Cranial MRI in Acute Hyperammonemic Encephalopathy

doi:10.1016/j.pediatrneurol.2009.02.012

Pediatric Neurology

Volume 41, Issue 2, August 2009, Pages 139-142

https://doi.org/10.1016/j.pediatrneurol.2009.02.012 Get rights and content

Cranial magnetic resonance imaging was performed in three cases of acute hyperammonemic encephalopathy with three diverse etiologies: infantile citrullinemia, acute hepatic encephalopathy, and proximal urea cycle disorder. All three patients exhibited diffuse extensive cortical signal changes and swelling. Neurologic outcome was poor in all three cases. Knowledge of the magnetic resonance imaging findings of hyperammonemic encephalopathy may help in early diagnosis and treatment and could influence the neurologic outcome.

Introduction

Hyperammonemia in children may be detected in a variety of conditions, including urea cycle disorders, hepatic encephalopathy, Reye's syndrome, and other metabolic or toxic encephalopathies. Prolonged hyperammonemic encephalopathy could lead to substantial parenchymal brain injury, and surviving patients develop impairment of intellectual function [1], [2]. Few reports are available on magnetic resonance imaging in acute hyperammonemic encephalopathy, and different patterns of imaging findings have been described [3]. Moreover, it is often believed that magnetic resonance imaging might reveal only normal findings, or at best reveal diffuse atrophy. The diagnostic role of magnetic resonance imaging in acute hyperammonemic encephalopathy merits further consideration. Described here are the magnetic resonance imaging observations in three cases of hyperammonemic encephalopathy, each with a different cause.

Section snippets

Patient 1

A 1-year-old boy presented with recurrent seizures, loss of acquired milestones, irritability, and frequent inconsolable crying spells of 20 days duration. There was a history of recurrent vomiting from early infancy. He had had left-side focal motor seizures with secondary generalization from the age of 3 months and was taking 30 mg daily of phenobarbital for control of seizures. He was born by cesarean section to healthy consanguineous parents. Birth and perinatal history were unremarkable.

Discussion

Extensive cortical signal changes were observed in three patients with hyperammonemia due to different underlying etiology. Takanashi et al. [3] have classified magnetic resonance imaging findings in hyperammonemic encephalopathy into four important groups: (a) diffuse cerebral edema followed by diffuse cerebral atrophy, (b) extensive infarct-like abnormality often presenting as acute hemiplegia, (c) ischemic lesions in cerebral vascular territory, and (d) reversible symmetric cortical

References (13)

M. Msall et al.
Neurologic outcome in children with inborn errors of urea synthesis: outcome of urea-cycle enzymopathies
N Engl J Med
(1984)
T. Uchino et al.
Neurodevelopmental outcome of long-term therapy of urea cycle disorders in Japan
J Inherit Metab Dis
(1998)
J. Takanashi et al.
Brain MR imaging in neonatal hyperammonemic encephalopathy resulting from proximal urea cycle disorders
AJNR Am J Neuroradiol
(2003)
J. Takanashi et al.
Brain MR imaging in acute hyperammonemic encephalopathy arising from late-onset ornithine transcarbamylase deficiency
AJNR Am J Neuroradiol
(2003)
Y.F. Chen et al.
MRI in a case of adult-onset citrullinemia
Neuroradiology
(2001)
M.D. Baganz et al.
Valproic acid-induced hyperammonemic encephalopathy: MR appearance
AJNR Am J Neuroradiol
(1994)

There are more references available in the full text version of this article.

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Brain imaging may reveal marked cerebral edema, similar to Reye syndrome (Metzeler et al., 2009). There may also be signal change in the insular and cingulate cortices, with sparing of the occipital cortex (in contrast to posterior and white-matter-predominant PRES pattern on MRI) (Bindu et al., 2009). Urea cycle defects including ornithine transcarbamylase deficiency should be excluded by measurement of urinary amino acids and orotic acid, as these can present in a similar manner.
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Case ReportCranial MRI in Acute Hyperammonemic Encephalopathy

Introduction

Section snippets

Patient 1

Discussion

Neurologic outcome in children with inborn errors of urea synthesis: outcome of urea-cycle enzymopathies

N Engl J Med

Neurodevelopmental outcome of long-term therapy of urea cycle disorders in Japan

J Inherit Metab Dis

Brain MR imaging in neonatal hyperammonemic encephalopathy resulting from proximal urea cycle disorders

AJNR Am J Neuroradiol

Brain MR imaging in acute hyperammonemic encephalopathy arising from late-onset ornithine transcarbamylase deficiency

AJNR Am J Neuroradiol

MRI in a case of adult-onset citrullinemia

Neuroradiology

Valproic acid-induced hyperammonemic encephalopathy: MR appearance

AJNR Am J Neuroradiol

Case Report
Cranial MRI in Acute Hyperammonemic Encephalopathy