Relationship between intracranial pressure as measured by an epidural intracranial pressure monitoring system and optic nerve sheath diameter in healthy dogs

Abstract

ICP was positively and nonlinearly associated with increasing maximum ONSD, especially when ICP was ≤ 20 mm Hg above baseline, supporting the conclusion that ultrasonographic measurement of maximum ONSD may provide a noninvasive monitoring tool for evaluation of ICP in dogs. Further research is needed to assess the utility of these measurements in clinical patients.

Transcranial Doppler Ultrasound Examination in Dogs with Suspected Intracranial Hypertension Caused by Neurologic Diseases

“…One study showed that the relationship of intracranial pressure to optic nerve sheath diameter was slightly nonlinear with optic nerve sheath diameter increased more in the early stages of intracranial hypertension. 36 On the other hand, another study demonstrated that the relationship between TCD vascular resistance variables and intracranial pressure was linear in dogs. 20 This discrepancy might be due to different effects of intracranial pressure on cerebral blood flow and optic nerve sheath size.…”

“…In addition to TCD, various noninvasive methods for assessment of intracranial pressure have been applied to dogs . The combination of MRI findings is useful and reliable for the diagnosis of intracranial hypertension in dogs .…”

“…Interestingly, the relationships between intracranial pressure and both optic nerve sheath diameter and TCD vascular resistance variable seem different in experimental studies. One study showed that the relationship of intracranial pressure to optic nerve sheath diameter was slightly nonlinear with optic nerve sheath diameter increased more in the early stages of intracranial hypertension . On the other hand, another study demonstrated that the relationship between TCD vascular resistance variables and intracranial pressure was linear in dogs .…”

“…In addition to TCD, various noninvasive methods for assessment of intracranial pressure have been applied to dogs. 7,9,24,35,36 The combination of MRI findings is useful and reliable for the diagnosis of intracranial hypertension in dogs. 9,24 In a recent study, the combination of these MRI findings yielded a sensitivity of 72% and a specificity of 96% for the diagnosis of intracranial hypertension in dogs.…”

“…Meanwhile, optic nerve sheath diameter assessment using ultrasound examination seems promising considering the relationship between optic nerve sheath diameter and intracranial pressure in dogs with experimental intracranial hypertension. 36 Based on a study that showed a moderately positive correlation between optic nerve sheath diameter measured using T2-weighted MRI and body weight (r = 0.71-0.76), 24 clinical studies enrolling dogs of various breeds with a wide range of body weights might be necessary for clinical application. Interestingly, the relationships between intracranial pressure and both optic nerve sheath diameter and TCD vascular resistance variable seem different in experimental studies.…”