Introduction
Posterior reversible encephalopathy syndrome (PRES) is a clinical entity first described in 1996, characterized by headache, seizures, nausea, vomiting, visual disturbances, focal motor deficits, and altered mental status (1,2). Although the exact pathophysiology of PRES remains unclear, hypertension and endothelial dysfunction are implicated in its development, both of which disrupt the blood-brain barrier leading to vasogenic cerebral edema (3). Known precipitating factors for PRES include hypertensive encephalopathy, preeclampsia and eclampsia, immunosuppressive and cytotoxic drugs, hypertensive renal failure, hepatic failure, elevated liver enzymes and low platelets (HELLP) syndrome, collagen vascular diseases, thrombotic thrombocytopenic purpura, high-dose steroid use, massive blood transfusion, acute intermittent porphyria, organ transplantation, and human immunodeficiency virus (4). Computed tomography (CT) and magnetic resonance imaging (MRI) can be used for the diagnosis of PRES, with CT typically showing nonspecific changes, whereas MRI demonstrates more specific findings (5). MRI is preferred over CT for diagnosis because while brain CT may appear normal, MRI readily reflects the characteristic features of cerebral edema, exhibiting bilateral and symmetric involvement in the occipital and parietal regions (3,6). Early diagnosis and prompt treatment can lead to reversibility of the syndrome (5). However, if left untreated and the underlying cause is not addressed, irreversible brain damage may ensue (3). This case presentation illustrates a patient brought to the emergency department with altered consciousness and subsequently diagnosed with PRES.
Case
An 85-year-old female patient was found lying face down at home in the morning by her relative and was brought to the peripheral emergency department via ambulance. Upon evaluation, the patient was intubated, and no pathology was detected on brain CT or pulmonary CT angiography. Due to the need for further assessment and MRI, the patient was referred to our emergency department. On arrival, the patient had a Glasgow Coma Scale (GCS) of 3 while sedated, blood pressure of 230/110 mmHg, heart rate of 52 beats per minute, fingertip blood glucose level of 152 mg/dL, and a temperature of 36.7°C. Due to sedation, neurological examination could not be performed. Blood tests were within normal limits. An electrocardiogram revealed a left bundle branch block; Sgarbossa and Modified Smith criteria were negative. The brain CT performed at the peripheral center was interpreted as normal. The patient underwent diffusion-weighted MRI, which was also interpreted as normal. Intravenous esmolol was initiated as anti-hypertensive treatment in the emergency department. Since cranial MRI could not be performed in the emergency department, the patient was admitted to the intensive care unit with a presumptive diagnosis of PRES.
Discussion
The term PRES was first coined by Hinchey et al. in 1996 to describe a radiological syndrome characterized by bilateral, symmetric, and reversible vasogenic edema (1). There are not many studies in the literature reporting the gender distribution of PRES. In a 15-case series by Hinchey et al., the female-to-male ratio was reported as 13:2 (1). In a study by Aydın et al., which examined 5 patients diagnosed with PRES over 5 years, it was found that all patients were female. The age range of the patients was between 18 and 28 years old, with a mean age of 24.4 years (6). In contrast, our patient was 85 years old. Patients typically present with symptoms such as headache, altered mental status, seizures, and symptoms associated with the occipital lobe. Symptoms may have an acute or subacute onset, followed by seizures. Other manifestations may include disturbances in consciousness and behavior, lethargy, stupor, and coma, or may be detected only as irritability and anxiety (6). In our case, the patient was brought to the hospital with a closed level of consciousness.
Among the causes of PRES are hypertension, sepsis and septic shock, preeclampsia and eclampsia, autoimmune diseases, electrolyte disturbances (such as hypercalcemia and hypomagnesemia), and medications. These medications include cyclophosphamide, methotrexate, cytarabine, vincristine, metronidazole, acyclovir, and infliximab (3, 7). In the study by Aydın et al., 4 out of 5 patients presented with hypertension (6). Similarly, our patient had elevated blood pressure values upon presentation.
In PRES, brain CT can be normal. In fact, in one study, only one patient had a hypodense area on CT, while the others were considered normal (6). In our patient, brain CT was reported as normal. MRI typically reveals hyperintensity characterized by vasogenic edema in the bilateral parieto-occipital regions (3, 8). However, evaluation could not be performed in our patient due to the inability to obtain cranial MRI in the emergency department.
In most studies, a sudden increase in blood pressure is suggested to be the cause of PRES. This increased blood pressure leads to vasospasm, resulting in cytotoxic edema. Another view regarding the etiology is the development of dilation in cerebral arterioles due to impaired cerebral autoregulation. In current literature, the hyperperfusion theory is widely accepted as the explanation for the pathophysiology of PRES (3, 9).
While sudden hypertension remains a primary factor in the pathogenesis, there have been reports of PRES occurring without severe hypertension (1, 10). In our case, the patient had elevated systolic and diastolic blood pressure values upon presentation, and hypertension was listed as a comorbidity in the medical history.
Studies and pathological evaluations have revealed findings such as fibrinoid necrosis in arteriolar walls, interstitial edema, and foci of petechial microhemorrhages, but infarction has not been observed. In cases of PRES associated with hypertension, vasospasm in arteries supplying the posterior circulation has been identified during hypertensive crises (11, 12).
While sudden hypertension remains a primary factor in the pathogenesis, there have been reports of PRES occurring without severe hypertension (1, 10). In our case, the patient had elevated systolic and diastolic blood pressure values upon presentation, and hypertension was listed as a comorbidity in the medical history.
Studies and pathological evaluations have revealed findings such as fibrinoid necrosis in arteriolar walls, interstitial edema, and foci of petechial microhemorrhages, but infarction has not been observed. In cases of PRES associated with hypertension, vasospasm in arteries supplying the posterior circulation has been identified during hypertensive crises (11, 12).
Conclusion
PRES poses diagnostic challenges, as it can occur without severe hypertension and may present with nonspecific symptoms. MRI typically reveals characteristic findings in the parieto-occipital regions. Early diagnosis and treatment are crucial for reversibility, emphasizing the importance of addressing underlying causes.
References
1. Hinchey J, Chaves C, Appignani B, Breen J, Pao L, Wang A, et al. A Reversibl Posterior Leukoencephalopathy Syndrome. N Engl Med 1996;334:494- 500.
2. Incecik F, Hergüner MO, Altunbasak S, Erbey F, Leblebisatan G. Evaluation of nine children with reversible posterior encephalopathy syndrome. Neurology India 2009;57:475-8.
3. Floeter AE, Patel A, Tran M, Chamberlain MC, Hendrie PC, Gopal AK, et al. “Posterior Reversible Encephalopathy Syndrome Associated With Doseadjusted EPOCH (Etoposide, Prednisone, Vincristine, Cyclophosphamide, Doxorubicin) Chemotherapy.” Clin Lymphoma Myeloma Leuk 2017;17:225- 30.
4. Teksam M, Casey SO, Michel E, Truwit CL. Posterior Reversibl Ensefalopati Sendromu: Patofizyoloji ve İleri MRG teknikleri ile korelasyon. Tanısal ve Girişimsel Radyoloji 2001;7:464-72.
5. Legriel S, Pico F, Azoulay E. Understanding Posterior Reversible Encephalopathy Syndrome. Annual Update in Intensive Care and Emergency Medicine 2011;1:631-53.
6. AYDIN İ, ALTUN Y, POYRAZ MK, ALGIN A, KAFADAR H. Posterior Reversible Ensefalopati Sendromu (PRES) Olgularının Retrospektif Olarak Analizi: Acil Servis Başvuruları. ADYÜ Sağlık Bilimleri Derg. Nisan 2016;2(1):197-207.
7. Zamvar V, Sugarman ID, Tawfik RF, Macmullen-Price J, Puntis JW. Posterior Reversible Encephalopathy Syndrome Following Infliximab Infusion. J Pediatr Gastroenterol Nutr 2009;48:102-5.
8. Sharma A, Whitesell RT, Moran KJ. Imaging pattern of intracranial hemorrhage in the setting of posterior reversible encephalopathy syndrome. Neuroradiology 2010;52:855-63.
9. Ergün T, Lakadamyalı H, Yılmaz A. Recurrent posterior reversible encephalopathy syndrome in a hypertensive patient with end-stage renal disease. Diagn Interv Radiol 2008;14:182- 5.
10. Garg RK. Posterior leukoencephalopathy syndrome. Postgrad Med J 2001;77:24-8
11. Yenigün Çoşkun E, Koç E, Akoğlu H, Pişkinpaşa SV, Öztürk R, Özkayar N, ve ark. Son dönem böbrek yetmezlikli hastada posterior reversibl ensefalopati sendromu (PRES): Nefrologlar olarak ne kadar farkındayız? Turk Neph Dial Transpl 2012;21:178-80.
12. Kaya D, Dinçer A, Us Ö. Reversibl posterior lökoensefalopatisendromu / Reversible Posterior Leucoencephalopathy (PRES) Syndrome. Turk Neurol J 2006;12:220-5.
13. Akgün N, Karaman M, Başyiğit S, Yılmaz H, Özcan AA. Posterior reversibl ensefalopati: 2 olgu sunumu. IMJ 2010;11:82-5
14. Bartynski WS. Posterior reversible encephalopathy syndrome, part 1: fundamental imaging and clinical features. AJNR Am J Neuroradiol 2008;29:1036-42.
15. Vaughan CJ, Delanty N. Hypertensive emergencies. Lancet 2000;356:411-7
16. Sibai BM, Stella CL. Diagnosis an management of atypical preeclampsiaeclampsia. Am J Obstet Gyneol 2009;200:481.
17. Tek, Ş. Ç., Uyar, A. Ş., Çakıcı, Z., İnal, M. T., Memiş, D., Tekataç, A., … & Varol, F. (2019). Posterior Reversible Ensefalopati Sendromu: İki Olgunun Sunumu. Türk Yogun Bakim Dergisi, 17(1), 44-48.
