|Year : 2016 | Volume
| Issue : 6 | Page : 1193--1194
Acute disseminated encephalomyelitis in children
Vimal K Paliwal
Department of Neurology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
Vimal K Paliwal
Department of Neurology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh
|How to cite this article:|
Paliwal VK. Acute disseminated encephalomyelitis in children.Neurol India 2016;64:1193-1194
|How to cite this URL:|
Paliwal VK. Acute disseminated encephalomyelitis in children. Neurol India [serial online] 2016 [cited 2020 Apr 2 ];64:1193-1194
Available from: http://www.neurologyindia.com/text.asp?2016/64/6/1193/193783
Acute disseminated encephalomyelitis (ADEM) is a relatively uncommon demyelinating disease of the central nervous system that affects both children and adults. As multiple sclerosis is relatively less common in children below 10 years of age, the characteristic polysymptomatic demyelinating disease of the brain with/without the involvement of spinal cord occurring in children below 10 years of age is usually considered as ADEM. Giri et al., described the clinical, radiological, and laboratory characteristics of 36 children diagnosed with ADEM over a period of 5 years. Though their study was not meant to find the incidence of ADEM, the inclusion of only 36 patients in 5 years suggests the rarity of the disease. The authors have carefully included the patients according to the consensus criteria for the diagnosis of ADEM. More than 90% of their children had encephalopathy, which is a mandatory criterion for the diagnosis of ADEM. Presence of encephalopathy also serves to differentiate the clinical illness from multiple sclerosis as the alteration of consciousness is not a “clinical presentation consistent with multiple sclerosis,” as required for fulfillment of the Modified McDonald Criteria for the diagnosis of multiple sclerosis. The clinical description of all the patients, especially those who presented with fever, mimics meningoencephalitis. Therefore, the conclusion made by the authors that “one should be careful in evaluation of these children and the presence of encephalopathy (any grade), absence of CSF leukocytosis and white matter involvement on cranial magnetic resonance imaging (MRI) should make a physician suspect ADEM” is really pertinent. However, the presence of cerebrospinal fluid (CSF) leucocytes does not exclude the diagnosis of ADEM. The MRI evidence of leptomeningeal enhancement may be an additional feature favoring meningoencephalitis. The proportion of various clinical features in patients with ADEM, as described in the study, is nearly similar to the previously described studies with little differences.,, Meningeal signs, seizures, and bilateral optic neuritis are not unusual for ADEM; however, they are reported in different proportions in different studies and the present study is no different. Vision loss is well-known in ADEM secondary to involvement of anterior as well as posterior visual pathways. The authors have described visual evoked potentials in some patients. However, the findings of perimetry would have been more helpful to understand the pattern of visual loss such as central scotoma, centrocecal scotoma, hemifield defect, or peripheral constriction of visual fields. This is more important because the fundus remains normal in the early stages of retrobulbar neuritis, which is not uncommon in ADEM.
ADEM is well-known to affect the thalamus, brainstem, cerebellum, and basal ganglia, and similar findings were reproduced in the study.,, The classification of supratentorial lesions into cortical, juxtacortical, and periventricular is more useful. It has been shown that patients with ADEM have more of juxtacortical lesions whereas those with multiple sclerosis have more periventricular lesions. The study reports that three patients had a relapsing disease. It would have been interesting to see the proportion of periventricular versus juxtacortical lesions in these three patients during their initial presentation as well during subsequent attacks.
The other important message that came forward was that a subgroup of patients relapsed. After the 2012 revision of the consensus definition, relapse in patients with ADEM is classified as multiphasic ADEM. Multiphasic ADEM is defined as “a new clinical event or the re-emergence of a prior clinical event, meeting the criteria for ADEM but involving new anatomic area of the central nervous system (CNS) at least 3 months or more after the onset of the initial ADEM.” After the consensus criteria, three studies reported on relapse in patients with ADEM, ranging from 5% to 30%. Some of these patients developed multiple sclerosis over a period of time. Previous studies have suggested a link between ADEM and multiple sclerosis. Mikeloff et al., studied the prognostic factors favoring a relapse among their cohort of 132 children with ADEM. They concluded that there is an increased risk of relapse in children with the initial presentation of optic neuritis in those with a family history of CNS demyelinating disease, those fulfilling the Barkoff's criteria for multiple sclerosis, and those without any neurological sequelae after the first attack. However, a long-term follow-up study in patients with ADEM (with initial encephalopathy) is needed to evaluate the prognostic markers favoring future conversion of these patients into multiple sclerosis. Patients with initial brainstem involvement and optic neuritis should also be evaluated for neuromyelitis optica (NMO). The initial presentation with encephalopathy does not provide safety for the diagnosis of NMO as it does for multiple sclerosis. NMO is well-known to have residual deficits and a relapsing course. The diagnosis of NMO requires the tests for anti-aquaporin antibodies in the serum or CSF. These patients usually require long-term immunosuppressive drugs.
There is a subgroup of ADEM who presents with severe fulminating disease usually with evidence of hemorrhage along with white matter abnormalities on MRI. These patients are classified as having acute hemorrhagic leukoencephalitis syndrome – a fulminant type of ADEM. However, with new MRI modalities, such as gradient recall echo and susceptibility weighted imaging, several of the less severe patients with ADEM also show areas of punctate blooming on cranial MRI. Therefore, there is a need to redefine the entity of acute hemorrhagic leukoencephalitis. There are other acute forms of multiple sclerosis such as acute Marburg variety and tumefactive multiple sclerosis, where the patients may have an initial encephalopathy; however, unlike the majority of patients with ADEM, they do not necessarily have a truncated course. Therefore, it is worthwhile to study and report the clinically/radiologically varied cohorts of ADEM, and the future prospective studies should be able to answer the long impending issues concerning ADEM.
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