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in an attempt to develop a uniform classification of the most common demyelinating disorder of childhood , the international pediatric multiple sclerosis study group proposes the definition of acute disseminated encephalomyelitis ( adem ) as  the first clinical event with a polysymptomatic encephalopathy , with acute or subacute onset , showing focal or multifocal hyperintense lesions predominantly affecting the cns white matter  . beyond that , evidences of previous destructive white matter changes or clinical setting of a demyelinating event must not be present in the patient 's history .
the risk of developing multiple sclerosis after adem has been focused by many studies in the literature.[13 ] the clinical features of adem are well known among pediatric neurologists and the outcome usually shows complete recovery in up to 50% , even in those patients who are not treated . nevertheless , some forms of presentation have peculiarities and they might be a challenge .
acute hemorrhagic encephalomyelitis ( ahem ) is considered a rare form of adem 's presentation due to acute brain vasculitis . immediate and aggressive treatment is required because this clinical scenario shows high mortality .
herein , the authors report a case of ahem with remarkable abnormalities of brain magnetic resonance imaging ( mri ) who had an unfavorable outcome . besides
, a review of similar pediatric cases previously reported in the literature has been given .
a 2-year - old , previously healthy girl was admitted to the hospital with a 1 week history of extreme irritability . associated with irritability
she did not have any antecedent history of infection or vaccination preceding the present symptoms .
the neurological examination on the first evaluation showed impairment of consciousness , ranging from irritability to numbness .
brisk deep tendon reflexes , bilateral babinski sign and ankle clonus were present . computed tomography scan was normal and the cerebrospinal fluid showed the following : white cell count 15 cells / mm(92% lymphocytes , 3% monocytes , 3% neutrophils ) , red blood cells 15/mm , protein levels 70 mg / dl , gamma globulin levels 18.3% on protein electrophoresis , and glucose levels 47 mg / dl .
acid - fast bacilli staining was negative as was polymerase chain reaction for herpes simplex and cytomegalovirus .
the first mri showed hyperintense flair / t2 lesions in cerebellar white matter [ figure 1a ] , and also in central , periventricular and juxtacortical white matter [ figure 1b and c ] .
axial flair images demonstrating hyperintense extensive and confluent lesions in cerebellar white matter ( a ) , affecting the corpus callosum ( b ) and compromising the central and juxtacortical white matter ( c ) she had significant improvement after iv administration of high - dose intravenous methylprednisolone ( 30 mg / kg / day ) for 5 days , followed by oral prednisolone ( 2 mg / kg / day ) taper for 6 weeks .
after 2 months of the initial symptoms , she had recurrence of her symptoms , associated with rapidly progressive refractory status epilepticus .
an electroencephalogram obtained showed delta wave activity that was consistent with diffuse , severe encephalopathy .
it was necessary to administer iv midazolam ( 23 g / kg / min ) followed by thiopental ( 50 mg / kg / hour ) to control the seizures .
the second mri , in addition to the impairment of cerebral and cerebellar white matter [ figure 2a and b ] , showed hemorrhagic lesions in the corpus callosum and right centrum semiovale [ figure 2c and d ] .
she was submitted to a new high - dose iv steroid therapy and iv immunoglobulin , but no improvement was observed and she died after a nosocomial pneumonia following 2 months of intubation .
axial flair image ( a ) demonstrating hyperintense extensive and confluent lesions in central and juxtacortical white matter ( dense arrow ) .
sagittal reformation ( b ) shows involvement of pericallosal and cerebellar white matter , sparing the u - fibers ( dense arrows ) .
axial t2 gradient echo - weighted images ( c and d ) showing areas of very low signal , corresponding to breakdown products of hemoglobin ( thin arrows ) , in the corpus callosum ( c ) and in the right centrum semiovale ( d )
whereas adem is more commonly diagnosed in children , ahem is seen most frequently among adults .
ahem is usually fatal , whereas full recovery is the rule for patients with adem . in 1997 , rosman et al .
reported a pediatric case of ahem with a good outcome , and they did a review of the cases published before , since the first description by hurst in 1941 . at that time , there were nine pediatric cases published with pathological or radiologic confirmation .
after 2000 , the largest adem series in childhood have demonstrated only three cases of ahem . in tenembaum and coworkers series ,
dale et al . have published 35 cases of adem , and only one scan had evidence of secondary hemorrhage .
three additional cases were published as case reports by leake , takeda , and mader in 2004 .
overall , 16 pediatric cases have been reported , including the one on this report [ table 1 ] .
the mortality of these 16 cases was 50% ( 8/16 ) . among the eight survivors , clinical information was available in seven :
four patients recovered with sequelae and three patients made a full recovery . despite the severe presentation of most adem cases , the outcome of nonhemorrhagic forms usually is favorable in childhood , with full recovery to normal neurological state in more than 5060% of patients , as previously demonstrated by the main series .
pediatric cases of acute hemorrhagic encephalomyelitis because of the epidemiological data , and especially the outcome between adem and ahem , some authors have tried to separate these conditions .
however , distinction between adem and ahem is not well established and they may be a continuation of disease spectrum .
the case presented herein is in agreement with the concept that both disorders are considered as autoimmune - mediated entities , with pathological features of prominent multifocal perivascular demyelination .
the patient had a typical presentation of adem with an initial good response to steroids , and in an unexpected way , she relapsed with recurrence of symptoms associated with refractory status epilepticus , and a new mri disclosing hemorrhagic features .
as the relapse took place within the first 3 months from the initial event , it was considered temporally related to the same acute monophasic condition , but with subsequent vessel occlusion leading to a secondary hemorrhage . even though some authors have reported favorable neurologic outcome in adult patients , the high rate of
ahem mortality mandates a quick and aggressive treatment using combinations of corticosteroids , immunoglobulin , cyclophosphamide , and plasma exchange.[1451719 ] the case reported here emphasizes that adem may present a severe outcome , making this well - known condition a challenge .
ahem must be properly investigated with mri whenever a patient presents with unexpected neurological worsening .
acute disseminated encephalomyelitis ( adem ) is an inflammatory immune - mediated disorder which is more common in pediatric patients . 
 the clinical setting is characterized by a rapid onset of encephalopathy and multifocal neurological features . 
 acute hemorrhagic encephalomyelitis ( ahem ) is considered a rare form of adem . this report shows a 2-year - old patient who presented with the classical features of adem and after 8 weeks developed severe neurological worsening . the second magnetic resonance image ( mri ) showed hemorrhagic lesions . 
 differences in prognosis between adem and ahem justify the investigation of ahem whenever a patient has neurological recrudescence in a known patient of adem .