Rhombencephalitis: pictorial essay / Rombencefalites: ensaio iconográfico

Abstract The term rhombencephalitis refers to inflammatory diseases affecting the hindbrain (brainstem and cerebellum). Rhombencephalitis has a wide variety of etiologies, including infections, autoimmune diseases, and paraneoplastic syndromes. Infection with bacteria of the genus Listeria is the most common cause of rhombencephalitis. Primary rhombencephalitis caused by infection with Listeria spp. occurs in healthy young adults. It usually has a biphasic time course with a flu-like syndrome, followed by brainstem dysfunction; 75% of patients have cerebrospinal fluid pleocytosis, and nearly 100% have an abnormal brain magnetic resonance imaging scan. However, other possible causes of rhombencephalitis must be borne in mind. In addition to the clinical aspects, the patterns seen in magnetic resonance imaging can be helpful in defining the possible cause. Some of the reported causes of rhombencephalitis are potentially severe and life threatening; therefore, an accurate initial diagnostic approach is important to establishing a proper early treatment regimen. This pictorial essay reviews the various causes of rhombencephalitis and the corresponding magnetic resonance imaging findings, by describing illustrative confirmed cases.

Resumo O termo rombencefalite se refere a doenças inflamatórias que afetam o rombencéfalo (tronco cerebral e cerebelo). Rombencefalites possuem grande variedade de causas, incluindo infecciosas, autoimunes e síndromes paraneoplásicas. Listeria é a causa mais comum das rombencefalites infecciosas. A rombencefalite primária por Listeria ocorre em adultos jovens e saudáveis, com um curso de tempo bifásico, como uma síndrome gripal acompanhada de disfunção do tronco cerebral. Em 75% dos pacientes manifesta-se pleiocitose no líquido cefalorraquidiano e em quase 100% a ressonância magnética cerebral é anormal. Mas há outras causas possíveis para rombencefalites que devem ser lembradas. Além de aspectos clínicos, os padrões de imagem encontrados na ressonância magnética podem ser úteis na definição da possível causa. Algumas das causas descritas de rombencefalites são potencialmente graves e fatais; assim, uma abordagem diagnóstica inicial precisa é importante para estabelecer um tratamento precoce adequado. Este ensaio iconográfico revisa as diversas causas de rombencefalites e os seus achados de ressonância magnética, por meio de casos ilustrativos confirmados.

A Wide Spectrum of Axial Mesodermal Dysplasia Complex With Rhombencephalic Anomaly: A Case Report

Axial mesodermal dysplasia complex (AMDC) arises in variable combinations of craniocaudal anomalies such as musculoskeletal deformities, neuroschisis, or rhombencephalic developmental disorders. To the best of our knowledge, the co-existence of AMDC with associated musculoskeletal anomalies, medullary neuroschisis with mirror movements, and cranial nerve anomalies has not yet been reported. Here, we report the case of a 4-year-old boy whose clinical features were suggestive of Goldenhar syndrome and Poland syndrome with Sprengel deformity. Moreover, he showed mirror movements in his hands suspected of rhombencephalic malformation, and infranuclear-type facial nerve palsy of the left side of his face, the opposite side to the facial anomalies of Goldenhar syndrome. After conducting radiological studies, he was diagnosed with medullary neuroschisis without pontine malformations and Klippel-Feil syndrome with rib anomalies. Based on these findings, we propose that clinical AMDC can be accompanied by a wide variety of musculoskeletal defects and variable degrees of central nervous system malformations. Therefore, in addition to detailed physical and neurological examinations, imaging studies should be considered in AMDC.

Acute Disseminated Encephalomyelitis Presenting as Rhombencephalitis: An Atypical Case Presentation

Acute disseminated encephalomyelitis (ADEM) is a demyelinating and inflammatory condition of the central nervous system, occurring predominantly in white matter. ADEM involving the rhombencephalon without affecting the white matter is very rare. Here, we present an unusual case of ADEM involving only the rhombencephalon in a 4-year-old Asian girl. The patient complained of pain in the right lower extremities, general weakness, ataxia, and dysarthria. The initial brain CT showed subtle ill-defined low-density lesions in the pons and medulla. On brain MRI, T2 high signal intensity (T2-HSI) lesions with mild swelling were present in the pons, both middle cerebellar peduncles, and the anterior medulla. The initial diagnosis was viral encephalitis involving the rhombencephalon. Curiously, a cerebrospinal fluid (CSF) study revealed no cellularity, and negative viral marker findings. Three weeks later, follow up brain MRI showed that the extent of the T2-HSI lesions in the brain stem had decreased. After reinvestigation, it was found that she had a prior history of upper respiratory infection. In this case, we report the very rare case of a patient showing isolated involvement of the rhombencephalon in ADEM, mimicking viral rhombencephalitis on CT and MR imaging. ADEM can involve unusual sites such as the rhombencephalon in isolation, without involvement of the white matter or deep gray matter and, therefore, should be considered even when it appears in unusual anatomical areas. Thorough history taking is important for making a correct diagnosis.