Case report on the neurological complications associated with Noonan syndrome

*Correspondence: [e-mail].

Abstract

Case Presentation: We report the case of a 5-year-old boy, born prematurely by cesarean section at 34 weeks due to gestational complications. During pregnancy, his mother developed preeclampsia and was hospitalized. In the second gestational trimester, his ultrasound displayed polyhydramnios, mild bilateral cerebral ventriculomegaly and renal pyelectasis. When he was born (APGAR 5/8), he demanded resuscitation, underwent endoscopic gastrostomy and had multiple deformities, polycystic kidney disease and bilateral cryptorchidism. A transfontanellar ultrasound revealed mild ectasia of the supratentorial ventricular system (SVS) and the fourth ventricle. At 5 months, he was diagnosed with neuropsychomotor developmental delay (NPMD), laryngomalacia and global tactile sensory dysfunction. At 12 months, an MRI revealed global dilation of the SVS and a diffusely tapered corpus callosum. When he was 20 months old, macrocrania, malnutrition, poor eye contact and global hypotonia were reported and, 2 months later, he was diagnosed with Noonan Syndrome (NS), with a BRAF gene variant of zero frequency. At 2 years old, he began to have seizures and to display hearing hypersensitivity, stereotypies, irregular sleep, myoclonus, inability to sit or speak and unresponsiveness to calls. At age 4, he presented with spastic tretraparesis-axial hypotonia, persisting with seizures, dysphagia and sensory dysfunction.

Discussion: The case describes complications of NS, a genetic disease that causes multiple malformations, short stature and heart disease, with less frequent digestive disorders, PMDN and cryptorchidism, except when the BRAF gene is altered. Furthermore, radiation, polyhydramnios and preeclampsia in the last trimester of pregnancy are major causes of premature birth, the latter being able to develop renal, cardiopulmonary and cerebral alterations in the fetus due to fetal growth restriction. This brain malformation can cause seizures, hydrocephalus, cerebral palsy and even autistic traits, conditions that are still corroborated by genetic factors.

Final Comments: Given the variety of complications that NS causes to patients, this syndrome should undergo further analysis by the scientific community, since there are few studies about it. Furthermore, early diagnosis is still complicated, making it difficult to offer personalized treatment for their needs.

 

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Publication History

Article published online:
12 May 2025