With regard to posterior reversible leukoencephalopathy syndrome (PRES), outline the risk factors, clinical features, differential diagnoses, radiological findings and management. 

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College answer

Clinical features: 
Onset acute – days/weeks 
Headache 
Encephalopathy -fluctuating conscious level to coma 
Hypertension 
Seizures 
Visual deficits 
 
Risk factors: 
Hypertension 
Cytotoxic therapy 
Eclampsia 
Renal disease 
Autoimmune disorders 
Transplantation 
 
Differential diagnoses 
CVA 
Encephalitis 
Migraine 
Demyelinating conditions 
Vasculitis 
 
Radiological findings: 
Vasogenic oedema in the posterior circulation territories on MRI  
 
Management: 
Aggressive blood pressure control 
Cease any precipitating agents 
Antiseizure medication 
 

Discussion

This is the second time PRES has appeared in the written papers. Little can be done to improve the direct brevity of the college answer, other than to add references and change structure.

Risk factors

Classical associations

  • Solid organ transplant
  • Bone marrow transplant
  • Graft vs. host disease following allogenic BMT
  • Immunosuppressant therapy, especially cyclosporine and tacrolimus
  • Pregnancy (particularly, pre-eclampsia)
  • Cancer chemotherapy, specifically cytarabine, cisplatin, gemcitabine and bevacizumab
  • Autoimmune disease, particularly scleroderma, SLE, polyarteritis nodosa and Wegener's granulomatosis
  • Sepsis and septic shock, specially when associated with MOSF

Other associated conditions

  • Immune system activation
  • T-cell hyperactivity
  • Endothelial cell activation (surface-marker expression, etc)
  • Endothelial injury
  • Systemic vasoconstriction
  • Systemic organ hypoperfusion

Clinical features (Fugate and Rabenstein, Lancet, 2015)

  • Altered level of consciousness, ranging from confusion to coma
  • Headache
  • Seizures
  • Visual symptoms (usually, blindness or hemianopia)
  • Neuroradiology findings
  • Exclusion of other pathology (eg. encephalitis or stroke)
  • Acute onset, and reversibility over days or weeks
  • Hypertension

Differential diagnosis (from UpToDate)

  • Eclampsia
  • Cerebral oedema due to hypertensive encephalopathy
  • Reversible cerebral vasoconstriction syndrome
  • Ischaemic stroke (posterior circulation)
  • Cerebral venous thrombosis
  • Encephalitis (infectious, paraneoplastic or autoimmune)
  • CNS malignancy, eg. lymphoma
  • Acute demyelinating encephalomyelitis (ADEM)

Radiological findings (Swarnalatha et al, 2012)

  • Oedema is symmetric (bilateral)
  • Posterior occipital or parietal distribution (but this is not essential): in fact three major anatomical patterns of distribution exist:
    • holohemispheric
    • superior frontal sulcal
    • primary parietal-occipital

Management of PRES:

  • Aggressively control the blood pressure.
  • Give antiepileptics if seizures were a presenting problem.
  • Stop the causative drug.
  • Deliver the baby (in eclampsia).
  • Protect the patient from the horrors of ICU stay by attentive FASTHUGish supportive care

References

Staykov, Dimitre, and Stefan Schwab. "Posterior reversible encephalopathy syndrome." Journal of Intensive Care Medicine 27.1 (2012): 11-24.

Bartynski, W. S. "Posterior reversible encephalopathy syndrome, part 1: fundamental imaging and clinical features." American Journal of Neuroradiology 29.6 (2008): 1036-1042.

Bartynski, W. S. "Posterior reversible encephalopathy syndrome, part 2: controversies surrounding pathophysiology of vasogenic edema." American Journal of Neuroradiology 29.6 (2008): 1043-1049.

Grioni, Daniele, et al. "The diagnosis of posterior reversible encephalopathy syndrome." The Lancet Neurology 14.11 (2015): 1073-1074.

Fugate, Jennifer E., and Alejandro A. Rabinstein. "Posterior reversible encephalopathy syndrome: clinical and radiological manifestations, pathophysiology, and outstanding questions." The Lancet Neurology 14.9 (2015): 914-925.

MacKenzie, ERIC T., et al. "Effects of acutely induced hypertension in cats on pial arteriolar caliber, local cerebral blood flow, and the blood-brain barrier." Circulation research 39.1 (1976): 33-41.

G Swarnalatha, R Ram, B. H. S. Pai, KV Dakshinamurty  "Posterior reversible encephalopathy syndrome in minimal change disease" Indian Journal of Nephrology, Vol. 22, No. 2, March-April, 2012, pp. 153-154

Hobson, Esther V., Ian Craven, and S. Catrin Blank. "Posterior reversible encephalopathy syndrome: a truly treatable neurologic illness." Peritoneal Dialysis International 32.6 (2012): 590-594.