Feline ischemic myelopathy and encephalopathy secondary to hyaline arteriopathy in five cats

Abstract

Five cats presented with acute-onset neurological signs. Magnetic resonance imaging in four cats showed a T2-weighted hyperintense spinal cord lesion that was mildly contrast-enhancing in three cats. Owing to inflammatory cerebrospinal fluid changes three cats were treated with immunosuppression. One cat was treated with antibiotics. All cats improved initially, but were eventually euthanased owing to the recurrence of neurological signs. Histopathology in all cats showed hyaline degeneration of the ventral spinal artery, basilar artery or associated branches with aneurysmal dilation, thrombosis and ischemic degeneration and necrosis of the spinal cord and brain. Two cats also had similar vascular changes in meningeal vessels. Vascular hyaline degeneration resulting in vascular aneurysmal dilation and thrombosis should be a differential diagnosis in cats presenting with acute central nervous system signs.

Ascending haemorrhagic myelomalacia associated with systemic hypertension in a hyperthyroid cat

“…16 Although there is no evident direct correlation between vessel degeneration and HT, 16 we suggest that the arteriolar hyalinosis, perivascular calcification, subintimal deposition of smooth muscle cells and thrombosis could have been secondary to the underlying HT. Based on the clinical presentation and information collected, the importance of SBP measurements, prior and after treatment of hyperthyroidism, is clear, even when cases lack clinical signs that implicate hypertensive encephalopathy.…”

Reduced field‐of‐view diffusion‐weighted MRI can identify restricted diffusion in the spinal cord of dogs and cats with presumptive clinical and high‐field MRI diagnosis of acute ischemic myelopathy

“…Up until recently, Diffusion-weighted imaging of the spinal cord was technically challenging in dogs and cats due to the small size of the cord and inherent low-resolution of Diffusion-weighted images, as well as the distortion caused by the osseous components of the vertebral column surrounding the cord. 5 In the few case series reporting on MRI findings in dogs and cats with ischemic myelopathy, diffusion-weighted imaging was not a pulse sequence included in the MRI protocol, [6][7][8][9]12,17,18 unlike studies reporting on canine brain ischemia. 1,3 Technological advances such as reduced field-of-view diffusion-weighted imaging allow to circumvent some of these limitations, allowing to obtain images at higher resolution with a smaller field-of-view in the phase-encoding direction, which matches the thin A study in 33 human patients showed that there were statistically significant differences in measured apparent diffusion coefficient values in patients with spinal cord infarct versus those with inflammatory myelopathies and in normal controls.…”

“…Ischemic myelopathy shares clinical and imaging features with other conditions, particularly acute non‐compressive hydrated nucleus pulposus extrusion. While we did not have a histopathologic confirmation of a diagnosis of ischemic myelopathy, our inclusion criteria followed diagnostic guidelines that have been widely published and are used routinely in clinical neurology and neuroimaging in veterinary patients to differentiate these two conditions 5‐9,12,15‐18 . The lack of contrast enhancement in the four animals that received postcontrast imaging and the favorable clinical improvement or lack of deterioration in most animals provides additional support for a diagnosis of ischemic myelopathy.…”

“…Clinical criteria consistent with ischemic myelopathy were an acute focal non‐progressive myelopathy with no evidence of trauma and minimal to absent spinal hyperesthesia 5,7,8,9,14 . Magnetic resonance imaging criteria were those that have been extensively published in the veterinary literature and included: presence of a focal T2‐weighted intramedullary hyperintensity with a longitudinal extension pattern and affecting mostly the grey matter, absence of extradural heterogeneous material at the level of the spinal cord hyperintense signal, absence of spinal cord compression, absence of a cleft in the dorsal annulus of the discs underlying the lesions, spinal cord swelling leading to a reduction of the cerebrospinal fluid signal on the single shot fast spin echo series (“T2‐myelogram”) at the site of the spinal cord parenchyma T2‐weighted hyperintensity 5‐9,12,15‐18 . The clinical diagnosis of ischemic myelopathy was originally made by a neurology resident and attending American College of Veterinary Internal Medicine board‐certified neurologist based on their clinical assessment and MRI findings.…”

“…Ischemic myelopathy is another common cause of acute neurologic presentation in dogs and cats, with fibrocartilaginous embolism being the most common underlying etiology. Other possible causes include thrombo‐embolization from parasites, sepsis, hypercoagulable states, or vasculopathy such as primary hyaline arteriopathy in felines 5,6 . On MRI, the most conspicuous sign of ischemic myelopathy is the presence of T2‐weighted spinal cord hyperintensities in the absence of a compressive lesion.…”