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Metabolic, Degenerative
& Nutritional Encephalopathies

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.

The image on the right is taken from this paper showing MR findings in day 2, day 39 and day 133 after the epilepsy onset.

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UNREPORTED MRI FINDINGS IN A CAT WITH A NEW PATHOGENIC GENE VARIANT OF L2HGA

Fantastic new case report published by our colleagues at the University of Glasgow and 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.

Selective symmetrical necrotizing encephalopathy secondary to primary mitochondrial disorder in a cat

A 2-year old female cat was referred for progressive neurological signs indicative of involvement of the forebrain, cerebellum, and brainstem. MRI identified multifocal, bilateral, symmetrical lesions with strong contrast enhancement, affecting multiple areas of the brain.

Neuropathology at necropsy showed demyelination, necrotic lesions, spongiosis, and neuropil edema with reactive astrogliosis and neovascularization. Ultrastructural study indicated mitochondrial polymorphism.

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INTRAVENOUS LIPID EMULSION THERAPY AS SYMPTOMATIC TREATMENT OF HEPATIC ENCEPHALOPATHY

Hepatic encephalopathy (HE) is a complex neurological condition that occurs as a consequence of acute or chronic liver disease, most frequently due to congenital portovascular anomalies, hepatic microvascular dysplasia or liver failure from any cause including intoxication or infection. Neurological signs may include head pressing, aimless wondering, blindness, seizures and coma. Signs of hepatic dysfunction (weight loss, polydipsia, anorexia and vomiting) may be present as well.

Intavenous lipid emulsion (ILE) has been used for treatment of various lipophilic drug toxicoses. A case report reported the rapid resolution of severe neurologic signs following ILE therapy in a young dog with a portosystemic shunt (PSS). Ammonia being a highly lipophilic compound, the use of ILE was considered as symptomatic treatment of HE. This ILE therapy resulted in rapid and complete resolution of HE in this young dog with a PSS. Although the use of ILE to treat HE should be investigated prospectively, it could represent a promising future treatment option to treat hyperammonemia in conjunction with standard treatment.

The video on the left is of a young Yorkshire terrier with confusion, obtundation, pacing and visual deficits related to hepatic encephalopathy.

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Polioencephalopathy in Eurasier dogs

The aim of this paper was to clinically and genetically characterize polioencephalopathy in a family of Eurasier dogs.

The three littermates had episodes which were characterized by generalized ataxia, as well as a hypermetric thoracic limb gait, dystonia, and irregular flexion and extension movements of the thoracic limbs. Magnetic resonance imaging of the brain in 2 dogs identified symmetrical, bilateral T2 and FLAIR hyperintense, T1 hypo to isointense, non-enhancing lesions of the caudate nucleus, lateral and medial geniculate nuclei, thalamus, hippocampus, rostral colliculus and mild generalized brain atrophy. Genetic analyses identified a homozygous mitochondrial trans-2-enoyl-CoA reductase (MECR) missense variant in all 3 dogs, and a homozygous autophagy-related gene 4D (ATG4D) missense variant in 2 dogs.

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).

All parents of the affected litters shared a common ancestor and relatedness of the puppies suggested an autosomal recessive mode of inheritance.

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