Selective occlusion of blood supply to the anterior perforated substance of the dog: a highly reproducible stroke model

Comparative anatomy of the middle cerebral artery, rhinal and endorhinal sulci, piriform lobe, entorhinal cortex, olfactory tubercule, anterior perforate substance, and hippocampus: A dissection study

The literature describing the complex anatomy of the middle cerebral artery (MCA), lenticulostriate arteries, and recurrent artery of Heubner, does not discuss the comparative anatomy of the cerebrum, MCA, the recurrent artery of Heubner, and the relationship of the MCA with the rhinal sulci. The entorhinal literature does not detail the comparative anatomic modification of the rhinal and endorhinal sulci, piriform lobe and the hippocampus's compressed positional change in the temporal lobe. This investigation's objectives were to analyze the comparative anatomic modifications of the cerebrum, the MCA, lenticulostriate arteries, recurrent artery of Heubner, olfactory tubercule, anterior perforate substance, rhinal sulcus, endorhinal sulcus, piriform lobe, entorhinal cortex, and hippocampus. Brain dissections of adult iguana, rabbit, sheep, cat, dog, macaque, human and human fetal specimens were analyzed. The MCA branches enter the striate nuclei via the endorhinal sulcus, with few branches present in the rhinal sulcus. Modifications of the cerebrum, with the development of gyri and sulci and opercula covering the insula, changes the linear surface configuration of the MCA into a tridimensional one. Similar changes are present in human fetal specimens. The cerebral neocortical expansion changes the position of the rhinal and endorhinal sulci, their relationship with the MCA, the size of the olfactory tubercule, the position and size of the piriform lobe, and the diagonal course of the lenticulostriates and recurrent artery of Heubner. The hippocampus becomes compressed in the inferomedial region of the human temporal lobe. The lenticulostriate arteries are likely the first developed component of the MCA.

A novel embolic stroke model resembling lacunar infarction following proximal middle cerebral artery occlusion in beagle dogs

It is estimated that lacunar infarcts account for 25% of all ischemic strokes, but its exact etiology is still on debating. The existing controversies include whether the embolisms can indeed cause lacunar stroke in humans or animal models. We hypothesized that lacunar infarction can be induced by the proximal middle cerebral artery (MCA) segmental occlusion involving the orifices of lenticulostriate arteries in animal models, which have abundant distal cerebral collateral anastomosis. Our work here establishes a proximal MCA occlusion model using thrombi (autologous blood clots about 1.7 mm in diameter and 5 mm in length) in 8 beagle dogs, evaluates the progression of ischemic lesions at 30 min interval within 6 h after embolization using the diffusion weighted imaging (DWI), and discusses the potential mechanisms of lacunar infarction. Our results indicate that the left proximal MCAs can be successfully occluded in all dogs using interventional single-thrombus method. The small solitary or multiple ischemic lesions shown in DWI were observed in the deep brain area, with the mean detecting time of 1.21 ± 0.45 h using DWI and diameter of 6.62 ± 0.60mm in 6h-DWI after procedure. In conclusion, our method established an ischemic model which can recapitulate the radiologic and histologic changes in lacunar infarcts, suggesting that emboli can cause lacunar infarcts in animal model.

Clinical and topographic magnetic resonance imaging characteristics of suspected thalamic infarcts in 16 dogs

Sixteen dogs with acute-onset, non-progressive signs of brain dysfunction and magnetic resonance imaging (MRI) characteristics compatible with thalamic infarction are described. Topographically the MRI lesions could be grouped in three thalamic regions, namely, paramedian (8/16), extensive dorsal (5/16) and ventrolateral (3/16). Paramedian lesions resulted in signs typical of vestibular dysfunction. Extensive dorsal lesions were associated with vestibular ataxia, circling and contralateral menace response deficits. Ventrolateral lesions resulted in circling and contralateral proprioceptive deficits. In several dogs, regions other than the thalamus were also affected: four extended into the midbrain; six extended to the internal capsule, and two dogs had a second lesion in the cerebellum. Three clinical syndromes were identified in association with thalamic infarction. These signs varied somewhat, most likely because lesions were not confined to specific nuclear boundaries and involved different combinations of thalamic nuclei.

Potential animal models of lacunar stroke: a systematic review

BACKGROUND AND PURPOSE

Lacunar ischemic stroke accounts for 25% of all ischemic strokes, but the exact etiology is unknown. Numerous pathophysiologies have been proposed, including atheroma and endothelial dysfunction. Models of any of these pathological features would aid understanding of the etiology and help develop treatments for lacunar stroke. We therefore aimed to assess the relevance of all available potential animal models of lacunar stroke.

METHODS

We systematically reviewed the published literature for animal models that could represent lacunar stroke using validated search strategies. We included studies that could represent an aspect of lacunar stroke as well as those aiming to model conditions with potentially similar pathology and extracted data on species, induction method, and resulting brain and vessel lesions.

RESULTS

From 5670 papers, 41 studies (46 papers) met inclusion criteria representing over 10 different classes of stroke induction. Important data like infarct size and animal numbers were often missing. Many models' infarcts were too large or affected the cortex. Emboli mostly caused cortical but not small subcortical lesions. Most models focused on creating ischemic lesions in brain tissue. Only one (spontaneous lesions in spontaneously hypertensive stroke-prone rats) also mimicked small vessel pathology. Here, the precursor to small vessel and brain damage was blood-brain barrier failure.

CONCLUSIONS

Some animal models produce small subcortical infarcts, but few mimic the human small vessel pathology. Models of small vessel disease could help improve understanding of human lacunar disease, particularly to clarify factors associated with the small vessel morphological changes preceding brain damage. Much lacunar stroke may arise after blood-brain barrier disruption.

Systematization and distribution of the middle cerebral artery on the brain surface in pampas fox (Pseudalopex gymnocercus)

The present study has analysed 30 pampas fox brains (Pseudalopex gymnocercus), injected with latex, aiming to systematize and describe the distribution and vascularization territories of the middle cerebral artery. After being originated from the rostral branch of the internal carotid artery this vessel formed the following collateral branches: rostral choroidal artery, rostral and caudal central branches and cortical branches. Before crossing the lateral rhinal sulcus, the common trunk of the middle cerebral artery frequently bifurcated in a rostral and a caudal branch. In a smaller amount, the common trunk did not show any bifurcation, ramifying in arborescence. The vascular territory of the pampas fox middle cerebral artery included the lateral cerebral fossa, the lateral third of the olfactory trigone, the two rostral thirds of the piriform lobe, the lateral olfactory tract and most of the convex surface of the cerebral hemisphere, except for the more rostromedial areas of the frontal lobe bordering the endomarginal sulcus in the parietal and occipital lobes as well as the transverse fissure at the caudal pole of the cerebral hemisphere.

Ischaemic stroke in dogs and humans: a comparative review

Cerebrovascular accidents, also known as strokes, are one of the major causes of disability and mortality among adult humans. The increased availability of magnetic resonance imaging in veterinary medicine means they are being increasingly recognised in dogs, too. Cerebrovascular accident is defined as the sudden onset of non-progressive, focal brain dysfunction as a result of ischaemic infarction or haemorrhage. Focal ischaemic stroke is caused by interruption of the arterial blood flow to a dependent area of brain parenchyma by a thrombus or an embolus. Once the diagnosis of ischaemic stroke is confirmed, potential sources of thrombosis or embolism should be investigated and treated accordingly. Dogs with ischaemic stroke tend to recover within several weeks with supportive care only.