Web-Vet TM Neurology Specialists
Anomalous / Congenital
Brain Diseases
Hydrocephalus
The aim of this study was to identify preoperative risk factors in dogs and cats with hydrocephalus for overshunting, the effect of surgical decompression, and their outcomes.
Overshunting had a prevalence of 18% of the study population of 75 dogs and 7 cats. An increase of 0.05 in ventricle:brain ratio increased the risk of overshunting. Biventricular hydrocephalus had the highest risk for overshunting compared to a tri- or tetraventricular hydrocephalus. There was no influence regarding the use of gravitational vs differential pressure valves. Overshunting resulted in hemispheric collapse, subdural hemorrhage, and peracute deterioration of neurological status in 15 animals. Subdural hematoma was removed in 8 dogs and 2 cats with prompt postoperative improvement of clinical signs.
Congenital internal hydrocephalus is a common malformation in dogs and cats. However, internal hydrocephalus is heterogeneous in nature and can be due to many other pathologies such as primary brain malformations (cysts, aqueductal stenosis, interventricular septae etc.), intraventricular hemorrhage, intracranial tumors, and infectious diseases. In many cases, the underlying cause remains undetermined (idiopathic hydrocephalus). This paper provides an overview of current knowledge of ventriculoperitoneal shunting techniques in animals, the surgical materials utilized as well as shunt-associated complications and their prevention and treatment.
This study is on the use of VPS as palliative treatment in patients with hypertensive hydrocephalus caused by tumors affecting the CSF drainage. In these cases, the main pathological process is not the tumour itself which is often small at the time of initial diagnosis but the secondary effect such as obstructive hydrocephalus. These patients are often presented with acute and severe intracranial signs associated with obstructive hydrocephalus when they have exhausted regulatory mechanisms of ICP compensation. VPS can provide a quick and efficient mean to address these secondary pathological effects although one of the main downside is the fairly high rate of long term complication associated with their use.
Chiari-Like Malformation
This article covers many topics including 1) clinical signs of Chiari-like malformation-associated pain and differential diagnosis, 2) clinical signs of syringomyelia and differential diagnosis, 3) diagnosis and MRI appearance of Chiari-like malformation-associated pain and syringomyelia, 4) medical and surgical management options for Chiari-like malformation-associated pain and syringomyelia and 5) breeding recommendations for dog breeds and crossbreeds predisposed to Chiari-like malformation-associated pain and syringomyelia.
The Need for Head Space: Brachycephaly and Cerebrospinal Fluid Disorders
There is increasing evidence that brachycephaly disrupts cerebrospinal fluid movement and absorption, predisposing to ventriculomegaly, hydrocephalus, quadrigeminal cistern expansion, Chiari-like malformation, and syringomyelia. In this review, the authors discuss cerebrospinal fluid physiology and how this is impacted by brachycephaly, airorhynchy, and associated craniosynostosis.
This study looks at the association between persistent fontanelles (PFs) and syringomyelia (SM), lateral ventricular volume, fourth ventricle dilation, SM maximum transverse width, as well as craniocervical junction (CCJ) overcrowding.
PFs are prevalent in Chihuahuas. In addition, Chihuahuas are predisposed to other craniomorphological abnormalities such as short cranial base and close proximity of the atlas to the occiput. Overcrowding of the CCJ disturbs CSF flow at the foramen magnum and predisposes to SM.
In this study, the number of cranial sutures affected by PFs and the total areas of the PFs were associated with SM, ventriculomegaly and the CCJ overcrowding, challenging the concept that PFs are a clinically irrelevant finding not associated with other structural abnormalities.
Atrophy of the gray matter (GM) of the cingulate gyrus is observed in humans with chronic pain, irrespective of the nature of the pain syndrome. This study evaluated Cavalier King Charles Spaniels (CKCS) with Chiari-like malformation and associated syringomyelia (SM) and pain to look for cerebral morphological differences compared to animals without signs of syringomyelia and pain.
MRI based volumetric analyses revealed a decrease in GM volumes in the cingulate gyrus in CKCS with SM and chronic pain when normalized to brain volume.
Clinical Application of Diagnostic Imaging of Chiari-Like Malformation (CM) and Syringomyelia (SM)
This article reviews the current knowledge of neuroanatomy associated with symptomatic CM and SM and imaging modalities used for the diagnosis of CM-pain or myelopathy related to SM. Canine CM-pain and SM is often associated with a short skull (cranial) base, rostrotentorial crowding with rostral forebrain flattening, small, and ventrally orientated olfactory bulbs, displacement of the neural tissue to give increased height of the cranium and further reduction of the functional caudotentorial space with cerebellar herniation. MRI may identify changes associated with suspected raised intracranial pressure such as loss of sulci definition in conjunction with ventriculomegaly.
The aim of this paper was to describe the use of a customized 3–D-printed titanium prosthesis as adjunctive treatment for foramen magnum decompression (FMD) in 8 dogs with Chiari-like malformation (CM) and syringomyelia (SM).
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.
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.
This study is looking at morphometric analysis of facial anatomy and dysmorphia in Chiari-like malformation‐associated pain and syringomyelia in the Cavalier King Charles Spaniel. Dogs with clinically relevant CM/SM are more likely to have brachycephalic features of the rostral skull flattening with reduction of nasal tissue and a well‐defined 'stop'. This study suggests that the whole skull should be analyzed and not just the hindbrain currently required in pre-breeding screening. It also provides further evidence of at-risk head conformation for this condition.
This study aimed to assess the efficacy and benefit-risk profile of pregabalin (PGN) to reduce the clinical signs of central neuropathic pain (CNeP) as reflected by scratching episodes in dogs with symptomatic syringomyelia (SM).
In teh 12 dogs studied, the treatment effect estimate was an 84% reduction in mean number of scratching events relative to baseline compared with placebo (p < 0.0001). Owner-assessed satisfactory quality of life was status quo and rated as ‘good’ or ‘could not be better’ in six/11 dogs and improved in four/11 dogs. The most prevalent adverse events were increased appetite in nine/12 dogs and transient ataxia in nine/12 dogs.
Other Anomalies
Symptomatic lateral ventricular cystic lesion in a young cat
Intraventricular cystic lesions are rare and mainly non-neoplastic with differential diagnoses including: arachnoid cyst (also referred to as intraventricular simple cyst), neuroepithelial cyst, ependymal cyst, colloid cyst, choroid plexus cyst, parasitic cyst (cysticercosis) and congenital cyst. High resolution images (e.g. FIESTA, CISS) are particularly useful to identify the cyst wall which is often difficult to see.
In this article, the authors present a case of symptomatic lateral ventricular cystic lesion. A choroid plexus cyst was suspected although an intra-arachnoid cyst or ependymal cyst could not be excluded owing to the absence of histological diagnosis. Although they provided temporary relief of raised ICP, endoscopic fenestration and CT-guided draining failed to provide long-term management. Cystoperitoneal shunting was eventually performed, allowing persistent reduction of the lesion and long-term improvement of the cat’s neurological status.
Are postnatal traumatic events an underestimated cause of porencephalic lesions in dogs and cats?
Porencephaly is defined as a fluid-filled cavity of variable size in the brain cortex. It is regarded as a congenital condition and is typically considered a developmental or an encephaloclastic defect. The aims of this study were to retrospectively investigate porencephaly in a large population of dogs and cats, detect MRI features that might be useful to differentiate postnatal acquired traumatic forms from congenital/perinatal porencephaly, and define the prevalence of seizure activity in porencephalic patients.
Thirty-two cases involving nine cats and twenty-three dogs were selected. Of all the cases, 21.9% were aged six years or older at the time of diagnosis. Epileptic seizures were observed in 71.8% of cases. Twenty cases showed concomitant musculoskeletal abnormalities overlying the porencephalic cavities. Fourteen of twenty cases showed evidence of fractures, of which thirteen showed depression of the calvarium and twelve masticatory muscle abnormalities. Of these, 7 of 14 had a history consistent with a head trauma in the first period of life.
The term meningoencephalocele (MEC) describes a herniation of cerebral tissue and meninges through a defect in the cranium, whereas a meningocele (MC) is a herniation of the meninges alone. The objective of this study was to describe the clinical features, magnetic resonance imaging (MRI) characteristics, and outcomes of dogs with cranial MC and MEC in 22 affected dogs. Most affected dogs were presented at a young age (median, 6.5 months; range, 1 month – 8 years). The most common presenting complaints were seizures and behavioral abnormalities. Intranasal MEC was more common than parietal MC. Magnetic resonance imaging identified meningeal enhancement of the protruded tissue in 77% of the cases. Porencephaly was seen in all cases with parietal MC. Cerebrospinal fluid (CSF) analysis identified mild abnormalities in 4 of 11 cases.