Cerebral vascular malformations: Viva

Branch 1: Classification and the bedside recognition

The candidate should classify cerebral vascular malformations into the high-flow arteriovenous malformation, the vein of Galen aneurysmal malformation, the low-flow cavernous malformation, and the developmental venous anomaly. A strong candidate states that the high-flow lesions present with haemorrhage or cardiac failure, that the low-flow lesions present with seizures, and that the developmental venous anomaly is found incidentally and left alone. The candidate should then state that this neonate, with the high-output cardiac failure and the loud cranial bruit, has the classic presentation of a vein of Galen malformation, because the malformation is the commonest extracardiac cause of high-output cardiac failure in the newborn. [4][1]

If the examiner presses on the bedside recognition, the candidate should state that the loud cranial bruit over the vertex is the clue that the heart failure is driven by an intracranial shunt and not by an intrinsic cardiac lesion. The echocardiogram shows a structurally normal heart, and the high-output state points to the extracardiac shunt. The candidate should request the urgent cranial ultrasound or the MRI brain with MRV to confirm the enlarged midline venous sac and the feeding choroidal arteries, and should arrange the early retrieval to a paediatric interventional neuroradiology centre. [5][3]

Branch 2: The Bicetre score and the timing of the embolisation

If asked to manage this neonate, the candidate should state that the definitive treatment is transarterial embolisation by an experienced paediatric interventional neuroradiology team, and that the timing is guided by the Bicetre neonatal evaluation score. The candidate should describe the score as a composite of the cardiac, the cerebral, the respiratory, the hepatic, and the renal function that ranges from zero to twenty-one. A high score means the neonate can tolerate the embolisation, and 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. [3][5]

If the examiner presses on the medical management while the embolisation is awaited, the candidate should state that the priority is to support the failing heart. The medical 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 candidate should cite Cory and colleagues, who rationalised this approach, and state that a profound acidosis or a multi-organ failure from the steal phenomenon is the mode of death, and that the medical therapy buys time for the definitive embolisation. [5]

If the examiner presses on the apparent paradox of embolising a sick neonate, the candidate should explain the haemodynamic shift. The sudden occlusion of a large shunt on the table can produce a dramatic shift in the venous return and the cardiac output, which is why a sick neonate with a low Bicetre score is not embolised acutely. The staged embolisation over several sessions closes the fistula gradually and avoids the haemodynamic shift, and the Lasjaunias framework governs this staging across the centres. [3]

Branch 3: The arteriovenous malformation and the cavernous malformation

If the examiner shifts the scenario to an older child with a sudden intracerebral haemorrhage, the candidate should state that the likely lesion is a brain arteriovenous malformation, which is the commonest lesion to present in childhood. The candidate should state that the imaging standard is an MRI brain with MRA and MRV, with a catheter angiogram for the confirmation and the treatment planning, and that the management is multidisciplinary. The choice between the microsurgery, the embolisation, and the stereotactic radiosurgery depends on the Spetzler-Martin grade, which sums the size, the eloquence, and the venous drainage. [1][2]

If the examiner asks about the follow-up, the candidate should state that the paediatric arteriovenous malformation recurs in up to eight percent of children after an apparent cure, because a residual nidus below the angiographic resolution can grow in the developing brain. The candidate should state that a post-treatment angiogram confirms the complete obliteration, and that the child is followed with the serial imaging for years, because the recurrence is silent until it bleeds. [11]

If the examiner shifts the scenario to a child with new focal epilepsy and a popcorn lesion on the MRI, the candidate should state that the likely lesion is a cavernous malformation, and that the popcorn appearance with the haemosiderin ring on the gradient-echo sequence is the diagnostic clue. The candidate should state that the symptomatic lesion that has bled or that causes a drug-resistant epilepsy is resected, while the incidental lesion is observed, and that the familial form with multiple lesions points to a CCM gene mutation and demands the family screening. [7][12]

If the examiner asks the trap question about the developmental venous anomaly, the candidate should state clearly that a developmental venous anomaly drains normal brain and must never be resected, because its removal causes a venous infarct. The candidate should recognise the medusa-head of draining veins on the contrast MRI and reassure the family. [1]