Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 58, Num. 4, 2010, pp. 645-647

Neurology India, Vol. 58, No. 4, July-August, 2010, pp. 645-647

Case Report

Cervical rib with stroke as the initial presentation

Sharma Sandeep, Kumar Subhash, Joseph Leve, Singhal Vikas

Department of Neuroradiology, AIIMS, Ansari Nagar, New Delhi-110 029

Correspondence Address:Department of Neuroradiology, AIIMS Ansari Nagar, New Delhi-110 029, drsharma_sandeep@yahoo.com

Date of Acceptance: 29-Oct-2009

Code Number: ni10170

PMID: 20739814

DOI: 10.4103/0028-3886.68691

Abstract

Keywords: Artery to artery thromboembolism, cervical rib, right carotid stroke

Introduction

Cervical ribs or malformed first ribs occur in one per cent of the population and account for 4.5% of thoracic outlet syndrome. The presenting symptoms of cervical rib are primarily neurologic and vascular symptoms are rare and account for only two percent. Vascular symptoms predominantly involve the distal upper limb and are thromboembolic from the proximal subclavian artery disease and are related to chronic trauma and aneurysm formation. Right sided stroke in patients with cervical rib is rare, but has been well documented. All these patients had a history of upper limb vascular symptoms before the cerebral event. ^{[1],[2],[3],[4],[5],[6]} We report a young patient with cervical rib and right carotid artery stroke. Only on retrospective questioning and examination symptoms and signs of thoracic outlet syndrome could be elicited and were not very prominent.

Case Report

An 18-year old male presented with a history of sudden onset weakness of left upper limb and deviation of face towards right of two months duration and at the onset of the symptoms he had loss of consciousness. Non-contrast computed tomography (CT) scan of brain done at that time showed right basal ganglia infarct [Figure - 1]. Patient was extensively investigated for the cause of stroke in young and finally sent for digital substraction angiogram (DSA). The angiogram revealed narrowing of right middle cerebral artery (MCA) and non visualization of ascending frontal branches of right MCA [Figure - 2]. During angiography a cervical rib was also noted on the right side [Figure - 3] and [Figure - 4] causing mild narrowing of right subclavian artery with subtle post stenotic dilatation. Angiogram during abduction [Figure - 4] revealed complete occlusion of the subclavian artery and filling of the right axillary artery by the collaterals. He had surgery and cervical rib excision. At operation right subclavian artery showed only minimal dilatation and was not explored as thrombus was not evident either on angiography or Doppler. Postoperative period was uneventful and the patient did not have further thromboembolic episodes during the short follow-up.

Discussion

Thoracic outlet syndrome has been classified into three forms: neurogenic, venous and arterial. Neurogenic form is the most common, accounting for more than 95% of the patients, while arterial form is least common comprising less than one per cent of the patients. Arterial form causes ischemic symptoms in the upper limb by antegrade artery to artery thromboembolization from the aneurysmal segment of the artery. Reports describing retrograde artery to artery thromboembolization into the proximal carotid or vertebral artery have also been reported, but are very rare. ^[1] In a series of 30 surgically treated patients with vascular thoracic outlet syndrome, Lazer et al. ^[2] could find only one patient with transient ischemic attack. In their literature review in 1966, Davis et al. ^[3] found five cases of cervical rib with stroke while Yamaguchi et al. ^[4] in 2008 found ten such cases. Right carotid artery stroke is more often described than vertebrobasilar stroke. Supratentorial strokes have always been described with right sided cervical rib while the vertebrobasilar strokes have always been described with left sided cervical rib. Left sided carotid stroke has not been described with cervical rib as left carotid arises from arch of aorta. Right cervical rib causing vertebrobasilar artery has also not been described with cervical rib, however such phenomenon has been described with malunited right clavicle fracture. Patients with cervical rib with stroke more commonly have upper limb symptoms before having the cerebral events. However, there were reports with short history of upper limb symptoms before the cerebral event. ^[5] Our patient did not have obvious upper limb symptoms before the cerebral event. Based on these observations, it can be assumed that in patients with cervical rib both retrograde and antrograde thromboemolism can occur independently depending on the limb position and flow direction.

Our patient had extensive investigation for young stroke and DSA was part of the evaluation. DSA revealed stenosis and post stenotic dilatation of the right subclavian artery and angiogram with upper limb in abduction position confirmed thoracic outlet syndrome. In the six cases reported by Raefel et al[6] the dilatation of subclavian artery in thoracic outlet syndrome was mild. However, none of their patients had cerebral symptoms. Our patient also had only mild dilatation distal to the subtle narrowing caused by the cervical rib in the neutral position, however he had retrograde artery to artery thromboembolism into the carotid system.

The number of case reports of stroke related to cervical rib is small. In a study of 120 patients of stroke in young, Awada et al. could attribute stroke to cervical rib in only one patient. ^[7] Transient reversal of flow in the subclavian artery together with the thrombus formation in the aneurysmal part of the subclavian artery has been considered the possible cause of stroke in patients with cervical rib in the absence of long retrograde thrombus propagating up to the ostia of the cranial vessel. ^[8] We propose a similar mechanism for the stroke in our patient, however, he did not have significant upper limb symptoms. Our patient highlights the importance of considering cervical rib as the cause of stroke in a patient with cervical rib with and without upper limb symptoms.

References

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