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Year : 2000  |  Volume : 10  |  Issue : 1  |  Page : 48-49
Unilateral cranial nerve palsies - An unusual presentation of spontaneous internal carotid artery dissection

N M Medical Centre, Mumbai, India

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How to cite this article:
Bhaya A. Unilateral cranial nerve palsies - An unusual presentation of spontaneous internal carotid artery dissection. Indian J Radiol Imaging 2000;10:48-9

How to cite this URL:
Bhaya A. Unilateral cranial nerve palsies - An unusual presentation of spontaneous internal carotid artery dissection. Indian J Radiol Imaging [serial online] 2000 [cited 2021 Feb 28];10:48-9. Available from:
Dear Sir,

A case of unilateral lower cranial nerve palsies due to spontaneous dissection of the ipsilateral internal carotid artery is presented.

The patient was a healthy 34-year old man with a short history of fever and upper respiratory tract infection, who presented with sudden onset of slurring of speech and dysphasia. On examination, he was found to have multiple left lower cranial nerve palsies (IX to XIIth -  Collet-Sicard syndrome More Details) without any pyramidal or cerebellar signs. There was no evidence of raised intracranial tension. Although he had spasmodic cough there was no history of trauma or any unusual neck movement. There was no history of hypertension or any past clinical illness.

An MR was performed using T1W and T2W spin-echo sequences in the axial and coronal planes. Additional T1W fat-suppressed images were obtained through the upper neck and skull base, in the transverse plane.

MR revealed a dissecting mural thrombus within the left internal carotid artery (ICA) originating distal to its origin in the proximal neck and extending to the petrous segment. The thrombus was hyperintense on T1W images (representing methemoglobin), semilunar in shape and had a spiral configuration along the course of the artery. The artery was enlarged at the level of the left retrostyloid space [Figure - 1] partially compressing the jugular vein. There was no parenchymal abnormality. Additional MR angiograms using the 2D time of flight technique through the course of the internal carotid artery, demonstrated the characteristic string sign - tapered long segment narrowing of the artery [Figure - 2]. A well-defined intimal flap was also noted on the axial raw data images. The rest of the vessels were normal. The patient was treated with anticoagulants (low molecular weight heparin followed by oral anticoagulants). The IX-XIth nerve palsies resolved completely within 7-10days. However, a partial left XIIth nerve palsy and mild left hemiatrophy of the tongue remained.

Dissection of the extracranial internal carotid artery is a recognized cause of ischemia, particularly in young persons who present with acute neurologic deficits both transient and permanent. Trauma and arteriopathies have been implicated as causative factors. In their absence, the dissection is termed spontaneous. In one reported series, the most common symptom was ipsilateral severe headache (89%) while cranial nerve palsy was seen in only 5% of cases [1]. Cranial nerve palsies could either be due to compression by the enlarged internal carotid artery wall or ischemia of the nerves. In patients with multiple palsies (IX-XIIth) compression due to the enlarging ICA mural hematoma is implicated as the primary cause [2]. The III, IV and VIth cranial nerves may be affected when the dissecting hematoma extends into the cavernous portion of the ICA. MR in combination with MR Angiography (MRA) is reported to be more accurate than conventional catheter angiography in the diagnosis of carotid artery dissection (sensitivity and specificity of 100% for MR and MRA as against 91.6% and 100%, respectively, for conventional angiography) [3]. When the dissection occurs in the subadventitial layer without significant narrowing of the arterial lumen, conventional angiography does not yield a reliable diagnosis.

Ultrasound may also be helpful in demonstrating a mobile or fixed echogenic intimal flap with or without an associated intraluminal thrombus. A striking image/Doppler mismatch with an abnormal pulsed Doppler waveform is also suggestive of dissection. Duplex US is less reliable than angiography and MR primarily because the dissection is usually distal to the region that can be well seen on US [4]. CT angiography generally reveals eccentric contrast enhancement (corresponding to the residual lumen) surrounded by relative hypodensity (corresponding to the mural hematoma) itself surrounded by thin annular enhancement. Although more experience is needed with this technique, early reports reveal promising results for the detection neck dissection [5]. MR reveals an eccentric signal void (corresponding to the residual lumen) surrounded by a semilunar hyperintensity (corresponding to a mural hematoma) on T1W images. Fat suppressed axial T1W images with inferior saturation pulses are probably the single most useful MR sequence [4]. In addition there is enlargement of the artery due to the hematoma. MRA generally demonstrates a gradual tapered occlusion beginning distal to the carotid bifurcation - the string sign [6].

Cervical internal carotid artery dissection has a fairly good overall prognosis. Treatment includes heparin in the acute stages followed by oral warfarin or aspirin for a period of 3-6months. In a select group of patients USG is of great value for monitoring therapeutic response and confirming recanalization.

Cervical ICA dissection should be included in the differential diagnosis of lower cranial nerve palsies especially when these are sudden in onset and are accompanied by headache / facial pain, Horner's syndrome and pulsatile tinnitus, followed by signs of cerebral or retinal ischemia. MR with MRA may help in the early diagnosis of such cases and help reduce the risk of stroke. MR with MRA is the ideal noninvasive modality for the diagnosis and follow-up of such cases.

   References Top

1.Sturzenegger M. Spontaneous internal carotid artery dissection: early diagnosis and management in 44 patients. J Neurol 1995:242: 231-238.  Back to cited text no. 1    
2.Sturzenegger M, Huber P. Cranial nerve palsies in spontaneous carotid artery dissection. J Neurol Neurosurg Psychiatry 1993; 56: 1191 - 1199.  Back to cited text no. 2  [PUBMED]  
3.Stringaris K, Liberopoulos, Giaka E et al . Three dimensional time of flight MR angiography and MR imaging versus conventional angiography in internal carotid artery dissections. Int Angiol 1996: 15: 20-25.  Back to cited text no. 3    
4.Nusbaum AO, Som PM, Dubois P, Silvers AP. Isolated vagal nerve palsy associated with a dissection of the extracranial internal carotid artery. Am J Neuroradiol 1998; 19:1845-1847  Back to cited text no. 4    
5.Leclerc X, Godefroy O, Salhi A, Lucas C, Leys D, Pruvo JP. Helical CT for the diagnosis of extracranial internal carotid artery dissection. Stroke, Mar 1996; 27: 461 - 466  Back to cited text no. 5  [PUBMED]  [FULLTEXT]
6.Shimada J, Banda H, Suzukawa K, Amou M. A case of spontaneous cervical internal carotid artery dissection. No Shinkei Geka (Japan) 1997: 25: 67-71.   Back to cited text no. 6    

Correspondence Address:
Anil Bhaya
N M Medical Centre, Mumbai
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[Figure - 1], [Figure - 2]


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