Posterior reversible encephalopathy syndrome presenting as papilledema

Optic nerve sheath diameter: present and future perspectives for neurologists and critical care physicians

BACKGROUND

Estimation of intracranial pressure (ICP) may be helpful in the management of neurological critically ill patients. It has been shown that ultrasonography of the optic nerve sheath diameter (ONSD) is a reliable tool for non-invasive estimation of increased intracranial pressure (ICP) at hospital admission or in intensive care. Less is known about the estimation of increased ICP and usefulness of ONSD in the prehospital setting. The aim of this review was to elucidate both prevailing and novel applications of ONSD for neurologists and critical care physicians.

METHODS

In this review, we discuss the technique and the novel approach of ONSD measurement, the clinical applications of ONSD in neurology and critical care patients.

RESULTS

ONSD measurement is simple, easy to learn, and has diverse applications. ONSD has utility for ICP measurement in intracranial hemorrhage and ischemic stroke, meningitis and encephalitis, and idiopathic intracranial hypertension (IIH). It is also valuable for lesser known syndromes, where an increase of ICP is postulated, such as acute mountain sickness and posterior reversible encephalopathy syndrome. ONSD changes develop in inflammatory or ischemic optic neuropathies. Some papers demonstrate the usefulness of ONSD studies in symptomatic intracranial hypotension.

CONCLUSIONS

ONSD is a safe and low-cost bedside tool with the potential of screening patients who need other neuroimaging and those who may need an invasive measurement of ICP.

Blood-retina-barrier disruption accompanying blood-brain-barrier dysfunction in posterior reversible encephalopathy syndrome

Blood-brain-barrier dysfunction is well known to accompany hypertensive posterior reversible encephalopathy syndrome (PRES) and is considered as the culprit of vasogenic edema and cerebral hemorrhage observed as part of this syndrome. An 84-year-old female was admitted with a diagnosis of PRES in the setting of malignant hypertension. The clinical course was further complicated by ischemic stroke and seizures. Contrast enhanced fluid attenuated inversion recovery (FLAIR) studies revealed diffuse enhancement within the subarachnoid space extending to regions without evidence of cytotoxic or vasogenic edema. These findings suggestive of increased permeability were not only confined to the blood-brain-barrier, but also involved the blood-retina-barrier interface. Our observations suggest that pathologic conditions that disrupt the integrity of blood-brain-barrier might concomitantly affect retinal microcirculation, which highly resembles cerebral microcirculation both anatomically and functionally. Imaging modalities sensitive for detection of blood-brain-barrier dysfunction, such as contrast enhanced FLAIR, might be helpful in identifying these abnormalities.