Cerebral Swelling: The Beginning of a Good Discussion

Upon entering a hospital system, the management of the patient with stroke should be focused on minimizing further injury to the ischemic brain. While intravenous or intra-arterial thrombolytic therapies have become more available, the significant reductions achieved in the time to recanalization have not obviated the need for a better understanding of what to do when “newer” therapies do not succeed. A statement on the management of the sequelae of cerebral or cerebellar hemisphere infarction is long overdue.

On first glance, any neurosurgeon may find it interesting that the writing group decided to tackle clinical management of supratentorial and infratentorial lesions in the same statement. It is engrained in the neurosurgical trainee that lesions of the middle cranial and posterior cranial fossae are different. This distinction is due to the minimal tolerance of swelling and close proximity to critical brainstem structures in the posterior fossa. The use of ventricular drainage is more frequent in mass lesions of the posterior fossa and provides less benefit in ischemic lesions of the supratentorial compartment. Surgical decompression of the posterior fossa is also much less controversial than decompression of anterior or middle fossa lesions.

But on a more global scale the reader of this statement should appreciate that the development of brain swelling in response to ischemia is the result of a physiological cascade that is not compartment specific. The interaction between intracranial pressure, fluid management, and respiratory and cardiac function remains nonetheless complex. This is where the strength of the statement by Wijdicks et al lies.¹ The authors appropriately emphasize that our clinical judgment must be augmented through an improved understanding and recognition of the imaging and biological characteristics associated with progressive ischemia.

As with many disease processes, the ability to understand biological processes in a non-invasive fashion is a rapidly changing landscape. While a major goal of acute stroke imaging is the assessment of collateral circulation to a hemisphere at risk for infarction, this need is obviated in this patient population. A large stroke has already occurred. The next concern is the rapidity, or malignancy, of the swelling process. While the authors suggest predictors of malignant edema, they do not adequately reference the venous drainage of the hemisphere at risk. This highlights another difference in the supra- and infra-tentorial spaces. The venous drainage of the supratentorial space is more easily evaluated noninvasively. While not addressed in large studies, the results of Yu et al suggest that a concept of collateral drainage may be just as important as collateral circulation in the management of hemispheric stroke.²

When reading this statement one cannot help but consider it in the context of the healthcare movement that has usurped the media over the past few months. A majority of strokes that occur are related to a failure of the primary care network. It is with this thought in mind that many advocate an increase in access to basic care that would address the hypertension, diabetes, and hypercholesterolemia that help to create the stroke population. Since initial publication in 2000, the Brain Attack Coalition (BAC) has led the charge for the creation of primary (PSC) and now comprehensive stroke centers (CSC).^3,4 The success of this movement is evident in the proliferation of PSCs and now CSCs that provide care to stroke patients of varying degrees of severity. Despite primary or comprehensive status, each certified center should be able to reliably diagnose and initially manage stroke. Based on the needs of a patient with a large infarct, a PSC should consider transfer to a CSC within 48 hours of diagnosis in order to maximize the therapies available. It should be considered a failure of the stroke system if appropriate preventative treatments are not accessible to the patient with hemispheric infarction and swelling.

The authors of the statement appropriately stress that their work is meant to revive a discussion on this topic, not end it. While some may take issue with some of the recommendations made, it would be useful to pay attention to the Levels of Evidence provided. The paucity of Class I and preponderance of Level C statements still leave adequate room for individualization of therapies. The ultimate therapy for the patient with a large ischemic infarct and swelling should be disease focused and patient centric. A conversation among experts is the best way to provide that therapy.