Synonyms include: posterior reversible encephalopathy syndrome, PRES, reversible posterior cerebral oedema syndrome

This is a rare 'encephalopathic' condition, where the diagnosis depends on clinical and radiological features. It was first described in 1996, although it is most likely to have occurred before then.¹ It has been suggested that this is a new name for old syndromes.²

Despite the name 'leukoencephalopathy', lesions can occur in both white and grey areas.

Epidemiology

It is rare but being recognised more often. Most of the literature is single or a few cases. It usually presents in adults but has been reported less often in children.³

Aetiology

It is commonly seen in association with:

• Severe hypertension, pre-eclampsia or renal disease leading to failed auto-regulation, hyperperfusion and endothelial injury/vasogenic oedema.⁴ Rapidly developing, fluctuating or intermittent hypertension is a particular risk. Vasoconstriction and hypoperfusion leads to brain ischaemia and subsequent vasogenic oedema. Recent evidence suggests that the latter is more likely.⁵
• A wide range of drugs but most commonly with immunosuppressants and chemotherapy.⁶
• Infection with sepsis and shock, which are being recognised more often as other aetiological factors.⁷
• Autoimmune disease has also been seen.⁸
• It can also occur after carotid endarterectomy when the carotid baroreceptors fail.
• In one series of seven patients, six were found to have an underlying bleeding diathesis or coagulopathy.⁹

Despite the name 'leukoencephalopathy', lesions can occur in both white and grey areas. It is also increasingly recognised that it can affect the anterior cerebrum, as well as the anterior and posterior cortex, brainstem, cerebellum or even the spinal cord.¹⁰

Presentation

Clinical signs and symptoms are nonspecific and may be acute or subacute:¹

• Headaches.
• Altered mental state, lethargy and somnolence, possibly progressing to confusion and coma.¹¹
• Convulsions - partial status epilepticus has been reported.¹²
• Blurred vision, hemianopia, visual neglect, hallucinations, cortical blindness.
• There is often papilloedema, haemorrhages and exudates.
• Blood pressure will be high.

The clinical symptoms are not enough to establish the diagnosis but MRI is often characteristic and essential to the diagnosis.

Imaging

MRI commonly shows oedema involving the white matter in the posterior portions of the cerebral hemispheres, especially bilaterally in the parieto-occipital regions.¹
Diffusion-weighted sequences can differentiate between oedema from leaking capillaries and cell damage and hence can predict conversion to infarction and irreversible damage.

These features may be seen on CT scan but MRI scan is clearer.

Differential diagnosis

The presentation is often nonspecific and it can easily be mistaken for other conditions:

• Cerebrovascular event
• Sinus thrombosis
• Demyelination
• Vasculitis
• Encephalitis

Associated diseases¹⁰

• Hypertensive encephalopathy.
• Eclampsia or severe pre-eclampsia.
• Use of stimulant drugs that can raise BP, including phenylephrine, pseudoephedrine and even caffeine.
• Abuse of cocaine and amfetamines.
• Phaeochromocytoma.³
• Haemolytic uraemic syndrome.
• Blood transfusion.
• Infection.
• Autoimmune disease, e.g. systemic lupus erythematosus.

This list is far from exhaustive but high blood pressure is a common theme.

The following drugs are just some that have been implicated:

• Ciclosporin A
• Vincristine
• Tacrolimus
• Cisplatin
• Interferon alfa
• Antiretroviral therapy
• Erythropoietin

Management

The diagnosis needs to be made and the blood pressure brought down or sepsis treated.¹³

If drugs are implicated they must be stopped.

Prognosis

• If it is caught in time it is reversible but, if infarction has occurred there, will be irreversible damage.
• Delay in diagnosis gives a worse prognosis.¹⁴
• The MRI scan is useful in giving prognosis.¹⁵
• Recurrence can occur but is unusual.¹⁶

Document references

1. Hinchey J, Chaves C, Appignani B, et al; A reversible posterior leukoencephalopathy syndrome. N Engl J Med. 1996 Feb 22;334(8):494-500. [abstract]
2. Pavlakis SG, Frank Y, Chusid R; Hypertensive encephalopathy, reversible occipitoparietal encephalopathy, or reversible posterior leukoencephalopathy: three names for an old syndrome. J Child Neurol. 1999 May;14(5):277-81. [abstract]
3. Sanjay KM, Partha PC; The posterior reversible encephalopathy syndrome. Indian J Pediatr. 2008 Sep;75(9):953-5. Epub 2008 Sep 22. [abstract]
4. Paulson OB, Strandgaard S, Edvinsson L; Cerebral autoregulation. Cerebrovasc Brain Metab Rev. 1990 Summer;2(2):161-92. [abstract]
5. Bartynski WS; Posterior reversible encephalopathy syndrome, part 2: controversies surrounding pathophysiology of vasogenic edema. AJNR Am J Neuroradiol. 2008 Jun;29(6):1043-9. Epub 2008 Apr 10. [abstract]
6. Marinella MA, Markert RJ; Reversible posterior leukoencephalopathy syndrome associated with anticancer drugs. Intern Med J. 2008 Nov 3. [abstract]
7. Bartynski WS, Boardman JF, Zeigler ZR, et al; Posterior reversible encephalopathy syndrome in infection, sepsis, and shock. AJNR Am J Neuroradiol. 2006 Nov-Dec;27(10):2179-90. [abstract]
8. Fugate JE, Claassen DO, Cloft HJ, et al; Posterior reversible encephalopathy syndrome: associated clinical and radiologic Mayo Clin Proc. 2010 May;85(5):427-32. [abstract]
9. Aranas RM, Prabhakaran S, Lee VH; Posterior Reversible Encephalopathy Syndrome Associated with Hemorrhage. Neurocrit Care. 2009 Feb 19. [abstract]
10. Pula JH, Eggenberger E; Posterior reversible encephalopathy syndrome. Curr Opin Ophthalmol. 2008 Nov;19(6):479-84. [abstract]
11. Thambisetty M, Biousse V, Newman NJ; Hypertensive brainstem encephalopathy: clinical and radiographic features. J Neurol Sci. 2003 Apr 15;208(1-2):93-9. [abstract]
12. Rossi R, Saddi MV, Ticca A, et al; Partial status epilepticus related to independent occipital foci in posterior reversible encephalopathy syndrome (PRES). Neurol Sci. 2008 Dec;29(6):455-8. Epub 2008 Dec 6. [abstract]
13. Singhi P, Subramanian C, Jain V, et al; Reversible brain lesions in childhood hypertension. Acta Paediatr. 2002;91(9):1005-7. [abstract]
14. Striano P, Striano S, Tortora F, et al; Clinical spectrum and critical care management of Posterior Reversible Encephalopathy Syndrome (PRES). Med Sci Monit. 2005 Nov;11(11):CR549-53. [abstract]
15. Covarrubias DJ, Luetmer PH, Campeau NG; Posterior reversible encephalopathy syndrome: prognostic utility of quantitative diffusion-weighted MR images. AJNR Am J Neuroradiol. 2002 Jun-Jul;23(6):1038-48. [abstract]
16. Sweany JM, Bartynski WS, Boardman JF; "Recurrent" posterior reversible encephalopathy syndrome: report of 3 cases--PRES can strike twice! J Comput Assist Tomogr. 2007 Jan-Feb;31(1):148-56. [abstract]