CLINICAL REPORTS 65 Postgrad Med J: first published as 10.1136/pgmj.69.807.65 on 1 January 1993. Downloaded from States 50% of such patients had prior muscle the clinical signs may mimic septic arthritis. trauma.' So far the evidence for the role of Although still rare in temperate climates, immunosuppression in pyomyositis is unproven. It pyomyositis has to be considered in such atypical has been recognized in patients with diabetes, presentations, because it is vital to institute treat- acquired immunodeficiency syndrome and haema- ment early in the course of the disease to prevent tological malignancies.4 S. pneumoniae, present progression to septic shock. here, is rare as it causes fewer than 1% of cases of At follow-up our patient received the 23-valent pyomyositis, S. aureus being causative in 90%.5 pneumococcal vaccine and was advised to seek an Muscle involvement is multiple in 40-60% of early medical opinion if he developed any symp- cases.2 The muscles of the upper leg are most toms of infection. The evidence for antibacterial frequently involved, those ofthe upper arm are less prophylaxis in asplenic patients is controversial commonly affected.5 and our patient did not receive such prophylaxis. In Pyomyositis is usually accompanied by pyrexia, the light of this case, it is reasonable to suggest that malaise, leucoytosis, a raised ESR and blood such patients should seek early medical help when cultures are usually sterile. The involved muscle they recognize any symptoms of an infectious becomes tender and the overlying skin illness. Re-immunization with pneumococcal vac- erythematous. Fluctuation is only present at a late cine is not widely recommended in view of the stage and if untreated progresses to systemic sep- potential reactions, however, due to the serious SiS.4 The diagnosis is difficult because the typical nature of sepsis in this case re-immunization was features of an abscess are absent. Diagnosis, how- considered an appropriate measure. ever, may be made by ultrasound scan, computed tomography scan, magnetic resonance imaging, direct aspiration or drainage. Treatment is with surgical drainage and antibiotics. Functional Acknowledgements recovery is usually good.5 We are grateful to Mr C. Pool and Dr P. Gillette for their This case illustrates the problem of diagnosis as help in this case. copyright. References 1. Horn, C.V. & Master, S. Pyomyositis tropicans in Uganda. E 4. Hall, R.L., Callaghan, J.J., Moloney, E., Martinez, S. & Afr Med J 1968, 45: 463-471. Harrelson, J.M. Pyomyositis in a temperate climate. Presenta- 2. Gibson, R.K., Rosenthal, S.K. & Lukert, B.P. Pyomyositis. tion, diagnosis and treatment. J Bone Joint Surg (Am) 1990, Increasing recognitiion in temperate climates. Am J Med 1984, 72: 1240-1244. 77: 768-772. 5. Chiedozi, L.C. Pyomyositis. Review of 205 cases in 112 3. Miyake, H. Beitrage zur Kenntnis der sogenannten Myositis patients. Am J Surg 1979, 137: 255-259. Infectiosa. Mitt Grenzgeb Med Chir 1904, 13: 155-198. http://pmj.bmj.com/ Cervical ribs: a cause ofdistal and cerebral embolism P. Bearn, J. Patel and the late W.R. O'Flynn on October 2, 2021 by guest. Protected Department ofSurgery, Guy's Hospital, London SE] 9RT, UK Summary: The thoracic outlet syndrome occurs when the neurovascular structures are compressed as they traverse the thoracic outlet. Degenerative changes can occur in the subclavian artery and the vessel may become a source of embolism with the risk of acute or chronic upper limb ischaemia. Rarely, distal thromboembolism in the thoracic outlet syndrome may be associated with retrograde flow when there is the added risk of cerebral thromboembolism. Correspondence: P. Bearn, M.A., F.R.C.S., Department of Surgical Studies, The Middlesex Hospital, London WI 1AA, UK. Accepted: 28 May 1992 Postgrad Med J: first published as 10.1136/pgmj.69.807.65 on 1 January 1993. Downloaded from 66 CLINICAL REPORTS Introduction Vascular sequelae of the thoracic outlet syndrome arise as a result of the intermittent but long-term compression of the subclavian artery by cervical rib, cartilage or fibrous band. Long-term trauma to the subclavian artery leads to degenerative changes within the vessel wall, localized atheroma and aneurysm formation. Dis- tal thromboembolism causes acute and chronic upper limb ischaemia. Retrograde flow can occur in the thoracic outlet syndrome and lead to cerebral embolism. We report a case of thoracic outlet syndrome secondary to cervical rib in which both distal and retrograde thromboembolism occurred. Case report A previously fit 41 year old storekeeper developed a painful right forearm and a cold hand. He did not seek help as the acute symptoms settled over the next few days. However, he was left with forearm claudication which led to his premature retirement from competitive squash. Two years later he developed a left hemiparesis which resolved after 4 copyright. days. A diagnosis of cerebral embolism in the distribution of the right middle cerebral artery was made. He was advised to stop smoking and com- menced on low-dose aspirin. Six months later he was referred for investigation Figure 1 Plain radiograph demonstrating a large right of the right forearm claudication which had cervical rib. become worse. On examination, both hands were equally warm but on the right, pulses were absent distal to the brachial artery. There were no signs of subclavian artery, including the saccular aneurysm http://pmj.bmj.com/ cerebrovascular disease. Biochemical and haema- which contained thrombus, were resected. The tological indices were normal. Since a plain chest artery was replaced with a 5 cm x 6 mm woven X-ray demonstrated a large right cervical rib, a Dacron graft, anastomosed end to end with the provisional diagnosis of thoracic outlet syndrome host vessel. The axillary and brachial arteries were was reached (Figure 1). Doppler sonography dem- cleared of thrombus distally using a Fogarty onstrated the brachial artery pressure to be reduced embolectomy catheter and the brachial pulse was from 108 mmHg on the left to 93 mmHg on the restored. Radial and ulnar pulses were present at right but was not reduced by shoulder abduction. one week. He was discharged on oral anti- on October 2, 2021 by guest. Protected Electrocardiogram and echocardiogram were car- coagulants to reduce early graft thrombogenicity. ried out and were both normal. Histology confirmed degeneration and fibrosis By the time he was admitted for angiography 3 of the wall of the artery, maximal at the site of months later, the right brachial artery was no aneurysmal formation. longer palpable in the cubital fossa. At digital subtraction angiography, the subclavian artery was narrowed at the thoracic outlet by the cervical rib Discussion and there was a post-stenotic saccular aneurysm (Figure 2a). Blood flow was reduced on shoulder The thoracic outlet syndrome was first recognized abduction (Figure 2b). The carotid and vertebral by a surgeon from this institution, Sir Astley arteries were free from atheromatous disease. Cooper in 1821. The neurological and vascular The patient underwent surgical exploration of symptoms and signs of the syndrome result from the right thoracic outlet by a supraclavicular the compression of the brachial plexus, subclavian approach with excision of the middle third of the artery or vein as they traverse the thoracic outlet, a clavicle. The cervical rib and a 3 cm length of space defined by the first rib inferiorly, scalenus Postgrad Med J: first published as 10.1136/pgmj.69.807.65 on 1 January 1993. Downloaded from CLINICAL REPORTS 67 Figure 2a Digital subtraction angiography demonstrating subclavian artery compression by the cervical rib with a post-stenotic saccular aneurysm. copyright. Figure 2b Digital subtraction angiography demonstrating reduced flow on arm abduction. medius posteriorly and the scalenus anterior anter- syndrome and has been associated with occlusion iorly. The neurovascular bundle may be impinged of the subclavian artery with retrograde flow.8'9 In http://pmj.bmj.com/ upon by cervical ribs or related structures (cervical this patient, emboli from the distal arterial lesion transferse process, cartilage or band); anomalous may have refluxed into the cerebral circulation insertions of muscles (scalenus anticus syndrome; during diastole to cause the stroke.9 hyperabduction syndrome) or local bony injury In the management ofcerebral and distal throm- (costoclavicular syndrome).'`2 Cervical ribs are boembolism caused by cervical ribs, the aim is to more commonly associated with unilateral upper identify the arterial pathology and the extent of limb arterial insufficiency than with neurological or arterial occlusion. This can be achieved by angio- on October 2, 2021 by guest. Protected venous symptoms. Those of ischaemia develop graphy or duplex Doppler ultrasound."'0 The aim during exercise whilst the neurological manifesta- must be to prevent further embolism and restore tions ofthe thoracic outlet syndrome appear at the function by surgical decompression of the thoracic start or after exercise. 1-4 outlet and resection of the embolic source.'0 12 Patients may present with an acutely ischaemic When a cervical rib is the cause, this must be hand or with disabling forearm claudication.25 excised.'3 Access to neurovascular structures can be Although arterial stenosis due to progressive fibro- further improved by resecting the clavicle or the sis at the site of arterial compression has been first rib. Removing the latter may also prevent the suggested as the aetiology, both presentations have development of neurological symptoms.'° There the same aetiology: thromboembolism originating are several different surgical approaches to the first from the damaged vessel wall or aneurysm.6'7 rib.'4"5 The largest series has suggested that a Two years after the onset of forearm claudica- combined infra- and supra-clavicular approach tion, this patient developed a transient hemiparesis with excision of the first rib may best facilitate affecting the right side.