Detection of intracranial hypertension in dogs using transorbital ultrasonographic measurement of optic nerve sheath diameter
Date Issued
2015
Date
2015
Author(s)
Yu, Chi-Te
Abstract
Direct intracranial pressure (ICP) measurement in veterinary medicine is not widely available. Based on the phenomenon of the optic nerve sheath diameter (ONSD) expansion during ICP elevation, ONSD has been applied as a noninvasive method for detecting increased ICP in humans. Measuring ONSD on magnetic resonance imaging (MRI) T2-weighted images for the same purpose has been evaluated in dogs. However, considering the anesthetic risk and cost, serial MRI examinations are impractical, especially in dogs with increased ICP. Transorbital ultrasonographic measurement of ONSD in humans has been reported to provide good diagnostic accuracy for detecting intracranial hypertension; however, relevant information in veterinary medicine is still lacking. In this research, we aim to evaluate the usefulness of ONSD measured on ultrasonography to predict intracranial hypertension in dogs. Dogs without cerebral dysfunction and dogs with at least two MRI characteristics of increased ICP were included in the study and further assigned into the control group and the intracranial hypertension group respectively. Dogs with major ocular diseases or systemic diseases were excluded. These MRI characteristics of increased ICP included mass effect, substantial edema, effacement of sulci or hydrocephalus with periventricular edema. Under general anesthesia, ONSD was measured at 3 mm behind the globe via a 15-MHz ultrasonographic probe placing on the cornea. Data were analyzed by using independent samples t-test and Mann-Whitney U test. P<0.05 was considered statistically significant. Sixty dogs and fourteen dogs were enrolled in the control and intracranial hypertension group respectively. No significant difference was detected in age and body weight between two groups. ONSD in the intracranial hypertension group was significantly larger than that in the control group (P<0.05). Subgroups were further divided by body weight (<10 kg and ≥10 kg). In dogs <10 kg, ONSD in the intracranial hypertension group was significantly larger than that in the control group (P <0.05). Although the difference of ONSD between the control and intracranial hypertension group in dogs ≥10 kg was insignificant, significantly larger ratio of ONSD to body weight and body surface area were noted in the intracranial hypertension group. The area under receiver operating characteristic curve of ONSD in dogs <10 kg and ratio of ONSD to body weight and body surface area in dogs ≥10 kg are both above 0.7. It indicates that ONSD is a discriminating tool in the detection of intracranial hypertension. Based on the current results, ultrasonographic measurement of ONSD potentially can be applied to detect the presence of intracranial hypertension in dogs.
Subjects
canine
intracranial hypertension
transorbital ultrasonography
optic nerve sheath diameter
SDGs
Type
thesis
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