Trip Answers

Question answered:17/08/07 Warning! this question is over two years old.

An article in the ‘American Family Physician’ states:

 

“Intracranial aneurysms are classified as saccular, fusiform, or dissecting. Approximately 90 percent are saccular (berry aneurysms). Saccular aneurysms are responsible for most of the morbidity and mortality caused by subarachnoid hemorrhage”

 

It adds in the summary:

 

“Unruptured intracranial aneurysms occur in up to 6 percent of the general population. Most persons with these aneurysms remain asymptomatic and are usually unaware of their presence. Risk factors for the formation of aneurysms include a family history of aneurysm, various inherited disorders, age greater than 50 years, female gender, current cigarette smoking, and cocaine use.”

 

But:

 

“Because of the morbidity and mortality associated with surgical intervention, screening for aneurysms remains controversial.”

 

However:

 

“Two groups of patients may benefit from early detection: those with autosomal dominant polycystic kidney disease and those with a history of aneurysmal subarachnoid hemorrhage. These patients should undergo magnetic resonance angiography, followed by neurosurgical referral if an aneurysm is detected. Screening of patients who have two or more family members with intracranial aneurysms is controversial. Screening of patients who have one first-degree relative with an aneurysm does not appear to be beneficial.” [1]

 

Of interest will be an answer by the NLH Q & A Service posted in September 2006 [2]. This reads:

 

Question:

 

Does subarachnoid haemorrhage have a hereditary basis? Are there any investigations recommended in a first degree relative?

 

Answer:
The literature appears to suggest first degree relatives of patients with subarachnoid haemorrhage (SAH) have an increased risk of SAH compared to the general population.

 

Bormberg et al examined the incidence of SAH in first and second degree relatives of patients with SAH and concluded:

 

“…a familiar factor is important in the development of subarachnoid haemorrhage. First degree relatives of patients run at least a three to seven times greater risk than the general population. This means that the lifetime risk of subarachnoid haemorrhage is between 2% and 5% in first degree relatives. Therefore, screening for unruptured aneurysms should at least be considered in first degree relatives of patients with subarachnoid haemorrhage. “ [3]

 

In 2005, Teasdale et al reported similar findings:

 

“… We studied two samples: 5478 relatives of patients from the whole of Scotland who had a SAH in one year and 3213 relatives of patients with a SAH admitted to the West of Scotland regional neurosurgical unit 10 years previously. Overall, 2% of all relatives in each sample had a SAH. In the Scotland-wide sample, the absolute lifetime risk of SAH (from birth to 70 years) was higher for first-degree relatives [4.7%; 95% confidence interval (CI): 3.1–6.3%] than for second-degree (1.9%; 95% CI: 1.0–2.9%). In the West of Scotland sample, the lifetime risks were very similar to the Scotland-wide sample. The 10-year prospective risk for first-degree relatives alive at the time of the index patient's SAH was 1.2% (95% CI: 0.4–2%) and for second-degree was 0.5% (95% CI: 0.1–0.8%).
There was a trend for risk to be highest in families with two first-degree relatives affected and lowest with only one second-degree affected."

 

However, they add:

 

“Most living relatives of patients who suffer a SAH are at low absolute risk of a future haemorrhage; screening is inappropriate except for the few families in whom two or more first-degree relatives, i.e. index case plus one extra have been affected.” [4]

 

We were unable to find guidelines detailing specific investigations required for relatives of patients with SAH; however, we did locate screening studies of familial SAH in which methods of screening were mentioned.
Wermer et al examined the yield of short-term follow up using CT/MR angiography for small aneurysms detected at screening in patients with a history of SAH or familial intracranial aneurysms (FIA). The authors found:

 

“The yield of follow-up CT/MR angiography (CTA/MRA) 1 or 2 years after detection to evaluate growth of these aneurysms is unknown. METHODS: We prospectively followed patients with small aneurysms detected at screening at a 1-year interval using CTA or MRA. We assessed size, site, and number of the aneurysms and risk factors such as smoking, alcohol use, and hypertension. We evaluated the short-term growth and rupture rate and possible risk factors for growth and rupture. RESULTS: Ninety-three patients (67 with a history of SAH, 16 with FIA, and 10 with a history of both SAH and FIA) with 125 aneurysms underwent CTA/MRA follow-up. Sixty-five patients were followed up once, and 28 patients were followed up twice (median follow-up time, 1.3 years). In 3 of the 93 patients (3.2%), an aneurysm enlarged slightly (0.5 to 1.5 mm). Two patients (2.2%) had a SAH: 1 from an aneurysm at the clip-site from a previous operation that ruptured without enlargement and the other from a newly developed dissecting aneurysm. The only statistically significant risk factor for growth and rupture was a history of both SAH and FIA (relative risk, 10.1; 95% CI, 1.3 to 81.9).”

 

From these findings, they conclude: “The yield of early follow-up of small aneurysms in patients with a history of SAH or FIA is small and does not eliminate the risk of rupture. Whether follow-up at intervals >1 year is useful requires further study.” [5]

 

In addition, an answer produced by the NLH Q & A Service on screening for berry aneurysms lists criteria for screening, and mentions another study by Wermer et al which used MR angiography as a follow up screening tool. This answer may be read by following this link [6]: http://www.clinicalanswers.nhs.uk/index.cfm?question=210

 

We updated our literature search in the NLH Specialist Library for Screening and  the NLH Guidelines, TRIP and Medline databases but found no additional studies examining family history of berry or intracranial aneurysms as a risk factor for suffering a subarachnoid haemorrhage or guidelines on screening relatives of patients with berry aneurysms.

 

References
1.Vega C, Kwoon JV and Lavine SD. Intracranial aneurysms: current evidence and clinical practice.
Am Fam Physician. 2002 Aug 15;66(4):601-8. (http://www.aafp.org/afp/20020815/601.html)
2. NLH Q & A Service. Does subarachnoid haemorrhage have a hereditary basis? Are there any investigations recommended in a first degree relative? 20th September 2006. (http://www.clinicalanswers.nhs.uk/index.cfm?question=3963)
3. Bromberg JE, Rinkel GJ, Algra A et al. Subarachnoid haemorrhage in first and second degree relatives of patients with subarachnoid haemorrhage. BMJ. 1995 Jul 29;311(7000):288-9. (http://bmj.bmjjournals.com/cgi/content/full/311/7000/288).
4. Teasdale GM, Wardlaw JM, White PM et al. The familial risk of subarachnoid haemorrhage. Brain. 2005 Jul;128(Pt 7):1677-85. Epub 2005 Apr 7. (http://brain.oxfordjournals.org/cgi/content/abstract/128/7/1677).
5. Wermer M, Van der Schaaf I and Velthius B. Yield of short-term follow-up CT/MR angiography for small aneurysms detected at screening. Stroke. 2006 Feb ; 37(2): 414-8. (http://www.hubmed.org/display.cgi?uids=16385095).
6. NLH Q & A Service. What are the current thoughts on screening for Berry aneurysm? - I have a lady whose father has recently had one confirmed - she was advised in Germany to be screened in UK!!! There is a known family history link & link to PCO disease but I can't find clear guidance on screening. Posted 11th February 2005. (http://www.clinicalanswers.nhs.uk/index.cfm?question=210).

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