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Authored By: Farrokh Dehdashti and Peter Phan.
Patient: 6 year old male

The patient is a 6 year old male with chronic seizures.

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Fig. 1
PET images

Fig. 2
PET Images

Fig. 3
T2 MRI images

Fig. 4
T2 MRI images
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The PET scan demonstrates diffuse hypometabolism of the right cerebral hemisphere, corresponding to diffuse atrophy on a recent MRI scan.  Additionally, decreased metabolism is noted in both temporal lobes, worse on the right.  This corresponds to volume loss and abnormal T2 signal of bilateral hippocampal formations.  Marked hypometabolism also involves the right thalamus.   

Diffuse hypometabolism of the cerebellum is also present and is likely related to anti-epileptic therapy.

Diagnosis: Rasmussen's encephalitis and bilateral mesial temporal sclerosis
General Discussion:

RADIOPHARMACEUTICAL: 3.4 mCi F-18 Fluorodeoxyglucose i.v.

In this 6 years old male with chronic seizures and diffuse atrophy of one of the hemispheres, the most likely diagnosis is Rasmussen’s encephalitis.  Encephalitis from prior TORCH infections would be unusual given the unilateral presentation. In addition, one would expect changes of encephalomalacia if this was a consequence of an old ischemic event.

Rasmussen’s encephalitis is a chronic inflammatory disease that involves a single hemisphere of the brain.  The patient may present with frequent seizures, hemiparesis, and cognitive deficits.  Throughout the disease’s course of about 8-12 months, further deficits can occur.  However, in most cases, brain damage stabilizes.  During the active phase of the disease, corticosteroids and intravenous immunoglobulin may be helpful.  Hemispherectomy and hemispherotomy can be performed to reduce the frequency of seizures after the neurolgic deficits stabilize given that most anti-epileptic medications are ineffective.

It was also noted the patient also has volume loss and gliosis of the hippocampal formations, compatible with bilateral mesial temporal sclerosis.


"NINDS Rasmussen's Encephalitis Information Page", National Institute of Neurological Disorders and Stroke National Institutes of Health Bethesda, 2008 (

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Additional Details:

Case Number: 206899Owner(s): Farrokh Dehdashti and Peter PhanLast Updated: 12-07-2011
Anatomy: Cranium and Contents   Pathology: Non-Infectious Inflammatory Disease
Modality: PETAccess Level: Readable by all users, writable by NucMed Certifiers
Keywords: pbnm

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Certified by Farrokh Dehdashti on 07-28-2010

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