For this aspect, it is possible that any criterion or combination of criteria cannot show this global view, but the blood flow study of inflow and outflow can help, in our opinion, to define a reliable and proper selleck screening library description of the global hemodynamics. “
“Over the past
few decades the sonographic investigation of the eye and the adjacent structures in the orbit has become an important and well established tool in ophthalmology. It is crucial in the clinical work-up of patients suffering from a wide variety of ocular and orbital disorders. Additionally, a growing body of literature demonstrates the usefulness of transbulbar B-mode sonography of the optic nerve for detecting raised intracranial Selleck IWR-1 pressure (ICP) in patients requiring neurocritical care. Therefore, neurologists increasingly take interest in this non-invasive and cost-effective bedside method. Even today ICP assessment continues to be a challenging task in critical care medicine. Invasive devices remain the cornerstone for measuring ICP in comatose or sedated patients but may not
always be feasible due to a lack of neurosurgeons or contraindications such as coagulopathy or thrombocytopenia. Noninvasively, evaluation of pressure elevation relies on clinical symptoms or repeated CT or MR scanning to monitor for complications of raised ICP. As part of the central nervous system the optic nerve is surrounded by cerebrospinal fluid and by meninges designated as optic nerve sheath. Hayreh shed light on the communication between the intracranial cerebrospinal
fluid spaces and the subarachnoid space of the optic nerve sheath . In his investigations in rhesus monkeys he described the development of papilledema in different situations of elevated ICP. Helmke and Hansen confirmed that ICP changes have an influence on the optic nerve sheath diameter (ONSD) . In intrathecal infusion tests they found that the sonographic ONSD assessment is not suitable to evaluate exact ICP values, but may be used as surrogate variable of raised ICP. In contrast to the evolution Adenosine triphosphate of papilledema, ONSD changes correlated well with short-term ICP variations. This has been recently reproduced in an ultrasound-based study on brain injured patients . Moreover, Helmke and Hansen developed a standardized transbulbar sonography technique for measuring the ONSD  and . In our ultrasound laboratory we use a 9–3 MHz linear array transducer for transbulbar sonography of the optic nerve. Patients are examined in supine position with the upper part of the body and the head elevated to 20–30°. For safety reasons of biomechanical side effects we reduce the mechanical index to 0.2. The probe is placed on the temporal part of the closed upper eyelid using a thick layer of ultrasound gel.