Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3644_Библиотеки_им_академика_М_И_Перельмана

These triggers may not be identifiable, but are likely to include me­chanical, hormonal, pharmaceutical, hemodynamic, thermal, radiation, viral, infectious and metabolic triggers. The nature and timing of the re­vealing trigger (or triggers) and the nature and timing of the abnormally functioning endothelial cell (or cells) may result in the variety of AVMS that are now recognized (Table 2.1,Scheme 2.6).

The developing central nervous system (CNS) is clearly more vulnera­ble than the mature one; if revealing triggers act during cell migration, myelinization or CSF physiology maturation, while the embryonic brain matures to a fetal one and then to a fully myelinated brain, or until the skull base has largely grown and sutures are fixed, the revealing trigger may affect the vascular target more severely (e.g.? widespread, multifo­cal). An AVM morphologically and clinically present early in life must have had a more severe initial abnormality to have been effectively trig­gered over such a short period of time.

Generally speaking, a review of the literature pertaining to CAVM in the pediatric age group is difficult. The upper limit of the pediatric age group has varied between 15 and 20 years. Few reports have documented the management of AVMs that were not vein of Galen malformations in neonates and infants,or in antenatal series.

The first description of a possible VGM occurred in 1895 (Steinhel,cited by Dandy 1928); it was actually a CAVM of the diencephalon draining into a dilated vein of Galen. Today it would be described as a false vein of Galen malformation (Berenstein 1992a; Lasjaunias et al. 1987b). The first thera­peutic attempts were recorded at the beginning of this century describing an infant who presented with intracranial hypertension and subsequently underwent bilateral internal carotid ligation. In 1946,Jeager reported bilat­eral arteriovenous (AV) communications draining into an aneurysmally dilated vein of Galen, and in 1949 Boldrey and Miller treated two similar patients with arterial ligation. Only the last case seems to correspond to a VGAM. Most authors have subsequently used the same generic name, VGAM,for very different entities.Failure to recognize the true nature of the lesion resulted in imprecise anatomic and natural history descriptions (Agee et al.1969; Amacher et al. 1979;Gold 1946; Gold et al.1964; Grossman et al. 1984;Horowitz et al. 1994;Martelli et al.1980; Merland et al.1987;Nor­man and Becker 1974; Stehbens et al.1973;Watson et al.1976;Yasargil et al.

1976). In fact, Litvak et al.in 1960, Raimondi in 1972, Clarisse et al. in 1978, and Diebler et al. in 1981 already suggested the possible existence of true and false vein of Galen malformations.Subsequent surgical series (Agee et al. 1969;Amacher and Shillito 1973; French and Peyton 1954; Gibson et al. 1959; Hoffman et al.1982; Johnston et al. 1987; Massey et al. 1982; Menezes et al. 1981; Mickle and Quisling 1986, Mickle and Peters 1993; Raimondi 1987; Smith and Donat 1973) and endovascular series (Casasco et al. 1991; Ciricillo et al. 1990; Dowd et al. 1990; Mickle and Quisling 1986; Reichman et al. 1993) attempted to deal with this rare,and still poorly understood dis­ease entity, often emphasizing the technical challenge related to the treat­ment,but failed to grasp the real nature of the disease.

consecutive clinical stages: neonates with cardiac insufficiency, infants and young children with hydrocephaly and convulsions, and older chil­dren or adults with headaches and subarachnoid hemorrhage. In 1978, Amacher (1973) added a fourth group, which included neonates and in­fants with macrocephaly and minimal cardiac symptoms. Knudson and Alden (1979) reviewed all cases of cardiac failure secondary to AV shunt and noted that 64% were caused by VGAM. In fact, these contributions were inadvertently combining clinical sequelae created by both the nat­ural evolution of the disease and their post-therapeutic modifications.In his excellent review,Johnston et al.(1987) exhaustively analyzed the clin­ical presentations of VGAM. In 82 infants, he found the following symp­toms:CSF disorders,70%; neurological deficits,31%; and neurocognitive delay,12%.In children 1–5 years of age, these symptoms occurred in 61%, 33%, and 5%,respectively.For comparison, in our series of neonates and infants in the same age group, more than 50% had neurocognitive delay and almost none had neurological manifestations unless they had been previously shunted. This apparent discrepancy in the clinical profile of our material emphasizes the variability in the way symptoms have been documented and interpreted by various specialists.We will, therefore,not use this type of approach in the analysis of the natural history.We favor the understanding of the various disease processes rather than the knowledge of the anticipated frequency of their occurrence.

Ta ble 3.1. VGAM patients referred to Bicêtre per age group each year (1981–2002)

The potential for prenatal diagnosis of VGAM has already been docu­mented using noninvasive tools such as ultrasound, including color flow Doppler and magnetic resonance imaging (MRI) (Abbitt et al.1990; Cub­berlay et al.1982; Heibel et al.1993; Martinez-Lage et al. 1993;Saliba et al. 1987a; Sivakoff and Nouri 1982; Stockberger et al.1993).

From October 1984 to October 2002, 317 children with VGAM were studied in Bicêtre Hospital (Table 3.1).We consider this group of patients to be homogeneous, since the neuroradiological assessment, the technical principles involved,and the perioperative clinical management have been similar over the past 20 years and were carried out by the same group of physicians.The following observations were derived from this experience.

Raybaud et al. (1989) was the first to recognize that the ectatic vein in VGAM was actually the median vein of the prosencephalon, the embry­onic precursor of the vein of Galen itself. This was based on the choroidal nature of the arterial vascularization of this malformation (Figs. 3.1–3.3). A complete pathology specimen of a neonatal case of VGAM was careful­ly analyzed and illustrated by Landrieu in the late 1980s (Fig. 3.4).We as­sessed the dural sinus abnormalities (Lasjaunias et al.1987b) and persis­tent alternative embryonic routes of the deep venous drainage associated with this condition (Lasjaunias 1991). From then on, the vein of Galen malformation was recognized as an embryonic vascular malformation (as the timing for the causative trigger).It is a choroidal AV malformation (as a target for that causative trigger) (Fig. 3.4).

artery; 4,posteromedial choroidal artery; 5,circum­ferential artery (tectal)

Fig. 3.3. View from above of the choroidal fissure showing the triangular shape of the nidus in choroidal type of vein of Galen aneurysmal malfor­mation (VGAM) (single arrow). The dilated median vein of the prosencephalon is seen posterior to the base of triangu­lar shaped nidus (double arrow)