Neonates with HLHS do not typically have a heart murmur, but in some cases, a pulmonary flow murmur or tricuspid regurgitation murmur may be audible.Co-occurring tricuspid regurgitation or right ventricular dysfunction can cause hepatomegaly to develop. Pathogenesis
The majority of HLHS cases are sporadic meaning they arise in patients with no family history of HLHS. Some cases may have a genetic component, as HLHS has been shown to be heritable and associated with specific gene mutations. Possible contributing factors may include intrauterine infarction, infectious changes, and a selective left ventricular cardiomyopathy. Genetics
Genetic loci associated with HLHS include GJA1 (connexin 43), HAND1, NKX2.5, 10q22, and 6q23. There is a slight risk of recurrence in future pregnancies, estimated to be 2-4%, which increases to 25% in families with two affected children. This is thought to be mediated by genetic mutations with incomplete penetrance.HLHS is also associated with several genetic syndromes, including trisomy 13 (Patau syndrome), trisomy 18 (Edwards syndrome), partial trisomy 9, Turners syndrome (XO), Jacobsen syndrome (11q deletion syndrome), Holt-Oram syndrome, and Smith-Lemli-Opitz syndrome. Altered Blood Flow
A popular theory termed the "no flow, no grow" hypothesis suggest that primary anatomic defects of the aortic and mitral valves lead to malformations of the left ventricle and its outflow tract. These primary defects can be divided into those that lead to outflow tract obstruction or reduced left ventricular filling. Outflow tract obstruction leads to left ventricular hypertrophy and reduction in the left ventricular lumen. One example of this would be in the case of aortic stenosis.
A thorough workup, including neuroimaging is essential to rule out anatomic lesions or other causes of this syndrome. Visually significant upgaze palsy can be relieved with bilateral inferior rectus recessions. Retraction nystagmus and convergence movement are usually improved with this procedure as well. Prognosis
The eye findings of Parinauds syndrome generally improve slowly over months, especially with resolution of the causative factor; continued resolution after the first 3–6 months of onset is uncommon. However, rapid resolution after normalization of intracranial pressure following placement of a ventriculoperitoneal shunt has been reported. References
Further reading
Aguilar-Rebolledo F, Zárate-Moysén A, Quintana-Roldán G (1998). "Parinauds syndrome in children". Rev. Invest. Clin. (in Spanish). 50 (3): 217–20. PMID 9763886. Waga S, Okada M, Yamamoto Y (1979). "Reversibility of Parinaud syndrome in thalamic hemorrhage". Neurology. 29 (3): 407–9. doi:10.1212/wnl.29.3.407. PMID 571990. S2CID 42247406. == External links ==