Web-Vet TM Neurology Specialists
Metabolic, Degenerative
& Nutritional Encephalopathies
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The aims of this study are: (I) to describe the MRI features of dogs and cats with metabolic/neurodegenerative encephalopathies; (II) to attempt an MRI recognition pattern classifying these conditions according to the involvement of grey matter, white matter or both; and (III) to correlate the MRI findings with previous literature. A total of 100 cases were recruited, comprising 81 dogs and 19 cats. These included hepatic encephalopathy (20 dogs and three cats), myelinolysis (five dogs), intoxications (seven dogs and one cat), thiamine deficiency (two dogs and seven cats), hypertensive encephalopathy (three dogs and two cats), neuronal ceroid lipofuscinosis (11 dogs and one cat), gangliosidosis (three dogs and two cats), fucosidosis (one dog), L-2-hydroxyglutaric aciduria (13 dogs and one cat), Lafora disease (11dogs),spongiform leukoencephalomyelopathy (one dog) and cerebellar cortical degeneration (four dogs and two cats). None of the hepatic encephalopathies showed the previously described T1-weighted hyperintensity of the lentiform nuclei. Instead, there was involvement of the cerebellar nuclei (8/23), which is a feature not previously described. Dogs with myelinolysis showed novel involvement of a specific white matter structure, the superior longitudinal fasciculus (5/5). Thiamine deficiency affected numerous deep grey nuclei with novel involvement of the oculomotor nuclei (3/9), thalamic nuclei, subthalamus and cerebellar nuclei (1/9). Cats with hypertensive encephalopathy had a more extensive distribution of the white matter changes when compared to dogs, extending from the parietal and occipital lobes into the frontal lobes with associated mass effect and increased brain volume. Lysosomal storage disease showed white matter involvement only, with neuronal ceroid lipofuscinosis characterised by severe brain atrophy when compared to gangliosidosis and fucosidosis. All patients with L-2-hydroxyglutaric aciduria had a characteristic T2-weighted hyperintense swelling of the cerebral and cerebellar cortical grey matter, resulting in increased brain volume. Lafora disease cases showed either normal brain morphology (5/11) or mild brain atrophy (6/11). Dogs with cerebellar cortical degeneration had more marked cerebellar atrophy when compared to cats.
Cortical laminar necrosis detected by diffusion-weighted imaging in a dog suspected of having hypoglycemic encephalopathy
Cerebrocortical laminar necrosis (CLN) is known to occur secondary to many different aetiologies, including lead and cyanide toxicoses, thiamine deficiency, hypoglycaemia, canine distemper meningoencephalitis, head trauma, and cardiac arrest, although the aetiology often remains unknown. The majority of these patients described with this type of lesion have convulsive seizures as part of their clinical history. However, the association between CLN and seizures remains unclear.
In this case report published in The Journal of Veterinary Medical Science, the authors described the MRI findings and use of DWI in the early diagnosis of CLN. Although this dog is suspected of having hypoglycaemic episodes, it is difficult to ascertain in this case if the MRI changes are caused by seizure-induced excitotoxicity or by hypoglycemia-induced changes as their distribution overlap as the authors rightly acknowledge in their discussion.
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The image on the left is taken from this paper showing MR findings in day 2, day 39 and day 133 after the epilepsy onset.
UNREPORTED MRI FINDINGS IN A CAT WITH A NEW PATHOGENIC GENE VARIANT OF L2HGA
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Fantastic new case report published by our colleagues at the University of Glasgow and the University of Bern. Over 20 years ago, we reported the MRI findings in Staffordshire bull terriers as well as in a WHWT. In these breeds, MRI showed bilaterally symmetrical lesions affecting the gray matter, cerebellar nuclei, cerebellar cortex, thalamus and colliculi. In this 9-month-old cat presented for seizures, MRI (see image attached) revealed multicystic lesions affecting the subcortical white matter bilaterally with no contrast enhancement. Urine organic acids evaluation showed increased excretion of 2-hydroxyglutaric acid and a new pathogenic gene variant in L-2-hydroxyglutaric aciduria was identified.
A hypomyelinating leukodystrophy in German Shepherd dogs
This paper documents 11 young German shepherd dogs with a suspected inherited hypomyelinating leukodystrophy resulting in tremors of the head and trunk, which improved gradually until 6 to 7 months of age - see videos of the affected dogs in the supplemental material of the paper.
MRI revealed hyperintense to isointense signal of the entire subcortical white matter compared to the hypointense signal in an unaffected littermate when compared to grey matter - see opposite figure taken from the article where the affected and unaffected littermates are compared on T2W (top) and FLAIR (bottom).
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All parents of the affected litters shared a common ancestor and relatedness of the puppies suggested an autosomal recessive mode of inheritance.
Phenotypic and genetic aspects of hereditary ataxia in dogs
Hereditary ataxias are a large group of neurodegenerative diseases that have cerebellar or spinocerebellar dysfunction as a core feature. Based on neuropathology, this group of diseases has so far been classified into cerebellar cortical degenerations, spinocerebellar degenerations, cerebellar ataxias without substantial neurodegeneration, canine multiple system degeneration, and episodic ataxia.
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​This review summarizes the current knowledge about hereditary ataxias in dogs, and proposes to add a “multifocal degenerations with predominant (spino)cerebellar component” category regrouping canine multiple system degeneration, new hereditary ataxia syndromes that do not fit in 1 of the previous categories, as well as specific neuroaxonal dystrophies and lysosomal storage diseases that cause major (spino)cerebellar dysfunction.
MRI findings of neuronal ceroid lipofuscinosis in a cat
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A 2-year-old male domestic shorthair cat presented to the University of Liverpool Small Animal Teaching Hospital with a 2 week history of altered mentation, blindness and focal epileptic seizures. MRI examination revealed generalised cerebral and cerebellar atrophy, diffuse T2-weighted hyperintensity of the white matter and meningeal thickening. Neuronal ceroid lipofuscinosis was confirmed on post-mortem examination.
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The objective of this study was to report 30-day survival of 59 cats that experienced postattenuation neurologic signs (PANS) after surgical attenuation of a single congenital portosystemic shunt (cPSS), and to investigate prognostic factors for short-term survival.
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A total of 46 (78.0%) PANS-affected cats survived to 30 days. A total of 13 (50.0%) of 26 cats that experienced postattenuation seizures (PAS) survived to 30 days, with most non-surviving cats experiencing generalized PAS. Cats that experienced PAS and treatment of PANS with propofol were associated with decreased odds of 30-day survival.
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