Germinal Matrix Haemorrhage

Germinal matrix haemorrhage is bleeding within the subependymal germinal matrix, typically at the caudothalamic groove, in the preterm brain. It is the initial lesion of intraventricular haemorrhage and is confined to the matrix in grade I disease.

It occurs mainly in infants under 32 weeks and is most frequent in those under 28 weeks. Most bleeds appear within the first 72 hours of life. In term infants it is rare and usually arises from the choroid plexus or a coagulopathy.

Isolated germinal matrix haemorrhage and haemorrhage with small intraventricular extension usually have a good outcome. Larger bleeds can extend into the ventricles or cause parenchymal infarction.

Pathophysiology

The germinal matrix is a highly vascular region that produces neurons and glia between 10 and 20 weeks and shrinks by 34 to 36 weeks. Its capillaries have thin walls, immature basement membrane and little glial support.

Fluctuations in cerebral blood flow, venous congestion and hypoxic injury rupture the capillaries. Immature autoregulation and coagulation add to the risk.

• Almost always silent and found by screening ultrasound.
• Acute deterioration with hypotension, apnoea, bulging fontanelle and seizures occurs with extensive extension.

Red flags.

• Falling haematocrit, tense fontanelle or seizures.
• Bleeding in a term infant with no clear cause, suggesting a coagulopathy or vascular lesion.

• Cranial ultrasound: an echogenic focus at the caudothalamic groove, anterior and inferior to the foramen of Monro, in the coronal and parasagittal views. The echogenicity fades and a cyst can form at 2 to 4 weeks.
• Screening ultrasound for infants under 32 weeks at days 1 to 3, day 7, 2 to 4 weeks and term equivalent age.
• In term infants or unexplained haemorrhage: platelet count, coagulation screen, factor levels, MRI and vascular imaging.

Differential diagnosis. Choroid plexus haemorrhage, subependymal cyst, periventricular leucomalacia, venous infarction and congenital infection.

• Isolated germinal matrix haemorrhage needs no specific treatment. Provide supportive care, with stable blood pressure, normal PaCO2 (45 to 55 mmHg), glucose and temperature, and minimal handling.
• Correct coagulopathy (fresh frozen plasma 10 to 15 mL/kg) and thrombocytopenia (platelets when under 50 x 10^9/L). Give vitamin K 1 mg IM or IV if not given at birth.
• Repeat ultrasound within 3 to 7 days to detect extension or dilatation, then at 2 to 4 weeks and term equivalent age.
• Treat seizures with phenobarbital 20 mg/kg IV over 20 minutes.
• Antenatal corticosteroids, delivery at a tertiary centre and delayed cord clamping for 30 to 60 seconds reduce incidence.

Monitoring. Head circumference each day, serial ultrasound and neurodevelopment at 2 years of corrected age.

Referral and escalation. Refer to neurosurgery for ventricular dilatation, and to neurodevelopmental follow up for any intraventricular or parenchymal extension.