Page 194 - Atlas of Small Animal CT and MRI

2.5

Metabolic, toxic, and degenerative disorders

Inherited metabolic disorders proton density images and possible cerebellar atrophy
(Figure 2.5.1).
Lysosomal storage disorders
Lysosomal storage disorders are a group of more than Galactosialidosis
50 rare inherited diseases characterized by failure of Galactosialidosis is caused by a cathepsin A mutation that
lysosomes to metabolize lipids or glycoproteins. Most results in β‐galactosidase and neuraminidase deficiency.
are autosomal recessive disorders that cause a single The disorder has three clinical variants and affects multi-
enzyme deficiency. Although the clinical presentations ple organs, but the central nervous system is consistently
associated with this spectrum of diseases vary depend- involved. In people, neuropathologic features include
ing on the specific defect, most include central nervous atrophy of the optic nerve, thalamus, globus pallidus, lat-
system pathology and consequent neurologic clinical eral geniculate bodies, brainstem, and cerebellum.
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signs. Comprehensive coverage of these disorders is Microscopic findings include neuronal loss, gliosis, and
beyond the scope of this text, but we will highlight two abnormal lysosomal storage in remaining neurons. A
representative examples. lysosomal storage disorder similar to galactosialidosis
has been reported in a 5‐year‐old Schipperke dog
Neuronal ceroid lipofuscinosis with progressive cerebellar and central vestibular signs.
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Neuronal ceroid lipofuscinosis has been reported in Enlarged and vacuolated neurons were seen on postmor-
many canine breeds, including Cocker Spaniels, Border tem examination, which were documented to be due to the
Collies, American Bulldogs, Chihuahuas, Schnauzers, presence of glycolipid‐laden intracytoplasmic lysosomes.
English Setters, Tibetan Terriers, and Polish Lowland Imaging reports in people are lacking, but the MR
1–9
Sheepdogs. The underlying pathology includes gener- features of the canine patient in Figure 2.5.2 with a pre-
alized neuronal loss with diffuse astrogliosis. Remaining sumptive diagnosis of galactosialidosis include cerebellar
neurons contain an intracytoplasmic accumulation of atrophy and ventriculomegaly. There was diffuse cerebel-
yellow lipopigments. 7,8,10 Retinal cells can be similarly lar purkinje cell and granular cell loss and extensive neu-
affected, and other organ involvement can occur. In a ronal cytoplasmic lysosomal storage in the cerebellum and
single case report of CT features of ceroid lipofuscinosis hippocampus on postmortem microscopic examination.
in a Border Collie, there was generalized cortical atrophy
and ventricular dilation. MR descriptions also include Acquired metabolic disorders
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cortical atrophy and ventriculomegaly. 6,7,12 One citation
describes intense enhancement of thickened meninges Thiamine deficiency
in a group of affected Chihuahuas, but this has not been Thiamine deficiency is rare and usually results from
reported elsewhere. In our experience, there is also a animals being fed commercial or noncommercial diets
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loss of definition of the gray–white matter interface on deficient in thiamine. The disorder has also been
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Atlas of Small Animal CT and MRI, First Edition. Erik R. Wisner and Allison L. Zwingenberger.
© 2015 John Wiley & Sons, Inc. Published 2015 by John Wiley & Sons, Inc.
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