Posterior Reversible Encephalopathy Syndrome

Abstract

Introduction - Posterior reversible encephalopathy
syndrome (PRES) is a
clinicoradiologic entity occurring in varied
clinical setting and characterized by
headaches, confusion, visual disturbances,
seizures, and posterior transient
changes on neuroimaging. The radiological
features are often reported as demyelination
which confounds the diagnosis.
Observations - Of the 14 patients included
for the study, 13 (93 percent)
were females. The common symptom
being Headache in 13 (93 percent), Seizure
in 10 (71 percent), Visual disturbance
in 7 (50 percent), altered sensorium
in 7 (50 percent) and hypertension in
11 (78percent). On MRI the sites involved
were Occipital 13 (92 percent),
Parietal 9 (64 percent), frontal 4 (28 percent),
temporal 2 (14 percent), deep nuclei
2 (14 percent), cerebellum 1 (7 percent)
and brain stem 1 (7 percent). The
symptoms were reversible in 12 (86 percent)
patients, the remaining 2 (14 percent)
had complications of PRES with 1
(7 percent) having right occipital infarct
and 1 (7 percent)
right parietal hemorrhagic transformation.
Discussion -Acute rise in blood pressure is
one of the factors in the pathogenesis of
PRES, degree of raise in blood pressure
doesnt correlate with the clinical severity or
radiological manifestations. Pathophysiology
of PRES remains controversial with
two main hypotheses contradicting each
other. One being impaired cerebral autoregulation
leading to increased cerebral
blood flow (CBF) as noticed in severe hypertension,
whereas the other postulate is
endothelial dysfunction with cerebral hypoperfusion
as in cases with normal blood
pressure or on cytotoxic therapy. The common
final outcome in both is alteration in
cerebral perfusion with blood brain barrier
dysfunction causing vasogenic cerebral
edema. The common etiology of PRES in
this study was eclampsia, autoimmune disease,
renal disease and other causes.
Conclusion - PRES can manifest with
atypical features like normal blood pressure,
presence of MRI evidence of infarct
or hemorrhage. Clinical suspicion in appropriate
setting will lead to early diagnosis
and appropriate therapeutic intervention.
Reversibility of

the clinical and radiological abnormalities is
contingent on ealy treatment. On the contrary
when unrecognized, conversion to irreversible
cytotoxic edema may occur.