Acute Disseminated Encephalomyelitis Associated with Oral Polio Vaccine

□ CASE REPORT □

Kensaku Shibazaki 1, Tatsufumi Murakami 1, Ryutaro Kushida 1, Katsumi Kurokawa 1,KiheiTerada2 and Yoshihide Sunada 1

Abstract

Abstract A 27-year-old woman presented with acute paresis after taking an oral polio vaccine (OPV). Deep tendon reflexes were preserved, needle electromyography showed no neurogenic changes, and there were no lesions on spine magnetic resonance imaging (MRI), suggesting that motor neurons of the spinal cord were not affected. Brain MRI showed abnormal lesions in the tegmentum of the upper pons, left cerebral peduncles, truncus of the corpus callosum, and right parietal lobe. Cerebrospinal fluid revealed mild pleocytosis. The most probable diagnosis was acute disseminated encephalomyelitis associated with OPV.

Key words: oral polio vaccine, magnetic resonance imaging, acute disseminated encephalomyelitis

(DOI: 10.2169/internalmedicine.45.6029)

blood pressure was 122/72 mmHg, and heart rate was 60 Introduction beats/min with regular sinus rhythm. The cranial nerves were intact. Manual muscle testing revealed mild weakness Poliomyelitis is caused by poliovirus infection, and is in the lower extremities: iliopsoas (4/4+), quadriceps (5-/5), characterized by impairment of motor neurons in the spinal hamstrings (4/4+) using the Medical Research Council rat- cord, brain, and brainstem (1). Since the introduction of the ing scale. Mingazzini sign was positive in the right lower oral polio vaccine (OPV), infection from the wild type po- extremity. The sensory system and coordination were intact. liovirus has not been reported in Japan since 1981 (2). How- Deep tendon reflexes were normal, and the plantar responses ever, OPV can cause vaccine-associated paralytic poliomye- were flexor. Gowers’ sign was positive. Blood counts, renal litis (VAPP) in rare cases (3), and acute disseminated en- and liver function tests, glucose, C-reactive protein, rheuma- cephalomyelitis (ADEM) associated with OPV has also been toid factor, and antinuclear antibody were normal. The se- described in one report (4). We describe a patient with acute rum poliovirus antibody titers (NT) were measured: type 1 paresis and brain MRI abnormalities after OPV intake. (1:128), type 2 (1:256), and type 3 (1:32) on the 23th day after OPV; and type 1 (1:64), type 2 (1:128), and type 3 (1: Case Report 32) on the 48th day. The titers for influenza A and B, mea- sles, herpes simplex virus, varicella-zoster virus, cytomega- A 27-year-old woman and her 6-month-old son received lovirus, Epstein-Barr virus, mycoplasma, echovirus 6, 7, 9, OPV in May 2005. Seven days later, she noticed weakness 11, 30, coxsackievirus A 4, 7, and B1-5 were not signifi- in her right upper extremity. Ten days later, she experienced cantly elevated. The cerebrospinal fluid (CSF) revealed pleo- muscular stiffness in her right extremities, and subsequently cytosis (13.6 /mm3), normal protein (23 mg/dl), IgG index suffered from a transient loss of consciousness while in her (0.62), and glucose (60 mg/dl). No myelin basic protein or bath. She then felt weakness in her lower extremities that oligoclonal bands were detected. Poliovirus was not detected progressed slowly. She was referred to our hospital 20 days in viral cultures of CSF or stools. Nerve conduction studies later. On examination, her body temperature was 37.3℃, were normal. Needle electromyography (EMG) revealed no

１ Division of Neurology, Department of Internal Medicine, Kawasaki Medical School, Kurashiki and ２ Division of Neurology, Department of Pe- diatrics, Kawasaki Medical School, Kurashiki Received for publication May 9, 2006; Accepted for publication July 13, 2006 Correspondence to Dr. Tatsufumi Murakami, Division of Neurology, Department of Internal Medicine, Kawasaki Medical School, 577 Mat- sushima, Kurashiki, Okayama 701-0192

1143 DOI: 10.2169/internalmedicine.45.6029

Figure 1. MRI on the 28th day after OPV intake. T2-weighted axial images of the midbrain (A) and the upper pons (B) revealed high intensity lesions in the left cerebral peduncle and the tegmentum of the upper pons, respectively. Coronal FLAIR image (C) revealed high intensitylesions in the truncus corpus callosum and central portions of the upper pons. Axial FLAIR images (C, D) showed high intensity lesions in the truncus of the corpus callosum. neurogenic findings in the right vastus lateralis, tibialis ante- completely disappeared in 2 months. rior and flexor digitorum longus on the 28th day after OPV. Electroencephalogram, electrocardiogram, visual, motor and Discussion short somatosensory evoked potentials, and brainstem audi- tory evoked potentials were normal. Diffusion-weighted im- We report a patient with acute paresis and brain MRI ab- aging (DWI), T2-weighted magnetic resonance imaging normalities after OPV intake. OPV has almost eradicated (MRI), and fluid-attenuated inversion recovery (FLAIR) on poliomyelitis, but it can cause VAPP in rare cases with a the 28th day after OPV intake showed high intensity signals morbidity incidence as low as one case per a few million in the tegmentum of the upper pons, left cerebral peduncle, (3). While our patient showed asymmetric paresis and CSF and truncus of the corpus callosum (Fig. 1). A second DWI, pleocytosis, her deep tendon reflexes were preserved, needle T2-weighted MRI, and FLAIR on the 38th day after OPV EMG showed no neurogenic changes, and there were no le- intake revealed high intensity signals in the right parietal sions of the spinal cord MRI, suggesting that motor neurons lobe in addition to the pons and corpus callosum (Fig. 2). in the spinal cord were not affected, and acute poliomyelitis Apparent diffusion coefficient was not decreased in the trun- was ruled out. cus of the corpus callosum. Gadolinium enhancements were Unexpectedly, brain MRI showed several lesions includ- present in the small parts of the corpus callosum and in the ing the upper pons, left cerebral peduncle, corpus callosum, right parietal lobe of the cortex. Cervical and thoracic MRIs and the right parietal lobe of the cerebral cortex. In polio- showed no abnormal findings of the anterior horn cells of myelitis, contrast enhancement in the anterior horn of the the spinal cord. We treated the patient with inravenous spinal cord has been described on MRI (5). With respect to methylprednisolone (1000 mg per day for 3 days) twice. the brainstem, Wasserstrom et al described a patient with The first methylprednisolone therapy was started on the 35th bulbar poliomyelitis in whom postmortem pathological tis- day, and the second one on the 42th day after OPV intake. sue sections reflected changes seen on MRI of the midbrain No oral corticosteroid therapy was given afterwards. The and medulla oblongata (6). Interestingly, an abnormal high clinical symptoms improved gradually with a decrease of intensity signal was described in the cerebral peduncles of pleocytosis and brain MRI abnormalities, and her symptoms the midbrain as seen in the present patient. Muscle weak-

1144 DOI: 10.2169/internalmedicine.45.6029

Figure 2. MRI on the 38th day after OPV intake. Axial FLAIR images show high intensity lesions in the right parietal cerebral lobe (A) and the truncus of the corpus callosum (C). Abnormal enhancements were observed in the right parietal cerebral lobe (B) and in the truncus of the corpus callosum (D) on gadolinium-enhanced T1-weighted images. ness in the right lower extremity in our patient may be at- was that post-infectious encephalitis had developed by tributed to the lesion in the left cerebral peduncle. We also immune-mediated mechanisms. ADEM has been described observed an abnormal high intensity signal mainly in the in one patient, and was associated with OPV (4). This 6- truncus of the corpus callosum. A reversible lesion in the year-old female patient showed spastic palsy, sensory distur- splenium of the corpus callosum has been reported in en- bances, visual deterioration, urinary incontinence, increased cephalopathy, encephalitis, ADEM and epilepsy, and two myelin basic protein, and lesions of the spinal cord on MRI. possible mechanisms have been postulated: intramyelinic Our patient showed symptoms of upper motor neuron in- edema and inflammatory infiltrates (7). In our study, the le- volvement, and the myelin basic protein or oligoclonal IgG sion in the tegmentum of the upper pons was unusual, and bands were not detected in CSF. Our patient’s neurophysi- seemed to correspond to decussation of the superior cerebel- ological examinations were normal. However, lesions in the lar peduncle. On the second MRI, the new lesion in the corpus callosum, upper pons, and cerebral peduncle might right parietal cortex appeared later, and contrast enhance- be explained by demyelination of the white matter. Though ments were observed in small regions of the corpus callo- multiple sclerosis must be considered as a differential diag- sum and right parietal cortex. These findings suggested that nosis, there are no new symptoms after recovery from her our patient might have had inflammatory infiltrates in the le- illness. Various white matter lesions and no detection of po- sions. liovirus in CSF suggest that she most likely had ADEM as- Why did our patient show various lesions on MRI? One sociated with OPV. possibility was that encephalitis had occurred by direct po- In conclusion, we reported a patient with acute paresis liovirus infection associated with OPV. Poliovirus was not and brain MRI abnormalities after OPV intake. There was detected in viral cultures of CSF or in the stool in our pa- no evidence of poliomyelitis, and the most probable diagno- tient. However, no virus was recovered from 24% of VAPP sis is ADEM associated with OPV. ADEM has not been re- patients (8), and we could not deny direct poliovirus infec- ported as a complication of inactivated polio vaccine (IPV). tion in our patient. In some VAPP patients, hyperactive re- OPV can also cause VAPP. While the incidence rate of com- flexes have been reported, and other authors speculated in- plications associated with OPV is very rare, the introduction volvement of the pyramidal tracts (8). Another possibility of IPV may be necessary in Japan.

1145 DOI: 10.2169/internalmedicine.45.6029

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