INTRACTABLE HICCUP INDUCED BY BRAIN-STEM LESION

Four patients with brainstem lesions presented with intractable hiccup and mild to moderate neurological signs. Two of the patients had been initially diagnosed as having a psychogenic cause for their hiccup. Magnetic resonance imaging (MRI) demonstrated brainstem infarction in one case, tuberculoma at the junction of the medulla oblongata and the cervical spinal cord in two, and a vermian tuberculoma compressing the brainstem in one. The brainstem infarct and one of the medullary tuberculoma were not detected on high resolution enhanced computed tomography. The 3 patients with CNS tuberculoma were free of hiccup 1-5 months after antituberculous chemotherapy. It is proposed that hiccup is not an abnormal reflex, but a myoclonus generated by repetitive activity of the "inspiratory solitary nucleus" due to release of higher nervous system inhibitory/-regulatory control. The neuroanatomical network and the mechanisms underlying the formation of intractable hiccup are outlined. The value of MRI in the initial diagnosis and follow-up of patients with intractable hiccup due to brainstem lesions is emphasised.