In Detail:  The CSF accumulation caused by Hydrocephaly (also called "Hydrocephalus" and "Water on the Brain"[1]) can occur at any time in life, and has various potential causes, including congenital defect, hemorrhage into the brain, infection, meningitis, tumor, or head injury [2]. The CSF can collect inside the tissues of the brain, externally, between the brain and the cranial wall, or both [3]. In infants and children with unfused cranial sutures, the increased internal cranial pressure from hydrocephaly causes the skull to enlarge by forcing the sutures to expand in all directions [4] (as shown right). In adults, suture fusion means there is no cranial expansion, thus exerting the pressure fully on the brain[5].

It should be noted that in addition to standard hydrocephaly, there are two classifications of hydrocephaly that do not result in abnormal CSF pressure: "Hydrocephalus ex vacuo," which occurs as the result of damage to the brain[6], and normal pressure hydrocephalus, which can occur due to a gradual blockage of the CSF drainage pathways in the brain[7], but as these do not relate to the Starchild Skull they will not be discussed further here.

Various observers have suggested that the Starchild was hydrocephalic as an infant, causing the abnormal parietal expansion and cranial shape evident in the skull. However, cranial expansion caused by Hydrocephalus results in a widening of any unfused cranial sutures [8] (as shown above), and there is no evidence of this in the Starchild Skull[9].

In 2004 the Starchild Skull was examined by respected craniofacial surgeon Dr. Ted Robinson, in consultation with ten other specialists with the goal of identifying a medical condition that could explain the skull[10]. In their discussion on Hydrocephaly, Dr David Hodges, a radiologist, confirmed that the suture lines were open and growing at the time of death, and could find no evidence of widening or other abnormality of the cranial sutures[11]. Dr. Bachynsky, also a radiologist, found no signs of erosion on the internal surfaces of the skull, ruling out fluid between the brain and skull, and supported Dr. Robinson's conclusion that the Starchild was not Hydrocephalic [12].

X-Rays of the Starchild Skull compared to that of a Hydrocephalic (below) clearly show that, while the Starchild Skull has an unusual shape, it lacks the "inflated" appearance caused by internal pressure forcing the cranium of a Hydrocephalic to expand in all directions like a balloon. Some observers have argued that the Starchild Skull does look "inflated," but cradleboarding or positional flattening of the occipital (the bone at the rear of the skull) caused it to have a different shape than a typical Hydrocephalic. However, in concert with his colleagues Dr. Robinson concluded that the shape of the skull was natural, and not caused by artificial shaping stating:

"Lacking even a hint of evidence of shaping, and of any unnatural or premature fusing of any sutures, it is entirely safe to say that the extreme flattening of the skull was caused by its natural growth pattern and is not artificial."[13]

Starchild Skull side view X-Ray                                  Hydrocephalic side view X-Ray

Although Dr. Robinson established that the skull's shape was not caused by artificial shaping techniques, it should be noted that even if the occipital flattening had been artificially produced, this would still not explain the dent at the Sagittal Suture. Because it has already been established that this suture was open and healthy at the time of death, this should have been one of the first places to be expanded by abnormal internal pressure. In the absence of such expansion, it can be concluded that no abnormal internal pressure existed, therefore the expansion of the parietal bones could not have been caused by internal pressure.

A typical expression of Hydrocephaly would include dilated scalp veins, disproportionately small facial features, and eyes that appear depressed within the sockets[14]. The X-Ray image below shows the vein imprints on the Starchild Skull compared to those of a normal healthy human skull as the exact same scale. Clearly the vein impressions on the Starchild are the same size as those on the healthy human skull, indicating no dilation and therefore indicating against Hydrocephaly. The Starchild Skull did have a disproportionately small face, and this has perhaps contributed to the speculations of Hydrocephaly.

Doctors Townsend and Parsons both concluded that the eye sockets were less than 50% normal depth, and that the eyes almost certainly protruded from the skull, rather than being depressed into it [15]. It should be noted that protruding eyes can be associated with Hydrocephaly when certain sutures have closed prematurely[16], but as the Starchild Skull's sutures were clearly unfused and healthy[17], this is clearly not the cause of the skull's shallow orbits.

It has been established that the Starchild Skull does not display the symptoms of Hydrocephaly, and the study headed by Dr. Robinson in 2004 concluded that it was not the cause of the Starchild Skull's unusual features. Therefore, Hydrocephaly did not contribute to the Starchild Skull's shape, appearance, or characteristics--it did not suffer from Hydrocephaly.