Multiphasic disseminated encephalomyelitis mimicking multiple sclerosis

Multiphasic disseminated encephalomyelitis mimicking multiple sclerosis

Brain & Development 1996; 18:412-414 ELSEVIER Case report Multiphasic disseminated encephalomyelitis mimicking multiple sclerosis Min-Lan Tsai *, K...

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Brain & Development 1996; 18:412-414

ELSEVIER

Case report

Multiphasic disseminated encephalomyelitis mimicking multiple sclerosis Min-Lan Tsai *, Kun-Long Hung Department of Pediatrics, Cathay General Hospital, 280 Jen-Ai Road, Sec 4, Taipei, Taiwan, Republic of China

Received 27 November 1995; accepted 27 March 1996

We report a case of multiphasic disseminated encephalomyelitis (MDEM) following viral illness presenting as multiple sclerosis (MS) in a 7-year-old boy. The patient had two episodes of alternating hemiparesis and other neurologic symptoms following viral infection, which were separated by 3 years. Neuroimaging studies demonstrated multiple, discrete, small nodules and large globular lesions in the cerebral white matter, basal ganglia, brainstem and cerebellar areas. Based on typical appearance of magnetic resonance imaging (MRI) and clinical manifestations including systemic symptoms such as fever, nausea, vomiting, headache and seizures followed by consciousness disturbance and other multifocal neurologic signs, the diagnosis of MDEM rather than that of MS was made. Because it is difficult to differentiate between MDEM and MS on the basis of the clinical history, the cerebrospinal fluid examination and evoked potential studies, this report emphasizes that the MRI study of the brain may provide an important clue for the diagnosis. Keywords: Multiphasic disseminated encephalomyelitis; Multiple sclerosis; Magnetic resonance imaging

1. I N T R O D U C T I O N Acute disseminated encephalomyelitis (ADEM) is a demyelinating disease of autoimmune etiology. Its clinical onset is often abrupt and usually occurs 5 days to 2 weeks after a viral illness or vaccination [1]. The diagnosis of ADEM has usually been made by exclusion or in retrospect. When it recurs in a patient, the diagnosis is somewhat more difficult and may resemble an exacerbation of multiple sclerosis (MS) [2]. Poser et al. reported two cases of recurrent disseminated vasculomyelinopathy that followed various infections and allergic challenges [3]. Alcock and Hoffman [4] reported another such patient and Lamarche et al. reported a patient with recurrent hemorrhagic encephalopathy [5]. We describe a patient with two episodes of alternating hemiparesis and other neurologic symptoms. After serial work-up and magnetic resonance imaging (MRI) study, relapsing MS was excluded. The final diagnosis was multiphasic disseminated encephalomyelitis (MDEM). 2. C A S E R E P O R T A 7-year-old boy was admitted with headache, vomiting and weakness in the right limbs. Fever and abdominal pain had

* Corresponding author. Fax: + 886 2 7074949.

occurred 3 days before admission. He was a monozygotic twin with an uncomplicated gestation as well as birth and had a generalized seizure when he was 2 months old, which subsided without any treatment. At 4 years of age, he had another seizure then developed left hemiparesis. Cranial computed tomography (CT) scan demonstrated a hypointense lesion in the right parietal area. After supportive care and treatment, it resolved over a period of 2 weeks. He made a partial recovery, being left with mild weakness of the left leg. On admission, physical examination showed no fever, pulse 90/rain, blood pressure 100/70 mmHg and respiratory rate 20 per min. Neurologic examination revealed lethargy, slurred speech, dysarthria and right upper motor neuron facial palsy. His eyes were conjugatively deviated to the fight side and the patient had limitation of eye movement to the left. Pupils were isocoric and reactive. His visual fields were intact. The eye fundi showed no papilledema and the optic disc appeared slightly pale over the left eye. He had weakness of fight upper and lower limbs, with muscle strength decreased to 2 - 3 / 5 with hyperreflexia. The bilateral plantar responses were extensor. There was no limb ataxia or disequilibrium and all modalities of sensation were intact. The following laboratory studies were normal: complete blood count, erythrocyte sedimentation rate, C-reactive protein and serum complements (C3, C4). Antinuclear antibodies and cold agglutinins were negative. Serum antibody titers for Epstein-Barr,

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uptake study. Bilateral carotid angiography was performed and revealed no evidence of occlusion or vascular abnormality. The patient was started on intravenous dexamethasone treatment (0.25 m g / k g / d a y ) for 2 weeks followed by oral prednisolone (2 m g / k g / d a y ) for 8 weeks. After treatment his symptoms gradually resolved with sequelae of right hemiparesis and decreased visual acuity in the left eye.

3. D I S C U S S I O N Fig. 1. Cranial CT revealing low-attenuation areas in the fight frontal (A) and the left parietal white matter (B). herpes simplex, cytomegalovirus and Mycoplasma pneumoniae were negative. Viral and bacterial cultures from throat, stool and cerebrospinal fluid (CSF) showed negative results. Blood urea nitrogen, blood glucose, serum electrolytes, liver function tests, lactate and creatine kinase revealed normal results. Examination of the CSF revealed five mononuclear leukocytes/mm 3, protein and glucose concentrations were 41 and 69 m g / d l , respectively. CSF IgG content was 7.68 m g / d l (18.7% of total protein) and IgG index was 0.64. No oligoclonal bands were found in the CSF; the myelin basic protein was within normal limits. An electroencephalogram (EEG) obtained on admission was interpreted as abnormal because of diffuse, widespread slow waves. The pattern-reversal visual evoked potentials (VEPs) showed no response to left side stimulation. Somatosensory evoked potentials (SSEPs) demonstrated prolonged latency of the left cortex. Brainstem auditory evoked potentials were normal. Cranial CT showed areas of low attenuation over the right fronto-parietal and left parietal areas (Fig. 1). The cerebral MRI scan demonstrated several discrete, small nodules and large globular white matter lesions of high signal intensity on T2-weighted and proton density images, predominantly within the bilateral subcortical cerebral white matter area including bilateral centrum semiovale, and also within the basal ganglia, cerebellum and brainstem (Fig. 2). No remarkable enhancement of these lesions was noted in the MRI Tl-weighted image after gadolinium

As acute disseminated encephalomyelitis (DEM) is usually a monophasic disease, it may be expected that all lesions occur in the acute phase. Case reports of MDEM are rare. The two cases reported by Poser et al. [3] had postinfectious and postimmunization neurologic symptoms. One case presented with recurrent infantile hemiplegia, the other presented with two episodes of postinfectious myelinoclastic encephalopathy with pathologic demonstration. Khan et al. also reported two adult patients with MDEM presenting as alternating hemiplegia [6]. Our patient had two episodes of alternating hemiparesis and multiple focal neurologic signs, which followed apparent viral illness. Considering the clinical pictures and paraclinical evidence of abnormalities of VEPs, SSEPs and with mildly elevated CSF IgG levels, the differential diagnosis included MS, MDEM, acute infantile hemiplegia, leukodystrophy and mitochondrial encephalopathy. The first two were considered most likely alter a series of laboratory examinations. The distinction between MS and MDEM is somewhat more difficult to make especially in young children [7]. It is important to differentiate these two conditions, since the prognosis of MDEM is much better. Certain clinical features may help to differentiate the two conditions. DEM episodes often produce widespread CNS disturbance with coma or drowsiness, seizures, and multifocal neurologic signs implicating the involvement of brain, spinal cord and optic nerves. In contrast, MS usually presents as a monosymptomatic syndrome such as optic neuritis or a subacute myelopathy [8]. However, no clinical feature is exclusive to one or the other disorder. Changes in CSF also do not permit reliable differentiation between the two conditions. In

Fig. 2. T2-weighted brain MRI (TR, 3,000 ms; TE, 120 ms) revealing multifocal areas of high signal intensity in the right basal ganglia (A) and the cerebral white matter on both sides (A-C). Extensive, lobular high-signal intensity areas in the fight parietal (B) and left parietal white matter (C).

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patients with DEM, the CSF most commonly shows moderate pleocytosis and increase in total protein content. Although oligoclonal IgG bands are a characteristic feature of MS, they may also occur in A D E M [8]. The elevated CSF IgG and absence of oligoclonal bands in this patient argued against MS and in favor of MDEM. Evoked responses are non-specific. It is the MRIs that in most instances can provide the means of differentiating between MDEM and MS. In ADEM and MDEM, the MRI patterns are quite different: on T2-weighted images, large lobar areas of increased signal intensity may involve the cortex or subcortical areas, or there may be a large globular lesion usually located at the posterior angle of the ventricular atrium. Such large lesions are never seen in MS [9]. Unlike those in MS, the lesions in DEM are extensive, often follow the outline of the cortical ribbon, or may consist, as in this case, of large globular areas of increased signal intensity on T2-weighted image that do not produce a mass effect [6,10]. In DEM, the multiple lesions are more likely to be in the peripheral, subcortical white matter rather than in the periventricular regions, which mostly occurs in MS. The cerebellum and cortex are often involved, as are occasionally the thalamus or the basal ganglia. The corpus callosum is usually not affected [9]. Gadolinium-DTPA enhanced MRI may show a mixture of enhancing and non-enhancing lesions in both MS and DEM patients, such enhancement is a consistent feature of new and active lesions [8]. Despite the lack of enhancement, the MRI of this patient demonstrated the typical feature of DEM. In addition, the very early age of onset and the low incidence of MS in Chinese people [11] argue against the diagnosis of MS in our patient. There are three types of 'chronic' DEM, reported by Poser [9]. The first one consists of exacerbations of an original episode of ADEM in a non-specific way. In these cases the recurrent symptoms are always the same, although the complete original syndrome is not necessarily present. This is called recurrent DEM (RDEM). The second consists of two or more episodes resulting in different symptomatology, i.e., two or more separate acute episodes that differ in clinical presentation, is termed MDEM, which is present in our patient. The third and rarest type, is steadily progressive and called chronic progressive DEM. Although this boy fulfilled the diagnostic criteria of clinical definite MS [12], the diagnosis of MDEM was presumed. In young children, great care must be taken to make a correct diagnosis of recurrent, or relapsing-remitting disseminated multi-

focal acute neurologic symptoms. MDEM should be one of the major considerations. As it is impossible to differentiate MDEM from MS on a purely clinical basis, serial MRI study and close follow-up provide the only clue for the diagnosis.

ACKNOWLEDGEMENTS We thank Dr. Charles M. Poser (Department of Neurology, Harvard Medical School, and Neurological Unit, Beth Israel Hospital, Boston, MA) for his comments regarding this case during his visit to Taipei in January 1994.

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