Pattern of Extracranial Peripheral Aneurysm at a Referral Hospital in Kenya

Introduction Peripheral aneurysms are rare compared to aortic ones but they are important because of their predictive value for existence of aortic aneurysms, and potential to thromboembolise or rupture (1-3). Their localization, age and gender distribution display ethnic and regional variations (1-4). In Subsaharan Africa, as cardiovascular risk factors increase (5), rise in aneurysms is imminent. Reports of aneurysms from the continent are however scarce and altogether absent from Kenya. The objective of this study was to describe the characteristics of peripheral aneurysms seen at a Kenyan referral hospital.


Background
Peripheral aneurysms are important because of concurrence with aortic ones and potential to thromboembolise or rapture.Their distribution shows population variations yet reports from Africa are scarce and altogether absent from Kenya.Objective To describe the pattern of peripheral aneurysms in a Kenyan national referral hospital.

Patients and methods
Records of in-patients with a diagnosis of peripheral aneurysms at Kenyatta National Hospital between January 1998 and December 2007 were analyzed for presentation, diagnostic method, risk factors, site, age and gender distribution.Only records containing all these data were included.Data were analyzed using SPSS version 13.0 and presented using tables, and bar charts.

Conclusion
Characteristics of peripheral aneurysms in the Kenyan study population vary from those of Caucasians.They are more widespread, trauma related, and occur in younger individuals.Prudent management of risk factors is recommended.

Age and Gender Distribution
The mean age was 45.6years with range of 13 -79 years.
Notably, 48 (50%) of the patients were aged 40 years and younger.The most frequently affected age group was 21 -40 (46.9%), followed by 51 -70 (28.1%).There were no aneurysms below 10 years, and only 9 (9.4%) of the aneurysms occurred after 70 years.The age distribution varied with the vascular field (Table 1).There was a male predominance in most cases except the brachiocephalic and subclavian in which the male:female ratio was 1:2.6; and 1:2 respectively.In common carotid artery, the male:female ratio approached 1:1 (Figure 2).

Discussion
Peripheral aneurysms are rarely reported in Africa (4).
Reports from western countries indicate that they are rare, but considered important because their presence may point to the concurrent involvement of the abdominal aorta (1,2).In the present study for example, half of the cases of popliteal aneurysms presented with concurrent abdominal aortic aneurysms.
The clinical features of pulsatile masses, painful swellings, pressure effects, bleeding and gangrene are consistent with literature reports (2,3,6).Similarly the diagnostic modalities of doppler ultrasound, angiography and CT are typical for reported series (7,8).Indeed the ultrasonography provides a non invasive and relatively inexpensive technique for accurate and prompt diagno- sis of aneurysm (8).
The result of site localization in this study is unique.
The popliteal artery is the most common site of peripheral aneurysms in Caucasian populations, accounting for 70 -85% of the total, followed by femoral artery (1,2,(10)(11)(12)(13)(14). In the current study, at variance with these reports, popliteal artery aneurysms ranked 5th and accounted for only 10.4% of the total, behind femoral (24%), common carotid (15.6%), brachial (12.5%) and brachiocephalic (11.5%).For the upper extremity aneurysms the frequency of reported involvement is subclavian followed by axillary, brachial, ulnar and radial in that order (15).Our observations show more frequent brachial artery involvement with no case involving the axillary artery, attesting to interpopulation differences.In Japan, popliteal artery aneurysms account for 15 -28% while femoral ones comprise about half of the cases (16), possibly related to a combination of unique environmental, genetic and lifestyle risk factor profiles (17)(18)(19).
In Thirdly, many of them affect the femoral and brachial arteries, frequent sites of accidental and iatrogenic arterial injury (21,22).
The non-trauma risk factors are modifiable.For this young cohort, the control for the risk factors may have to commence early.The male predominance observed in the this study compares with that reported for the femo-ral1 and subclavian-axillary arteries ( 23).This appears to support the view widely held that in atherosclerotic aneurysms female hormones may confer protection.
In conclusion, peripheral aneurysms in this Kenyan study population are more widespread, trauma related,

Table 1 :
Age spread of peripheral aneurysms

Table 2 :
Comparison of some mean ages reported in literature