Atypical presentation of posterior reversible encephalopathy syndrome: Two cases.

Posterior reversible encephalopathy syndrome (PRES) is a clinico-neuroradiological entity, first described in 1996. It is commonly associated with systemic hypertension, intake of immunosuppressant drugs, sepsis and eclampsia and preeclampsia. Headache, alteration in consciousness, visual disturbances and seizures are common manifestations of PRES. Signs of pyramidal tract involvement and motor dysfunction are uncommon clinical findings. However, clinical presentation is not diagnostic. On neuroimaging, lesions are characteristically found in parieto occipital region of the brain due to vasogenic edema. We report two cases of PRES with atypical clinical presentation-one which was suggestive of neurocysticercosis and the other in which agitation and opisthotonic posture were predominant features.

Introduction

Posterior reversible encephalopathy syndrome (PRES) also known as reversible posterior leuco-encephalopathy syndrome,[1] is a clinical-neuroradiological entity,[2] first described in 1996 by Hinchey et al.[1] PRES is commonly associated with systemic hypertension, intake of immunosuppressant drugs, nephrotic syndrome, sepsis, systemic lupus erythromatosis, preeclampsia, eclampsia or hemolysis, elevated liver enzyme levels, and low platelet levels syndrome.[1345] Headache is the most common clinical presentation followed by alteration in consciousness which may range from lethargy to somnolence and coma. Visual disturbances ranging from blurred vision to permanent visual field defects are common. Seizures or status epilepticus may be the initial clinical presentation in some of the cases.[6] Signs of pyramidal tract involvement [7] and motor dysfunction [1] are uncommon while brainstem involvement [89] and memory disturbances [10] are rare features of PRES.

We report two cases of PRES, both of which presented with atypical features.

Case Report

Case 1

A 19-year-old primigravida, vaginally delivered at home, presented after 9 days with complaints of abdominal pain and distension for 4 days and breathlessness for 2 days. On examination, her general condition was poor. Patient was dehydrated with pulse rate of 130/min, blood pressure of 80/40 mmHg and respiratory rate of 40/min. Her chest auscultation did not reveal any abnormality. On abdominal examination, diffuse tenderness was present. She was resuscitated initially with fluids and then noradrenaline infusion was started at 5 μg/min. Ultrasound abdomen revealed hypoechoic collection of approximately 800–900 ml. Exploratory laparotomy was done under general anaesthesia and 1 L of pus was drained. Patient was shifted to (ICU) for mechanical ventilation in view of sepsis and hemodynamic instability. During her course of stay in ICU, sepsis was controlled and she became haemodynamically stable. Ionotropes were gradually tapered and stopped. However all the efforts of weaning her off the ventilator proved futile. Patient continued to be lethargic, stuporous and was not obeying verbal commands. On 7th postoperative day, she developed hypertension (153/90 mmHg) for which amlodipine 5 mg once a day was started. On the 8th day, she passed a tapeworm in stools which were followed by two episodes of generalised tonic clonic seizures lasting about 30 s each. Loading dose of phenytoin 1000 mg was administered intravenously which was followed by 100 mg thrice daily. Computed tomography (CT) scan was planned keeping the diagnosis of neurocysticercosis in mind. However CT head revealed hypodensities in bilateral occipital lobe which the radiologist diagnosed as PRES. After the diagnosis was made, dose of amlodipine was increased to 10 mg OD to keep blood pressure <130/90 mmHg. Intravenous Dexamethsaone 8 mg thrice daily was added to the treatment. Gradually her level of consciousness improved. Trachea was extubated on day 11 and she was shifted to ward on day 15 without any neurological sequelae.

Case 2

An 18-year-old primigravida term pregnancy with pregnancy induced hypertension on irregular treatment, presented to emergency with a history of six episodes of seizures. On examination, patient was drowsy but arousable. Her pulse rate was 120/min and blood pressure was 156/100 mmHg. Her chest auscultation revealed no abnormality. She was initially managed conservatively on magnesium sulphate (MgSO4) administered intravenously and tab labetalol (100 mg thrice a day). Labour was induced on admission. However, patient developed another episode of seizure 4 h later. Immediate vaginal delivery, with birth of a healthy female baby, was carried out. Patient developed a large episiotomy hematoma, which was drained under general anaesthesia as the patient was drowsy and not maintaining her airway reflexes. Patient was shifted to ICU postoperatively for mechanical ventilation and observation. The patient however remained agitated with opisthotonic posture despite midazolam infusion. Hence, midazolam was substituted by diazepam and intermittent boluses of sodium thiopentone were given for control of convulsions. For control of persistent high blood pressure, infusion of sodium nitroprusside (0.5 μg/kg/min) along with tab amlodipine through nasogastric tube was started. As the patient remained agitated despite above treatment, CT head was planned to rule out intracranial bleed or oedema. CT head revealed hypodensities in bilateral parietal and frontal lobes suggestive of PRES. Hypertension was aggressively controlled by titrating the dose of sodium nitroprusside. Injection dexamethasone was added. Patient was mechanically ventilated for 3 days and observed in ICU for a further 4 days. She was shifted to ward without any neurological sequelae.

Discussion

Posterior reversible encephalopathy syndrome in the postpartum period is an infrequent diagnosis in day-to-day obstetric care. There have been only a few published case reports describing the known clinical features of the syndrome. The exact etiopathogenesis of PRES is not known. However hypothesis states that in sepsis, virulent agent and release of immunological mediators cause endothelial dysfunction and microcirculation disturbances. This leads to development of vasogenic cerebral edema and features of PRES.[4] In hypertensives, rapid rise in blood pressure with abnormal cerebral auto regulation leads to breakage of blood brain barrier and consequent leaking of plasma.[11] This results in cerebral edema in posterior areas of brain and hence, PRES.

Diagnosis based on clinical presentation is difficult, which can be atypical - as was seen in our cases. PRES usually presents with hypertension [12] however, in the first case, high blood pressure first occurred 16 days after delivery. Moreover, the history was suggestive of neurocysticercosis associated with seizures. In the second case, instead of typical features like lethargy and somnolence, patient was atypically agitated and maintaining an opisthotonic posture throughout. Therefore clinical presentation can be inconclusive. If PRES is suspected, early neuroimaging is a must for diagnosis.

On neuroimaging, characteristic lesions of PRES are located at parietal and occipital lobes in 94% cases, followed by frontal lobes in 77%. Inferior temporal occipital junction and cerebellum are the other sites where PRES lesions are located.[13] On magnetic resonance imaging (MRI) T1-weighted scan, lesions appear hypointense and on T2-weighted scan lesions of PRES appear hyperintense. On CT scan, bilateral symmetrical areas of low attenuation of white mater are seen.[14]

Early diagnosis of PRES is imperative to prevent development of complications like infarction, haemorrhage and coma.[15] Due to vague and nonspecific clinical features, one should be cognizant of this entity and possible causative factors. Management of PRES includes treatment of underlying conditions, prompt delivery and maintaining normotension. Use of antiepileptics and antihypertensive drugs are necessary to control PRES. Addition of steroids may ameliorate the associated cerebral oedema. Prophylactic MgSO4 therapy plays no role in prevention in development of PRES.

To conclude, PRES is a relatively rare condition with multifactorial etiological factors, varied clinical presentation and grave complications. So, a high index of suspicion should be maintained while treating patients with altered mental status and seizures particularly in pregnant patients. Early CT/MRI is necessary for diagnosis with prompt treatment of underlying condition, particularly of hypertension to prevent development of permanent neurological damage.