Dados do Trabalho

Título

A rare case of isolated nuclear oculomotor palsy due to a Pure Midbrain Infarction in a healthy teenager

Apresentação do caso único

14-years-old healthy girl, using progestin-only contraceptive injectable, suddenly presented with vertical binocular diplopia worsened with conjugate horizontal gaze to the left, blurred vision and difficulty walking due to diplopia. She denies ocular pain and other neurological or systemic symptoms. Examination of the left eye revealed reduced visual acuity, fixed dilated pupil, downward and outward deviation in primary gaze and impaired adduction, supradduction and convergence. She also had bilateral ptosis worse on the left and horizontal nystagmus evoked when looking to the right. Fundoscopy and tonometry were normal. There were no further alterations in neurological examination. Computed tomography (CT) of the head and CT angiography of the cerebral arteries were normal, however MRI evidenced a subacute ischemic lesion in the left midbrain tegmentum involving the oculomotor nerve nucleus. Laboratory exams were normal, including metabolic and inflammatory tests, hemoglobin electrophoresis, serologies, rheumatogram and investigation of thrombophilias and antiphospholipid syndrome. Cerebrospinal fluid and IgG index were normal and oligoclonal bands was absent. Transthoracic echocardiogram with bubble test and electrocardiogram were also normal. She started treatment with acetylsalicylic acid 100 mg/day. Control angiography MRI evidenced signs of vasculitis of small/medium arteries, although previous exams were unremarkable.

Discussão

incidence of pediatric stroke is up to 13 cases per 100.000 children and pure midbrain infarction is even more uncommon because of the complex blood supply of mesencephalon, corresponding to around 0.7% of all the posterior circulation strokes. In addition, until now there are no reported cases in younger than 30 years-old. Because ischemia of neighboring structures other neurological symptoms is usually present in midbrain infarct and unilateral third nerve palsy mimicking peripheral nerve lesion can delay diagnosis.

Comentários finais

there is many causes to isolated unilateral oculomotor paresis, however pure midbrain stroke as we exposed here is very rare, especially in this age. The sudden presentation and bilateral ptosis suggesting involvement of the central caudal nucleus of the oculomotor complex were key points, allowing early diagnosis and adequate management. We also highlight that, particularly in young people, initial investigation is not always sufficient to define etiology therefore, longitudinal follow-up is crucial.

Referências

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Palavras Chave

stroke; oculomotor nucleus; midbrain