[Causes of paralysis of the hypoglossal nerve. Apropos of 32 cases].

Thirty-two consecutive cases of hypoglossal nerve palsy (excluding syringomyelia and amyotrophic lateral sclerosis) collected between 1971 and 1987 were reviewed. The XIIth nerve palsy was clinically isolated in 8 cases, associated with other cranial nerve palsies in 16 cases and with long tracts involvement in 8 cases. Seventeen cases were related to tumours. Malignant tumours were predominant, especially middle and posterior fossa bone metastases. Carcinomatous meningitis and brainstem glioma were also found, as well as lymphoproliferative disorders and benign tumours such as chemodectoma and neurinoma. A vascular origin was established in 6 cases, related to vertebrobasilar infarct, truncular ischaemia and internal carotid dissection. The paralysis was consecutive to head or neck trauma in 4 cases and to various inflammatory processes in 4 other cases. The last case was caused by Chiari's malformation. To our knowledge, this is the first aetiological review of XIIth nerve palsy in the literature.