervical junction, which disrupts the normal cerebrospinal fluid flow, leading to secondary syringomyelia. The clinical signs of CLM and syringomyelia include phantom scratching, head tilt, head tremor, ataxia, tetraparesis, pain, muscle atrophy, and scoliosis or torticollis. Magnetic resonance imaging remains the gold standard for diagnosing CLM, since it allows the visualisation of abnormal findings such as the caudal cerebellar herniation, caudal cerebellar compression from occipital dysplasia, and attenuated cerebrospinal fluid cisternae. Although various medical and surgical interventions, including foramen magnum decompression, can provide temporary symptomatic/clinical sign relief, current literature shows a lack of sustained long-term efficacy. Therefore, additional research is needed to evaluate the long-term effects of existing treatment strategies and to compare different techniques utilised in conjunction with foramen magnum decompression.

Longitudinal assessment of syringomyelia in Pomeranians

Introduction

Chiari-like malformation (CM) and syringomyelia (SM) are disorders that, in dogs, affect mainly small and toy breeds, including the Pomeranian. These disorders are linked to a great number of (owner-reported) clinical signs (ORCS) suggestive of pain. Aging was associated with an increased risk of having SM in several studies. However, there are only a few longitudinal studies that assess the presence and severity of CM/SM over time in CKCS dogs and progression of SM was linked to progression of clinical signs. The aim of this study was to investigate ORCS, CM/SM classification, and quantitative syrinx parameters in relation to progression of time (age) within individual Pomeranians.

Materials and methods

Pomeranians with or without ORCS and with or without diagnoses of CM/SM were included that had undergone two (or more) MRI studies of the craniocervicothoracic region between January 2020 and June 2023. Classification of CM/SM and quantitative syrinx measurements were performed. Absolute values as well as ratios for syrinx height, width, and cross-sectional area were included for analysis.

Results

A total of 19 Pomeranians were included in the study, of which 11 were male (58%) and 8 were female (42%). The median age at the time of MRI1 was 26 months (range 7-44 months). The median scan interval was 26 months (range 11-49 months). Eleven dogs (58%) were presented with ORCS at the time of MRI1, whereas the other 8 dogs (42%) had no ORCS at that time. At the time of MRI2, there were 17/19 dogs (89%) with ORCS and 2/19 dogs without ORCS (11%). Dogs were significantly more likely to have ORCS at MRI2 than MRI1 (p = 0. 0411). There was no significant difference between CM/SM classification at the time of MRI1 and MRI2. Significant differences were found between MRI1 and MRI2 for syrinx height (based on transverse images) (absolute value and ratio P = 0.0059), syrinx width (absolute value P = 0.1055, ratio P = 0.0039), and syrinx cross sectional area (absolute value P = 0.0195, ratio P = 0.0217).

Discussion

There are differences in the presence or absence of ORCS as well as quantitative syrinx measurements in Pomeranians at different ages. This finding supports that longitudinal changes occur in the SM status of Pomeranians.

Relationship between syringomyelia and myxomatous mitral valve disease in Cavalier King Charles spaniels

BACKGROUND

Syringomyelia (SM) and myxomatous mitral valve disease (MMVD) are highly prevalent in Cavalier King Charles spaniels (CKCS). Cardiac status in CKCS with and without SM is currently unknown.

OBJECTIVES

To investigate the association between SM and MMVD severity in CKCS and CKCS with SM with and without clinical signs of SM.

ANIMALS

Fifty-five CKCS: 40 with SM (22 symptomatic and 18 asymptomatic) and 15 without SM.

METHODS

A combined retrospective and prospective study. MRI and echocardiography were used to diagnose SM and MMVD, respectively. The association between SM and MMVD severity (left ventricle internal diameter in diastole normalized to bodyweight [LVIDDN] and left atrium to aortic ratio [LA/Ao]) were tested using multivariable linear regression analysis adjusting for sex and age.

RESULTS

Overall, no significant difference in LVIDDN and LA/Ao was found between CKCS with or without SM. However, CKCS with symptomatic SM had significantly smaller LVIDDN (1.45 [1.30-1.50]) (median [IQR]) and LA/Ao (1.20 [1.10-1.28]) compared to CKCS with asymptomatic SM (1.60 [1.50-1.90] and 1.40 [1.20-1.75]) as well as CKCS without SM (0.24 [0.03-0.45] and 0.30 [0.05-0.56]) (all P values <.03).

CONCLUSIONS AND CLINICAL IMPORTANCE

An association between MMVD and SM was not confirmed in this cohort of CKCS, indicating that MMVD and SM do not co-segregate. However, CKCS with symptomatic SM had smaller left ventricle and atrial size compared to CKCS with asymptomatic SM and CKCS without SM.

Clinical predictors of syringomyelia in Cavalier King Charles Spaniels with chiari-like malformation based on owners' observations

BACKGROUND

Syringomyelia (SM) is a prevalent inherited developmental condition in Cavalier King Charles Spaniels (CKCSs) with Chiari-like malformation (CM), accompanied by a variety of clinical manifestations, including signs of neuropathic pain. Magnetic resonance imaging (MRI) is the gold standard in SM diagnosis. However, it is desirable to establish clinical predictors that can identify CKCSs with a large clinical syrinx that needs treatment, as some owners cannot afford or lack access to MRI. The aims of the study were to investigate owner-reported clinical signs of SM and clinical predictors of a large clinical syrinx, using predictive values of significant signs, individually and in combinations. Eighty-nine CKCSs participated in this retrospective study. Based on MRI diagnosis, dogs were distributed into three groups: CM without syrinx or with a maximum transverse width < 2 mm (n = 13), CM with small syrinx 2.00-3.99 mm (n = 26) and CM with large syrinx ≥4 mm (n = 50). A structured investigator-owner interview using a standardized questionnaire was used to collect data regarding clinical signs of CM and SM. The statistical tests Pearson's chi-square, Fisher's Exact and Spearman's rank order were used to assess the difference in owner-reported signs between groups. For signs with significant differences, positive and negative predictive values (PPV and NPV) were calculated.

RESULTS

Following clinical signs were reported significantly more frequent in dogs with a large syrinx: phantom scratching, bilateral scratching of the neck or shoulder, aversion when that area is touched, or exacerbation of clinical signs when the dog is emotionally aroused. Each individual sign had a high PPV, indicative of a large clinical syrinx. The PPV increased further when the signs phantom scratching, aversion to touch to the head, neck or shoulder, and a preferred head posture during sleep were present in combination.

CONCLUSIONS

Specific clinical signs can be used individually and in combination as clinical predictors of a large clinical syrinx in CKCSs with CM and SM. General practitioners can utilize this information to identify CKCSs with a large syrinx to initiate necessary treatment. This is particularly useful in cases where access to or affordability of an MRI diagnosis is limited.

Head tilt as a clinical sign of cervical spinal or paraspinal disease in dogs: 15 cases (2000-2021)

OBJECTIVES

To characterise head tilt as a rare clinical sign of cervical spinal or paraspinal disease in dogs.

MATERIALS AND METHODS

Retrospective single-centre case-series study of dogs with head tilt and cervical spinal or paraspinal disease in the absence of intracranial abnormalities. Descriptive statistics were used.

RESULTS

Fifteen dogs met the inclusion criteria of this study. Median age at onset was 6 years (range 2.5 to 12 years). Onset of neurological signs was mainly chronic (9/15, 60%). Most common presenting complaints included head tilt (9/15, 60%) and cervical hyperaesthesia (8/15, 53%). Most common neurological findings included head tilt (15/15, 100%), generalised proprioceptive ataxia and tetraparesis (6/15, 40%) and cervical hyperaesthesia (8/15, 53%). Diagnoses included post-operative complication of C2 spinal nerve root mass removal (2/15, 13%), C3-C4 intervertebral disc extrusion (2/15, 13%), cervical paraspinal myositis (2/15, 13%) and one of each: C2 vertebral malformation, C2 spinal nerve root mass, C1-C2 meningioma, C2 vertebral fracture, C4-C5 intervertebral disc extrusion, C4 vertebral body mass, C5-C7 osseous-associated cervical spondylomyelopathy, and concurrent C5-C6 and C6-C7 intervertebral disc protrusions. Two dogs were euthanased shortly after diagnosis and two of 15 were dogs lost to follow-up. No post-mortem examination was performed for these cases. For the 11 of 15 remaining dogs, head tilt resolved in eight of 15 (53%) dogs after treatment of the underlying condition and in three of 15 (20%) dogs, it remained static.

CLINICAL SIGNIFICANCE

Head tilt can be a rare clinical sign of cervical spinal or paraspinal disease in dogs.

Phenotypic characterization of Pomeranians with or without Chiari-like malformation and syringomyelia

Introduction

Chiari-like malformation (CM) and syringomyelia (SM) are frequently diagnosed conditions in small and toy dog breeds, such as the Cavalier King Charles Spaniel and Griffon Bruxellois. CM/SM is only rarely reported in Pomeranians in literature to date. The aims of this study are to 1/describe the phenotype of Pomeranians with or without CM/SM and 2/evaluate for differences and associations between CM/SM and owner-reported clinical signs (ORCS) or signalment factors.

Materials and methods

From February 2015 to June 2023, historical data and signalment (including country of origin, pedigree, sex and neuter status, age, and body weight) and ORCS of Pomeranians were recorded at multiple institutions. MRI studies of all dogs were evaluated for classification of CM/SM. Additionally, quantitative measurements were performed for SM.

Results

A total of 796 dogs from 22 different countries were included. Total prevalence of CM was 54.9% (437/796) and the prevalence of SM was 23.9% (190/796). The top 5 ORCS included 1/scratching with skin contact, rubbing head or ears, or both (57.6% of dogs with ORCS), 2/air licking (30.7% of dogs with ORCS), 3/spontaneous signs of pain (26.0% of dogs with ORCS), 4/persistent licking front and/or hind paws (22.6% of dogs with ORCS), 5/phantom scratching (22.6% of dogs with ORCS). Phantom scratching, vocalization, head shaking, spontaneous signs of pain, and air licking were associated with having SM. There were no statistically significant associations between quantitative syrinx measurements and ORCS. There were statistically significant associations between CM classification and 1/country of origin, 2/having a pedigree, and 3/age. There were statistically significant associations between SM classification and 1/age and 2/body weight.

Discussion

This is the first large study evaluating CM/SM in the Pomeranian dog breed. Veterinary clinicians can use these findings to increase the likelihood of correctly determining the presence or absence of CM/SM in Pomeranians. Breeders may consider using the information regarding signalment factors as well as ORCS associated with CM/SM classifications to select dogs for screening procedures. But an MRI-based diagnosis is needed to properly ascertain the exact CM/SM status of their breeding stock until a fool-proof characteristic or genetic marker is found.

Interleukin-31 in serum and cerebrospinal fluid of dogs with syringomyelia

BACKGROUND

Syringomyelia is a spinal cord cavity containing cerebrospinal fluid (CSF)-like fluid. If syringomyelia asymmetrically involves the dorsal horn grey matter of the spinal cord, affected dogs show increased signs of dysesthesia and neuropathic pain, like increased itching behaviour. In the dorsal horn, amongst others, receptors for Interleukin-31 (IL-31) can be found. IL-31 is one of the main cytokines involved in the pathogenesis of pruritus in atopic dermatitis in different species. This study investigates suspected elevated levels of IL-31 in serum and CSF of dogs showing signs of pain or increased itching behaviour related to syringomyelia. The IL-31 were measured in archived samples (52 serum and 35 CSF samples) of dogs with syringomyelia (n = 48), atopic dermatitis (n = 3) and of healthy control dogs (n = 11) using a competitive canine IL-31 ELISA.

RESULTS

Mean serum IL-31 level in dogs with syringomyelia was 150.1 pg/ml (n = 39), in dogs with atopic dermatitis 228.3 pg/ml (n = 3) and in healthy dogs 80.7 pg/ml (n = 10). Mean CSF IL-31 value was 146.3 pg/ml (n = 27) in dogs with syringomyelia and 186.2 pg/ml (n = 8) in healthy dogs. Individual patients with syringomyelia (especially dogs with otitis media or otitis media and interna or intervertebral disc herniation) showed high IL-31 levels in serum and CSF samples, but the difference was not statistically significant. IL-31 serum and CSF levels did not differ significantly in dogs with syringomyelia with or without itching behaviour and with or without signs of pain.

CONCLUSION

Based on this study, increased IL-31 levels seem not to be correlated with itching behaviour or signs of pain in dogs with syringomyelia, but might be caused by other underlying diseases.

Reduced cingulate gyrus volume in Cavalier King Charles Spaniels with syringomyelia and neuropathic pain revealed by voxel-based morphometry: a pilot study

Objective

Pathomorphological alterations of the central nervous system in dogs, such as syringomyelia and Chiari-like malformation, can cause cranial and cervical hyperesthesia and neuropathic pain. The long-term activity of the pain network can induce functional alteration and eventually even morphological changes in the pain network. This may happen especially in the prefrontal and cingulate cortex, where atrophy of the gray matter (GM) was observed in humans with chronic pain, irrespective of the nature of the pain syndrome. We tested the hypothesis that Cavalier King Charles Spaniels (CKCS) with Chiari-like malformation and associated syringomyelia (SM) and pain show cerebral morphological differences compared to animals without signs of syringomyelia and pain.

Methods

Volumetric datasets of 28 different brain structures were analyzed in a retrospective manner, including voxel-based morphometry, using magnetic resonance imaging data obtained from 41 dogs.

Results

Volumetric analyses revealed a decrease in GM volumes in the cingulate gyrus (CG) in CKCS with SM and chronic pain when normalized to brain volume. This finding was supported by voxel-based morphometry, which showed a cluster of significance within the CG.

Conclusion

GM atrophy in the CG is associated with chronic pain and thus may serve as an objective readout parameter for the diagnosis or treatment of canine pain syndromes.

A Critical Update of the Classification of Chiari and Chiari-like Malformations

Chiari malformations are a group of craniovertebral junction anomalies characterized by the herniation of cerebellar tonsils below the foramen magnum, often accompanied by brainstem descent. The existing classification systems for Chiari malformations have expanded from the original four categories to nine, leading to debates about the need for a more descriptive and etiopathogenic terminology. This review aims to examine the various classification approaches employed and proposes a simplified scheme to differentiate between different types of tonsillar herniations. Furthermore, it explores the most appropriate terminology for acquired herniation of cerebellar tonsils and other secondary Chiari-like malformations. Recent advances in magnetic resonance imaging (MRI) have revealed a higher prevalence and incidence of Chiari malformation Type 1 (CM1) and identified similar cerebellar herniations in individuals unrelated to the classic phenotypes described by Chiari. As we reassess the existing classifications, it becomes crucial to establish a terminology that accurately reflects the diverse presentations and underlying causes of these conditions. This paper contributes to the ongoing discussion by offering insights into the evolving understanding of Chiari malformations and proposing a simplified classification and terminology system to enhance diagnosis and management.

Biopsy and histologic findings of the dura mater at the level of the foramen magnum in 121 CKCS with Chiari-like malformation

To describe histopathologic features found in dural biopsies of Cavalier King Charles Spaniels (CKCS) with Chiari-like malformation (CM) and identify any associations between age, duration of clinical signs, syrinx location or syringomyelia (SM, and quality of life (QOL). The medical records of 121 consecutive client owned CKCS with CM and SM, confirmed by whole body magnetic resonance imaging (MRI), that underwent foramen magnum decompression (FMD) with cranioplasty and durectomy with biopsy from 2006 to 2016 were retrospectively reviewed. Dural biopsies were submitted to a board-certified veterinary pathologist for histopathologic interpretation. The chi-square test was used to analyze associations between histologic findings and categorical variables. For continuous measures, the Kruskal–Wallis non-parametric test was used to compare distributions across pathology categories. A result was considered statistically significant at the p < 0.05 level of significance. The mean age, duration of pre-surgical clinical signs, and pre-operative QOL (1–5 scale) were 44.27 months, 44.78 weeks, and 2.72, respectively. Syringomyelia was found in the cervical region only in 39 of 121 (32.23%) of dogs, in the cervical and thoracic region only in 17 of 121 (14.05%) of dogs, and in the cervical, thoracic, and lumbar region combined in 65 of 121 (53.72%) of dogs. Sixty-six of one hundred twenty-one (54.55%) dural biopsy specimens had histopathology changes; fifty-five (45.45%) did not. Forty-three of one hundred twenty-one (35.54%) dural biopsy specimens had osseous metaplasia, 16 of 121 (13.22%) had evidence of fibrosis, 4 of 121 (3.31%) had arachnoid hyperplasia, and 3 of 121 (2.48%) had evidence of mineralization. Most dogs with CM were found to have histopathologic changes in the dura at the time of FMD cranioplasty was performed. These dural changes can be observed in dogs experiencing clinical signs for a time period as short as 4 weeks prior to presentation. The histopathologic changes were not associated with age, breed, duration of clinical signs, the location of syringomyelia or QOL. The influence of histopathologic changes on long-term prognosis in dogs without dural decompression is unknown since all dogs in this study had dural resection.

Ventriculomegaly in Cavalier King Charles Spaniels with Chiari-like malformation: relationship with clinical and imaging findings

The objective of this study was to calculate lateral ventricles dimension in Cavalier King Charles Spaniel dogs with Chiari-like malformation and investigate the association between ventriculomegaly and signalment, clinical signs, ventricular asymmetry, grade of Chiari-like malformation, syringomyelia and index of medullary kinking. Retrospectively, 43 client-owned Cavalier King Charles Spaniels, older than 1 year of age, with magnetic resonance imaging diagnosis of Chiari-like malformation were enrolled. Initial and follow-up (up to 36 months) clinical status was graded. Images were reviewed to quantify the enlargement of lateral ventricles, evaluate ventricular symmetry, grade of Chiari-like malformation, grade of syringomyelia and medullary kinking index. Cases presenting epileptic seizures during the evaluation period were also recorded. The most common initial clinical signs were scratching and neck pain. Ventriculomegaly was identified in 70% of dogs, Chiari-like malformation grade 2 was observed in 77% of cases, ventricular asymmetry and syringomyelia were identified in 54% and 80% of dogs, respectively; the median medullary kinking index was 37.77%. Moreover, 28% of dogs presented epileptic seizures. No significant association was identified between dimension of lateral ventricles and signalment, clinical signs, and imaging findings; no significant association was identified between ventriculomegaly and epilepsy (P≥0.05). In conclusion, the prevalence of ventriculomegaly in Cavalier King Charles Spaniels is high but this finding does not seem related to the severity of clinical signs, presence of Chiari-like malformation, syringomyelia and craniocervical junction abnormalities such as medullary kinking.

Case Report: Anti-GABAA Receptor Encephalitis in a Dog

Autoantibodies against neurotransmitter receptors detected in cerebrospinal fluid (CSF) and serum are increasingly recognized in people with human autoimmune encephalitis causing severe neurological deficits, such as seizures and behavioral abnormalities. This case report describes the first encephalitis associated with antibodies against the γ-aminobutyric acid-A receptor (GABA_AR) in a dog. A young male intact Cavalier King Charles Spaniel was presented with recent onset of initial multiple generalized tonic-clonic seizures progressing into a status epilepticus. Interictally, he showed alternating stupor and hyperexcitability, ataxia, pleurothotonus and circling behavior to the left side. Magnetic resonance imaging (MRI) of the brain showed breed-specific anatomical abnormalities. Standard CSF analysis was unremarkable. Despite treatment with multiple antiseizure medications (ASMs) seizures and behavior abnormalities sustained. Immunotherapy with dexamethasone was started on the fifth day after disease manifestation. This led to rapid improvement of clinical signs. An extensive antibody search in CSF and serum demonstrated a neuropil staining pattern on a tissue-based assay compatible with GABA_AR antibodies. The diagnosis was confirmed by binding of serum and CSF antibodies to GABA_AR transfected Human Embryonic Kidney cells. The serum titer was 1:320, the CSF titer 1:2. At the control visit 4.5 weeks after start of immunotherapy, the dog was clinically normal. The GABA_AR antibody titer in serum had strongly decreased. The antibodies were no longer detectable in CSF. Based on clinical presentation and testing for GABA_AR binding antibodies, this describes the first veterinary patient with an anti-GABA_AR encephalitis with a good outcome following ASM and corticosteroid treatment.

Dorsal horn volume loss and pain pathway changes in Cavalier King Charles Spaniels with syringomyelia, signs of pain, and phantom scratching

ABSTRACT

Central neuropathic pain is a core clinical sign of syringomyelia in humans and Cavalier King Charles Spaniel (CKCS) dogs. This histopathological study used spinal cords from CKCS with syringomyelia to investigate: 1) whether specific structural cervical spinal cord entities involved in nociception are affected by loss of neuroparenchyma or other pathological changes in CKCS with pain-related behaviour and phantom scratching, 2) if pain related behaviour or phantom scratching correlated with loss of a specific anatomical entity or upregulation of glia cells, and 3) if syringomyelia-related lesions affected specific functional spinal cord units of nociception.Spinal cord segments C1-C8 from CKCS with MRI-confirmed syringomyelia and clinical signs of pain and phantom scratch (n=8) were compared to CKCS without syringomyelia (n=4). Dogs with unilateral scratching (n=7) had a volume loss (P=0.043) of the dorsal horn laminae I-III in the ipsilateral side compared to the contralateral dorsal horn. A clear pattern of ipsilateral changes in the dorsal root entry zone characterised by deafferentation and reorganization of first-order axons into deeper laminae was found in cases with lateralised scratching. Significant changes in cell number density were not found for astrocytes or microglia, suggesting that the dogs represented cases of end-stage syringomyelia and thus could not reveal astrogliosis and microgliosis, which may be involved in the early phases of syrinx development and phantom scratch.The present relationship between clinical findings and dorsal horn and pain pathway pathology in CKCS suggests that these dogs may be of interest as a supplement to experimental model pain research.

Occipital cranioplasty using customized titanium prosthesis yields successful outcome in association with foramen magnum decompression in dogs suffering by Chiari-like malformation

OBJECTIVE

To describe the use of a customized 3-D-printed titanium prosthesis as adjunctive treatment for foramen magnum decompression (FMD) in dogs with Chiari-like malformation (CM) and syringomyelia (SM).

ANIMALS

8 dogs with clinical signs and MRI findings of CM-SM.

PROCEDURES

3-D reconstruction of CT images of the head was used to simulate an occipital craniectomy and design the prosthesis. FMD was performed, and the prosthesis was implanted. Follow-up was performed 1, 6, and 12 months later, and clinical status was scored. Repeated MRI images were compared to identify changes involving the neural structures, particularly the syrinx.

RESULTS

All prostheses were easily positioned based on the preoperative 3-D models, with no complications. At 12 months after surgery, 3 dogs were free of previous medications, 4 were still receiving steroid medications but at lower doses, and 1 was occasionally receiving acupuncture. MRI of 5 dogs 6 to 20 months after surgery revealed resolution of SM (n = 1), reduced size of SM (3), or worse SM (1). All dogs showed an increase in size of the caudal cranial fossa. Dogs with a longer presurgical duration of the clinical signs and wider syrinx generally had worse outcomes than other dogs.

CLINICAL RELEVANCE

Findings suggested that use of customized 3-D-printed titanium prosthesis and associated FMD can represent an adjunctive option to medically treated dogs with CM-SM. Although the small number of cases precludes definitive conclusions, early surgical treatment, particularly in dogs with a small syrinx, could ensure better long-term outcomes, as previously suggested.

The Puppy in the Pit: Osteobiography of an Eighteenth-Century Dog at the Three Cranes Tavern, Massachusetts

Boston's "Big Dig" construction project resulted in the excavation of multiple archaeological sites dating from the seventeenth to nineteenth centuries, including the Great House/Three Cranes Tavern in Charlestown, Massachusetts (USA). An otherwise unremarkable pit below the tavern foundation contained bones originally identified as a cat skeleton, which has subsequently been reidentified as a dog. This paper discusses site context, osteological evidence for the dog's reclassification, and the shifts in cultural meaning this may indicate. Employing an osteobiographical approach, it draws together points of connection between the modern skeletal assessment, a series of 1980s excavations, and the motivations of eighteenth-century tavern inhabitants.

Mortality Resulting from Undesirable Behaviours in Dogs Aged Three Years and under Attending Primary-Care Veterinary Practices in Australia

Simple Summary

There is increasing evidence that undesirable behaviours (UBs) in dogs can compromise the welfare of both canine companions and their associated humans. Indeed, in a recent UK study of patient records from primary-care veterinary practices, UBs emerged as the predominant cause for mortality in young dogs. The current companion study of dogs attending veterinary practices in Australia from 2013 to 2018 reports a comparable proportion of mortality (29.7%) due to UBs among dogs aged three years and under. The most commonly reported UB was aggression. Neutered dogs and purebred dogs (and specifically Australian Cattle Dogs and American Staffordshire terriers) had an elevated risk of death ascribed to at least one UB. The risk factors associated with these UBs are also reported, including interventions applied by the attending clinician (if any). The results highlight the influence of UBs on dog welfare in Australia, and infer the benefits of educating dog owners and veterinary professionals in modifying and managing UBs.

Abstract

There is increasing evidence that undesirable behaviours (UBs) in dogs can compromise the welfare of both canine companions and their carers. Veterinarians are regularly consulted about affected animals and may be asked to euthanase the more severely affected individuals. A recent study of veterinary records showed that UBs were the predominant cause of mortality in young dogs in the UK. This companion study from Australia reports the proportion of mortality due to UBs among dogs aged three years and under that attended veterinary practices from 2013 to 2018. Deidentified patient records were extracted from the VetCompass Australia database and manually assessed to reveal the prevalence and type of UBs reported. The results reveal that 29.7% of the 4341 dogs that died at three years of age or under had deaths ascribed to at least one UB, and that the most commonly reported UB was aggression. Neutered dogs had 2.5× the odds of death due to an UB compared to intact dogs, and crossbred dogs were found to have 1.43× the odds of a UB related death compared to purebred dogs. The breeds at highest risk were Australian cattle dogs (odds ratio (OR) 4.77) and American Staffordshire terriers (OR 4.69). The attending veterinarian referred behaviour cases to a behaviourist or dog trainer in 11.0% of all UB cases, and attempted pharmacological therapy in 5.9% of cases. The results reveal how often UBs affect dogs and their owners in Australia, and infer the beneficial impact that educating dog owners and veterinary professionals in modifying and managing UBs may have.

The Need for Head Space: Brachycephaly and Cerebrospinal Fluid Disorders

Brachycephalic dogs remain popular, despite the knowledge that this head conformation is associated with health problems, including airway compromise, ocular disorders, neurological disease, and other co-morbidities. There is increasing evidence that brachycephaly disrupts cerebrospinal fluid movement and absorption, predisposing ventriculomegaly, hydrocephalus, quadrigeminal cistern expansion, Chiari-like malformation, and syringomyelia. In this review, we focus on cerebrospinal fluid physiology and how this is impacted by brachycephaly, airorhynchy, and associated craniosynostosis.

Association between filum terminale internum length and pain in Cavalier King Charles spaniels with and without syringomyelia

Background

Lumbar syringomyelia (SM), lumbosacral pain, and more caudal spinal cord termination are reported in Cavalier King Charles spaniels (CKCS). Data are lacking on the clinical relevance of alterations in their spinal cord terminal structures.

Objectives

To compare spinal cord termination level and filum terminale internum length (FTIL) with presence of lumbar SM and clinical signs in CKCS.

Animals

Forty‐eight CKCS.

Methods

In this prospective study, pain was quantified using owner and clinician assessments. Vertebral level of spinal cord and dural sac termination, presence of SM, and FTIL were determined from sagittal magnetic resonance imaging (MRI) sequences. Kappa and intraclass correlation (ICC) analyses determined interobserver reliability. The MRI findings were compared to owner and clinician‐reported pain quantification.

Results

Interobserver reliability was good for spinal cord and dural sac termination (kappa = 0.61 and 0.64, respectively) and excellent for FTIL (ICC: 92% agreement). The spinal cord terminated at 6th lumbar vertebra in 1, 7th lumbar vertebra in 31, and the sacrum in 15 dogs, and termination level was associated with lumbar SM (P = .002) but not clinical signs. Mean FTIL was 2.9 ± 1.08 mm; it was associated with owner‐reported pain (P = .033) and spinal palpation scores (P = .023). Painful CKCS without SM had shorter FTIL compared to normal CKCS and painful CKCS with SM (P = .02).

Conclusions

Painful CKCS without SM have decreased distance between the termination of the spinal cord and dural sac, suggesting a shorter FTIL. More caudal spinal cord termination is associated with development of lumbar SM.

Clinical reasoning in canine cervical hyperaesthesia: which presenting features are important?

BACKGROUND

To evaluate whether clinical features from the history, presentation, physical and neurological examination of dogs with cervical hyperaesthesia are statistically predictive of the underlying diagnosis.

METHODS

Two hundred and ninety-eight dogs presenting with cervical hyperaesthesia between January 2010 and October 2018 were investigated. Only neurologically normal dogs with cervical hyperaesthesia on examination were included, while those with concurrent neurological deficits including gait abnormalities and proprioceptive deficits were excluded. Univariate analysis of clinical variables was performed, and those associated with each diagnosis were retained for multivariable binary logistic regression models.

RESULTS

Ninety-five per cent of cervical hyperaesthesia presentations were represented by eight conditions that included steroid-responsive meningitis arteritis (SRMA; n=100), intervertebral disc extrusion (n=78), syringomyelia (SM; n=51), intervertebral disc protrusion (n=30), neoplasia (n=8), cervical spondylomyelopathy (n=7), immune-mediated polyarthritis (n=5) and meningoencephalomyelitis of unknown aetiology (n=5). Younger age (P=0.003), pyrexia (P=0.003) and haematology abnormalities (P=0.03) comprising leucocytosis, neutrophilia or monocytosis were associated with a diagnosis of SRMA.

CONCLUSIONS

Easy-to-recognise clinical features can be used to identify the most likely differential diagnosis in neurologically normal dogs with cervical hyperaesthesia, which may aid the decision making of veterinary surgeons evaluating dogs with this presentation.

Clinical Presentation of Chiari-like Malformation in 2 Persian Cats

Two Persian breed cats, 10 and 5 years of age, were presented separately for difficulty prehending food as well as behavioral abnormalities including interanimal aggression and restlessness, pacing, or compulsive overgrooming. Both cats would regularly rest their head and neck in an extended position. Neurologic examination demonstrated calvarial and craniocervical junction pain in both and an L4-S3 myelopathy in one. Brain MRI of both cases, and CT and necropsy in 1 case, demonstrated ventriculomegaly and caudal fossa crowding, cerebellar indentation, and foramen magnum herniation consistent with Chiari-like malformation. No syringomyelia was present in either cat. The 2 cats were treated with anti-inflammatory doses of prednisolone with little to no clinical response, but experienced improvement with pregabalin and omeprazole. The 2 cats' clinical signs were consequently attributed to neuropathic and posture-related pain secondary to Chiari-like malformation. Persian breed cats may have a predisposition to Chiari-like malformation, which may not be solely a morphometric variant, and symptomatic cats may present with manifestations of neuropathic pain different from the classic signs reported in dogs.

Syringopleural shunt placement in a pug with a cervical spinal diverticulum and associated syringomyelia

We report persistence of associated syringomyelia and formation of newly caudal spinal arachnoid diverticulum, following marsupialization surgery. We describe syringopleural shunt placement as a novel approach to treat both conditions in a Pug dog.

Pain and Problem Behavior in Cats and Dogs

We argue that there is currently an under-reporting of the ways in which pain can be associated with problem behavior, which is seriously limiting the recognition of this welfare problem. A review of the caseloads of 100 recent dog cases of several authors indicates that a conservative estimate of around a third of referred cases involve some form of painful condition, and in some instances, the figure may be nearly 80%. The relationship is often complex but always logical. Musculoskeletal but also painful gastro-intestinal and dermatological conditions are commonly recognized as significant to the animal's problem behavior. The potential importance of clinical abnormalities such as an unusual gait or unexplained behavioral signs should not be dismissed by clinicians in general practice, even when they are common within a given breed. In general, it is argued that clinicians should err on the side of caution when there is a suspicion that a patient could be in pain by carefully evaluating the patient's response to trial analgesia, even if a specific physical lesion has not been identified.

Facial changes related to brachycephaly in Cavalier King Charles Spaniels with Chiari-like malformation associated pain and secondary syringomyelia

BACKGROUND

Recent studies including an innovative machine learning technique indicated Chiari-like malformation (CM) is influenced by brachycephalic features.

OBJECTIVES

Morphometric analysis of facial anatomy and dysmorphia in CM-associated pain (CM-P) and syringomyelia (SM) in the Cavalier King Charles Spaniel (CKCS).

ANIMALS

Sixty-six client-owned CKCS.

METHODS

Retrospective study of anonymized T2W sagittal magnetic resonance imaging of 3 clinical groups: (1) 11 without central canal dilation (ccd) or SM (CM-N), (2) 15 with CM-P with no SM or <2 mm ccd (CM-P), and (3) 40 with syrinx width ≥4 mm (SM-S). Morphometric analysis assessed rostral skull flattening and position of the hard and soft palate relative to the cranial base in each clinical group and compared CKCS with and without SM-S.

RESULTS

Sixteen of 28 measured variables were associated to SM-S compared to CM-N and CM-P. Of these 6 were common to both groups. Predictive variables determined by discriminant analysis were (1) the ratio of cranial height with cranial length (P < .001 between SM-S and CM-N) and (2) the distance between the cerebrum and the frontal bone (P < .001 between SM-S and CM-P). CM-P had the lowest mean height of the maxillary area.

CONCLUSIONS AND CLINICAL IMPORTANCE

CKCS with CM-P and SM-S have cranial brachycephaly with osseous insufficiency in the skull with rostral flattening and increased proximity of the hard and soft palate to the cranial base. Changes are greatest with CM-P. These findings have relevance for understanding disease pathogenesis and for selection of head conformation for breeding purposes.

Behavioral and clinical signs of Chiari-like malformation-associated pain and syringomyelia in Cavalier King Charles spaniels

Background

Diagnosis of Chiari‐like malformation‐associated pain (CM‐P) or clinically relevant syringomyelia (SM) is challenging. We sought to determine common signs.

Animals

One hundred thirty client‐owned Cavalier King Charles spaniels with neuroaxis magnetic resonance imaging (MRI) and diagnosis of CM‐P/SM. Dogs with comorbidities causing similar signs were excluded with exception of otitis media with effusion (OME).

Methods

Retrospective study of medical records relating signalment, signs, and MRI findings. Dogs were grouped by SM maximum transverse diameter (1 = no SM; 2 = 0.5‐1.99 mm; 3 = 2‐3.9 mm: 4 = ≥4 mm). Differences between all groups—groups 1 versus 2‐4 and groups 1‐3 versus 4—were investigated. Continuous variables were analyzed using 2‐sample t‐tests and analysis of variance. Associations between categorical variables were analyzed using Fisher's exact or chi‐square tests.

Results

Common signs were vocalization (65.4%), spinal pain (54.6%), reduced activity (37.7%), reduced stairs/jumping ability (35.4%), touch aversion (30.0%), altered emotional state (28.5%), and sleep disturbance (22%). Head scratching/rubbing (28.5%) was inversely associated with syrinx size (P = .005), less common in group 4 (P = .003), and not associated with OME (P = .977). Phantom scratching, scoliosis, weakness, and postural deficits were only seen in group 4 (SM ≥4 mm; P = .004).

Conclusions and Clinical Importance

Signs of pain are common in CM/SM but are not SM‐dependent, suggesting (not proving) CM‐P causality. Wide (≥4 mm) SM is associated with signs of myelopathy and, if the dorsal horn is involved, phantom scratching (ipsilateral) and torticollis (shoulder deviated ipsilateral; head tilt contralateral).