|Year : 2006 | Volume
| Issue : 1 | Page : 11-15
Paediatric intracranial aneurysms
AA Wani, S Behari, RN Sahu, AK Jaiswal, VK Jain
Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Rae Bareily Road, Lucknow - 226 014, UP
Source of Support: None, Conflict of Interest: None
Intracranial aneurysms in childhood account for 1-2% of intracranial aneurysms., These aneurysms have unique characteristics that make them different from those in adults. These differences are evident in their epidemiology, location, clinical spectrum, association with trauma and infection, complications and outcome.
|How to cite this article:|
Wani A A, Behari S, Sahu R N, Jaiswal A K, Jain V K. Paediatric intracranial aneurysms. J Pediatr Neurosci 2006;1:11-5
Intracranial paediatric aneurysms are rare, with most studies quoting an incidence of less than 5%., In the cooperative study by Sahs et al, there was only one child less than 4 y of age with an intracranial aneurysm. In the study by Kapoor and Kak, where 1000 human cadaver brains were examined, only one patient under the age of 20 y harbouring an intracranial aneurysm was found. In adults, there is a female predominance but in the paediatric population, this trend is not seen. In children less than 2 y of age, there is a male predominance; while in adolescents, there is an equal incidence of aneurysms in both sexes.,
A 75% of these patients present with subarachnoid haemorrhage. In adolescents, the presentation is similar to that in adults, but younger patients are often associated nonspecific symptoms like irritability, drowsiness and seizures. The frequency of patients presenting with features of an intracranial mass lesion is higher in the paediatric group than in adult patients. This may be due to a higher incidence of giant aneurysms in the former group. Rebleeding frequently occurs in the paediatric population. The incidence of rebleeding in adults varies from 16-29% and in paediatric patients, the incidence is much higher. ,,, The higher incidence of rebleeding may be due to failure of attending physician to consider a diagnosis of SAH when a child initially presents with complaints of headache, or due to difficulty in eliciting the history of the characteristic features of headache of SAH origin. Storrs et al found that neurological deterioration was related to rebleeding in nearly 52% of the children harbouring aneurysms. The incidence of angiographic vasospasm seen in Proust's series of paediatric patients was 36.4%. Ferrante et al and Proust et al found that despite a high incidence of angiographic vasospasm, the incidence of clinical vasospasm was relatively low. The children tend to present in a better clinical grade as compared to adults after aneurysmal rupture and seem to be less susceptible to the delayed ischemic deficits due to vasospasm., In children, the incidence of seizures is higher than that seen in the adult population. One possible explanation may be the higher incidence of intracerebral bleed in children due to the frequent location of the aneurysms at ICA bifurcation or the MCA branches. There is also a higher incidence of giant aneurysm in children that may manifest as seizures or as mass effect rather than as SAH.,
Aneurysm characteristics: Number, location, size [Figure - 1][Figure - 2][Figure - 3][Figure - 4].
The commonest site of aneurysm in the paediatric group is ICA bifurcation,, while in adults, the commonest site is anterior communicating artery complex. ICA accounts for 20-50% of paediatric cases., Only one series recorded the incidence as 9.7%. The other common site is the middle cerebral artery. At this location, it is the segment distal to MCA bifurcation that is the commonest site of involvement. The reason for ICA bifurcation being the commonest site in children is possibly due to the presence of a wide ICA bifurcation angle. This exposes a wider area of vessel wall to the turbulent blood flow at the bifurcation predisposing to aneurysm formation. Involvement of the posterior circulation in the paediatric population is quite varied, ranging from 4-16% in some series, to 30-57% in others., In our study, the incidence was higher in patients d" 18 y of age (24%) compared to the adult population. Most of the studies report a higher incidence of giant aneurysms in paediatric patients,, though in some studies, no difference was seen.,, In a metanalysis of paediatric aneurysm literature, about 50% of giant aneurysms were located in the vertebro-basilar system. Multiplicity of aneurysm is not a frequent feature in children., Infective aneurysms, however, tend to be multiple in children.
Traumatic and mycotic aneurysms
Traumatic intracranial aneurysms are rare. Benoit et al reported their incidence as less than 0.5%. Paediatric patients constitute most of the reported cases of traumatic aneurysms. An extensive review by Buckingham et al. revealed 69 cases of traumatic intracranial aneurysms with good or excellent outcome in 75% of the operated cases. Infective or mycotic aneurysms have a higher incidence in children with the commonest predisposing factors being infective endocarditis and septicaemia.
In the formation of paediatric aneurysms, both congenital and acquired factors have been incriminated. The presence of saccular aneurysms during early years of life point against degenerative causes in the etiopathogenesis of aneurysm formation. Bremer et al. supported the congenital origin of aneurysms and proposed that aneurysms developed from remnants of small vascular trunks originating from arterial bifurcation. Diseases like fibromuscular dysplasia, coarctation of aorta, Marfan's disease have a high incidence of aneurysm formation. Thus, congenital defects of connective tissue in the vessel wall may be the predisposing factor for aneurysm formation in children. Histopathological studies, however, show no difference between adults and paediatric aneurysms, i.e, in both groups, there is absence of both internal elastic lamina and muscularis layer of tunica media. Stephens in his extensive histopathological study of paediatric aneurysms concluded that most of the published literature does not contain sufficient evidence to support a congenital mechanism.,
Many studies support the presence of acquired causes for aneurysm formation. The degenerative changes may first appear in the intimal pads proximal to the blood vessel bifurcation, which then extend to the media. The increased haemodynamic stress at branching points leads to injury to internal elastic lamina and this initiates the development of aneurysm. In traumatic cases, there may be tears in the internal elastic lamina leading to dissecting aneurysms in large arteries. Stephens suggested lodgement of bacteria at the site of trauma. The bacteria then multiply in the thrombus at the site of vessel injury leading to aneurysm formation.
Incidental aneurysms need to be treated early because the chances of rupture are higher due to the increased period of risk in paediatric patients. The incidence of SAH due to the presence of a previously existing unruptured aneurysm in a 20-year-old person is 16.6% according to one study. In the series by Weibers, the incidence of rupture was 11.5%.
In the case of ruptured aneurysms , the operative or endovascular techniques are similar to that used in adults. Infants have a poorly developed thermoregulatory mechanism and a disproportionately more surface area as compared to weight. Thus, special precautions are needed to prevent hypothermia. The blood volume in children is less, hence one has to take extreme care during surgery to prevent aneurysm rupture. Due to higher incidence of complex aneurysms in children, more extensive procedures may often be required to facilitate clipping. These include microanastomosis, bypass procedures and trapping. Endovascular approach should be chosen with the indications being similar to that of adults.
In the case of infective aneurysms, initial efforts focus on treating them conservatively using antibiotics and serial angiograms, with surgery being reserved for patients who have persistence of the aneurysm on follow-up angiogram. The aneurysm is often friable and may not be amenable to clipping. The surgical treatment usually consists of occluding the parent vessel proximal to the aneurysm if the aneurysm is on a terminal branch in a non-eloquent region. In proximal aneurysms, due to the risk of ischemia involved in trapping a major vessel, reconstruction or trapping with bypass may be preferred depending on the status of cross circulation.
In the case of traumatic aneurysms, an often used modality is excision of aneurysm (because these are usually false aneurysms), especially when it is situated on a terminal branch. In aneurysms on main stem of vessel, trapping with bypass may be required.
In many series, it was found that children tend to present in better clinical grades after aneurysm rupture and hence the outcome is better as compared to adults.,, The better functional capacity of brain and a better vascular status with greater collateralization of the vessels distal to the site of aneurysm in children may also account for a better outcome.
In spite of the fact that the children seem to have favourable outcome, only few centres have acquired enough cases to provide a meaningful conclusion regarding outcome.
Twenty-two patients less than 18 y of age (male:female ratio=1.75:1; mean age 14.18 + 3.8 y, age range 5 to 18 y) and 451 adult patients of age greater than 18 y (male:female ratio=1:1.05; mean age of 48.21 + 12.71 y, age range 19 to 81 y) were treated for intracranial aneurysms at our centre between January 1991 and July 2003. The patients < 18 y constituted 4.6% of the total patient population having intracranial aneurysms. The incidence of associated medical diseases was more in patients < 18 y than in the adults (9% vs. 2.6%). The incidence of seizures was more than double in patients < 18 y (36% vs. 17%). The incidences of intracerebral haematoma (ICH; 41% vs. 22%), intraventricular haemorrhage (IVH; 45% vs. 34%) and hydrocephalus (36% vs. 25%) were higher in patients < 18 y. In the adult patients, the anterior communicating artery (AcoA) was the most common site of aneurysm, while in children the ICA bifurcation was the most frequent site of aneurysm formation. The incidence of giant aneurysms was nearly double in children (13.6% vs. 6.5%). The incidence of clinical vasospasm was almost the same in both the groups. The overall outcome was favourable in 82% of patients < 18 years and 58.8% of patients in adults. The management mortality in patients < 18 y was 9.1%, while in the adult patients, it was 19%. In patients < 18 y, there was a definite male predominance, a higher incidence of seizures and the ICA bifurcation formed the most frequent site of the intracranial aneurysms. Rebleeding and delayed ischaemic deficits were the major causes of morbidity. However, favourable outcome after surgery in young patients was much higher in comparison to their adult counterparts.
| Conclusions|| |
Intracranial paediatric aneurysms are different from adults in having a male predominance, having ICA as the commonest site and also in having a higher incidence of infective, traumatic and giant aneurysms. The clinical presentation of mass effect or subtle cognitive dysfunction occurs more often than in adults. These patients tend to have lesser incidence of clinical vasospasm and appear to have a better outcome as compared to adults.
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[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4]
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