Posterior reversible encephalopathy syndrome (PRES) and CT perfusion changes
© Hedna et al; licensee Springer. 2012
Received: 7 November 2011
Accepted: 29 February 2012
Published: 29 February 2012
Posterior reversible encephalopathy syndrome ( PRES) can present with focal neurologic deficits, mimicking a stroke and can often represent a diagnostic challenge when presenting atypically. A high degree of suspicion is required in the clinical setting in order to yield the diagnosis. Cerebral CT perfusion (CTP) is utilized in many institutions as the first line in acute stroke imaging. CTP has proved to be a very sensitive measure of cerebral blood flow dynamics, most commonly employed to delineate the infarcted tissue from penumbra (at-risk tissue) in ischemic strokes. But abnormal CTP is also seen in stroke mimics such as seizures, hypoglycemia, tumors, migraines and PRES. In this article we describe a case of PRES in an elderly bone marrow transplant recipient who presented with focal neurological deficits concerning for a cerebrovascular accident. CTP played a pivotal role in the diagnosis and initiation of appropriate management. We also briefly discuss the pathophysiology of PRES.
Common location of PRES
Common location of PRES
Parietal-occipital - most common.
Etiology of PRES
Common causes of PRES
E clampsia and preeclampsia
- Recreational: Cocaine, Amphetamines, PCP, LSD
- Others: Anti-depressants (Tricyclics, MAO Inhibitors), Bronchodilators, Erythropoietin, Midodrine, Fludrocortisone, Triple H therapy, Intravenous immunoglobulins (IVIG).
N eoplastic drugs: Cyclosporine-A, Tacrolimus, Interferons, Indinavir, Cisplatin, Cytarabine, Gemcitabine.
A utoimmune and S ystemic: Systemic lupus erythematosus (SLE), Scleroderma, Vasculitis like PAN, Wegener's, Thrombotic thrombocytopenic purpura (TTP), Henoch-Schönlein purpura, Hemolytic uremic syndrome (HUS), Amyloid angiopathy, Tumor lysis syndrome, Systemic inflammatory response syndrome (SIRS), Sepsis, Multiple organ Dysfunction, Electrolyte imbalance (Hypomagnesemia, hypercalcemia), Hypocholesterolemia,, GBS, Head injury, Renal failure due to any etiology.
We suggest that PRES is the result of various etiological factors that lead to blood brain barrier injury either by hyper- or hypoperfusion, endothelial dysfunction, changes in blood vessel morphology, hypocapnia or immune system activation [2, 4, 5]. It usually affects parietal and occipital area, s but other regions can be involved as well .
In our patient we feel that elevated MAP led to regional dysautoregulation, consequently causing hyperperfusion, explaining the findings of increased CBF, CBV and reduced TTP. It is important to recognize that this patient had a recent history of bone marrow transplant with exposure to chemotherapy, which may also be a causative factor in the development of PRES, or may have independently contributed to the tissue injury.
We conclude that the mechanism of PRES is individualized in each patient and depends mainly on the causative factor identified in each case. In the setting of HTN, PRES is most likely due to the mechanism described in the previously discussed theories. In the setting of normotensive PRES, the mechanism may be based on endothelial dysfunction, immune system activation and other systemic features. Although initially edema is vasogenic in nature, a failure to reverse the disease etiology will subsequently cause cytotoxic edema and eventually brain infarction, further emphasizing the importance of early disease recognition.
CT perfusion changes in various brain insults
Varies; usually ↑
Usually ↑ but can be ↓
↑ or ↓
The management of this condition depends on the etiology and should be initiated in a timely manner. The treatment of the underlying cause is typically sufficient to reverse this condition. However, a word of caution: this condition can lead to irreversible brain insult if the treatment is delayed or if there is prolonged brain insult, in which case a brain insult then becomes irreversible brain infarctions. Additionally, there may be hemorrhagic complications and raised intracranial pressure contributing further to the cerebral damage . The MAP should be reduced quickly but with caution in the cases of hypertensive PRES. In cases of non-hypertensive PRES, especially in case of neoplastic drugs, the offending agent should be withdrawn quickly to avoid further damage to the blood brain barrier. In the setting of transplant, alternative medications can be substituted to avoid organ rejections . If an autoimmune etiology is suspected, then immunosuppression has a role in the management . Seizures are managed with anti-epileptic medications.
Posterior reversible encephalopathy syndrome is a relatively rare syndrome that sometimes presents as a stroke mimic. As such, it is important for the emergency physician to recognize. Urgent recognition and early initiation of management of this condition are imperative as it directly impacts the neurological outcome. Brain CT perfusion can play an important role in the diagnosis.
Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.
Publication of this article was funded in part by the University of Florida Open-Access Publishing Fund.
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