Dados do Trabalho

Título

Dentate nucleus hyperintensity: an important diagnostic clue in a woman with encephalopathy

RESUMO

Case Presentation
A 56-year-old woman with invasive ductal carcinoma was admitted to the gynaecology department with a 2-week history of somnolence, weakness, mental confusion and reduced fluency of speech. Two months before onset of current symptoms, she had been hospitalized due to a febrile neutropenia, herpes-zoster and a local infected large ulcer on her right hemithorax. Because of this skin lesion, topic metronidazole was prescribed. About two weeks later, she started with the referred symptoms. Metabolic causes were discharged and the only alteration was a pleural effusion with unproven malignancy involvement. Neurologic evaluation was requested and a severe encephalopathy without focal deficits was diagnosed. Brain magnetic resonance imaging (MRI) revealed T2/FLAIR hyperintensities in dentate nuclei and white matter nonspecific lesions. Cerebrospinal fluid was normal and electroencephalogram showed nonspecific findings. The diagnosis of metronidazole induced encephalopathy was made because of history taking and MRI patterns. Hence, the antibiotic was immediately suspended.

Discussion
Encephalopathy may be caused by toxic, metabolic, infectious and autoimmune mechanisms. Metronidazole-induced brain toxicity can cause altered mental status, seizures and cerebellar ataxia with a wide variation of doses and time of use. In up to 93% of cases of this intoxication, MRI shows bilateral T2/FLAIR hyperintensities in dentate nuclei, which is a very specific pattern. The radiologic differential must be taken with inborn errors of metabolism, totally discharged in the presented case because of the patient's past medical history. Hence, we assume that the extent of the ulcer being treated with topic metronidazole had great cutaneous absorption and within some weeks the antibiotic intoxication led to the current symptoms. In such cases, the antibiotic must be promptly suspended and most patients show mental status improvement.

Final Comments
The aim of this case report is to present an uncommon diagnosis in which MRI pattern recognition and a well-taken anamnesis are essential to the final diagnosis. The faster the metronidazole suspension, the better the patient's prognosis. Neurologists must be familiarized with this cause of encephalopathy.

Palavras Chave

Metronidazole; Encephalopthy