Case Report: Complex Congenital Brain Anomaly in a BBxHF Calf-Clinical Signs, Magnetic Resonance Imaging, and Pathological Findings

Abstract

This case report describes the clinical signs, magnetic resonance imaging (MRI) findings and associated (histo)pathological findings in a crossbred Belgian Blue calf with congenital complex brain anomaly. The calf was presented with non-progressive signs (including cerebellar ataxia) since it was born, suggestive of a multifocal intracranial lesion. A congenital anomaly was suspected and after hematology, biochemistry, serology, and cerebrospinal fluid analysis, a magnetic resonance imaging study was performed. The following suspected abnormalities were the principal changes identified: severe hydrocephalus, porencephaly, suspected partial corpus callosum agenesis (CCA), and increased fluid signal between the folia of the cerebellum. Post-mortem examination predominately reflected the MRI findings. The origin for these malformations could not be identified and there was no evidence of a causative infectious agent. Corpus callosum abnormalities have been reported in bovids before and have been linked to bovine viral diarrhea virus (BVDV) infections, as have several other central nervous system anomalies in this species. In this case, BVDV was deemed an unlikely causative agent based on serology test results and lack of typical histopathological signs. The etiology of the congenital anomaly present in this bovine calf remains unknown.

Keywords: bovid; cerebellar ataxia; corpus callosum agenesis; hydrocephalus; porencephaly.

Figure 1

(A) Transverse T2W MR images at the level of the third ventricle, (B) transverse T1W MR images at the level of the caudal aspect of the lateral ventricles and rostral colliculi of the mesencephalon, (C) transverse T2W MRI image at the caudal aspect of the cerebellum, (D) mid-sagittal T2W MR image. The asterisk (*) in (A,B) demarcates the communication between the left lateral ventricle and the subarachnoid space and represents the porencephaly. Also, in (A), communication between the left lateral and right lateral ventricle is visible due to partial absence of the septum pellucidum and no corpus callosum is identifiable. In (B), fusion of the rostral colliculi is appreciated. In (C), the black arrow points toward the irregular and apparently incomplete separation between right and left cerebellar hemisphere (not confirmed on post-mortem examination; likely represents in situ displacement). Partial herniation of the left hemisphere over the midline into the right hemisphere is visible (not confirmed on post-mortem examination; likely represents in situ displacement). In (D), the corpus callosum and mesencephalic aqueduct are hard to identify and increased fluid signal between cerebral gyri and cerebellar folia is seen, which can also be appreciated in (A–C).

Figure 2

Transverse T2W images of the brain at the level of interthalamic adhesion of (A) our current case with a hypoplastic/absent interthalamic adhesion (white arrow) in comparison with the interthalamic adhesion in (B) of a calf without brain lesions (at 7 months of age). Also note the ventriculomegaly and thin white matter tracts (corona radiata), thin cortex and increased CSF signal ventral to the thalamus in (A) compared to (B).

Figure 3

Macroscopic photographs of the bovine encephalon of this case report and corresponding reference images (fixated in formalin) at approximately the same level–courtesy of dr. FG Wouterlood and dr. P. Voorn, Dept Anatomy and Neurosciences, AmsterdamUMC, VU, Amsterdam, The Netherlands. (A) Dorsal view of the cerebrum and cerebellum in situ after removal of the dorsal and caudal parts of the skull and dura mater. (B) Rostrocaudal view of a transverse slab at the level of the olfactory recesses. (C) Rostrocaudal view of a transverse slab at the level of the septal area. (D) Rostrocaudal view of a transverse slab at the level of the interthalamic adhesion. (E) Rostrocaudal view of a transverse slab at the level of the rostral mesencephalon. (F) Rostrocaudal view of a transverse slab at the level of the caudal mesencephalon. (G) Rostrocaudal view of a transverse slab at the level of the cerebellum, fourth ventricle, and medulla. (H) Caudorostral view of the cerebrum and cerebellum in situ after removal of the dorsal and caudal parts of the skull and dura mater. (I) laterolateral view of the cerebrum in situ after removal of the dorsal and caudal parts of the skull and dura mater. The anatomical terms differ from those of the Nomina Anatomica Veterinaria, as the images are composed and labeled by human neuroanatomists/-scientists.