MRI of lobar holoprosencephaly in a cat with hypodipsic hypernatraemia

Abstract

Case summary: A 2-year-old neutered female domestic shorthair cat presented with a history of hypodipsia, recurrent hypernatraemia, pelvic limb ataxia and tremor. The serum arginine vasopressin level was low for the serum osmolality. MRI of the brain revealed a failure of separation of the cerebrum, which manifested as absence of the rostral part of the corpus callosum, fornix and septum pellucidum, thus resulting in a single fused ventricle. The diagnosis was lobar holoprosencephaly with hypodipsic hypernatraemia.

Relevance and novel information: To our knowledge, this is the first description of the MRI characteristics of lobar holoprosencephaly in a cat. This report suggests that MRI examination should be considered for precise diagnosis of hypodipsic hypernatraemia in young cats.

Keywords: Brain malformation; holoprosencephaly; hypernatraemia; hypodipsia; magnetic resonance imaging.

Figure 1

Midsagittal T2-weighted MRI image of a normal cat (a) and corresponding image from the present case (b). Arrowheads indicate the corpus callosum and the arrow indicates the fornix. Note the absence of the fornix and rostral portion of the corpus callosum, as well as the presence of hypoplastic olfactory bulbs, in the present case

Figure 2

Dorsal T2-weighted image at the level of the corpus callosum of a normal cat (a) and corresponding image from the present case (b). The arrowhead indicates the corpus callosum. The lateral ventricles are not separated in the present case (arrow)

Figure 3

Transverse T2-weighted images at levels immediately (a) rostral or (b) caudal to the interthalamic adhesion of a normal cat and (c,d) corresponding images from the present case. The lateral ventricles were abnormally fused (arrow), and demonstrated upturned and pointed corners (arrowheads)