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The origin of secondary brainstem hemorrhages following an acute expansive hemispheric lesion has been attributed to Henri Duret, who proposed that hemorrhaging was caused by a shock wave through the cerebral spinal fluid. However, other experiments have shown important findings correlating brainstem hemorrhages to arterial hemorrhages. Animal studies found that the rapidity of expansion of a lesion would be crucial in producing these lesions, but there was no consistent correlation with paratentorial grooving so commonly seen with increased intracranial pressure. This historical perspective studies the different experimentalists who paved the way for the discovery of these secondary brainstem hemorrhages-often named after Duret-and now known not to be invariably associated with poor outcome.

This comment refers to the article available at https://doi.org/10.1007/s12028-019-00722-7 .

External ventricular drains (EVD) are used as a method of diverting cerebral spinal fluid out of the cranium. After placement of these drains, it has been customary to initiate antibiotics to prevent drain-related infections. Prophylactic regimes include peri-operative and prolonged administration of antibiotics. Little evidence exists to support either regime. To determine current practices or to determine if an unintended consensus has developed, a survey was taken concerning antibiotic prophylaxis with EVD insertion.E-mail survey from a membership database of the Neurocritical Care Society, a database of neurosurgeons maintained by the LSU Department of Neurosurgery and infectious diseases practitioners from a Department of Medicine database.There was an approximate 781 responses. Of the responders, 77% (599) were neurosurgeons, 10.5% (82) neurocritical care, 5.0% (41) intensivists, 6.5% (50) infectious diseases specialist, and 1% (9) others. The majority of responders (64%) have been in practice10 years. Most respondents from outside Europe recommended use of prophylactic antibiotics. Of those that did use antibiotics prophylaxis, the majority (56%) recommend use for the duration the catheter is in place. The exception is European responders used peri-operative prophylaxis most frequently. The majority of responders (78%) support a prospective trial to address this issue.The use of antibiotics prophylaxis after EVD placement is disparate among specialties that deal with EVD placement and complications. There is no consistent practice pattern based on specialty, locale, and years of practice. The majority of all responders felt a prospective trial was warranted.

Intracranial pressure (ICP) monitoring is currently an invasive procedure that requires access to the intracranial space through an opening in the skull. Noninvasive monitoring of ICP via the auditory system is theoretically possible because changes in ICP transfer to the inner ear through connections between the cerebral spinal fluid and the cochlear fluids. In particular, low-frequency distortion-product otoacoustic emissions (DPOAEs), measured noninvasively in the external ear canal, have magnitudes that depend on ICP. Postural changes in healthy humans cause systematic changes in ICP. Here, we quantify the effects of postural changes, and presumably ICP changes, on DPOAE magnitudes.DPOAE magnitudes were measured on seven normal-hearing, healthy subjects at four postural positions on a tilting table (angles 90 degrees , 0 degrees , - 30 degrees , and - 45 degrees to the horizontal). At these positions, it is expected that ICP varied from about 0 (90 degrees ) to 22 mm Hg ( - 45 degrees ). DPOAE magnitudes were measured for a set of frequencies 750f24000, with f2/f1 = 1.2.For the low-frequency range of 750or=f2or= 1500, the differences in DPOAE magnitude between upright and - 45 degrees were highly significant (all p0.01), and above 1500 Hz there were minimal differences between magnitudes at 90 degrees versus - 45 degrees. There were no significant differences in the DPOAE magnitudes with subjects at 90 degrees and 0 degrees postures.Changes in ICP can be detected using the auditory-based measurement of DPOAEs. In particular, changes are largest at low frequencies. Although this approach does not allow for absolute measurement of ICP, it appears that measurement of DPOAEs may be a useful means of noninvasively monitoring ICP.