Microdialysis enables the chemistry of the extracellular interstitial space to be monitored. Use of this technique in patients with acute brain injury has increased our understanding of the pathophysiology of several acute neurological disorders. In 2004, a consensus document on the clinical application of cerebral microdialysis was published. Since then, there have been significant advances in the clinical use of microdialysis in neurocritical care. The objective of this review is to report on the International Microdialysis Forum held in Cambridge, UK, in April 2014 and to produce a revised and updated consensus statement about its clinical use including technique, data interpretation, relationship with outcome, role in guiding therapy in neurocritical care and research applications.

As of April 22, 2021, around 1.5 million individuals in three districts of Kerala, India had been vaccinated with COVID‐19 vaccines. Over 80% of these individuals (1.2 million) received the ChAdOx1‐S/nCoV‐19 vaccine. In this population, during this period of 4 weeks (mid‐March to mid‐April 2021), we observed seven cases of Guillain‐Barre syndrome (GBS) that occurred within 2 weeks of the first dose of vaccination. All seven patients developed severe GBS. The frequency of GBS was 1.4‐ to 10‐fold higher than that expected in this period for a population of this magnitude. In addition, the frequency of bilateral facial weakness, which typically occurs in <20% of GBS cases, suggests a pattern associated with the vaccination. While the benefits of vaccination substantially outweigh the risk of this relatively rare outcome (5.8 per million), clinicians should be alert to this possible adverse event, as six out of seven patients progressed to areflexic quadriplegia and required mechanical ventilatory support. ANN NEUROL 2021;90:312–314

OBJECT: Increased intracranial pressure (ICP) in patients with traumatic brain injury (TBI) is associated with a higher mortality rate and poor outcome. Mannitol and hypertonic saline (HTS) have both been used to treat high ICP, but it is unclear which one is more effective. Here, the authors compare the effect of mannitol versus HTS on lowering the cumulative and daily ICP burdens after severe TBI. METHODS: The Brain Trauma Foundation TBI-trac New York State database was used for this retrospective study. Patients with severe TBI and intracranial hypertension who received only 1 type of hyperosmotic agent, mannitol or HTS, were included. Patients in the 2 groups were individually matched for Glasgow Coma Scale score (GCS), pupillary reactivity, craniotomy, occurrence of hypotension on Day 1, and the day of ICP monitor insertion. Patients with missing or erroneous data were excluded. Cumulative and daily ICP burdens were used as primary outcome measures. The cumulative ICP burden was defined as the total number of days with an ICP of > 25 mm Hg, expressed as a percentage of the total number of days of ICP monitoring. The daily ICP burden was calculated as the mean daily duration of an ICP of > 25 mm Hg, expressed as the number of hours per day. The numbers of intensive care unit (ICU) days, numbers of days with ICP monitoring, and 2-week mortality rates were also compared between the groups. A 2-sample t-test or chi-square test was used to compare independent samples. The Wilcoxon signed-rank or Cochran-Mantel-Haenszel test was used for comparing matched samples. RESULTS: A total of 35 patients who received only HTS and 477 who received only mannitol after severe TBI were identified. Eight patients in the HTS group were excluded because of erroneous or missing data, and 2 other patients did not have matches in the mannitol group. The remaining 25 patients were matched 1:1. Twenty-four patients received 3% HTS, and 1 received 23.4% HTS as bolus therapy. All 25 patients in the mannitol group received 20% mannitol. The mean cumulative ICP burden (15.52% [HTS] vs 36.5% [mannitol]; p = 0.003) and the mean (± SD) daily ICP burden (0.3 ± 0.6 hours/day [HTS] vs 1.3 ± 1.3 hours/day [mannitol]; p = 0.001) were significantly lower in the HTS group. The mean (± SD) number of ICU days was significantly lower in the HTS group than in the mannitol group (8.5 ± 2.1 vs 9.8 ± 0.6, respectively; p = 0.004), whereas there was no difference in the numbers of days of ICP monitoring (p = 0.09). There were no significant differences between the cumulative median doses of HTS and mannitol (p = 0.19). The 2-week mortality rate was lower in the HTS group, but the difference was not statistically significant (p = 0.56). CONCLUSIONS: HTS given as bolus therapy was more effective than mannitol in lowering the cumulative and daily ICP burdens after severe TBI. Patients in the HTS group had significantly lower number of ICU days. The 2-week mortality rates were not statistically different between the 2 groups.

Background and Purpose—: Although preclinical studies have shown inflammation to mediate perihematomal edema (PHE) after intracerebral hemorrhage, clinical data are lacking. Leukocyte count, often used to gauge serum inflammation, has been correlated with poor outcome but its relationship with PHE remains unknown. Our aim was to test the hypothesis that leukocyte count is associated with PHE growth. Methods—: We included patients with intracerebral hemorrhage admitted to a tertiary-care stroke center between 2011 and 2015. The primary outcome was absolute PHE growth during 24 hours, calculated using semiautomated planimetry. Linear regression models were constructed to study the relationship between absolute and differential leukocyte counts (monocyte count and neutrophil–lymphocyte ratio) and 24-hour PHE growth. Results—: A total of 153 patients were included. Median hematoma and PHE volumes at baseline were 14.4 (interquartile range, 6.3–36.3) and 14.0 (interquartile range, 5.9–27.8), respectively. In linear regression analysis adjusted for demographics and intracerebral hemorrhage characteristics, absolute leukocyte count was not associated with PHE growth (β, 0.07; standard error, 0.15; P =0.09). In secondary analyses, neutrophil–lymphocyte ratio was correlated with PHE growth (β, 0.22; standard error, 0.08; P =0.005). Conclusions—: Higher neutrophil–lymphocyte ratio is independently associated with PHE growth. This suggests that PHE growth can be predicted using differential leukocyte counts on admission.