Cerebral vascular malformations: Case

This neonate has a vein of Galen aneurysmal malformation until proven otherwise. The severe high-output cardiac failure with a structurally normal heart and the loud cranial bruit together form the classic presentation, because the vein of Galen malformation is the commonest extracardiac cause of high-output cardiac failure in the newborn. The metabolic acidosis and the poor perfusion signal that the shunt is large and that the circulation is failing, and the priority is to support the heart while the imaging confirms the diagnosis and the retrieval is arranged. [4][5]

Clinical findings and assessment

The key findings are the high-output cardiac failure, the structurally normal heart on the echocardiogram, the loud cranial bruit, and the metabolic acidosis. The cranial bruit is the sign that separates an intracranial shunt from an intrinsic cardiac lesion, because it reflects the turbulent flow through the arteriovenous fistula. The metabolic acidosis and the poor perfusion reflect the steal phenomenon, in which the large shunt diverts the cardiac output away from the systemic circulation and produces a multi-organ hypoperfusion. [5]

The bedside assessment confirms that the airway is patent but the breathing is laboured, and the team supports the circulation with the ventilation, the fluids, and the inotropes. The differential of neonatal high-output cardiac failure with a structurally normal heart includes the vein of Galen malformation, a large systemic arteriovenous malformation such as a hepatic lesion, and a severe anaemia. The loud cranial bruit points to the intracranial shunt, and the urgent cranial ultrasound or the MRI brain with MRV will confirm the enlarged midline venous sac and the feeding choroidal arteries. [4][1]

Immediate management

The immediate management is to support the airway, the breathing, and the circulation, and to obtain the urgent imaging. The imaging request is for a cranial ultrasound at the bedside or an MRI brain with MRV, because the MRV is the sequence that will reveal the enlarged median prosencephalic vein that a plain ultrasound may misread as a cyst. The scan in this neonate would show the enlarged midline venous sac with the prominent feeding choroidal arteries, and the choroidal angioarchitecture would mark the severe form of the lesion. [4][1]

The medical management of the heart failure is the priority while the transfer to a paediatric interventional neuroradiology centre is arranged. Cory and colleagues rationalised this approach, and the therapy combines the ventilation, the diuretics such as furosemide to reduce the volume overload, the inotropes to support the cardiac output, and the careful management of the pulmonary hypertension. The metabolic acidosis is corrected with the fluid and the inotrope support, because a profound acidosis from the steal phenomenon is the mode of death in the untreated neonate. [5]

The Bicetre score and the embolisation

The Bicetre neonatal evaluation score guides the timing of the definitive treatment, and the fellow should be able to apply it. The score combines the cardiac, the cerebral, the respiratory, the hepatic, and the renal function into a number that ranges from zero to twenty-one, and a higher score means a healthier neonate who can tolerate the embolisation. A low score means the procedural mortality outweighs the benefit, and the embolisation is deferred to around five to six months of age after the medical stabilisation and the growth. [3][5]

This neonate, with the metabolic acidosis, the poor perfusion, and the multi-organ strain, would score low, and the immediate embolisation is not the safe choice. The team optimises the medical heart failure therapy, supports the neonate through the acute phase, and plans the staged transarterial embolisation for around five to six months of age when the procedural risk has fallen. The embolisation is performed by an experienced paediatric interventional neuroradiology team, and the fistula is closed with a glue or a coil over several staged sessions to avoid the haemodynamic shift that a single large occlusion can produce. [3]

The in-utero embolisation reported by Orbach and colleagues is the new frontier for the most severe fetal cases, and it is performed when the mid-trimester ultrasound shows an enlarging venous sac and a failing fetal circulation. This neonate was not diagnosed antenatally, so the postnatal staged embolisation is the plan, and the family is counselled about the severity of the lesion and the staged nature of the treatment. [6][3]

Follow-up and prognosis

The prognosis of the vein of Galen malformation is shaped by the severity of the shunt and the timing of the embolisation. The neonatal mortality of the severe choroidal type reaches up to a third in some series, and the survivors carry a burden of developmental delay, epilepsy, and cognitive impairment from the cerebral venous congestion and the steal. The mural type carries a better prognosis, and the staged embolisation in the older infant allows the normal development in a substantial proportion. [3][4]

The long-term follow-up is mandatory, because the persistent hydrocephalus and the residual shunt can declare themselves years after the initial treatment. The developmental surveillance is built into the plan from the outset, and the child is followed by the paediatric neurology and the developmental teams. The family is counselled in honest terms about the severity of the lesion and the long road ahead, and the engagement with the local health service and the early intervention supports the family as the child grows. [5][1]

The disposition is to a paediatric neurosciences centre with the paediatric interventional neuroradiology and the neonatal intensive care expertise, and the retrieval is arranged with a team that can manage the airway and the haemodynamics. The transition to the long-term follow-up is planned as the child leaves the acute phase, because the vein of Galen malformation is a lesion that the child lives with for life. [3][4]