Journal of Clinical Neuroscience xxx (2013) xxx–xxx

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Journal of Clinical Neuroscience

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Case Report

Acute pseudotumoral hemicerebellitis: Diagnosis and neurosurgicalconsiderations of a rare entity

0967-5868/$ - see front matter � 2013 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.jocn.2013.04.006

⇑ Corresponding author. Tel.: +972 2 677 7092.E-mail address: jcohenns@yahoo.com (J.E. Cohen).

Please cite this article in press as: Cohen JE et al. Acute pseudotumoral hemicerebellitis: Diagnosis and neurosurgical considerations of a rare entitNeurosci (2013), http://dx.doi.org/10.1016/j.jocn.2013.04.006

José E. Cohen a,b,⇑, Moshe Gomori a,b,c, Moni Benifla a, Eyal Itshayek a, Yigal Shoshan a

a Department of Neurosurgery, Hadassah-Hebrew University Medical Center, P.O. Box 12000, Jerusalem 91120, Israelb Department of Endovascular Neurosurgery and Interventional Neuroradiology, Hadassah-Hebrew University Medical Center, Jerusalem, Israelc Department of Radiology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel

a r t i c l e i n f o a b s t r a c t

Article history:Received 3 April 2013Accepted 8 April 2013Available online xxxx

Keywords:Acute disseminated encephalomyelitisCerebellar tumorCerebellitisPosterior fossa decompression

Acute pseudotumoral hemicerebellitis is an exceptionally rare unilateral presentation of acute cerebellitismimicking a tumor. It typically has a benign course without specific therapy; thus, recognizing this entityis important to avoid needless surgical intervention. MRI provides the key for diagnosis and usuallyreveals a diffusely swollen cerebellar hemisphere with no well-defined mass. Some patients will requireneurosurgical assistance by means of ventriculostomy or posterior fossa decompression. We present a17-year-old girl with pseudotumoral hemicerebellitis, review the available literature, and discuss thediagnosis and therapeutic dilemma from the neurosurgical perspective.

� 2013 Elsevier Ltd. All rights reserved.

1. Introduction

Acute pseudotumoral hemicerebellitis is a very rare presenta-tion of cerebellitis in children. Patients may present with a varietyof symptoms, ranging from headaches to cranial nerve palsies thatare attributable to ventricular or brainstem compression. MRI canassist in excluding a tumor and establishing a diagnosis of acutecerebellitis based on the absence of a well-defined mass and thepresence of pial enhancement along the cerebellar folia, togetherwith a hyperintense T2 signal, and a hypointense T1 signalabnormality.

Most patients recover from acute cerebellitis without specifictreatment, although antiviral medications, steroids, and mannitolare administered in some patients.1,2 Close monitoring is usuallyadvised due to the potential for cerebellar swelling that may resultin compression of the fourth ventricle and obstructive hydroceph-alus requiring ventriculostomy or posterior fossa decompres-sion.3,4 We report a pediatric patient with acute hemicerebellitisthat resembled a tumor on imaging studies, review the availableliterature, and focus the discussion from a neurosurgicalperspective.

2. Case report

A 17-year-old girl was admitted to our hospital with a historyof headaches, dizziness, gait imbalance, and recurrent episodes

nausea and vomiting. Two weeks earlier she had developed anextensive cutaneous rash but no fever. At admission, the patientwas febrile, oriented, and conscious. She complained of headachesand dizziness. Her neurological examination revealed nystagmuswith left dysmetria and adiadochokinesis, as well as findings com-patible with left hemispheric cerebellar syndrome. No signs ofmeningeal irritation were found. A fundoscopic evaluation showedpapilledema. Her hematological examination was unremarkable.Hepatic and renal function tests and coagulation profile were inthe normal range. A lumbar puncture was not performed and thuscerebrospinal fluid (CSF) studies were not available. A head CT scanshowed an ill-defined poorly-enhancing hypodense area in the leftcerebellar hemisphere causing mass effect and signs ofhydrocephalus.

MRI revealed a diffusely swollen left cerebellar hemispherewithout a well-defined mass, appearing hypointense on T1-weighted images, and hyperintense on the T2-weighted (Fig. 1A)and fluid-attenuated inversion recovery (FLAIR) studies. Pialenhancement was noted in post-contrast studies (Fig. 1B). Therewas a moderate mass effect on the fourth ventricle and brainstem.No diffusion restriction was seen. The possibility of hemicerebelli-tis was considered.

Acyclovir and steroids were initiated. Cultures and neutrophilicvirus antibodies, as well as polymerase chain reaction (PCR) anal-ysis for herpes and tuberculosis were negative in blood studies.Unrevealing laboratory tests included the following: a completeblood count with differential, C-reactive protein, alanine amino-transferase, aspartate aminotransferase, and serum measurementsfor toxoplasma and rickettsia antibodies.

y. J Clin

Fig. 1. (A) Axial T2-weighted MRI of a 17-year-old girl showing a swollen left cerebellar hemisphere with hyperintense signal. (B) Axial contrast-enhanced T1-weighted MRIshowing pial enhancement.

2 Case Report / Journal of Clinical Neuroscience xxx (2013) xxx–xxx

The patient’s neurological status gradually improved and re-peat contrast-enhanced MRI performed 3 weeks after admissionrevealed a decrease in swelling and mass effect of the left cere-bellar hemisphere (Fig. 2). Signal abnormalities were much lessprominent and the pial enhancement had resolved. The patientcompletely recovered and was discharged 4 weeks afteradmission.

Fig. 2. Axial fluid attenuated inversion recovery MRI 3 weeks after that in Fig. 1showing regression of swelling with residual hyperintense signal in the affectedcerebellar hemisphere.

Please cite this article in press as: Cohen JE et al. Acute pseudotumoral hemicerNeurosci (2013), http://dx.doi.org/10.1016/j.jocn.2013.04.006

3. Discussion

Acute cerebellitis is one of the major causes of cerebellar dys-function in children and adolescents. It may result from viral orautoimmune etiologies and has a benign course in the majorityof patients, as was seen in our patient.

Hemicerebellitis is considered rare,5,6 and pseudotumoralhemicerebellitis as described in this report is exceptionallyrare.7–9 Although hemorrhage is not a recognized feature of thedisease, pseudotumoral hemicerebellitis with hemorrhage was re-cently reported in a 12-year-old boy with with coagulopathy.10,11

The mean and median age at the time of diagnosis of 33 patientsreviewed by De Bruecker et al. was 13 and 11 years, respectively(range 1–64 years).5 The origin of this para-infectious disorderhas been variously attributed to the varicella-zoster virus, Ep-stein–Barr virus, rubeola, pertussis, diphtheria, or the coxsackievirus,7,12 and patients with cerebellitis caused by Coxiella burnetti,Mycoplasma pneumoniae, Borrelia burgdorferi, rotavirus and the hu-man herpes virus have also been reported.2,4,13–15 However, morethan half of the reviewed patients with cerebellitis were reportedas idiopathic.

As seen in acute disseminated encephalomyelitis (ADEM), clin-ical manifestations of cerebellitis may occur from days to weeksafter a viral illness. The differential diagnosis includes posteriorfossa tumor, demyelination/ADEM, cerebellar infarct, and dysplas-tic cerebellar gangliocytoma (Lhermitte–Duclos disease).1 Thediagnosis depends on findings from CSF examination and MRI,the modality of choice for diagnosis as for any posterior fossaabnormality. In cerebellitis, CT scans may be completely normalor show low-density areas in the cerebellar hemisphere. In theacute setting, CT scanning is indicated mainly to exclude evidenceof raised intracranial pressure.

In cerebellitis, CSF is usually normal and MRI shows cerebellarswelling associated with variable degrees of pial enhancementalong the cerebellar folia. Contrary to ADEM, abnormal findingsare restricted to the cerebellum, with the absence of cerebral orbrainstem lesions.16 MRI demonstrates the cerebellar involvementthat may remain undetected on CT scans. In contrast to ADEM,acute cerebellitis is typically characterized by diffuse abnormali-ties in both cerebellar hemispheres, but absence of cerebral orbrainstem lesions and pial enhancement along the folia is a fre-

ebellitis: Diagnosis and neurosurgical considerations of a rare entity. J Clin

Case Report / Journal of Clinical Neuroscience xxx (2013) xxx–xxx 3

quent finding. MRI typically reveals bilaterally symmetricenhancement with a hypointense signal on T1-weighted imagesand hyperintensity on T2-weighted and FLAIR images.5,7,12 On fol-low-up scans, mass effect tends to diminish and then disappear,leaving a residual hyperintense signal on T2-weighted MRI thatpersists even after symptoms have improved, as well as variabledegrees of cerebellar atrophy.

Other much less frequent patterns of cerebellar involvementhave been described, including involvement of one cerebellarhemisphere (hemicerebellitis), both cerebellar hemispheres andthe vermis, and even a normal MRI appearance.5–9 In dysplasticcerebellar gangliocytoma, MRI reveals a cerebellar mass with atypical striated, ‘‘corduroy’’, or ‘‘tiger-striped’’ folial pattern thatconsists of alternating bands on both T1- and T2-weighted images.The bands are hyper- and iso-intense relative to gray matter on T2-weighted images17 and iso- and hypo-intense on T1-weightedimages. Most dysplastic gangliocytomas do not enhance. Patholog-ical specimens obtained after biopsy for unclear mass lesions con-firmed parenchymal chronic inflammation without necrosis,abscess, or granuloma formation, with negative cultures and PCRfor microorganisms.7,18

Acute cerebellitis presents a variable clinical course. Mild, mod-erate, severe, and even fulminant cases leading to death have beendescribed and thus each patient must be treated and consideredindividually based on clinical and radiological condition and pro-gression.17–21 Gradual development of severe cerebellar atrophyhas been reported in association with recurrence of cerebellarataxia.18 Treatment consists of supportive measures, steroids,antivirals, and mannitol. Surgical procedures such as external ven-tricular drain and posterior fossa decompression, that is, craniec-tomy and duroplasty with or without tonsillar or parenchymalresection,1,2,4,7,19,20 may be required to achieve decompression.The most common presenting symptoms include truncal ataxia,dysmetria, and headache, as well as positive cerebellar signs, andan altered mental state. Mild and moderate patients with stableclinical and radiological findings should be closely monitored withserial MRI. In severe patients with progressing symptoms, markedcerebellar swelling with fourth ventricle collapse may result inobstructive hydrocephalus, requiring steroids and placement ofan external ventricular drain.

Hydrocephalus can be attributed to progressive inflammatorysubarachnoid space obstruction preventing CSF reabsorption com-bined with fourth ventricle obstruction.7 Our patient presentedwith hydrocephalus and papilledema; however, the fourth ventri-cle was displaced but clearly patent. This led us to consider hydro-cephalus as non-obstructive in the early stages. As usual,ventriculostomy in a tight posterior fossa setting should be care-fully evaluated, and is indicated only after consideration of poster-ior fossa decompression has been discussed. Patients withventriculostomy who do not achieve posterior fossa decompres-sion should be closely monitored in an intensive care setting dueto the low but real risk of upward herniation. In patients wherecerebellar swelling results in brainstem compression or whenpatients deteriorate despite aggressive medical management,

Please cite this article in press as: Cohen JE et al. Acute pseudotumoral hemicerNeurosci (2013), http://dx.doi.org/10.1016/j.jocn.2013.04.006

aggressive surgical measures consisting of external ventriculardrainage and posterior fossa decompression must be considered.

Pseudotumoral hemicerebellitis as described in this report israre, but should be kept in mind when dealing with a young pa-tient presenting with an acute cerebellar syndrome and the previ-ously described radiological findings to avoid an unnecessaryneurosurgical intervention. Although the role of neurosurgeons islimited to clinical–radiological monitoring of the moderate formsof the disease, active intervention is essential and can be life-sav-ing in patients with unusual, severe forms of this disease who re-quire decompression.

Conflict of interest/disclosure

The authors declare that they have no financial or other con-flicts of interest in relation to this research and its publication.

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ebellitis: Diagnosis and neurosurgical considerations of a rare entity. J Clin