gms | German Medical Science

Objective: The most common form of external hydrocephalus (eHC) in infants is „idiopathic“. Recently venous hypertension has been associated to idiopathic external hydrocephalus. The associated intracranial pressure (ICP) increase results in accelerated skull growth. Since brain size remains unchanged, the picture of external hydrocephalus (mismatch of skull to brain) is created. One known reason for venous hypertension is sinus stenosis. In adult idiopathic intracranial hypertension reversibility of sinus stenosis (collapsible sinus) has been described, however, so far not in children with eHC.

Method: We report on three infants, two following meningitis, one idiopathic, with eHC on MRI and associated sinus stenosis on MR venography (MRV). The sinus stenosis was shown to be due to floppy collapsible sinus walls, since it was reversible alongside spontaneous or shunt induced resolution of external hydrocephalus.

Results: In two infants following meningitis, eHC with widening of the frontal subarachnoidal space developed and, consecutively, the head circumference increased. MR 3D-venography showed attenuation of the torcular, and narrowing of the transverse sinus in one case, distal sagittal sinus attenuation and sigmoid sinus narrowing in the other. After i.v. antibiotics both improved clinically, and in the due course head circumference normalized. Repeat MRV showed improvement of eHC and and stenoses disappeared. In the idiopathic case eHC developed together with developmental delay. MRV showed stenosis of sagittal and transverse sinus. After VP Shunt implantation an immediate increase in activity was seen and accelerated development was noted. After he seemed cured at age 1 year, the distal shunt catheter was ligated. Consecutively, child deteriorated, sinus collapsed and eHC reoccurred. Shunt was reopened and further course was uneventful.

Conclusions: A reversible collapse of venous sinus can occur in infants, which increases venous pressure and volume, resulting in increase of intracranial pressure (ICP). The ICP increase itself prevents reopening of the sinus, thus creating a vicious cycle. In case of developmental delay, a shunt treatment can be considered to reverse pressure gradients thus reopening sinuses. So far, the reasons for instable floppy sinus walls, as demonstrated on MRV in these cases, is unknown.