First described by Jaeger, Forees, and Dandy in 1937 [4, 8], Galen’s vein aneurysm is an embryonic malformation occurring between the 6th and 11th week of pregnancy, consisting of a set of fistulas leading to an abnormally persistent and dilated Markowski’s porencephalic median vein which is the embryological precursor of Galen’s vein (described by Pergame Galien in the second century AD in animals as a deep venous structure behind the third ventricle which bears his name) .
It is a rare congenital condition that accounts for less than 1% of intracranial AVMs [2, 9]. Although rare, it is one of the most frequently diagnosed AVMs in children before and after birth. It mainly affects newborns and infants: two thirds of cases are diagnosed before the age of 28 months [1, 10]. This is the case of our first observation, which was diagnosed at 7 months of age. Although congenital in origin, the clinical manifestations of Galen’s vein aneurysm can appear at different ages. Three clinical groups have been established :
Group 1. Aneurysms occurring at or soon after birth due to heart failure and head murmur. Heart failure may be associated with cyanosis.
Group 2. Symptoms appear between 1 and 6 months after birth and are characterized by hydrocephalus and milder heart failure. A cranial murmur may be heard.
Group 3. Cases in which neonatal problems are absent, and the diagnosis is made at a later age with the appearance of subarachnoid hemorrhage, convulsions, hydrocephalus, symptoms of the “flying phenomenon” or limitation of upward gaze (Parinaud’s syndrome).
Our 3 observations were revealed by a table of acute ICH associating for the first observation generalized seizures and for the 2nd observation a moderate heart failure. This ICH was related to triventricular hydrocephalus diagnosed in our study by brain CT scan. This hydrocephalus is thought to be related to cerebral venous hypertension, caused by the fistula and responsible for a decrease in cerebrospinal fluid resorption or by obstruction of the Sylvius aqueduct [1, 5]. As for the age of revelation, it was longer for our 2nd and 3rd observations, 15 and 26 years, respectively. This variability in clinical expression over time could be explained by the angioarchitectural varieties of vascular origin that evolve over time. Two angioarchitectural varieties exist: the choroidal variety with contribution from all choroidal arteries, which is expressed in the neonatal period, and the mural variety with presence of arteriovenous fistulas with the porencephalic median vein, which is expressed in the neonatal period moderately or later in childhood or adulthood .
The diagnosis is most often made during routine antenatal ultrasound examinations. In the neonatal period, transfontanel ultrasound is currently a routine examination performed during the first year of life. Coupled with Doppler, ultrasonography makes it possible to study the deep cerebral vessels and finds the same semiological elements as in the antenatal period . In computed tomography, arteriovenous malformations are spontaneously discreetly hyperdense and sometimes present calcifications within them. After injection, a very intense vascular type of contrast is observed. The malformities vessels appear as tubular and curvilinear opacities. The deep venous drainage of the malformation is often clearly identifiable in the form of a tubular opacity draining into a dilated Galen vein . Magnetic resonance imaging (MRI) is the most sensitive examination for the search for parenchymal lesions and must be systematically performed. MRI makes it possible to better specify the anatomical relationships of the malformation, particularly with deep brain structures. In aneurysmal dilatation, arteries and veins are empty of signal on T1 and T2 sequences [3, 15]. For our 3 observations, the diagnosis was made by brain CT scan. MRI was not performed in any of our patients due to the high cost and relative availability of the test.
Differential diagnoses of Galen’s great vein aneurysm are essentially made with fluid lesions of the midline, including pineal gland cyst, colloid cyst, arachnoid cyst, and subependymal pseudocysts .
Once surgical with a disappointing result, endovascular embolization methods are currently the treatment of choice with a satisfactory success rate but require a team of experienced neuroradiologists. The goal of the treatment is the occlusion of the shunts of the malformation. Its effectiveness depends largely on the size of the malformations and the complications developed . This technique has not been performed in our patients due to the lack of an adequate technical platform. Therefore, we considered that cerebrospinal fluid derivation by ETV performed in one patient (observation 1) or VPS performed in 2 patients (observations 2 and 3) would seem to relieve our patients. However, the literature mentions that VPS could be one of the factors that increase bleeding and exacerbate the symptoms of Galen’s vein aneurysm . Some authors [18, 19] advocate ETV as a relatively recent alternative to bypass valve implantation, mainly used in obstructive hydrocephalus with an overall success rate of about 75% and a low complication rate of less than 5%.
Over drainage is another disadvantage of VPS which can cause symptoms later on, such as subdural hematoma, hygroma, and slit ventricles. Such complications can be avoided with ETV, as this would not change the balance between supra- and infra-tentorial pressures . Without ignoring the fact that even in environments with an adapted technical platform, embolization is a major treatment and has a success rate of about 60% according to some studies [20, 21]. Despite the risks of complications related to VPS, no cases of complications were noted in our study at one year of follow-up.