Clinical and Diagnostic Imaging Features of Brain Herniation in Dogs and Cats

Abstract

BackgroundQuantification of brain herniation on MRI and its immediate clinical implications are poorly described.ObjectivesDefine the normal position of caudal fossa structures on brain MRIs in dogs and cats utilizing morphometry, compare this to dogs and cats with caudal transtentorial herniation (CTH), foramen magnum herniation (FMH) or both identified on MRI, and investigate associations between herniation severity, clinical signs, and 24‐hour outcome.AnimalsNinety‐two controls (66 dogs, 26 cats), 119 cases with herniation (88 dogs, 31 cats).MethodsRetrospective case series. The MRI database was searched for controls with normal brain anatomy and cases with brain herniation. Morphometry in controls established TTX (transtentorial to rostroventral cerebellum) to quantify CTH and FMX (caudoventral cerebellum to foramen magnum) to quantify FMH. Measurements were compared between cases and controls. Correlations with specific clinical variables and outcome were investigated.ResultsMeasurements in medium/large control dogs versus small dog and cat controls were significantly different (P < .001, TTX: −0.46, −0.305, −0.3, FMX: 0.695, 0.27, 0.25, respectively). 119/1564 (7.6%) cases that underwent brain imaging had brain herniation. TTX and FMX were significantly different between controls and cases with CTH or FMH (P < .001). 67/89 (75%) cases with supratentorial lesions had no signs directly attributable to herniation. 71/119 (60%) had a normal anesthetic recovery. TTX was significantly associated with 24‐hour survival (P < .001).Conclusions and clinical importanceBrain herniation can be quantified on MRI. Clinical signs directly attributable to brain herniation commonly are absent, and more severe CTH based on TTX is associated with a worse short‐term outcome.

Relationships among neuroscore, magnetic resonance imaging features, and intracranial pressure in sheep affected by slow‐growing brain lesions

“…The most common clinical signs were mental status alteration with confusion/disorientation or dulling, deficits of postural reactions, menace response, and cranial nerves. According to previous studies, clinical signs directly attributable to brain herniation were not always present . Circling and head pressing, related to small cysts involving the basal nuclei or the superficial cortex, and the frontal lobe respectively, were not observed in the population of our study .…”

“…The Cushing reflex is more closely correlated with brainstem ischemia than high intracranial pressure, which limits the clinical usefulness of systemic hypertension as a specific indicator of high intracranial pressure . Several authors have reported a poor relationship between clinical signs and brain herniation in dogs . Mass effect, effacement of the cerebral sulci, perilesional edema, and brain herniation, all detectable by magnetic resonance imaging (MRI), are considered signs of presumed intracranial hypertension .…”

Feline meningioma with extensive nasal involvement

“…A recent study failed to show a directly attributable association between brain herniation and anaesthetic complications in dogs and cats. 23…”

Neural Stem Cell Extracellular Vesicles Disrupt Midline Shift Predictive Outcomes in Porcine Ischemic Stroke Model

“…Cerebellar herniation was measured on sagittal T2W image slices as previously described in canine and feline models (Fig. 4a, b) [42]. Nontreated animals with HMLS had a significant increase in caudal transtentorial herniation (p = 0.0284; Fig.…”

“…All foremen magnum and transtentorial herniation analysis was performed on midsagittal T2W MR images as described [42]. Briefly, bony landmarks were utilized to create three linear measurements: skull length line (SLL; Fig.…”