CO2-related vasoconstriction superimposed on ischemic medullary brain autonomic nuclei may contribute to sudden death.

INTRODUCTION: In 2015, a multinational randomized controlled phase IV clinical trial of adaptive servoventilation for the management of heart failure with central sleep apnea was halted in progress because more patients in the study group were dying than in the control group. One year later, another large clinical trial reported results on the effectiveness of continuous positive airway pressure (CPAP) in preventing sudden death and other cardiovascular events such as heart attack and stroke in patients with preexisting vascular disease as well as obstructive sleep apnea. BACKGROUND: Sudden unexpected death has been associated with many types of small and nonmalignant medullary brain lesions, like demyelination plaques - largely asymptomatic until they caused sudden death. Many such medullary lesions, typically without hemorrhage or mass effect, have in themselves been previously considered relatively harmless - in cases where they have been known to be present. DISCUSSION: Why did not the improved pulmonary ventilation and subsequently improved gas exchange provided during the CPAP and servoventilation clinical trials help to resolve any ischemic lesions that may have been present both in the heart and in the medulla, thereby tending to normalize interactions between the vagal neural structures and the heart? CO2 is a potent dilator of brain vasculature, thereby increasing blood flow to the brain. When ventilation is increased, even if only to improve it back toward normal from a depressed steady-state level, the alveolar partial pressure of carbon dioxide is decreased, likely resulting in a converse relative vasoconstriction in the brain, thereby reducing blood flow in the brain, especially in watershed areas like the solitary tract nucleus. In normal physiology, this is demonstrated impressively by the ability of hyperventilation to induce loss of consciousness. CONCLUSIONS: The findings of several clinical trials recently reported, taken together with neuropathology case studies reported elsewhere, suggest that additional research is warranted in regard to the mechanisms by which focal medullary autonomic brain ischemia may be related to sudden death in general medical illnesses - and how it may additionally be influenced by changes in arterial CO2 levels.

Relationship Between the Hypersensitive c-Reactive Protein (hs-CRP) Level and the Prognosis of Acute Brainstem Infarction.

The objective of this study is to explore the relationship between the hypersensitive c-reactive protein (hs-CRP) level and the prognosis of acute brainstem infarction. Serum levels of hs-CRP were measured in 68 patients with acute brainstem infarction 72 h after disease onset. The hs-CRP levels in the U.S. National Institutes of Health Stroke Scale (NIHSS) score group and in the modified RANKIN scale (mRS) score group were compared. The independent risk factors of brainstem infarction were analyzed using Logistic binary regression. The hs-CRP level was significantly higher in the group with NIHSS >5 compared with the one with NIHSS ≤ 5 (P = 0.004). In the group with mRS > 2, the age, smoking history, and blood glucose level were significantly higher than those in the group with mRS ≤ 2 (P < 0.05), whereas the hs-CRP level was significantly higher (P = 0.001). Age and hs-CRP level were the independent prognostic factors of the brainstem infarction. The serum hs-CRP level is closely related with the severity and prognosis of brainstem infarction, and is an independent risk factor of acute brainstem infarction.

Ischemic volumes and early neurologic deterioration in acute brainstem infarctions with hemoglobin A1c.

AIM: To investigate the association of hemoglobin A1c (HbA1c) with acute diffusion-weighted imaging lesion volumes (DIV) and early neurologic deterioration (END) in brainstem infarctions (BSIs). METHODS: 152 patients with acute BSIs were included in this study. The relationship between HbA1c and DIV quartiles was examined. Data considered potentially associated with HbA1c and END after admission and patients' symptomatic changes prior to admission were collected. RESULTS: There was a significant correlation between HbA1c (%) and DIV (Spearman ρ=0.201, p=0.013). The median HbA1c (%) values for successive DIV quartiles (lowest to highest quartile) were as follows: 5.90, 6.35, 6.25, and 7.50 (p=0.033). The incidence of diabetes mellitus had a significant association with DIV quartiles (p=0.042). HbA1c was significantly associated with symptomatic progression prior to admission (p=0.015). 29 patients developed END after admission. Age, HbA1c, systolic blood pressure, and fibrinogen were significantly associated with END. On logistic regression analysis, HbA1c and fibrinogen proved to be independent variables. CONCLUSIONS: HbA1c may be a possible predictor for ischemic severity, early deterioration of acute BSIs, and short-term prognosis. Long-term good glycemic control is very important in BSIs. Further studies are warranted to confirm these results.

Hemoglobin A1C is independently associated with severity and prognosis of brainstem infarctions.

OBJECTIVE: To assess the association of Hemoglobin A1C (HbA1c) with acute brainstem infarctions (BSIs) and to determine whether HbA1c is an independent risk factor in BSIs patients. METHODS: 96 only BSIs patients were categorized into four groups according to HbA1c as <6%, ≥ 6% but <7%, ≥ 7% but <8%, or ≥ 8%, respectively. The association of the four HbA1c groups with diffusion-weighted imaging (DWI) infarct volumes (DIV), National Institutes of Health Stroke Scale (NIHSS), and follow-up modified Rankin Scale (FmRS) scores were analyzed. Patients also were categorized into two groups according to HbA1c<6% or ≥ 6%. Logistic regression analyses were performed to determine independent risk factors. RESULTS: There was a significant correlation between HbA1c and DIV (Spearman ρ=0.339, P=0.001), NIHSS scores (ρ=0.292, P=0.004) and FmRS scores (ρ=0.315, P=0.002). The incidence of pons infarction was highest in BSIs and patients with HbA1c ≥ 6% showed significantly more frequent isolated pontine infarction. Logistic regression analyses showed that only HbA1c was independently associated with larger DIV (P=0.025) and FmRS scores (P=0.026). CONCLUSIONS: These results suggest that elevated HbA1c level may be a potential serologic marker in the evaluation of the severity and prognosis of acute BSIs. There is an urgent need to study control of diabetes mellitus (DM) before and after BSIs.

Reversal of vision metamorphopsia caused by pons and cerebellum infarction.

Metamorphopsia is a visual illusion related to the perception of an object's shape, size, colour or angle. Reversal of vision metamorphopsia is a rare, transient form of metamorphopsia described as an inversion of the field of vision, usually a 180-degree reversion within the frontal plane. We describe the case of a 64-year-old male patient who first experienced a 90-degree rotation of the field of vision and then had the impression of his body rotating in space. The symptoms were preceded by disequilibrium, astigmatism and vomiting. Magnetic resonance imaging of the head showed focuses of vasogenic lesions in the pons and left cerebellar hemisphere. Magnetic resonance angiography of cerebral vessels did not reveal the left vertebral artery. This is the first described case of reversal of vision metamorphopsia with 90-degree rotation of the field of vision with accompanying disorder of the spatial position of the body.