What is Subgaleal fluid?

A subaponeurotic (subgaleal) fluid collection is an extracranial accumulation of fluid occurring between the scalp aponeurosis and the periosteum that characteristically presents as a soft, non-tender, ill-defined, highly mobile, fluctuant scalp swelling not limited by suture lines.

Discussion

Subaponeurotic fluid collections have been reported infrequently. These collections are obvious clinically and are often noticed a few weeks after delivery and resolve spontaneously. A few cases have been reported in which the swelling had been tapped on one or two occasions when it recurred and later resolved spontaneously within 5-24 weeks.

Usually, these children are healthy, alert, and without any abnormalities of the skull; however, in our case, there were associated wormian bones. There was no evidence of these bones being responsible for CSF collections as none of the bone ossicles were directed inward to injure the dura. Usually, wormian bones are small and less numerous unless associated with skeletal dysplasia.

The swellings are cystic, soft, compressible, fluctuant, and usually cross the suture lines.

The etiology of this condition is not well understood; however, it may occur due to birth trauma resulting from prolonged vacuum-assisted delivery; disruption of the lymphatic drainage, venous drainage, and CSF leakage may be contributory. Schoberer et al. proposed microfractures disrupting the emissary and diploic veins. Aspirates from the swellings revealed CSF, the origin of which was uncertain. This condition is more common in children monitored with fetal scalp electrodes and ventouse delivery. In our case, ventouse application may have been responsible. In our patient, the CSF swelling was not noticed immediately after birth and it was diagnosed a few weeks after the birth, which has been the experience of others as well.

CSF collection does not cause periosteal ridging as seen with cephalhematoma. Aspiration of the swelling is not indicated as there is a potential risk of infection.

Hopkins et al. treated 1 of 7 patients with aspiration twice, later it resolved spontaneously.Petraglia et al. could collect 12 cases from the literature, and all of them were from Europe and presented three of his own.Schoberer et al. reported a series of 5 cases presenting 7–8 weeks after birth. Four of these cases had ventouse delivery.Fluid was aspirated in three cases (twice in one case) and fluid reaccumulated after aspiration on all three occasions. The aspirate showed high concentrations of B trace protein and B2 transferrin was present in the range of within CSF indicating that these fluid collections appeared to be related to traumatic labor because of serosanguinous nature. In our case, the fluid was slightly bloodstained and biochemically confirmed to be CSF.