SUMMARY An unusual case of peripheral hypoglossal nerve palsy, caused by lateral position of the external carotid artery and an abnormally high carotid bifurcation is reported. Improvement followed ligation and cutting of the external carotid artery at its origin. Stroke Vol 15, No 4, 1984 VARIATIONS AND ANOMALIES are common at the bifurcation of the external and internal carotid arteries.1 Lateral position of the external carotid artery 2 " 6 formerly considered extremely rare, has recently been found to be more common.7 8 However, there are few reports, that this condition causes neurological signs.1 In this paper, a case of peripheral hypoglossal nerve palsy caused by lateral position of the external carotid artery and a carotid high bifurcation is presented.Case Report A 49-year-old man was admitted because of tongue deviation and dysarthria on December 8, 1980. At age 42, his blood pressure was found to be high and antihypertensive drugs were presented. He had felt throbbing pains in the occipital region beginning November 10, 1980, but these pains became intense from midday of November 21. At that time he visited a neurosurgical clinic, but no abnormalities could be found. On the morning of November 22, eating became difficult, and movement of the tongue was impeded, making speech inarticulate.Tongue deviation to the right and atrophy and fasciculation of the right lingual muscle were observed ( fig. 1). Tactile sensibility and taste sensation of the tongue were normal, and no abnormality of other cranial nerves was observed. There were no other abnormalities on neurological examination. Homer's sign was not presented and no bruit was heard in the neck. A diagnosis of peripheral hypoglossal nerve palsy with suspected hypoglossal neurinoma was made.A CT scan demonstrated no abnormality related to the right hypoglossal palsy. Right jugular venography revealed good filling by contrast medium and no abnormal findings. Tomography of the hypoglossal ca- nals, was normal. Bilateral carotid angiography and bilateral vertebral angiography were performed. No abnormalities were observed in the vertebral angiogram, except conspicuous elongation of the basilar artery. In the right carotid angiogram, marked lateral displacement of the right external carotid artery was noticed and the bifurcation of the external and internal carotid arteries was abnormally high (upper margin of the C 2 vertebra); there was conspicuous kinking and elongation of the external and internal carotid arteries and, in particular, prominent dilatation of the proximal portions of both arteries. In the lateral view of the angiogram, a loop-like elongation was observed 3.5 cm distal to the bifurcation ( fig. 2). In the left carotid angiogram, as in that of right side, the bifurcation was at a high level (center of C 2 vertebra) and elongation was conspicuous, but a lateral position of the external carotid artery was not seen.From this examination, the possibility of hypoglossal neurinoma was excluded and the following two mechanical processes wer...
