Prenatal intracranial hemorrhage and neurologic complications in alloimmune thrombocytopenia

Fetal stroke and cerebrovascular disease: Advances in understanding from lenticulostriate and venous imaging, alloimmune thrombocytopaenia and monochorionic twins

Fetal stroke is an important cause of cerebral palsy but is difficult to diagnose unless imaging is undertaken in pregnancies at risk because of known maternal or fetal disorders. Fetal ultrasound or magnetic resonance imaging may show haemorrhage or ischaemic lesions including multicystic encephalomalacia and focal porencephaly. Serial imaging has shown the development of malformations including schizencephaly and polymicrogyra after ischaemic and haemorrhagic stroke. Recognised causes of haemorrhagic fetal stroke include alloimmune and autoimmune thrombocytopaenia, maternal and fetal clotting disorders and trauma but these are relatively rare. It is likely that a significant proportion of periventricular and intraventricular haemorrhages are of venous origin. Recent evidence highlights the importance of arterial endothelial dysfunction, rather than thrombocytopaenia, in the intraparenchymal haemorrhage of alloimmune thrombocytopaenia. In the context of placental anastomoses, monochorionic diamniotic twins are at risk of twin twin transfusion syndrome (TTTS), or partial forms including Twin Oligohydramnios Polyhydramnios Sequence (TOPS), differences in estimated weight (selective Intrauterine growth Retardation; sIUGR), or in fetal haemoglobin (Twin Anaemia Polycythaemia Sequence; TAPS). There is a very wide range of ischaemic and haemorrhagic injury in a focal as well as a global distribution. Acute twin twin transfusion may account for intraventricular haemorrhage in recipients and periventricular leukomalacia in donors but there are additional risk factors for focal embolism and cerebrovascular disease. The recipient has circulatory overload, with effects on systemic and pulmonary circulations which probably lead to systemic and pulmonary hypertension and even right ventricular outflow tract obstruction as well as the polycythaemia which is a risk factor for thrombosis and vasculopathy. The donor is hypovolaemic and has a reticulocytosis in response to the anaemia while maternal hypertension and diabetes may influence stroke risk. Understanding of the mechanisms, including the role of vasculopathy, in well studied conditions such as alloimmune thrombocytopaenia and monochorionic diamniotic twinning may lead to reduction of the burden of antenatally sustained cerebral palsy.

A severe case of intracranial hemorrhage due to alloimmune thrombocytopenia

Alloimmune thrombocytopenia (AIT) is an important cause of intrauterine hemorrhagic lesions that result from platelet-antigen incompatibility between mother and foetus. Foetal platelets are destroyed by cross-reactive maternal antibodies that cross the placenta. The most serious complication of AIT is foetal intracranial bleeding that may eventually result in intrauterine death or severe neurological impairments.

Neonatal thrombocytopenia

Thrombocytopenia (platelets <150 x 10(9)/L) is one of the most common haematological problems in neonates, particularly those who are preterm and sick. In those preterm neonates with early thrombocytopenia who present within 72 h of birth, the most common cause is reduced platelet production secondary to intrauterine growth restriction and/or maternal hypertension. By contrast, the most common causes of thrombocytopenia arising after the first 72 h of life, both in preterm and term infants, are sepsis and necrotizing enterocolitis. The most important cause of severe thrombocytopenia (platelets <50 x 10(9)/L) is neonatal alloimmune thrombocytopenia (NAIT), as diagnosis can be delayed and death or long-term disability due to intracranial haemorrhage may occur. Platelet transfusion is the mainstay of treatment for severe thrombocytopenia. However, the correlation between thrombocytopenia and bleeding is unclear and no studies have yet shown clinical benefit for platelet transfusion in neonates. Studies to identify optimal platelet transfusion practice for neonatal thrombocytopenia are urgently required.

Thrombocytopenia in the neonate

Thrombocytopenia is one of the commonest haematological problems in neonates, affecting at least 25% of all admissions to neonatal intensive care units (NICUs) [Murray NA, Howarth LJ, McCloy MP et al. Platelet transfusion in the management of severe thrombocytopenia in neonatal intensive care unit patients. Transfus Med 2002;12:35-41; Garcia MG, Duenas E, Sola MC et al. Epidemiologic and outcome studies of patients who received platelet transfusions in the neonatal intensive care unit. J Perinatol 2001;21:415-20; Del Vecchio A, Sola MC, Theriaque DW et al. Platelet transfusions in the neonatal intensive care unit: factors predicting which patients will require multiple transfusions. Transfusion 2001;41:803-8]. Although a long list of disorders associated with neonatal thrombocytopenia can be found in many textbooks, newer classifications based on the timing of onset of thrombocytopenia (early vs. late) are more useful for planning diagnostic investigations and day-to-day management. The mainstay of treatment of neonatal thrombocytopenia remains platelet transfusion although it is important to note that no studies have yet shown clinical benefit of platelet transfusion in this setting. Indeed some reports even suggest that there may be significant adverse effects of platelet transfusion in neonates, including increased mortality, and that the effects of transfusion may differ in different groups of neonates with similar degrees of thrombocytopenia [Bonifacio L, Petrova A, Nanjundaswamy S, Mehta R. Thrombocytopenia related neonatal outcome in preterms. Indian J Pediatr 2007;74:269-74; Kenton AB, Hegemier S, Smith EO et al. Platelet transfusions in infants with necrotizing enterocolitis do not lower mortality but may increase morbidity. J Perinatol 2005;25:173-7]. There is also considerable variation in transfusion practice between different countries and between different neonatal units. Here we review recent progress in understanding the prevalence, causes and pathogenesis of thrombocytopenia in the newborn, the clinical consequences of thrombocytopenia and developments in neonatal platelet transfusion.

Postnatal management of fetal and neonatal alloimmune thrombocytopenia: the role of matched platelet transfusion and IVIG

We evaluated the effects of platelet transfusions and intravenous immunoglobulin (IVIG) in neonates with fetal and neonatal alloimmune thrombocytopenia (FNAIT) with and without antenatal treatment with IVIG. Records of neonates with FNAIT admitted between January 2000 and November 2005 were reviewed. The patients were divided into group I, treated antenatally with IVIG for known FNAIT, and group II, postnatally diagnosed with FNAIT. The primary outcome was the time interval to reach a platelet level above 100 x 10(9)/L in relation to the type of treatment. Nineteen neonates with FNAIT were identified, 13 in group I and 6 in group II. In group I, four children were born with a platelet count above 100 x 10(9)/L and never needed treatment, and four received a single matched platelet transfusion at birth with a maintained response. Five neonates received IVIG and one matched transfusion, with all but one rapidly responding. In antenatally treated cases, postnatal IVIG had no apparent effect on the platelet count. In group II, two neonates died on day 1 with severe intracranial hemorrhage. Two of the four other patients responded to a number of unmatched platelet transfusions, with one neonate rapidly responding after one matched transfusion, while another needed nine matched transfusions before a persistent adequate platelet count was reached after 9 weeks. Postnatal IVIG had no apparent effect on the platelet count in any of our cases. In neonates with FNAIT treated antenatally with IVIG, neonatal management using a single matched platelet transfusion was adequate in all cases. In neonatally diagnosed cases not treated before birth, multiple matched platelet transfusions may be required. We found no evidence to support the use of IVIG in neonates with FNAIT.

Neonatal porencephaly and adult stroke related to mutations in collagen IV A1

OBJECTIVE

The objective of this study was to describe leukoencephalopathy, lacunar infarcts, microbleeds and macrobleeds in the context of a collagen IV A1 mutation.

METHODS

We examined a family with autosomal dominant porencephaly, in whom a defect in collagen IV A1 was detected recently. The patients underwent neurological, ophthalmological, and cardiological examinations and magnetic resonance imaging of the brain. Electron microscopy of a skin biopsy was performed. Extensive laboratory screening was performed for thrombophilia and increased bleeding tendency.

RESULTS

The porencephaly was symptomatic in the infantile period in two patients, whereas it led to only minor neurological dysfunction in their affected mother. However, she experienced development of recurrent strokes in her 40s. In addition to the porencephaly, all patients had a leukoencephalopathy, which was most severe in the mother. Her magnetic resonance imaging results also showed lacunar infarcts, macrobleeds and a multitude of microbleeds. No other risk factors for recurrent stroke were found. Electron microscopy showed interruptions of the basement membrane of skin capillaries and inhomogeneous thickening of the basement membrane with pools of basement membrane fragments.

INTERPRETATION

Leukoencephalopathy, ischemic infarcts, microbleeds, and macrobleeds are indicative of an underlying microangiopathy, of which the best-known causes are hypertension, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, and cerebral amyloid angiopathy. Mutations in collagen IV A1, a major component of the vascular basement membrane, appear to be another risk factor.

Clinical and diagnostic comparison of neonatal alloimmune thrombocytopenia to non-immune cases of thrombocytopenia

BACKGROUND

Affected patients with neonatal alloimmune thrombocytopenia (AIT) are often severely thrombocytopenic and, if so, may suffer an intracranial hemorrhage (ICH). This study was undertaken to compare the outcome of cases of AIT to cases of neonatal thrombocytopenia shown not to be AIT and to identify clinical features that would facilitate the diagnosis.

PROCEDURE

Two hundred twenty two cases of neonatal thrombocytopenia for which serologic testing was obtained by the referring physician were accrued for this study from 11 testing laboratories. The relevant clinical information was pursued.

RESULTS

The mean birth platelet count in 110 neonates with AIT was 26,000/mm(3) x 10(9)/L and the rate of ICH was 11% (not all neonates had head sonos). Three criteria distinguished cases of AIT from other causes of neonatal thrombocytopenia (n = 56): (1) severe thrombocytopenia <50,000/mm(3) x 10(9)/L; (2) ICH associated with 1 or more of: a 1-min Apgar score >5, birthweight >2,200 g, grade >1, antenatal occurrence, or signs of bleeding, that is, petechiae, ecchymoses; and (3) no additional, non-hemorrhagic neonatal medical problems.

CONCLUSIONS

AIT is a unique type of neonatal thrombocytopenia with significant hemorrhagic consequences. Identification of AIT at the bedside should guide institution of appropriate treatment and lead to serologic testing for confirmation.

Thrombopénies néonatales dues à un allo-anticorps anti-HPA-5b : à propos de deux cas observés en Tunisie

Alloimmune thrombocytopenia is due to feto-maternal incompatibility in the HPA systems and is usually considered in the diagnosis of neonatal thrombocytopenia after other causes have been excluded. We report on two Tunisian observations of alloimmune neonatal thrombocytopenia due to anti-HPA-5b (Bra) antibodies.

CASE REPORT

Two neonates presented at birth with a thrombocytopenic purpura unexplained by usual causes of neonatal thrombocytopenia. Alloimmune neonatal thrombocytopenia was diagnosed by the determination of parental and neonatal platelets antigens phenotypes and by the presence of HPA-5b (antiBra) antibodies in maternal sera. A favourable evolution was obtained after maternal platelet transfusions.

CONCLUSION

Alloimmune neonatal thrombocytopenia is a serious affection, which exposes to intracranial haemorrhage. These observations of HPA-5 neonatal alloimmunisation in Tunisia provide additional information on the geographic distribution of the disease and its prognosis.

Neonatal thrombocytopenia: causes and management

Neonatal thrombocytopenia is a common clinical problem. Thrombocytopenia presenting in the first 72 hours of life is usually secondary to placental insufficiency and caused by reduced platelet production; fortunately most episodes are mild or moderate and resolve spontaneously. Thrombocytopenia presenting after 72 hours of age is usually secondary to sepsis or necrotising enterocolitis and is usually more severe and prolonged. Platelet transfusion remains the only treatment. There is a need for trials to define the safe lower limit for platelet count and which neonates will benefit from treatment.

Thrombocytopenia in the newborn

Thrombocytopenia remains a common problem in sick newborns. A quarter of all neonates admitted to neonatal intensive care units develop thrombocytopenia, and in 20% of episodes the thrombocytopenia is severe (platelets <50 x 10(9)/L). Practical and clinically relevant classifications of neonatal thrombocytopenia have now been developed which, by highlighting the principal conditions precipitating severe thrombocytopenia (eg, sepsis, necrotizing enterocolitis, perinatal asphyxia, and the immune thrombocytopenias), aid the practicing neonatologist. Recent reviews demonstrate that many neonates with severe thrombocytopenia receive repeated platelet transfusions, although evidence of their clinical benefit is lacking, and there exists a significant variation in platelet transfusion practice between centers. These facts support the need for the development of evidence-based protocols for platelet transfusion in the newborn and stimulate continued interest in the potential of hemopoietic growth factors (, thrombopoietin and interleukin-11) to prevent or treat neonatal thrombocytopenia.