Dr Ira Shah
M.D, DNB, DCH(Gold Medalist), FCPS

An 8 year old male child presented with weakness of left upper limb & lower limb with inability to walk since 3 days. He had a previous history of vomiting and loose motions 8 days back. On examination, his power on left side was 4/5 and normal on right side. He had cerebellar signs predominantly on the left side and reflexes were normal. He was suspected to have an acute cerebellar ataxia due to either infarct or demyelination. CT Scan revealed a non-enhancing hypodensity in the left cerebellar hemisphere adjacent to the 4th ventricle suggestive of either demyelination or infective etiology. CSF studies were normal. He was treated with IV Methyl Prednisolone with which he showed slight improvement. He was readmitted in 30 days with right-sided hemiplegia and right facial nerve palsy. His MRI brain showed multiple varying signaled patchy nodular enhancing lesions involving the supra and infratentorial compartment. MRI spine showed no abnormality.

A differential diagnosis of Recurrent ADEM or Multiple Sclerosis was considered. Fundus examination revealed mild optic nerve dysfunction suggestive of optic neuritis. CSF showed absence of oligoclonal bands. Hence a diagnosis of recurrent acute disseminated encephalomyelitis was made. He was treated with IV Methyl Prednisolone (30mg/kg/day) for 3 days and then started on oral prednisolone on long-term basis. He showed a dramatic improvement to the same and resolution of all his neurological deficits.

ADEM is :

1. Immunologically mediated inflammatory demyelinating disease of CNS in temporal relationship to a viral disease or immunization.
   
2. Most of the times, it occurs only once. Sometimes may be recurrent.
   
3. Highest prevalence is seen in prepubertal boys.
   
4. Sometimes it may evolve into multiple sclerosis.
   
   

Pathology: Histology shows symmetric perivenular inflammatory infiltration and periaxial demyelination.

1. Common in winter months when GI and respiratory infections are common.
   
2. Typically, children recovering from viral prodrome abruptly develop irritability and neurological signs- Ataxia, optic neuritis; cranial nerve palsies, seizures and focal neurological deficits are commonly seen.
   
3. Changes in long tract signs and mental status are commonly observed.
   
4. Sometimes may even mimic GBS, transverse myelitis if associated with spinal cord involvement.

1. MRI is sensitive in the detection of lesions the brain but it lacks specificity because of overlapping appearances with other forms of demyelinating diseases especially multiple sclerosis, Devic’s disease etc. MRI shows discrete areas of increased signal on T2 weighted images particularly at gray-white junction. Plaque like lesions are seen throughout the neuraxis. The margins of the plaques are often indistinct.
   
MRI contrast studies are used to pick up enhancement of plaques, which is suggestive of active lesions.

2. CSF- oligoclonal bands are absent. MBP is frequently elevated.
   
3. EEG- Disturbances of normal sleep rhythms and slowing during waking state may be seen.
   
   

	ADEM	MULTIPLE SCLEROSIS.
AGE	<12 YEARS	ADOLESCENTS & ADULTS
PROVOKING FACTOR	PRECEDING INFECTION	-
CSF OLIGOCLONAL Ig	NORMAL	+Ve
RECURRENCE	UNCOMMON	COMMON
MRI	Plaques more amorphous, less sharply defined particularly at gray-white junction matter.Thalamus involved.	Rounded, elongated plaques with sharp margins in periventricular white matter. Thalamus not involved.
CLINICAL FEATURES	Accompanied by fever, lethargy, and disturbances of consciousness, seizures or movement disorders.	No other constitutional symptoms.

RISK OF MS FOR CHILDREN < 12 YEARS WITH 1 EPISODE OF ADEM - 6%
RISK OF MS FOR CHILDREN < 12 YEARS WITH 1-3 relapses -15 to 33%
RISK OF MS FOR CHILDREN > 12 YEARS WITH 1 episode – 50%

1. Corticosteroids: During the acute phase high dose steroids such as methylprednisolone is required which needs to be followed up with long-term oral steroids with slow tapering over months.
   
2. IVIG: In patients resistant to steroids IVIG has been tried and found to be useful
   
3. Other therapies that have been tried in resistant cases are cyclosporin and plasmapharesis.
   
   

Prognosis: In most of the cases with ADEM, the prognosis is good with almost 100% recovery. Recovery is unrelated to the severity of the illness. Recovery is poorest in children less than 2 years of age.


Last updated on 10-11-2002