Review Question - QID 217705

This fetus likely has congenital hydrocephalus as evidenced by the enlarged ventricles (superior greater than inferior) on ultrasound. A possible complication of congenital hydrocephalus is hyperreflexia.

Congenital hydrocephalus is the accumulation of cerebrospinal fluid (CSF) in the ventricles that develops in utero. It is often secondary to congenital malformations or, in prematurity, intraventricular hemorrhage. Intrauterine infections are also common causes, including rubella, cytomegalovirus, and toxoplasmosis. The etiology of hydrocephalus can be obstructive (blockage of normal CSF flow) or communicating (decreased absorption of CSF). For congenital hydrocephalus, common signs and symptoms include an abnormally large head, bulging fontanelles, suture disjunction, up-gaze palsy, and feeding difficulties. With many upper motor neuron axons passing through periventricular white matter (such as corona radiata and internal capsule), upper motor neuron signs such as spasticity, hyperreflexia, and contractions are also expected given ventricular enlargement. Diagnosis is confirmed with imaging, with computed tomography and magnetic resonance imaging commonly used. Ultrasound is used for infants given the open fontanelles and avoidance of radiation. Management is surgical. Ventriculoperitoneal shunts drain CSF from the ventricles to the peritoneal cavity. Endoscopic third ventriculostomy creates another path of CSF flow through the floor of the ventricle into the prepontine cistern.

McAllister explores the pathophysiology of congenital hydrocephalus. Acutely, ventriculomegaly leads to compression and stretch of periventricular tissues and ischemia. Chronically, edema and demyelination develop and can lead to abnormal connectivity and cell death. Despite more robust plasticity and recovery in younger brains, the earlier the age of hydrocephalus onset, the worse the prognosis. It is emerging that neuroinflammation is a key component of pathophysiology, and treatments against the process are being explored.

Figure A is a prenatal ultrasound demonstrating ventriculomegaly consistent with congenital hydrocephalus. Illustration A has yellow lines demonstrating the increased length between the lateral walls of the ventricles to the central septum pellucidum (yellow arrow).

Incorrect Answers:
Answer 1: Cardiac abnormalities are not associated with congenital hydrocephalus. Genetic disorders such as Down syndrome, Edward syndrome, Patau syndrome, William syndrome, and DiGeorge syndrome. Given the normal quad screen and amniocentesis analysis, this patient is unlikely have these conditions.

Answer 3: Hypotonia is decreased muscle tone. It is linked to multiple genetic disorders (Down syndrome, Prader-Willi syndrome, and Tay-Sachs disease), muscle disorders (muscular dystrophy and myotonic dystrophy), and central nervous system disorders (cerebral palsy). Hypotonia would not be expected in patients with congenital hydrocephalus.

Answer 4: Photophobia is when light causes sensory disturbance. Conditions that are associated with photophobia include traumatic brain injury, meningitis, and subarachnoid hemorrhage. The exact mechanism of photophobia is still unknown, but the photosensitive retinal ganglion cells have been implicated. Congenital hydrocephalus patients would not be expected to have photophobia.

Answer 5: Quadrantanopia is a visual field defect linked to a lesion of optic radiations. This is a possible complication seen in strokes. Visual defects are possible complications of hydrocephalus. They may arise through various mechanisms: posterior cerebral artery occlusion through herniation, papilledema, or optic chiasm compression. However, the specificity of a quadrantanopia lesion would not be expected in this patient.

Bullet Summary:
Spasticity and hyperreflexia are possible findings in congenital hydrocephalus.