Learning objectives
The aim of this exhibit is to pictorially demonstrate
Imaging spectrum of the common toxic and acquired metabolic encephalopathies.
Formulate a differential diagnosis based on clinical and imaging findings which will help in correctly identifying the cause of encephalopathy.
Background
Acute toxic-metabolic encephalopathy is an acute condition of global cerebral dysfunction encompassing delirium and the acute confusional state in the absence of primary structural brain disease.
Toxic and metabolic encephalopathies are common among critically ill patients and usually present with seizures and focal neurological deficits.
A large number of conditions can present with similar clinical condition and MRI can help narrow the differential diagnosis.
Also,
in a patient with known exposure to a toxic agent,
topographic distribution of the lesions can help exclude other causes...
Findings and procedure details
1.
Acute Hyperammonaemic Encephalopathy
Hyperammonaemic encephalopathy can occur in acute fulminant hepatic failure or in patient with chronic liver disease.
Patients present with progressive drowsiness,
seizures,
and coma due to toxic effects of ammonia on the brain parenchyma with elevated serum ammonia levels (normal levels 9-30umol/l).
MRI shows diffusion restriction in symmetrical pattern involving insular and cingulate gyri (Fig.
1).
These cortical changes appear to be early imaging findings and potentially reversible if aggressive treatment is instituted.
Involvement of brain regions other than the insular...
Conclusion
MRI plays an important role in diagnosing acute toxic-metabolic encephalopathies and can rule out surgically correctable causes of altered consciousness.
Awareness of the spectrum of imaging features of such cases including the characteristic pattern involvement can often aid in quickly establishing a correct diagnosis and help predict early complications.
Personal information
S.
Sood,
Division of Radiology,
Medanta – The Medicity,
Gurgaon 122001,
India
R .Gupta,
Division of Radiology,
Medanta – The Medicity,
Gurgaon 122001,
India
J.
Sharma,
Division of Radiology,
Medanta – The Medicity,
Gurgaon 122001,
India
J.
Modi,
Division of Radiology,
Medanta – The Medicity,
Gurgaon 122001,
India
References
Chen,
R,
Young,
GB.
Metabolic Encephalopathies.
In: Bolton,
CF,
Young,
GB,
(Eds),
Baillere's Clinical Neurology,
Balliere Tindall,
London 1996.
p.577
U-King-Im JM,
Yu E,
Barlett E,
et al.
Acute hyperammonemic encephalopathy in adults: imaging findings.
AJNRAmJ Neuroradiol 2011;32:413-8.
McKinney AM,
Lohman BD,
Sarikaya B,
et al.
Acute hepatic encephalopathy:diffusion-weighted and fluid-attenuated inversion recovery findings,
and correlation with plasma ammonia level and clinical outcome.
AJNR Am J Neuroradiol 2010;31:1471-9.
Ruzek KA,
Campeau NG,
Miller GM.
Early diagnosis of central pontine myelinolysis with diffusion-weighted imaging.
AJNR Am...