posterior reversible encephalopathy syndrome ( pres ) is a rare , poorly understood disease with a number of associated factors but no clearly delineated etiology .
of described cases , it is estimated that greater than one third of patients will never regain baseline neurologic function .
the physiologic causes for pres are difficult to ascertain in light of the myriad of associated diagnoses and presentations . while pres is generally associated with hypertension , more recently it has been linked to drug toxicities ( e.g. chemotherapy agents , immunosuppressive medications ) . however , even with these other instigating factors , hypertension likely still plays a significant role .
pres appears to be more common in women though the prevalence data may be skewed by the association of this diagnosis with pregnancy .
presentation is highly variable but generally features a depressed level of consciousness among other sequelae of intracranial hypertension .
other , less common , presentations range from new - onset seizure activity to focal neurologic deficits .
the hallmark vasogenic edema on imaging is similar to that found with eclampsia but is unambiguous enough to be diagnostic [ 57 ] .
significant variation exists , however , such that some authors have observed that this imaging pattern does not necessarily need to be strictly  posterior and in some cases it is not 
we present a patient who developed pres in the immediate post - operative period following complications of a hemicolectomy .
anesthesia and sepsis initially confounded her diagnosis but do not appear to have delayed her treatment and eventual complete neurological recovery .
the patient is a 67-year - old woman who presented with a near - obstructing adenocarcinoma of the right colon .
she underwent an uneventful laparoscopic - assisted extended right hemicolectomy and was discharged in stable condition on post - operative day 5 .
she presented to our emergency department ( ed ) on post - operative day 10 complaining of diffuse abdominal pain , hematemesis and subjective fevers .
computerized tomography ( ct ) of the abdomen demonstrated a significant amount of free intraperitoneal fluid and associated pneumoperitoneum ; she was started on broad spectrum antibiotics and taken to the operating room for an exploratory laparotomy . upon entry into the abdomen , she was found to have a significant volume of succus and a small anastomotic leak .
the patient 's vital signs were stable and remarkable only for a low grade tachycardia throughout the procedure .
however , due to the patient 's persistent obtundation following extubation , she was brought to the intensive care unit ( icu ) .
while her oxygen saturation remained above 95% on supplemental oxygen with both oropharyngeal and nasopharyngeal airways in place , she failed to regain consciousness . when she was noted to be apneic ,
the patient was given naloxone , glycopyrrolate and neostigmine to counteract the opioid and paralytic agents received during her procedure without any clinical improvement in her neurologic status .
while bedside blood glucose testing was within normal limits , an arterial blood gas demonstrated a profound respiratory acidosis with a ph of 7.03 , a pco2 of 107 and a pao2 of 375 .
she was re - intubated for hypercapnic respiratory failure and all sedating medications were held .
this included hypertonic saline , head of bed elevation to 30 degrees , maintenance of normotension and normoglycemia .
she was also started on levetiracetam as seizure prophylaxis . a magnetic resonance imaging ( mri )
non - contrast head ct showing hydrocephalus with tonsillar herniation and vasogenic edema of the parietal and occipital lobes . 

vasogenic edema involving the bilateral cerebral hemispheres , with relative sparing of the frontal lobes suggestive of pres .
pneumocephalus is present secondary to interval placement of an external ventricular drain ( seen in the right lateral ventricle ) .
non - contrast head ct showing hydrocephalus with tonsillar herniation and vasogenic edema of the parietal and occipital lobes .
vasogenic edema involving the bilateral cerebral hemispheres , with relative sparing of the frontal lobes suggestive of pres .
pneumocephalus is present secondary to interval placement of an external ventricular drain ( seen in the right lateral ventricle ) . with the initiation of treatment described above
, the patient slowly began to recover neurologic function . by post - operative day 33
five months later , she underwent a successful ileostomy reversal and was back to her pre - operative quality of life .
she experienced complete resolution of her neurological symptoms and normalization of her neuroimaging ( fig .
3 ) . 
 figure 3:mri brain 3 months post - diagnosis , axial t2 sequence .
pres was identified as a clinical entity in 1996 by hinchey et al . in their seminal paper , they described patients with renal insufficiency and hypertension that had extensive bilateral white matter changes within their cerebrum , brainstem , and cerebellum . of note ,
seven of the patients they described were on immunosuppressant therapy and were treated in part by decreased or stopped immunosuppression .
prior to hinchey 's formal codification of the diagnosis , this specific set of clinical findings had been attributed to eclampsia given the relative predominance of these findings in pregnant patients with associated hypertension , neurologic sequelae and characteristic vasogenic edema .
it is hypothesized that pres is a direct complication of endothelial injury related to a loss of cerebral autoregulation in the setting of poorly controlled hypertension .
recovery generally occurs within 56 days with supportive care including maintenance of normotension , treatment of sepsis and the cessation of any offending medications . while pres has been associated with sepsis , colorectal cancer and a history of chemotherapy administration ; fulminant presentation in the immediate post - operative period in the setting of normotension has not been described .
while subtle manifestations were seen in two of the four total perioperative cases identified , these patients exhibited mild to moderate new onset hypertension in the immediate post - operative period . in the case
we describe , the patient was obtunded from the immediate postoperative period until diagnosis and subsequent management aimed at reducing intracranial hypertension .
we theorize that the systemic vasodilation and capillary leak associated with this patient 's abdominal sepsis was exacerbated by the induction of anesthesia and precipitated pres . despite her resultant vasogenic edema and intracranial hypertension progressing to tonsillar herniation , timely surgical intervention and optimal medical management facilitated a complete neurologic recovery .
the views expressed in this manuscript are those of the authors and do not reflect the official policy or position of the department of the army , department of defense , or the us government .
 posterior reversible encephalopathy syndrome ( pres ) is an unusual disease of unknown incidence and cause . 
 there are a wide range of associated , predisposing medical causes to include pregnancy , renal failure , immunosuppressive medication administration and hypertension . 
 the diagnosis is made following the radiographic identification of characteristic vasogenic edema in the setting of neurologic impairment . 
 a significant portion of patients will have long - term , if not permanent , sequelae of the disease . 
 we present a patient who developed pres following a hemicolectomy that was complicated by an anastomotic leak . 
 she went on to a complete recovery following surgical treatment of the leak and supportive care . 
INTRODUCTION
CASE REPORT
DISCUSSION
DISCLOSURE STATEMENT
CONFLICT OF INTEREST STATEMENT