LETTER TO THE EDITOR
|Year : 2013 | Volume
| Issue : 2 | Page : 173-175
"Reversible" stroke like episodes with bilateral diffusion restriction brain magnetic resonance imaging changes
Manish Prasad1, Shanawaz Hussain2, Daniele Connolly2, Santosh Mordekar2
1 Department of Paediatric Neurology, Leicester Royal Infirmary, Leicester, United Kingdom
2 Sheffield Children's Hospital, Sheffield, United Kingdom
|Date of Web Publication||7-Sep-2013|
Leicester Royal Infirmary, Leicester
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Prasad M, Hussain S, Connolly D, Mordekar S. "Reversible" stroke like episodes with bilateral diffusion restriction brain magnetic resonance imaging changes
. J Pediatr Neurosci 2013;8:173-5
Diffusion restriction on magnetic resonance imaging (MRI) brain scan is considered as a marker of acute ischemia and is associated with long term neurological deficit. Apart from posterior reversible encephalopathy syndrome, there are not many reported reversible leucoencephalopathies in pediatrics. We present a 7-year-old girl presenting with recurrent stroke like episodes and symmetrical diffusion restriction in brain MRI who had complete clinical and radiological recovery.
A well 7-year-old girl presented acutely with a right sided stroke like episode evolving over 45 min. She was fully alert on examination with the right facial and limb weakness and brisk reflexes and up going planters on the right side. There was no history of preceding illness/vaccination or chicken pox. Urgent Computed Tomography head with contrast was normal. She made complete spontaneous clinical recovery within 6 h, but then again had a recurrence of a similar episode after 12 h.
Her past history was unremarkable and in particular there was no history of high blood pressure or seizure disorder. Her blood pressure during her admission was within normal range.
Urgent brain MRI showed bilateral symmetrical high signal changes on T2 weighted images with diffusion restriction over centrum semiovale [Figure 1] not consistent with clinical presentation or vascular stroke territory.
|Figure 1: Axial T2 and diffusion-weighted imaging showing centrum semiovale hyperintensity and diffusion restriction respectively. Also noticed is diffusion restriction involving the corpus callosum|
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She again made a complete recovery within 6 h with no residual signs of weakness.
Repeat MRI brain at 6 weeks showed complete resolution of abnormalities with no volume loss [Figure 2].
|Figure 2: Axial T2 and diffusion-weighted imaging 6 weeks later showing complete resolution of the changes in association with resolution of previous clinical signs|
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She has remained symptom free at 12 months follow-up. Extensive investigation for metabolic, auto-antibody screening and stroke work up has been negative.
Human studies have demonstrated that damage in the areas showing decreased apparent diffusion coefficient (ADC) levels is rarely reversible (in contrast to that in animal models);  although, a few studies have indicated that intra-arterial thrombolysis (in the context of acute stroke) may occasionally result in the disappearance of the diffusion defect.
Numerous studies have shown that ADCs in ischemic areas are lower by 50% or more compared with those of normal brain areas, and they appear as bright areas (i.e. hyperintensities) on diffusion-weighted imaging. Studies have demonstrated that changes in the ADC occur as early as 10 min following the onset of ischemia. 
Bilateral symmetrical MRI changes with unilateral stroke like episodes with complete clinical and radiological recovery (exactly similar to our index case) have recently been described in patients with X-linked Charcot-Marie-Tooth disease More Details, but this was ruled out in our index case by normal neurophysiology and genetic investigations. 
Bilateral symmetrical brain MRI changes together with no clinical encephalopathy ruled out the possibility of acute disseminated encephalomyelitis. Prolonged focal seizure can result in unilateral weakness (Todd's paralysis), however this was not considered in our index case in view of no history of seizure, bilateral changes in MRI and the second episode of weakness was witnessed by our self-whilst she was admitted in the ward and was not preceded by seizure. Her clinical presentation and the MRI changes were not consistent with the cerebral venous sinus disease.
It is still possible for our index case to have gene negative X-Charcot-Marie-Tooth and being a girl the disease will be milder and hence the neurophysiology may become positive in her later life as reported in other female population in the literature.
Although diffusion restriction, measured by reduced ADC, is generally associated with brain volume loss and associated neurological deficit, this case highlights that complete clinical and radiological recovery is possible and the prognosis may not always be bleak.
| References|| |
|1.||Maas LC, Mukherjee P. Diffusion MRI: Overview and clinical applications in neuroradiology. Applied Radiology 2005;34:44-60. |
|2.||Hanemann CO, Bergmann C, Senderek J, Zerres K, Sperfeld AD. Transient, recurrent, white matter lesions in X-linked Charcot-Marie-Tooth disease with novel connexin 32 mutation. Arch Neurol 2003;60:605-9. |
[Figure 1], [Figure 2]