Refractory Intracranial Hypertension in Posterior Reversible Encephalopathy Syndrome

Introduction

Posterior reversible encephalopathy syndrome (PRES) is a largely reversible disease with long-term favorable outcome. A minority of patients, however, may develop progressive cerebral edema and ischemia resulting in severe disability or death. We report a case of severe intracranial hypertension associated with PRES that was successfully treated according to intracranial pressure (ICP)- and cerebral perfusion pressure (CPP)-driven therapy.

Methods

Case report.

Results

A 42-year-old woman underwent bilateral lung transplantation for severe bronchiectasis. Her immunosuppressive regimen consisted of azathioprine, prednisone, and tacrolimus. She acutely developed an aggressive form of PRES that rapidly resulted in severe refractory intracranial hypertension despite discontinuation of potentially causative medications and adequate supportive therapy. Accordingly, second-tier therapies, including barbiturate infusion, were instituted and immunosuppression was switched to anti-thymocyte globulin followed by mycophenolate mofetil. Within 10 h of barbiturate administration, ICP dropped to 20 mmHg. Thiopental was administered for two days and then rapidly tapered because of severe urosepsis. Six months after discharge from the intensive care unit the patient returned to near-normal life, her only complaint being short-term amnesia.

Conclusions

The decision to undertake ICP monitoring in medical conditions in which no clear recommendations exist greatly relies on physicians’ judgment. This case suggests that ICP monitoring may be considered in the setting of acute PRES among selected patients, when severe intracranial hypertension is suspected, provided that a multidisciplinary team of neurocritical care specialists is readily available.     

Add-on phenytoin fails to prevent early seizures after surgery for supratentorial brain tumors: a randomized controlled study

PURPOSE: To determine the potential effectiveness of phenytoin (PHT) in preventing early postoperative seizures in patients undergoing craniotomy for supratentorial brain tumors. METHODS: Two hundred patients requiring elective craniotomy for supratentorial brain tumors were randomized to two groups of equal size, with a prospective, open-label, controlled design. One group received PHT (18 mg/kg as an intravenous intraoperative load, followed by additional daily doses aimed at maintaining serum PHT concentrations within the 10- to 20-aeg/ml range) for 7 consecutive days. In the other group, PHT was not administered. More than 90% of patients in both groups continued to take preexisting anticonvulsant medication (AEDs) with carbamazepine or phenobarbital throughout the study. The primary efficacy end point was the number of patients remaining free from seizures during the 7-day period after the operation. RESULTS: Of 100 patients allocated to PHT, 13 experienced seizures during the 7-day observation period, compared with 11 of 100 patients in the placebo group (p > 0.05). Most seizures occurred in the first day after surgery in both groups. There were no differences between groups in the proportion of patients experiencing more than one seizure, but there was a trend for generalized seizures to be more common in PHT-treated patients than in controls (11 vs. five patients, respectively). Status epilepticus occurred in one patient in the PHT group and in two patients in the control group. Of the 13 PHT-treated seizure patients, 11 had serum PHT concentrations within the target range, and only two had concentrations below range on the days their seizures occurred. CONCLUSIONS: PHT, given at dosages producing serum concentrations within the target range, failed to prevent early postoperative seizures in patients treated with concomitant AEDs. Prophylactic administration of PHT cannot be recommended in these patients.     

Oxygen and carbon dioxide in the cerebral circulation during progression to brain death

BACKGROUND: The authors propose that for a moderate reduction of perfusion during progressive irreversible ischemia, oxygen extraction increases to maintain aerobic metabolism, and arteriojugular oxygen difference (AJDo2) increases. Because of reduced carbon dioxide washout, venoarterial difference in carbon dioxide tension (DPco2) increases, with no change in the DPco2/AJDo2 ratio. With further reduction of cerebral perfusion, the aerobic metabolism will begin to decrease, AJDo2 will decrease while DPco2 will continue to increase, and the ratio will increase. When brain infarction develops, the metabolism will be abated, no oxygen will be consumed, and no carbon dioxide will be produced. METHODS: The authors studied 12 patients with acute cerebral damage that evolved to brain death and collected intermittent arterial and jugular blood samples. RESULTS: Four patterns were observed: (1) AJDo2 of 4.1 +/- 0.7 vol%, DPco2 of 6.5 +/- 1.9 mmHg, and a ratio of 1.55 +/- 0.3 with cerebral perfusion pressure of 62.5 +/- 13.4 mmHg; (2) a coupled increase of AJDo2 (5.8 +/- 0.7 vol%) and DPco2 (10.1 +/- 1.0 mmHg) with no change in ratio (1.92 +/- 0.14) and cerebral perfusion pressure (57.9 +/- 5.8 mmHg); (3) AJDo2 of 4.7 +/- 0.4 vol% with an increase in DPco2 (11.8 +/- 1 mmHg) and correspondingly higher ratio (2.7 +/- 0.2); in this phase, cerebral perfusion pressure was 39.7 +/- 10.5 mmHg; (4) immediately before diagnosis of brain death (cerebral perfusion pressure, 17 +/- 10.4 mmHg), there was a decrease of AJDo2 (1.1 +/- 0.1 vol%) and of DPco2 (5.3 +/- 0.6 mmHg) with a further ratio increase (5.1 +/- 0.8). CONCLUSIONS: Until compensatory mechanisms are effective, AJDo2 and DPco2 remain coupled. However, when the brain's ability to compensate for reduced oxygen delivery is exceeded, the ratio of DPco2 to AJDo2 starts to increase.     

Impact of pyrexia on neurochemistry and cerebral oxygenation after acute brain injury

BACKGROUND: Postischaemic pyrexia exacerbates neuronal damage. Hyperthermia related cerebral changes have still not been well investigated in humans. OBJECTIVE: To study how pyrexia affects neurochemistry and cerebral oxygenation after acute brain injury. METHODS: 18 acutely brain injured patients were studied at the onset and resolution of febrile episodes (brain temperature > or = 38.7 degrees C). Intracranial pressure (ICP), brain tissue oxygen tension (PbrO2), and brain tissue temperature (Tbr) were recorded continuously; jugular venous blood was sampled intermittently. Microdialysis probes were inserted in the cerebral cortex and in subcutaneous tissue. Glucose, lactate, pyruvate, and glutamate were measured hourly. The lactate to pyruvate ratio was calculated. RESULTS: Mean (SD) Tbr rose from 38 (0.5) to 39.3 (0.3) degrees C. Arteriojugular oxygen content difference (AJD(O2)) fell from 4.2 (0.7) to 3.8 (0.5) vol% (p < 0.05) and PbrO2 rose from 32 (21) to 37 (22) mm Hg (p < 0.05). ICP increased slightly and no significant neurochemical alterations occurred. Opposite changes were recorded when brain temperature returned towards baseline. CONCLUSIONS: As long as substrate and oxygen delivery remain adequate, hyperthermia on its own does not seem to induce any further significant neurochemical alterations. Changes in cerebral blood volume may, however, affect intracranial pressure.     

Control of the side effects of ketamine: chlordemethyldiazepam vs diazepam in pre-anesthesia

The pre-operative circulatory and psychotomimetic side-effects are studied in one hundred patients undergoing elective plastic-reconstructive surgery and anesthetized by ketamine 5-8 mg/kg i.m. Fifty patients were premedicated by atropine 0.01 mg/kg + CDDz 0.0285 mg/kg i.m. (group C), fifty by atropine 0.01 mg/kg + Dz 0.14 mg/kg i.m. (group D). All patients breathed spontaneously. Statistical analysis was performed with X 2 test. Not statistical difference was observed for the circulatory side-effects, whereas the frequency of emergence phenomena fell significantly from 31% to 14% (p less than 0.05) with CDDZ in greater than 16 years old patients. These finding seem confirm that CDDZ is more effective than DZ in reducing the psychotomimetic side-effects of ketamine, though it may be recommended a its wider experiment in this connection.