Chewarat Wirojtananugoon, MD. Jiraporn Laothamatas, MD. POSTERIOR REVERSIBLE ENCEPHALOPATHY SYNDROME WITH OBSTRUCTIVE HYDROCEPHALUS: A Case Report Chewarat Wirojtananugoon, MD. Jiraporn Laothamatas, MD. Good afternoon, everyone. Now I am going to present my case report of PRES with obstructive hydrocephalus. Good afternoon everyone. Department of Radiology, Ramathibodi Hospital, Bangkok, Thailand

Introduction Posterior reversible encephalopathy syndrome is a disorder of cerebrovascular autoregulation with diverse etiologies, and diverse clinical findings. Common causes: rapid BP, renal disease, treatment with immunosuppressive drugs Mechanism : probably cerebrovascular endothelial dysfunction BBB break down and leakage of plasma fluid into the extracellular space

Typical S&S : Headache, alteration of consciousness, seizures, vomiting, visual disturbance. Imaging: T2 hyperintensity (edema) of the cortical and subcortical region of bilateral parieto-occipital lobes Posterior fossa involvement of PRES with obstructive hydrocephalus is rare, and may be misdiagnosed as an infiltrative tumor, infarction or rhombencephalitis

Purpose To report an unusual case of PRES with predominant posterior fossa involvement, causing obstructive hydrocephalus, and discuss the usefulness of MRI, MRS and MRP

Case report A 43 YOM with unknown UD was brought to ER by his wife due to decreased consciousness for 2 days. He had 2 week history of occipital headache prior to confusion. 20-year heavy alcohol drinking

Physical examination BP: 210-230 mmHg/ 145 -162 mmHg PR, RR, Temperature  WNL Stiffness of neck -ve No papilledema No focal neurological deficit

Laboratory investigation Creatinine 1.3 mg/dL UA: heavy proteinuria CXR: cardiomegaly EKG: bifasicular block, LAE and LVH LFT: GGT ( gamma glutamyl transpeptidase) Otherwise : WNL On lab investigation, slightly high Cr was found. UA was abnormal with heavy proteinuria. Cardiomegaly was detected on CXR and EKG. LFT was abnormal with high GGT.

High BP was treated promptly at ER and ICU with some clinical improvement. This was suspicious for hypertensive encephalopathy to the clinician.

CT -/+ C However, CT was performed to exclude intracranial lesion. CT shows hypodensity of the bilateral cerebellar hemispheres, BS, thalami, with obstruction of the 4th ventricle, hydrocephalus, transependymal CSF resorption and upward transtentorial herniation.

Infiltrative mass was suspected on the CT, and MRI/MRS/MRP were suggested.

Ax T2 T2 high SI in brainstem, cerebellum, thalami. Dark T2foci at brainstem suggest microbleeds from chronic HT

Ax FLAIR Better visualization of the hyperintense lesions in the posterior fossa and thalami with obstructive hydrocephalus, tonsillar and upward transtentorial herniaiton.

Ax T1 T1 without

Ax T1+C With Gd shows no iso-hypoSI without E

Ax DWI isointensity

EDC hypointensity

Ax ADC hyperintensity of the lesions, suggestive of increased diffusion.

Cor GRE Microbleeds at BG, BS, suggestive unrecognized chronic hypertension.

MV 1H MRS, TE 144 msec On MRI, diagnosis of acute infarct is excluded given lack of restricted diffusion. Both PRES and gliomatosis cerebri have increased diffusion. So MRS was done to differentiate the two. And we see normal metabolite ratio, lack of high Cho/Cr ratio. Suggest nonneoplastic lesion.

SV 1H MRS, short TE (35 msec) mI On SV, metabolite ratio was normal, and mI is not high, so it does not support dx of glioma.

MRP MR perfusion shows relative hypoperfusion, suggest nonneoplastic legion.

Ventriculostomy was done after completion of the MR examination due to the concern of posterior fossa tumor. MRI/MRS/MRP suggested dx of PRES. However, ventriculostomy was done right after completion of the MR exam, due to concern of posterior fossa tumor, without knowing the MR result.

He developed seizure and left hemiparesis at 6 and 10 hours after ventriculostomy, respectively.

Follow up CT on the 10 th hospital day shows resolution of the hypodense lesions in the posterior fossa and thalami, marked improvement of hydrocephalus and evolution of the right thalamic hemorrhage

Discussion/Conclusion PRES is a syndrome of cerebrovascular autoregulatory failure, which usually present with HA, confusion, visual disturbance, and seizure. Pathogenesis is unclear, probably cerebrovascular endothelial dysfunction related to many causes (most of which cause high BP), leading to plasma fluid leakage and extracellular edema. Typical imaging finding is edematous change of the cortical/subcortical areas of bilateral parieto-occipital lobes, which usually resolves after normalization of BP.

Edema of the posterior fossa with secondary obstructive hydrocephalus is a rare presentation of PRES. MRI, MRS and MRP can help discriminate PRES from tumor. Early diagnosis of PRES and aggressive treatment of high BP are important, because CSF diversion may not be necessary and hemorrhagic complication may be prevented.

Thank you