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Dysgeusia resulting from internal carotid dissection. A limited glossopharyngeal nerve palsy
  1. Service de Neurologie 1, Clinique Paul Castaigne, Hôpital de la Salpêtrière, 47 Boulevard de l’Hôpital, 75651 Paris Cedex 13, France
  1. Dr B Bazin, Service de Neurologie 1, Clinique Paul Castaigne, Hôpital de la Salpêtrière, 47 Boulevard de l’Hôpital, 75651 Paris Cedex 13, France. Telephone 0033 142161811; fax 0033 142176061.

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Cases of internal carotid artery dissection resulting in palsies of the cranial nerves are now well known.1 The nerve most often involved is the hypoglossal nerve, either individually or in association with other lower cranial nerves.1 2 We report on a patient with glossopharyngeal nerve (IXth) damage without involvement of other lower cranial nerves, resulting from a limited internal carotid artery dissection, a syndrome not previously described.

A 54 year old man suddenly developed a left periorbital headache without cervicalgia, and a left sided Horner’s syndrome. On subsequent days, he developed dysgeusia and a left inferior sore throat in swallowing. No recent relevant cervical or cranial trauma was reported. However, the patient had been in the habit of performing lateral and flexion-extension movements of the neck every morning, and had cut branches of a tree three days before the initial symptoms. On clinical examination, left-sided Horner’s syndrome and dysgeusia, with involvement of the posterior third of the left hemitongue, were found. Protraction of the tongue was normal. Examination of pharyngeal and vocal cord motricity showed no abnormality. Audiometry and a study of the stapedial reflex were normal. The other cranial nerves were normal. Brain MRI showed a crescent shaped area of high intensity in the prepetrosal portion of the left internal carotid artery, involving the medial part of this artery (figure, A). The angiography of the four arterial axes showed an irregular 2 cm stenosis limited to the prepetrosal part of the left internal carotid artery (figure, B). No local aneurysm was present and other arteries were normal.

(A) Axial T1 weighted MRI shows a medial and posterior mural haematoma around the internal carotid artery.(B) Lateral view of left internal carotid arteriogram shows a stenosis circumscribed in the prepetrosal segment of the internal carotid artery. (C) Diagrammatic parasagittal slice of the skull at the level of the internal carotid artery showing the internal carotid artery and nearby cranial nerves. Open circle indicates the presumed location of the mural haematoma, where the IXth nerve crosses medially the internal carotid artery. The XIIth nerve is located more laterally and therefore not seen in this schema.

Dysgeusia associated with a left inferior sore throat and left sided Horner’s syndrome were noted in our patient, who presented with an arterial dissection of the internal carotid artery. The prepetrosal segment of the artery is involved in all internal carotid artery dissections resulting in ipsilateral cranial nerve palsies.1 Horner’s syndrome, which is due to a sympathetic nerve involvement at the same level, is also seen in more than 50% of patients with such a dissection.3

Dysgeusia has already been reported in internal carotid artery dissection.1 3-5 It indicates a IXth nerve or a chorda tympani involvement. A taste deficit in the posterior third of the ipsilateral hemitongue suggests damage to the IXth nerve. The existence of a left inferior sore throat, which could correspond to the sensitive laryngeal territory of this nerve, supports such a hypothesis. Isolated dysgeusia, presumably due to chorda tympani palsy, has already been reported, but in that case, the taste deficit is supposed to involve the anterior part of the tongue; moreover, such a mechanism is unlikely in our patient, as the chorda tympani emerges from the skull by the fissura petrotympanica, which is located more than 1 cm lateral and anterior from the carotidian canal.4 5 Therefore, dysgeusia was more probably due to direct compression of the IXth nerve by the mural haematoma seen in MRI. The lesion was located at the level of the second cervical vertebra, where the IXth nerve crosses the internal carotid artery medially (figure C).

When the IXth nerve is involved, other lower cranial nerves are usually affected, most often the hypoglossal nerve (XII).1 2Nerves X and XI are the other lower cranial nerves usually involved in cases of IXth nerve palsy.1 All these nerves emerge together from the skull by the foramen jugular and are therefore close to each other at the prepretrosal level. However, it should be noted that, at this level, the IXth nerve is closer to the internal carotid artery than the Xth and XIth nerves and, and may therefore be the only nerve affected by a small mural haematoma such as that in our patient.

Dysgeusia related to an isolated glossopharyngeal palsy in a case of internal carotid artery dissection has not, to our knowledge, previously been reported. The absence of involvement of other cranial nerves in our patient may be explained by the limited vertical extent of the dissection, which affected only the final prepetrosal segment of the internal carotid artery at level C2. The dissection thus spared the XIIth nerve, located at a lower level (third cervical vertebra), and the Vth and VIIth nerves, located at a higher level. Furthermore, the small lateral extent of the mural haematoma would seem to explain why the Xth and XIth nerves were spared.