Joseph D. Burns

Intracranial Aneurysm Enlargement on Serial Magnetic Resonance Angiography: Frequency and Risk Factors

Background and Purpose— Size of an unruptured intracranial aneurysm (UIA) may be an important risk factor for rupture. Accordingly, serial noninvasive imaging is commonly used to assess untreated UIA for enlargement. Few data exist regarding the frequency and predictors of enlargement. We obtained this information from a group of patients followed with serial MR angiography (MRA). Methods— We retrospectively identified 165 patients with 191 UIA followed with serial MRA. Fusiform aneurysms, UIA <2 mm, and UIA that were surgically or endovascularly treated before the first MRA were excluded. MRA was performed using 1.5-T and 3-T MRI. Maximal diameter was determined on MRA source images. Multivariate regression analysis was used to determine independent risk factors for growth. Results— Twenty aneurysms (10%) grew over a median follow-up period of 47 months. Frequency of enlargement was 6.9%, 25%, and 83% for aneurysms <8 mm, 8 to 12 mm, and ≥13 mm, respectively (P<0.001 for trend). Of the variables we evaluated, original aneurysm diameter (OR, 1.28 per mm; 95% CI, 1.07 to 1.58) was the only independent predictor of enlargement. Aneurysms ≥8 mm in diameter were at highest risk for enlargement (OR, 7.25; 95% CI, 1.96 to 27.1). There was a trend toward increased risk of enlargement in patients with multiple aneurysms (OR, 2.50; 95% CI, 0.86 to 7.53). Conclusions— Over a median follow-up period of 47 months, 10% of UIA enlarged. Larger aneurysms had a significantly increased risk of enlargement. The likelihood of enlargement was highest in aneurysms with diameters ≥8 mm. However, a clinically significant proportion of small aneurysms grow, and this growth can be detected by serial MRA.

Cerebral Salt Wasting: Pathophysiology, Diagnosis, and Treatment

Cerebral salt wasting (CSW) is a syndrome of hypovolemic hyponatremia caused by natriuresis and diuresis. The mechanisms underlying CSW have not been precisely delineated, although existing evidence strongly implicates abnormal elevations in circulating natriuretic peptides. The key in diagnosis of CSW lies in distinguishing it from the more common syndrome of inappropriate secretion of antidiuretic hormone. Volume status, but not serum and urine electrolytes and osmolality, is crucial for making this distinction. Volume and sodium repletion are the goals of treatment of patients with CSW, and this can be performed using some combination of isotonic saline, hypertonic saline, and mineralocorticoids.

Paroxysmal Atrial Fibrillation in Cryptogenic Stroke: A Case-Control Study

BACKGROUND It is unclear if brief episodes of paroxysmal atrial fibrillation (PAF) detected by prolonged cardiac monitoring are an occult of cause of cryptogenic strokes (CS). We compared the incidence of PAF in patients with CS and patients with stroke of known cause (SKC) using prolonged ambulatory cardiac monitoring. METHODS We prospectively enrolled patients within 3 months of ischemic stroke to undergo noninvasive cardiac monitoring for 3 weeks. Primary end point was PAF detection independently confirmed by 2 blinded cardiologists. RESULTS The study consisted of 132 patients, 66 had CS and 66 had SKC. Episodes of PAF were detected in 16 of 64 (25%) patients with CS and 9 of 64 (14%) patients with SKC (P=.12). Duration and number of PAF episodes, PAF burden, and time of first PAF detection did not differ significantly between the 2 groups (P>.05 for all). In patients younger than 65 years, PAF was more common in the CS group (22% versus 3%; P=.07), whereas in patients 65 years or older, the rates of detection were similar (27% in CS versus 25% in SKC; P=.9). Among patients younger than 65 years with embolic imaging pattern, PAF was only observed in the CS group (21% versus 0%; P=.03). CONCLUSIONS Very short episodes of PAF are common in patients with CS and with SKC, but their pathogenic significance is unclear. Predominance of PAF in younger patients with CS and embolic infarct pattern suggests a causative role in these cases. More research is needed before prolonged cardiac rhythm monitoring can be recommended to guide anticoagulation in CS patients.

Prolonged High-Dose Isoflurane for Refractory Status Epilepticus: Is It Safe?

Isoflurane is an alternative treatment for refractory status epilepticus. Little is known regarding human toxicities caused by isoflurane. We present 2 patients with prolonged refractory status epilepticus treated with high concentrations of isoflurane who developed signal abnormalities on magnetic resonance imaging. Patient 1 was treated with isoflurane for 85 days with 1975.2% concentration-hours. Patient 2 was treated with isoflurane for 34 days with 1382.4% concentration-hours. Serial brain magnetic resonance images in both showed progressive T2 signal hyperintensity involving thalamus and cerebellum, which improved after discontinuation of isoflurane. These cases suggest that isoflurane may be neurotoxic when used in high doses for long time periods.

Prophylaxis of Venous Thrombosis in Neurocritical Care Patients: An Evidence-Based Guideline: A Statement for Healthcare Professionals from the Neurocritical Care Society

The risk of death from venous thromboembolism (VTE) is high in intensive care unit patients with neurological diagnoses. This is due to an increased risk of venous stasis secondary to paralysis as well as an increased prevalence of underlying pathologies that cause endothelial activation and create an increased risk of embolus formation. In many of these diseases, there is an associated risk from bleeding because of standard VTE prophylaxis. There is a paucity of prospective studies examining different VTE prophylaxis strategies in the neurologically ill. The lack of a solid evidentiary base has posed challenges for the establishment of consistent and evidence-based clinical practice standards. In response to this need for guidance, the Neurocritical Care Society set out to develop and evidence-based guideline using GRADE to safely reduce VTE and its associated complications.

Incidence and Predictors of Myocardial Infarction After Transient Ischemic Attack A Population-Based Study

Background and Purpose— Coronary artery disease is the leading cause of death after TIA. Reliable estimates of the risk of MI after TIA, however, are lacking. Methods— Our purpose was to determine the incidence of and risk factors for MI after TIA. We cross-referenced preexisting incidence cohorts from the Rochester Epidemiology Project for TIA (1985–1994) and MI (1979–2006) to identify all community residents with incident MI after incident TIA. Incidence of MI after TIA was determined using Kaplan–Meier life-table methods. This was compared to the age-, sex-, and period-specific MI incidences in the general population. Proportional hazards regression analysis was used to examine associations between clinical variables and the occurrence of MI after TIA. Results— Average annual incidence of MI after TIA was 0.95%. Relative risk for incident MI in the TIA cohort compared to the general population was 2.09 (95% CI, 1.52–2.81). This was highest in patients younger than 60 years old (relative risk, 15.1; 95% CI, 4.11–38.6). Increasing age (hazard ratio, 1.51 per 10 years; 95% CI, 1.14–2.01), male sex (hazard ratio, 2.19; 95% CI, 1.18–4.06), and the use of lipid-lowering therapy at the time of TIA (hazard ratio, 3.10; 95% CI, 1.20–8.00) were independent risk factors for MI after TIA. Conclusions— Average annual incidence of MI after TIA is ≈1%, approximately double that of the general population. The relative risk increase is especially high in patients younger than 60 years old. These data are useful for identifying subgroups of patients with TIA at highest risk for subsequent MI.

Evaluation of brain biopsy in the diagnosis of severe neurologic disease of unknown etiology

OBJECTIVE To determine the value of non-stereotactic brain biopsies in patients with severe neurologic disease of unknown etiology and indeterminate brain imaging. METHODS We reviewed 42 consecutive patients who underwent non-stereotactic brain biopsy at a single institution for evaluation of severe neurologic disease of unknown etiology. All patients had indeterminate or normal imaging results. Seventy-nine percent had been symptomatic for less than a year. Exclusion criteria were immunocompromise or a preoperative diagnosis of intracranial neoplasm. Diagnostic yield and surgical complication rate were calculated. We performed exploratory univariate analysis aimed at identifying clinical features possibly predictive of diagnostic biopsies. RESULTS A histologic diagnosis was achieved in 12 of 42 biopsies (29%). Three patients experienced minor transient complications from the procedure (7%). There were no permanent deficits or deaths. Treatment was altered based on biopsy result in five patients (12%). A more precise prognosis was obtained in eight patients (19%). In total, 11 different patients (26%) benefited from biopsy. Exploratory univariate analysis showed a possible inverse relationship between age and the likelihood of a diagnostic biopsy (OR=0.929; 95% CI=0.864-0.998). CONCLUSIONS Our data suggest that the value of non-stereotactic brain biopsy is sufficiently high and the morbidity sufficiently low to justify its use in carefully selected patients with severe neurologic disease that remains undiagnosed despite thorough less invasive evaluation.

Tension pneumothorax complicating apnea testing during brain death evaluation.

Tension pneumothorax is a rare complication of the apnea test using the apneic oxygenation method. In reported cases, it has been attributed to massive air trapping beyond a supplemental oxygen cannula that was obstructing the airway. We report a case of tension pneumothorax, pneumomediastinum, and pneumoperitoneum that developed during the apnea test as a result of direct airway perforation by the supplemental oxygen cannula. We review the literature concerning catastrophic airway complications associated with the apneic oxygenation method and suggest ways to avoid them.

Atypical Acute Hemorrhagic Leukoencephalitis (Hurst's disease) Presenting with Focal Hemorrhagic Brainstem Lesion

BackgroundAcute hemorrhagic leukoencephalitis (AHL; Hurst’s disease) is a rare, severe, inflammatory CNS disease that is typically diffuse, multifocal and associated with petechial hemorrhage. The objective of this study is to report the clinical, radiologic, and pathologic findings in a fatal AHL case with focal brainstem involvement and gross hemorrhage.MethodsPatient evaluation in a tertiary neurointensive care unit with serial brain magnetic resonance imaging (MRI) and neuropathological examination on autopsy were performed.ResultsThe patient presented with mild, then rapidly worsening, brainstem impairment to a locked-in syndrome. Brain MRI demonstrated an isolated gadolinium enhancing brainstem lesion that enlarged dramatically over weeks and was associated with gross hemorrhage and necrosis. The patient died despite aggressive treatment with intravenous corticosteroids and plasma exchange. Autopsy demonstrated the isolated severe necrotic lesion consistent with AHL.ConclusionsAHL may present as a solitary brainstem lesion with gross hemorrhage and should be considered in patients with isolated enhancing brainstem lesions. AHL may be fatal even despite early, aggressive immunomodulatory therapy.

Decompressive Laparotomy for Refractory Intracranial Hypertension After Traumatic Brain Injury

BackgroundIntracranial hypertension is a crucial modifiable risk factor for poor outcome after traumatic brain injury (TBI). Limited evidence suggests that decompressive laparotomy may be an effective treatment for refractory ICH in patients who have elevated intra-abdominal pressure.MethodsCase report.ResultsWe present a multi-trauma patient who sustained severe TBI in a motor vehicle collision. Intracranial pressure (ICP) was initially medically managed but became refractory to standard therapies. Emergent decompressive laparotomy performed in the surgical intensive care unit for abdominal compartment syndrome concomitantly improved the patient’s ICP.ConclusionsElevated intra-abdominal pressure can exacerbate intracranial hypertension in patients with TBI. Recognition of this condition and treatment with decompressive laparotomy may be useful in patients with intracranial hypertension refractory to optimal medical therapy.