MAGNETIC RESONANCE IMAGING FINDINGS INACUTE CEREBELLITIS

ROHIT BAKSHI, MD, VERNICE E. BATES, MD,PETER R. KINKEL, MD, LASZLO L. MECHTLER, MD,AND WILLIAM R. KINKEL, MD

Cerebellitis, also known as acute cerebellar ataxia, is only been sparsely described, most commonly inyoung children (4–10). We present serial MRI, bothan inflammatory syndrome of cerebellar dysfunction

that may reflect an infectious, post-infectious, or post- with and without intravenous contrast, in a youngadult with a partially reversible, idiopathic, acutevaccination disorder. We present serial magnetic reso-

nance imaging (MRI) findings in a partially reversible, cerebellitis.idiopathic cerebellitis. Bilateral cerebellar parenchy-mal abnormalities were noted, including hyperintensi-ties on T2-weighted images and cerebellar swelling. CASE REPORTAfter contrast administration, the cerebellum showed A 21-year-old right-handed college student was ad-abnormal bilateral enhancement. The authors state mitted to the Dent Neurologic Institute with a 3-daythis represents the first report of abnormal contrast en- history of nausea, vomiting, and generalized weak-hancement in this condition. The MRI lesions most ness. Two days after symptom onset, he developedlikely reflect the reversible, inflammatory nature of an occipital headache, imbalance, and lethargy. Hethe syndrome. Elsevier Science Inc., 1998 denied previous illnesses, medication use, homosex-

uality, or substance abuse. On admission, he was ill-KEY WORDS: appearing, somewhat lethargic, and afebrile with sta-Magnetic resonance imaging; Cerebellitis; Infection; ble vital signs. No meningismus was detected. He

Central nervous system; Acute cerebellar ataxia was fully oriented, with normal language and mem-ory function. Speech was mildly dysarthric. The cra-nial nerve and sensory exam was unremarkable. Mo-

INTRODUCTION tor examination revealed mild right arm and legdystaxia, with normal power. Casual gait was wide-Cerebellitis is an inflammatory syndrome resultingbased and mildly ataxic; tandem walking was poor.in acute cerebellar dysfunction, which may occur asDeep tendon reflexes were physiologic and symmet-a primary infectious, post-infectious, or post-vacci-ric; plantar responses were flexor. A noncontrast cra-nation disorder (1–3). Also known as acute cerebel-nial computed tomography (CT) scan revealed mildlar ataxia, cerebellitis occurs most commonly incerebellar swelling and mild obstructive hydroceph-young children and may be difficult to diagnose onalus (not shown). Cerebrospinal fluid (CSF) studies,routine clinical and laboratory studies. Magnetic res-obtained by lumbar puncture, revealed a mild lympho-onance imaging (MRI) lesions in cerebellitis havecytic pleocytosis and an elevated protein (Table 1).On hospital day (HD) 2, an MRI scan (Picker 1.5 T,

From the Dent Neurologic Institute, Millard Filmore Health conventional spin echo) showed marked cerebellarSystem, Department of Neurology, University at Buffalo, Stateswelling; after contrast administration (intravenousUniversity of New York School of Medicine and Biomedical Sci-

ences, Buffalo, New York. gadoteridol), the cerebellum showed symmetric, bi-Address reprint requests to: Rohit Bakshi, MD, Lucy Dent Im-

lateral abnormal enhancement (Figure 1). A 14-dayaging Center, 3 Gates Circle, Buffalo, NY 14209.Received April 6, 1997; accepted May 2, 1997. course of intravenous acyclovir was initiated. On HD

CLINICAL IMAGING 1998;22:79–85 Elsevier Science Inc., 1998. All rights reserved. 0899-7071/98/$19.00655 Avenue of the Americas, New York, NY 10010 PII S0899-7071(97)00093-4

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Figure 1 continued

81MARCH/APRIL 1998 MRI IN ACUTE CEREBELLITIS

FIGURE 1. HD 2 (5 days after symptom onset). (A–E)T1-WI (TR/TE, 550/20), post-contrast. (A–C) Axial. (D–E)Sagittal. Cerebellar swelling is noted, resulting in mildbrain stem compression. The cerebellum shows markedabnormal areas of linear enhancement, both of the vermisand cerebellar hemispheres (arrows). (F–G) T2-WI (TR/TE,2300/80), axial. Moderate hyperintensities are noted of thecerebellum, corresponding to the regions of abnormal en-hancement.

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TABLE 1. Summary of CSF Findings

Hospital WBC Glucose Proteinday (% differential) RBC (mg/dL) (mg/dL) Negative studies

1 17 (100L) ,100 55 72 Cytology, bact., fung., kappa, toxo., VDRL, viral3 20 (98L, 2N) ,100 57 62 Cytology, bact., fung., India ink, TB, viral

Abbreviations: Bact. 5 routine bacterial culture; CSF 5 cerebrospinal fluid; fung. 5 fungal culture; kappa 5 free kappa light chains; L 5 lymphocytes;N 5 neutrophils; RBC 5 erythrocytes per high power field; TB 5 mycobacterial culture; toxo. 5 toxoplasmosis antibodies; VDRL 5 Venereal Disease ResearchLaboratory titer; viral 5 viral culture; WBC 5 white blood cells per high power field.

3, because of increasing lethargy and a repeat head active systemic infection. The CSF abnormalitiesand the reversible MRI findings of swelling, paren-CT showing a more prominent obstructive hydro-

cephalus (not shown), a ventriculostomy catheter chymal signal changes, and cerebellar enhancementpoint to a parainfectious or post-infectious inflam-was placed. Repeat MRI on HD 5 revealed increasing

severity of multiple abnormalities, including hydro- matory etiology. The improvement that occurredafter acyclovir therapy alone favors a viral cause. Acephalus, cerebellar hyperintense lesions on T2-

weighted images (T2-WI), cerebellar enhancement, definite etiology remains undetermined.The sensitivity of MRI for the detection of cerebel-and swelling, resulting in progressive brain stem

compression (Figure 2A to D). His headache, leth- litis is not known. Many patients with cerebellitishave been described with a normal MRI (1–3). Ab-argy, and nausea began to improve. A repeat noncon-

trast MRI on HD 10 showed significant improvement; normal noncontrast MRI findings in cerebellitis haveonly been described in a few case reports, many ofthe hydrocephalus, cerebellar swelling, and cerebellar

hyperintense lesions on T2-WI had diminished (Fig- which occurred in young children (4–10). Isolatedcerebellar abnormalities were noted, including pa-ure 2E to H). Neurological improvement was noted.

Unremarkable were serum antinuclear antibodies, renchymal hyperintensities on T2-WI, swelling, andtoxoplasmosis, cytomegalovirus, Epstein–Barr virus secondary obstructive hydrocephalus. Changes in-(EBV), human immunodeficiency virus (HIV) type 1, volved the cerebellar cortex more than the whiteand syphilis serologies, as well as viral cultures of matter. Follow-up studies showed reversal of thethe throat, rectum, and nasal mucosa. Outpatient re- acute changes and the development of atrophy inhabilitation therapy led to continued gradual clinical some instances. Only four previous patients had con-improvement during the next several months. Ten trast-enhanced MRI studies, each of which failed tomonths after symptom onset, much of this deficits detect abnormal enhancement (2, 6, 8, 10). Only onehad improved. Mild dysarthria and right hand dys- case of abnormal MRI findings demonstrating adultmetria persisted; his handwriting remained slow. Ca- cerebellitis has been presented to date; reversiblesual and tandem gait returned to normal. A repeat moderate cerebellar swelling and areas of increasedneuroimaging study was not performed. signal on T2-WI in the bilateral cerebellar cortex

were noted, without abnormal enhancement (10).Our noncontrast MRI findings are similar to the pre-

DISCUSSION vious findings in cerebellitis. The current report rep-resents the first description of abnormal contrast en-Cerebellitis (1–10), an encephalitis largely restrictedhancement in this condition.to the cerebellum, may occur as a primary infectious

The etiology of the MRI signal changes and en-or post-infectious inflammatory disorder due to ahancement in our case remains speculative. The cer-host of viral agents such as enteroviruses, herpes vi-ebellar swelling and parenchymal signal changesruses, HIV, and rabies. Bacterial infections have alsomost likely reflects an encephalitis, with edema andbeen associated with cerebellitis, including Borreliainflammation. The hyperintensities on T2-WI involvedburgdorferi (Lyme disease), Mycoplasma pneumon-the cerebellum diffusely and symmetrically, includingiae, Legionella, and Coxiella burnetti (Q fever). In ad-the vermis and cerebellar hemispheres; the grey mat-dition, cerebellitis may follow immunizations suchter appeared more abnormal than the white matter.as hepatitis, smallpox, and measles vaccination orThe abnormal cerebellar enhancement appeared lin-may occur without evidence for an antecedent orear and may represent leptomeningeal or intravascu-concurrent factor. Our patient most likely had a para-lar enhancement. In addition, the abnormal enhance-infectious or post-infectious viral cerebellitis. He de-ment may have involved the cerebellar parenchyma,veloped an idiopathic acute cerebellar ataxia with-

out clinical or laboratory evidence of a preceding or particularly the cortex, in areas corresponding to

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Figure 2 continued

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Figure 2 continued

85MARCH/APRIL 1998 MRI IN ACUTE CEREBELLITIS

FIGURE 2. HD 5 (A–D) and 10 (E–H). (A–D) Axial noncontrast T1-WI (A, B) and T2-WI (C, D). Clinical deterioration, HD 5.Compare to initial MRI (Figure 1). Cerebellar mass effect has increased, resulting in more compression of the pons (small arrows)and a more prominent obstructive hydrocephalus. The temporal horns of the lateral ventricles are more enlarged (larger arrows).The cerebellar hyperintense lesions on T2-WI are more apparent. The lesions on T2-WI involve both the cerebellar grey andwhite matter. (E–H) Axial T1-WI (E, F) and T2-WI (G, H). Clinical improvement; HD 10. Each of the abnormalities of the previousMRI of 5 days before have improved. Cerebellar swelling and secondary mass effect (E, F), and parenchymal hyperintensitieson T2-WI (G, H) have diminished and are even less prominent than the initial study (Figure 1).

2. Case records of the Massachusetts General Hospital; case 38-increased signal on T2-WI. The abnormal enhance-1996. N Engl J Med 1996;335:1829–1834.

ment in this condition may reflect leptomeningeal3. Mario-Ubaldo M. Cerebellitis associated with Lyme disease.inflammation, encephalitis, or perivenular compro- Lancet 1995;345:1060.

mise of the blood–brain barrier with alterations in4. Hayakawa H, Katoh T. Severe cerebellar atrophy following

cerebellar blood flow. acute cerebellitis. Pediatr Neurol 1995;12:159–161.We conclude that cerebellitis may be detected by 5. Hayashi T, Ichiyama T, Kobayashi K. A case of acute cerebel-

MRI in adults and may include abnormal contrast en- lar ataxia with an MRI abnormality. Brain Dev 1989;11:435–436.hancement. The changes on noncontrast MRI are

6. Horowitz MB, Pang D, Hirsch W. Acute cerebellitis: case re-similar to that which have been noted in young chil-port and review. Pediatr Neurosurg 1991;17:142–145.dren and most likely reflect the reversible, inflamma-

7. Hurst DL, Mehta S. Acute cerebellar swelling in varicella en-tory nature of the syndrome.cephalitis. Pediatr Neurol 1988;4:122–123.

8. Lester A, Alpigiani MG, Franzone G, Cohen A, Puleo MG,We wish to thank Kim Marie Malicki, Evelyn Calderon, Janice To-Tortori-Donati P. Magnetic resonance imaging in right hemi-karczyk, Joan Schurr, and James Pierotti for technical assistance.sphere cerebellitis associated with homolateral hemiparesis.

We acknowledge the Kidney Health Sciences Library staff for as- Childs Nerv System 1995;11:118–120.sistance with the literature review.

9. Nakagawa E, Yamanouchi H, Sakuragawa N, Takashima S.Vermis lesions in acute cerebellar ataxia: a sequential imagingstudy. Brain Dev 1994;16:488–490.

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