Case Report
Posterior Reversible Encephalopathy Syndrome after Surgical Resection of a Giant Vestibular Schwannoma: Case Report and Literature Review Christina Sayama1
William T. Couldwell1
1 Department of Neurological Surgery, Clinical Neurosciences Center,
University of Utah, Salt Lake City, Utah, United States J Neurol Surg A
Abstract
Keywords
► ► ► ►
acoustic neuroma hypertension posterior fossa posterior reversible encephalopathy syndrome ► vestibular schwannoma
Background Posterior reversible encephalopathy syndrome (PRES) is a constellation of neurologic symptoms—seizures, headaches, altered mental status, and visual changes—associated with characteristic brain magnetic resonance imaging findings seen on T2 and fluid-attenuated inversion recovery sequences. Classically, this condition is caused by hypertension, but several other risk factors have been described. The development of PRES after surgical resection of posterior fossa tumors has mostly been linked to the pediatric neurosurgical practice. Case Report We report the first case of PRES after resection of a giant vestibular schwannoma in an adult patient. This 57-year-old female patient underwent a retrosigmoid approach for total resection of her left-sided giant tumor. On the second postoperative day, she developed the classic clinical and radiologic characteristics of PRES. She was treated aggressively with antihypertensive and anticonvulsant medications and showed complete recovery without sequelae. Conclusion PRES is a potential yet rare complication of surgeries to posterior fossa tumors that are compressing the brainstem. Rapid diagnosis and aggressive management are essential for achieving the best outcome.
Introduction Posterior reversible encephalopathy syndrome (PRES) was first described by Hinchey et al1 in 1996. This unique clinical and radiographic diagnosis describes a constellation of symptoms including headache, seizures, altered mental status, vomiting, and visual changes in association with distinctive radiologic changes seen on T2 and fluid-attenuated inversion recovery (FLAIR) sequences of brain magnetic resonance imaging (MRI).1 MRI findings demonstrate bilateral symmetrical vasogenic brain edema, most commonly affecting the parieto-occipital areas.2 Classically, this condition was well described in association with hypertension and eclampsia,
received September 16, 2013 accepted after revision February 25, 2015
Address for correspondence William T. Couldwell, MD, PhD, Department of Neurological Surgery, University of Utah Medical Center, 30 North 1900 East, Salt Lake City, UT 84132-2303, United States (e-mail: [email protected]).
although other conditions described in literature that predispose to PRES include sepsis, some autoimmune diseases, posttransplantation/immunosuppression, hypercalcemia, and hypomagnesemia.2,3 The outcome to PRES is generally benign, and aggressive management with antihypertensive and antiepileptic medications usually results in complete resolution of this condition without any deficits.3 PRES after surgical resection of a posterior fossa tumor has been described previously in five patients. Two patients had fourth ventricular ependymomas, the third had a cerebellar juvenile pilocytic astrocytoma, the fourth was a patient with a fourth ventricular tumor (pathology not mentioned by authors), and the fifth had two infratentorial
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DOI http://dx.doi.org/ 10.1055/s-0035-1554807. ISSN 2193-6315.
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Mohammad Sorour1
Sorour et al.
hemangiopericytomas neighboring the confluence of sinuses. The first four were pediatric male patients (ages between 4 and 19 years).4–7 The fifth was a 63-year-old male patient. To the best of our knowledge, we present the first case of PRES that occurred after resection of a vestibular schwannoma in an adult female patient. We believe that PRES developed as a consequence of severe postoperative hypertension. We describe the pathophysiology that led to this outcome.
Clinical Presentation History and Presentation A 57-year-old woman presented to our hospital with worsening balance, nausea, vomiting, anxiety, and several falls. She reported a 2-year history of complete hearing loss in her left ear, diminished sensation on the left side of her face, difficulty with leftward gaze, and occasional occipital headaches. Computed tomography (CT) scans and MRI of her brain demonstrated marked ventriculomegaly and a large left cerebellopontine angle tumor (►Fig. 1). The imaging characteristics were consistent with a vestibular schwannoma. The patient was otherwise healthy except for a history of hypothyroidism secondary to thyroiditis, for which she was on thyroid hormone replacement medication, and a history of
mild hypertension, for which she was not on any medication. Her systolic blood pressure the day of admission ranged from 120 to 160 mm Hg. Her neurologic examination was notable for left-sided hearing loss, decreased left facial sensation, left cranial nerve VI weakness, and gait instability with a positive Romberg sign.
Operation The patient underwent a retrosigmoid approach for resection of this large vestibular schwannoma. Neuromonitoring was used that included brainstem auditory evoked responses, facial nerve monitoring, somatosensory evoked potentials, and motor evoked potentials. A retrosigmoid craniectomy was performed by the neurosurgery team followed by drilling of the internal auditory canal (IAC). The facial nerve and cranial nerves V, VI, VIII, IX, and X were identified. The tumor was removed using the Sonopet (Stryker, Kalamazoo, Michigan, United States) to debulk internally first and then resect the capsule afterward. Muscle and BioGlue (CryoLife, Kennesaw, Georgia, United States) were placed in the IAC. The dura was closed with Durepair (Medtronic, Goleta, California, United States), and a lumbar drain was placed. Intraoperatively, the patient had no severe elevations in blood pressure, and systolic blood pressures ranged from 80 to 150 mm Hg.
Fig. 1 Computed tomography scan of the head without contrast showing (A) an ill-defined hyperdense left cerebellopontine angle mass and (B) ventriculomegaly. (C) Axial and (D) coronal T1-weighted and (E) axial T2-weighted magnetic resonance imaging of the brain demonstrated a 3.6 4.4 2.9-cm enhancing left cerebellopontine mass. Journal of Neurological Surgery—Part A
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Posterior Reversible Encephalopathy Syndrome
Posterior Reversible Encephalopathy Syndrome
Sorour et al.
Postoperatively, the patient was found to have a HouseBrackmann (HB) grade IV facial palsy in addition to her preoperative deficits. Lumbar drainage was kept at 5 to 10 mL/hour. She required multiple doses of intravenous hydralazine and labetalol on postoperative day 0 to maintain her systolic blood pressure < 150 mm Hg, and within 6 hours of surgery, she required a nicardipine drip. On postoperative day 1, a head CT showed expected postoperative changes (►Fig. 2). When we attempted to wean her from the nicardipine drip, she had several systolic blood pressure spikes > 180 mm Hg that required us to increase the rate of the drip. On the evening of postoperative day 2, the patient had two generalized tonic-clonic seizures within a 20-minute period and was given a loading dose of levetiracetam and 1 mg lorazepam. A head CT revealed decreased attenuation with areas of loss of gray-white differentiation in both occipital lobes and the high left parietal lobe, possibly representing ischemia, PRES, or postictal changes (►Fig. 3). Postictally, she was also noted to have new left-sided weakness (3–4/5 throughout) with a prominent left pronator drift. The following morning, an electroencephalogram showed excessive background slow waves without any lateralizing features. A brain MRI with and without contrast enhancement demonstrated bilateral symmetrical areas of vasogenic edema on T2 and FLAIR imaging affecting predominantly the parieto-occipital lobes (►Fig. 4). This was most characteristic of PRES, so her systolic blood pressure goal was tightened to < 140 mm Hg, and we initiated propranolol to help with weaning of the nicardipine drip. Over the following days, we also initiated captopril and were able to wean her from the nicardipine drip and propranolol. Thyroid studies were consistent with hypothyroidism. Her seizures were thought to be related to PRES, and she had no other seizures while in the hospital.
Fig. 2 Noncontrast computed tomography of the head on postoperative day 1 showing expected postoperative changes in the resection cavity.
Fig. 3 Noncontrast computed tomography of the head on postoperative days 1 (A) and 2 (B) demonstrating the development of decreased attenuation with areas of loss of gray-white differentiation in both occipital lobes and the high left parietal lobe.
Fig. 4 Brain magnetic resonance imaging demonstrating the characteristic finding of bilateral posterior hyperintensity on (A) T2 and (B) fluid-attenuated inversion recovery imaging, consistent with posterior reversible encephalopathy syndrome. Diffusion-weighted imaging (not shown) demonstrated no abnormalities. Journal of Neurological Surgery—Part A
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Postoperative Course
Posterior Reversible Encephalopathy Syndrome
Sorour et al. modified to the more recent and accepted PRES, which encompasses PRLS. The condition was originally described in conjunction with hypertension or eclampsia; however, PRES was also described in many patients without hypertension, such as those who receive immunosuppressive therapy after organ transplantation (especially with cyclosporin) and those with renal disease, autoimmune diseases, sepsis, hypomagnesemia, and hypercalcemia.1,2
Fig. 5 Noncontrast head computed tomography 1 month after surgery demonstrating resolution of previous bilateral occipital vasogenic edema.
The patient’s strength continued to improve so that upon discharge for rehabilitation on postoperative day 13, she only had residual 4/5 weakness in her left triceps muscle and had a left HB grade III/VI. She was taking 30 mg lisinopril daily (instead of captopril) at discharge. Her systolic blood pressure now ranged from 100 to 140 mm Hg. CT imaging of her head 1 month later revealed complete resolution of the vasogenic edema in her bilateral occipital lobes (►Fig. 5). The patient was found to have normal blood pressure without the use of any antihypertensive medications at her 1- and 17-month follow-up appointments. She had complete return of facial nerve function.
Discussion The term posterior reversible leukoencephalopathy syndrome (PRLS) was initially used to describe a syndrome of neurologic manifestations in association with distinctive brain MRI findings.1,2 Patients in the initial report had symptoms that included seizures, headache, altered mental status, vomiting, and blurring of vision.1 Seizures are the most common presenting symptom,8 although less commonly focal neurologic signs like motor or sensory deficits can be seen.2 The diagnosis is confirmed with the appearance on MRI that characteristically involves bilateral and symmetrical increased signal intensity on T2 and FLAIR MRI sequences. This intensity represents vasogenic edema that most commonly affects the parieto-occipital lobes; however, increased signal intensity can affect other regions like frontal lobes, cerebellum, and deep gray matter areas and can be unilateral or asymmetric.9 For this reason, the original term PRLS was Journal of Neurological Surgery—Part A
Several hypotheses have been proposed regarding the pathophysiology behind PRES, but two contrasting theories are commonly reiterated.10 The original theory suggested that brain edema is a consequence of a cerebral vasoconstrictive autoregulatory response to systemic hypertension that leads to global cerebral ischemia.10 The more recent theory suggests that severe hypertension exceeds the cerebral autoregulatory limits, leading to global cerebral vasodilatation, increased hydrostatic pressure inside the cerebral blood vessels, and subsequent vasogenic edema.10,11 The exact mechanism is still not well understood. The presence of hypertension in 50 to 70% of patients who develop PRES and the significant clinical improvement of these patients after treatment with antihypertensive medications strongly support the new theory.3,12 However, in the remaining patients who develop PRES, normal blood pressures have been documented, and PRES was attributed to other risk factors.10,13 The predilection of PRES for the posterior circulation is thought to occur because the anterior circulation (internal carotid artery) has more sympathetic innervation and thus has tighter autoregulatory response to significant increases in blood pressure.4 Interestingly, most hypertensive patients who develop PRES do not have mean arterial pressures that exceed the limit of failed autoregulation.1,14 It has also been noted that the degree of vasogenic edema does not correlate with the severity of hypertension; some reports document more brain edema in patients with mild hypertension than in those with severe hypertension.14,15 These observations have yet to be explained by the newer theory. In most conditions that cause PRES in the absence of hypertension, it is thought that a complex process related to a systemic inflammatory response involving activation of T cell and certain inflammatory cytokines leads to systemic vasoconstriction and hypoperfusion.10
Correlation between Posterior Fossa Tumors and Arterial Hypertension Arterial hypertension induced by posterior fossa tumor has been described previously in the literature,16 and several authors have shown normalization of blood pressure after surgical excision of these tumors.17 Several theories have been suggested to explain this phenomenon. In some patients, tumor compression of the rostral ventrolateral medulla (RVLM), which is believed to be the pressor center, leads to overstimulation of the sympathetic nervous system and subsequent high blood pressure.16,18 Studies have suggested that the RVLM exhibits a left-sided dominance in blood
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Mechanism of PRES
pressure regulation.16,19 Another theory stems from the fact that some posterior fossa tumors were found to express certain neuropeptides that cause systemic hypertension.20 A simpler theory is that tumors causing obstructive hydrocephalus lead to increased intracranial pressure, and the subsequent Cushing reflex is responsible for the hypertension.16 In our case, we believe that compression of the tumor on the RVLM was responsible for the preoperative hypertension. The patient’s tumor was on the left side, which corresponds to those in previous reports. Normalization of blood pressure by the patient’s 1-month and 17-month follow-up visits corroborates this hypothesis. Hypertension has never previously been described as a symptom of giant vestibular schwannomas, except in patients with neurofibromatosis type 2, in whom hypertension has been the result of a different mechanism.21
PRES after Posterior Fossa Tumor Surgery PRES after surgery for a posterior fossa tumor was previously described in five different settings (►Table 1).4–7 Most (four of five) were male patients belonging to the pediatric age group (ages 4–19 years), which may be attributed to the higher incidence of posterior fossa tumors in pediatrics. The first case was reported by Moriarity et al4 in 2001. The authors described PRES occurring after resection of a large fourth ventricular ependymoma. This patient developed significant intraoperative cerebellar swelling in addition to alternating hyper- and hypotensive episodes throughout the surgery for inexplicable reasons. In the second case, Patel et al5 described a 6-year-old boy with cerebellar juvenile pilocytic astrocytoma. The authors reported that intraoperative hypertension
Sorour et al.
occurred as a result of applying forceful traction over the brainstem. In the third case, Gephart et al6 described the case of a young boy with recurrent ependymoma with brainstem involvement. The patient developed perioperative PRES after repeat posterior fossa craniotomy for resection of a recurrent tumor. The authors believed that brainstem dysregulation caused by the tumor invasion was responsible for the perioperative hypertension and PRES. In the same article, the authors described another case of PRES in a 7-year-old boy with recurrent posterior fossa ependymoma who underwent shunt placement before his scheduled resection. Five days after the placement of the shunt, the boy developed hypertension and subsequent PRES. This also contributed to brainstem dysregulation caused by tumor invasion.6 This case is excluded from our discussion because the patient developed PRES prior to surgical resection of his tumor. More recently, Avecillas-Chasín et al7 described the fourth case of PRES, which occurred in a 19-year-old male patient with a fourth ventricular tumor that extended to the left foramen of Luschka (pathology not mentioned by authors). This patient developed delayed-onset hypertension 8 days after suboccipital craniotomy for uneventful resection of his tumor. The authors attributed the development of hypertension to surgical manipulation to the left RVLM. All four of these cases showed the classical clinical and radiologic manifestations of PRES. In the final case, Kuhnt et al reported a PRES case that occurred following surgery of a posterior fossa tumor in an adult patient. This 63-year-old man had recurrent supra/infratentorial hemangiopericytomas, for which he had multiple surgical resections as well as radiosurgery. Shortly after an uneventful surgical resection of two infratentorial
Table 1 Reported cases of posterior reversible encephalopathy syndrome after resection of posterior fossa tumors Study
Age, y/sex
Initial diagnosis
Mechanism of PRES
19/M
Fourth ventricular ependymoma
Intraoperative hypertension due to cerebellar swelling?
Patel et al5
6/M
Cerebellar juvenile pilocytic astrocytoma
Postoperative hypertension due to brainstem manipulation during surgical resection
Gephart et al6
7/M
WHO grade II ependymoma of the posterior fossa with brainstem involvement
Intra- and perioperative hypertension due to brainstem dysregulation by tumor invasion
Avecillas-Chasín et al7
19/M
Fourth ventricular tumor (pathology not mentioned)
Delayed-onset hypertension possibly due to surgical manipulation of the RVLM
Kuhnt et al22
63/M
Two infratentorial hemangiopericytomas
Severe blood pressure fluctuations perioperatively and preoperative injury to the blood–brain barrier caused by previous surgeries and radiosurgery
Current case
57/F
Giant acoustic schwannoma
Postoperative hypertension possibly due to alteration in brainstem compression and irritation of the RVLM during resection
Moriarity et al
4
Abbreviations: F, female; M, male; PRES, posterior reversible encephalopathy syndrome; RVLM, rostral ventrolateral medulla; WHO, World Health Organization.
Journal of Neurological Surgery—Part A
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Posterior Reversible Encephalopathy Syndrome
Sorour et al.
hemangiopericytomas, the patient developed altered mental status, along with diplopia and internuclear ophthalmoplegia. MRI scanning of the brain showed brainstem involvement as well as the classical cortical features suggestive of PRES. The authors attributed its occurrence to the few episodes of severe blood pressure fluctuations, which were recorded perioperatively, as well as the preoperative existence of vasogenic edema in that area of the brain that indicated preexisting injury of the blood–brain barrier after recurrent surgeries and radiation.22 All five patients experienced complete resolution of their symptoms after aggressive management with antihypertensive and anticonvulsant medications. We believe that our case is unique because it is the first reported case of PRES after posterior fossa surgery in an adult female patient, and it is the first reported case to take place after resection of a vestibular schwannoma. The higher incidence of posterior fossa tumors in pediatrics patients and consequently the more surgical resections performed on these patients could explain why almost all of the previously reported cases were in the pediatric age group. It is not entirely clear why our patient developed severe hypertensive episodes after surgery, but we believe that the alteration in brainstem compression after resection and further irritation of the RVLM might be the reason.
Conclusion We report a case of a 57-year-old woman with a giant vestibular schwannoma compressing the brainstem who developed PRES after undergoing a retrosigmoid approach to completely resect the tumor. There was no inappropriate brainstem manipulation or severe fluctuations in blood pressure during surgery, making a precise determination of cause difficult. We postulate that the hypertension and resultant PRES were related to irritation of the RVLM after resection of this large tumor and possibly to dynamic changes in the brainstem itself. Normalization of our patient’s blood pressure at follow-up suggests that hypertension could be a possible presenting symptom in giant vestibular schwannomas compressing the RVLM, especially on the left side.
Acknowledgments We thank Kristin Kraus, MSc, for editorial assistance with this article.
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References 1 Hinchey J, Chaves C, Appignani B, et al. A reversible posterior
leukoencephalopathy syndrome. N Engl J Med 1996;334(8): 494–500 2 Staykov D, Schwab S. Posterior reversible encephalopathy syndrome. J Intensive Care Med 2012;27(1):11–24 3 Servillo G, Bifulco F, De Robertis E, et al. Posterior reversible encephalopathy syndrome in intensive care medicine. Intensive Care Med 2007;33(2):230–236 4 Moriarity JL Jr, Lim M, Storm PB, Beauchamp NJ Jr, Olivi A. Reversible posterior leukoencephalopathy occurring during resection of a posterior fossa tumor: case report and review of the
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21
22
literature. Neurosurgery 2001;49(5):1237–1239; discussion 1239–1240 Patel AJ, Fox BD, Fulkerson DH, et al. Posterior reversible encephalopathy syndrome during posterior fossa tumor resection in a child. J Neurosurg Pediatr 2010;6(4):377–380 Gephart MG, Taft BP, Giese AK, Guzman R, Edwards MS. Perioperative posterior reversible encephalopathy syndrome in 2 pediatric neurosurgery patients with brainstem ependymoma. J Neurosurg Pediatr 2011;7(3):235–237 Avecillas-Chasín JM, Gómez G, Jorquera M, Alvarado LR, Barcia JA. Delayed posterior reversible encephalopathy syndrome (PRES) after posterior fossa surgery. Acta Neurochir (Wien) 2013; 155(6):1045–1047 Casey SO, Sampaio RC, Michel E, Truwit CL. Posterior reversible encephalopathy syndrome: utility of fluid-attenuated inversion recovery MR imaging in the detection of cortical and subcortical lesions. AJNR Am J Neuroradiol 2000;21(7):1199–1206 McKinney AM, Short J, Truwit CL, et al. Posterior reversible encephalopathy syndrome: incidence of atypical regions of involvement and imaging findings. AJR Am J Roentgenol 2007; 189(4):904–912 Bartynski WS. Posterior reversible encephalopathy syndrome, part 2: controversies surrounding pathophysiology of vasogenic edema. AJNR Am J Neuroradiol 2008;29(6):1043–1049 Kevil CG, Payne DK, Mire E, Alexander JS. Vascular permeability factor/vascular endothelial cell growth factor-mediated permeability occurs through disorganization of endothelial junctional proteins. J Biol Chem 1998;273(24):15099–15103 Striano P, Striano S, Tortora F, et al. Clinical spectrum and critical care management of posterior reversible encephalopathy syndrome (PRES). Med Sci Monit 2005;11(11): CR549–CR553 Bartynski WS. Posterior reversible encephalopathy syndrome, part 1: fundamental imaging and clinical features. AJNR Am J Neuroradiol 2008;29(6):1036–1042 Bartynski WS, Boardman JF. Catheter angiography, MR angiography, and MR perfusion in posterior reversible encephalopathy syndrome. AJNR Am J Neuroradiol 2008;29(3):447–455 Bartynski WS, Boardman JF, Zeigler ZR, Shadduck RK, Lister J. Posterior reversible encephalopathy syndrome in infection, sepsis, and shock. AJNR Am J Neuroradiol 2006;27(10):2179–2190 Kan P, Couldwell WT. Posterior fossa brain tumors and arterial hypertension. Neurosurg Rev 2006;29(4):265–269; discussion 269 Geiger H, Naraghi R, Schobel HP, Frank H, Sterzel RB, Fahlbusch R. Decrease of blood pressure by ventrolateral medullary decompression in essential hypertension. Lancet 1998;352(9126): 446–449 Nicholas JS, D’Agostino SJ, Patel SJ. Arterial compression of the retro-olivary sulcus of the ventrolateral medulla in essential hypertension and diabetes. Hypertension 2005;46(4): 982–985 Naraghi R, Schuster H, Toka HR, et al. Neurovascular compression at the ventrolateral medulla in autosomal dominant hypertension and brachydactyly. Stroke 1997;28(9):1749–1754 Hedderwick SA, Bishop AE, Strong AJ, Ritter JM. Surgical cure of hypertension in a patient with brainstem capillary haemangioblastoma containing neuropeptide Y. Postgrad Med J 1995; 71(836):371–372 Hornigold RE, Golding JF, Ferner RE, Ferner RE. Neurofibromatosis 2: a novel risk factor for hypertension? Am J Med Genet A 2011; 155A(7):1721–1722 Kuhnt D, Becker A, Benes L, Nimsky C. Reversible cortical blindness and internuclear ophthalmoplegia after neurosurgical operation: case report and review of the literature. J Neurol Surg A Cent Eur Neurosurg 2013;74(Suppl 1):e128–e132
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Posterior Reversible Encephalopathy Syndrome
Posterior Reversible Encephalopathy Syndrome after Surgical Resection of a Giant Vestibular Schwannoma: Case Report and Literature Review Christina Sayama1
William T. Couldwell1
1 Department of Neurological Surgery, Clinical Neurosciences Center,
University of Utah, Salt Lake City, Utah, United States J Neurol Surg A
Abstract
Keywords
► ► ► ►
acoustic neuroma hypertension posterior fossa posterior reversible encephalopathy syndrome ► vestibular schwannoma
Background Posterior reversible encephalopathy syndrome (PRES) is a constellation of neurologic symptoms—seizures, headaches, altered mental status, and visual changes—associated with characteristic brain magnetic resonance imaging findings seen on T2 and fluid-attenuated inversion recovery sequences. Classically, this condition is caused by hypertension, but several other risk factors have been described. The development of PRES after surgical resection of posterior fossa tumors has mostly been linked to the pediatric neurosurgical practice. Case Report We report the first case of PRES after resection of a giant vestibular schwannoma in an adult patient. This 57-year-old female patient underwent a retrosigmoid approach for total resection of her left-sided giant tumor. On the second postoperative day, she developed the classic clinical and radiologic characteristics of PRES. She was treated aggressively with antihypertensive and anticonvulsant medications and showed complete recovery without sequelae. Conclusion PRES is a potential yet rare complication of surgeries to posterior fossa tumors that are compressing the brainstem. Rapid diagnosis and aggressive management are essential for achieving the best outcome.
Introduction Posterior reversible encephalopathy syndrome (PRES) was first described by Hinchey et al1 in 1996. This unique clinical and radiographic diagnosis describes a constellation of symptoms including headache, seizures, altered mental status, vomiting, and visual changes in association with distinctive radiologic changes seen on T2 and fluid-attenuated inversion recovery (FLAIR) sequences of brain magnetic resonance imaging (MRI).1 MRI findings demonstrate bilateral symmetrical vasogenic brain edema, most commonly affecting the parieto-occipital areas.2 Classically, this condition was well described in association with hypertension and eclampsia,
received September 16, 2013 accepted after revision February 25, 2015
Address for correspondence William T. Couldwell, MD, PhD, Department of Neurological Surgery, University of Utah Medical Center, 30 North 1900 East, Salt Lake City, UT 84132-2303, United States (e-mail: [email protected]).
although other conditions described in literature that predispose to PRES include sepsis, some autoimmune diseases, posttransplantation/immunosuppression, hypercalcemia, and hypomagnesemia.2,3 The outcome to PRES is generally benign, and aggressive management with antihypertensive and antiepileptic medications usually results in complete resolution of this condition without any deficits.3 PRES after surgical resection of a posterior fossa tumor has been described previously in five patients. Two patients had fourth ventricular ependymomas, the third had a cerebellar juvenile pilocytic astrocytoma, the fourth was a patient with a fourth ventricular tumor (pathology not mentioned by authors), and the fifth had two infratentorial
© Georg Thieme Verlag KG Stuttgart · New York
DOI http://dx.doi.org/ 10.1055/s-0035-1554807. ISSN 2193-6315.
Downloaded by: Washington University. Copyrighted material.
Mohammad Sorour1
Sorour et al.
hemangiopericytomas neighboring the confluence of sinuses. The first four were pediatric male patients (ages between 4 and 19 years).4–7 The fifth was a 63-year-old male patient. To the best of our knowledge, we present the first case of PRES that occurred after resection of a vestibular schwannoma in an adult female patient. We believe that PRES developed as a consequence of severe postoperative hypertension. We describe the pathophysiology that led to this outcome.
Clinical Presentation History and Presentation A 57-year-old woman presented to our hospital with worsening balance, nausea, vomiting, anxiety, and several falls. She reported a 2-year history of complete hearing loss in her left ear, diminished sensation on the left side of her face, difficulty with leftward gaze, and occasional occipital headaches. Computed tomography (CT) scans and MRI of her brain demonstrated marked ventriculomegaly and a large left cerebellopontine angle tumor (►Fig. 1). The imaging characteristics were consistent with a vestibular schwannoma. The patient was otherwise healthy except for a history of hypothyroidism secondary to thyroiditis, for which she was on thyroid hormone replacement medication, and a history of
mild hypertension, for which she was not on any medication. Her systolic blood pressure the day of admission ranged from 120 to 160 mm Hg. Her neurologic examination was notable for left-sided hearing loss, decreased left facial sensation, left cranial nerve VI weakness, and gait instability with a positive Romberg sign.
Operation The patient underwent a retrosigmoid approach for resection of this large vestibular schwannoma. Neuromonitoring was used that included brainstem auditory evoked responses, facial nerve monitoring, somatosensory evoked potentials, and motor evoked potentials. A retrosigmoid craniectomy was performed by the neurosurgery team followed by drilling of the internal auditory canal (IAC). The facial nerve and cranial nerves V, VI, VIII, IX, and X were identified. The tumor was removed using the Sonopet (Stryker, Kalamazoo, Michigan, United States) to debulk internally first and then resect the capsule afterward. Muscle and BioGlue (CryoLife, Kennesaw, Georgia, United States) were placed in the IAC. The dura was closed with Durepair (Medtronic, Goleta, California, United States), and a lumbar drain was placed. Intraoperatively, the patient had no severe elevations in blood pressure, and systolic blood pressures ranged from 80 to 150 mm Hg.
Fig. 1 Computed tomography scan of the head without contrast showing (A) an ill-defined hyperdense left cerebellopontine angle mass and (B) ventriculomegaly. (C) Axial and (D) coronal T1-weighted and (E) axial T2-weighted magnetic resonance imaging of the brain demonstrated a 3.6 4.4 2.9-cm enhancing left cerebellopontine mass. Journal of Neurological Surgery—Part A
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Posterior Reversible Encephalopathy Syndrome
Posterior Reversible Encephalopathy Syndrome
Sorour et al.
Postoperatively, the patient was found to have a HouseBrackmann (HB) grade IV facial palsy in addition to her preoperative deficits. Lumbar drainage was kept at 5 to 10 mL/hour. She required multiple doses of intravenous hydralazine and labetalol on postoperative day 0 to maintain her systolic blood pressure < 150 mm Hg, and within 6 hours of surgery, she required a nicardipine drip. On postoperative day 1, a head CT showed expected postoperative changes (►Fig. 2). When we attempted to wean her from the nicardipine drip, she had several systolic blood pressure spikes > 180 mm Hg that required us to increase the rate of the drip. On the evening of postoperative day 2, the patient had two generalized tonic-clonic seizures within a 20-minute period and was given a loading dose of levetiracetam and 1 mg lorazepam. A head CT revealed decreased attenuation with areas of loss of gray-white differentiation in both occipital lobes and the high left parietal lobe, possibly representing ischemia, PRES, or postictal changes (►Fig. 3). Postictally, she was also noted to have new left-sided weakness (3–4/5 throughout) with a prominent left pronator drift. The following morning, an electroencephalogram showed excessive background slow waves without any lateralizing features. A brain MRI with and without contrast enhancement demonstrated bilateral symmetrical areas of vasogenic edema on T2 and FLAIR imaging affecting predominantly the parieto-occipital lobes (►Fig. 4). This was most characteristic of PRES, so her systolic blood pressure goal was tightened to < 140 mm Hg, and we initiated propranolol to help with weaning of the nicardipine drip. Over the following days, we also initiated captopril and were able to wean her from the nicardipine drip and propranolol. Thyroid studies were consistent with hypothyroidism. Her seizures were thought to be related to PRES, and she had no other seizures while in the hospital.
Fig. 2 Noncontrast computed tomography of the head on postoperative day 1 showing expected postoperative changes in the resection cavity.
Fig. 3 Noncontrast computed tomography of the head on postoperative days 1 (A) and 2 (B) demonstrating the development of decreased attenuation with areas of loss of gray-white differentiation in both occipital lobes and the high left parietal lobe.
Fig. 4 Brain magnetic resonance imaging demonstrating the characteristic finding of bilateral posterior hyperintensity on (A) T2 and (B) fluid-attenuated inversion recovery imaging, consistent with posterior reversible encephalopathy syndrome. Diffusion-weighted imaging (not shown) demonstrated no abnormalities. Journal of Neurological Surgery—Part A
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Postoperative Course
Posterior Reversible Encephalopathy Syndrome
Sorour et al. modified to the more recent and accepted PRES, which encompasses PRLS. The condition was originally described in conjunction with hypertension or eclampsia; however, PRES was also described in many patients without hypertension, such as those who receive immunosuppressive therapy after organ transplantation (especially with cyclosporin) and those with renal disease, autoimmune diseases, sepsis, hypomagnesemia, and hypercalcemia.1,2
Fig. 5 Noncontrast head computed tomography 1 month after surgery demonstrating resolution of previous bilateral occipital vasogenic edema.
The patient’s strength continued to improve so that upon discharge for rehabilitation on postoperative day 13, she only had residual 4/5 weakness in her left triceps muscle and had a left HB grade III/VI. She was taking 30 mg lisinopril daily (instead of captopril) at discharge. Her systolic blood pressure now ranged from 100 to 140 mm Hg. CT imaging of her head 1 month later revealed complete resolution of the vasogenic edema in her bilateral occipital lobes (►Fig. 5). The patient was found to have normal blood pressure without the use of any antihypertensive medications at her 1- and 17-month follow-up appointments. She had complete return of facial nerve function.
Discussion The term posterior reversible leukoencephalopathy syndrome (PRLS) was initially used to describe a syndrome of neurologic manifestations in association with distinctive brain MRI findings.1,2 Patients in the initial report had symptoms that included seizures, headache, altered mental status, vomiting, and blurring of vision.1 Seizures are the most common presenting symptom,8 although less commonly focal neurologic signs like motor or sensory deficits can be seen.2 The diagnosis is confirmed with the appearance on MRI that characteristically involves bilateral and symmetrical increased signal intensity on T2 and FLAIR MRI sequences. This intensity represents vasogenic edema that most commonly affects the parieto-occipital lobes; however, increased signal intensity can affect other regions like frontal lobes, cerebellum, and deep gray matter areas and can be unilateral or asymmetric.9 For this reason, the original term PRLS was Journal of Neurological Surgery—Part A
Several hypotheses have been proposed regarding the pathophysiology behind PRES, but two contrasting theories are commonly reiterated.10 The original theory suggested that brain edema is a consequence of a cerebral vasoconstrictive autoregulatory response to systemic hypertension that leads to global cerebral ischemia.10 The more recent theory suggests that severe hypertension exceeds the cerebral autoregulatory limits, leading to global cerebral vasodilatation, increased hydrostatic pressure inside the cerebral blood vessels, and subsequent vasogenic edema.10,11 The exact mechanism is still not well understood. The presence of hypertension in 50 to 70% of patients who develop PRES and the significant clinical improvement of these patients after treatment with antihypertensive medications strongly support the new theory.3,12 However, in the remaining patients who develop PRES, normal blood pressures have been documented, and PRES was attributed to other risk factors.10,13 The predilection of PRES for the posterior circulation is thought to occur because the anterior circulation (internal carotid artery) has more sympathetic innervation and thus has tighter autoregulatory response to significant increases in blood pressure.4 Interestingly, most hypertensive patients who develop PRES do not have mean arterial pressures that exceed the limit of failed autoregulation.1,14 It has also been noted that the degree of vasogenic edema does not correlate with the severity of hypertension; some reports document more brain edema in patients with mild hypertension than in those with severe hypertension.14,15 These observations have yet to be explained by the newer theory. In most conditions that cause PRES in the absence of hypertension, it is thought that a complex process related to a systemic inflammatory response involving activation of T cell and certain inflammatory cytokines leads to systemic vasoconstriction and hypoperfusion.10
Correlation between Posterior Fossa Tumors and Arterial Hypertension Arterial hypertension induced by posterior fossa tumor has been described previously in the literature,16 and several authors have shown normalization of blood pressure after surgical excision of these tumors.17 Several theories have been suggested to explain this phenomenon. In some patients, tumor compression of the rostral ventrolateral medulla (RVLM), which is believed to be the pressor center, leads to overstimulation of the sympathetic nervous system and subsequent high blood pressure.16,18 Studies have suggested that the RVLM exhibits a left-sided dominance in blood
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Mechanism of PRES
pressure regulation.16,19 Another theory stems from the fact that some posterior fossa tumors were found to express certain neuropeptides that cause systemic hypertension.20 A simpler theory is that tumors causing obstructive hydrocephalus lead to increased intracranial pressure, and the subsequent Cushing reflex is responsible for the hypertension.16 In our case, we believe that compression of the tumor on the RVLM was responsible for the preoperative hypertension. The patient’s tumor was on the left side, which corresponds to those in previous reports. Normalization of blood pressure by the patient’s 1-month and 17-month follow-up visits corroborates this hypothesis. Hypertension has never previously been described as a symptom of giant vestibular schwannomas, except in patients with neurofibromatosis type 2, in whom hypertension has been the result of a different mechanism.21
PRES after Posterior Fossa Tumor Surgery PRES after surgery for a posterior fossa tumor was previously described in five different settings (►Table 1).4–7 Most (four of five) were male patients belonging to the pediatric age group (ages 4–19 years), which may be attributed to the higher incidence of posterior fossa tumors in pediatrics. The first case was reported by Moriarity et al4 in 2001. The authors described PRES occurring after resection of a large fourth ventricular ependymoma. This patient developed significant intraoperative cerebellar swelling in addition to alternating hyper- and hypotensive episodes throughout the surgery for inexplicable reasons. In the second case, Patel et al5 described a 6-year-old boy with cerebellar juvenile pilocytic astrocytoma. The authors reported that intraoperative hypertension
Sorour et al.
occurred as a result of applying forceful traction over the brainstem. In the third case, Gephart et al6 described the case of a young boy with recurrent ependymoma with brainstem involvement. The patient developed perioperative PRES after repeat posterior fossa craniotomy for resection of a recurrent tumor. The authors believed that brainstem dysregulation caused by the tumor invasion was responsible for the perioperative hypertension and PRES. In the same article, the authors described another case of PRES in a 7-year-old boy with recurrent posterior fossa ependymoma who underwent shunt placement before his scheduled resection. Five days after the placement of the shunt, the boy developed hypertension and subsequent PRES. This also contributed to brainstem dysregulation caused by tumor invasion.6 This case is excluded from our discussion because the patient developed PRES prior to surgical resection of his tumor. More recently, Avecillas-Chasín et al7 described the fourth case of PRES, which occurred in a 19-year-old male patient with a fourth ventricular tumor that extended to the left foramen of Luschka (pathology not mentioned by authors). This patient developed delayed-onset hypertension 8 days after suboccipital craniotomy for uneventful resection of his tumor. The authors attributed the development of hypertension to surgical manipulation to the left RVLM. All four of these cases showed the classical clinical and radiologic manifestations of PRES. In the final case, Kuhnt et al reported a PRES case that occurred following surgery of a posterior fossa tumor in an adult patient. This 63-year-old man had recurrent supra/infratentorial hemangiopericytomas, for which he had multiple surgical resections as well as radiosurgery. Shortly after an uneventful surgical resection of two infratentorial
Table 1 Reported cases of posterior reversible encephalopathy syndrome after resection of posterior fossa tumors Study
Age, y/sex
Initial diagnosis
Mechanism of PRES
19/M
Fourth ventricular ependymoma
Intraoperative hypertension due to cerebellar swelling?
Patel et al5
6/M
Cerebellar juvenile pilocytic astrocytoma
Postoperative hypertension due to brainstem manipulation during surgical resection
Gephart et al6
7/M
WHO grade II ependymoma of the posterior fossa with brainstem involvement
Intra- and perioperative hypertension due to brainstem dysregulation by tumor invasion
Avecillas-Chasín et al7
19/M
Fourth ventricular tumor (pathology not mentioned)
Delayed-onset hypertension possibly due to surgical manipulation of the RVLM
Kuhnt et al22
63/M
Two infratentorial hemangiopericytomas
Severe blood pressure fluctuations perioperatively and preoperative injury to the blood–brain barrier caused by previous surgeries and radiosurgery
Current case
57/F
Giant acoustic schwannoma
Postoperative hypertension possibly due to alteration in brainstem compression and irritation of the RVLM during resection
Moriarity et al
4
Abbreviations: F, female; M, male; PRES, posterior reversible encephalopathy syndrome; RVLM, rostral ventrolateral medulla; WHO, World Health Organization.
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Posterior Reversible Encephalopathy Syndrome
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hemangiopericytomas, the patient developed altered mental status, along with diplopia and internuclear ophthalmoplegia. MRI scanning of the brain showed brainstem involvement as well as the classical cortical features suggestive of PRES. The authors attributed its occurrence to the few episodes of severe blood pressure fluctuations, which were recorded perioperatively, as well as the preoperative existence of vasogenic edema in that area of the brain that indicated preexisting injury of the blood–brain barrier after recurrent surgeries and radiation.22 All five patients experienced complete resolution of their symptoms after aggressive management with antihypertensive and anticonvulsant medications. We believe that our case is unique because it is the first reported case of PRES after posterior fossa surgery in an adult female patient, and it is the first reported case to take place after resection of a vestibular schwannoma. The higher incidence of posterior fossa tumors in pediatrics patients and consequently the more surgical resections performed on these patients could explain why almost all of the previously reported cases were in the pediatric age group. It is not entirely clear why our patient developed severe hypertensive episodes after surgery, but we believe that the alteration in brainstem compression after resection and further irritation of the RVLM might be the reason.
Conclusion We report a case of a 57-year-old woman with a giant vestibular schwannoma compressing the brainstem who developed PRES after undergoing a retrosigmoid approach to completely resect the tumor. There was no inappropriate brainstem manipulation or severe fluctuations in blood pressure during surgery, making a precise determination of cause difficult. We postulate that the hypertension and resultant PRES were related to irritation of the RVLM after resection of this large tumor and possibly to dynamic changes in the brainstem itself. Normalization of our patient’s blood pressure at follow-up suggests that hypertension could be a possible presenting symptom in giant vestibular schwannomas compressing the RVLM, especially on the left side.
Acknowledgments We thank Kristin Kraus, MSc, for editorial assistance with this article.
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