Paraneoplastic Brainstem Encephalitis Associated with Anti-Hu Antibody

Abstract

Introduction: Paraneoplastic neurological syndromes (PNS) occur in less than 1% of patients with cancer mainly small-cell lung carcinoma (SCLC). PNS may present as brainstem encephalitis, isolated or as a part of paraneoplastic encephalomyelitis. Seropositivity for anti-Hu antibodies is associated with small-cell lung carcinoma (SCLC) in 87% of cases. The tumour is generally confined to the mediastinum. Seropositivity for anti-Hu associated with brainstem encephalitis was described in approximately 20 cases. Clinical case: A 63-year-old-woman, with previous history of hysterectomy with bilateral anexectomy, referred fatigue and weight loss since November/03. In July/04 she presented with hypophonia, dysphonia, dysphagia, right-gaze impairment, abolished pharyngeal reflex, right hemiparesis and ataxia. T2-weighted MRI showed high signal in the posterior medulla and pons, with no abnormal contrast enhancement. CSF was normal, except for positive oligoclonal bands. Infectious and immunological investigations were negative. Thoracic-CT revealed a 3.5 cm sub-carinal nodule. Serum anti-neuronal antibodies study was positive for anti-Hu. The patient received high-dose corticosteroid and intravenous immunoglobulin therapy, but, in August/04, new neurological deficits emerged, presenting complete ophtalmoparesis, jaw opening dystonia and increased dysfagia. Two months later, a progressive hypoventilation syndrome installed, in spite of tracheostomy and BIPAP ventilatory support. She died in February/05, from respiratory failure. Discussion: We present a case of paraneoplastic brainstem encephalitis, diagnosed by anti-Hu antibodies study, probably associated with SCLC. Recently uniformized diagnostic criteria for these rare entities are discussed.