Here is how AMuS describes the reading. Their source for this information is unknown, though they mention the FIA in their report.
This season, it is mandatory that drivers carry G-sensors in their earplugs. They measure the deceleration on the head. They must not be equivalent to the deceleration of the car, because the head accelerates and decelerates differently as the vehicle. HANS and neck protection ensure that the helmet cushions a soft landing. They distribute the deceleration over a period of time.
In the case of Bianchi, an incredible value of 92 g was recorded by the sensors in the ear. That is why it is understandable when the doctors talk about a miracle. The crucial question here is, over what time period.
To put this figure in perspective, Robert Kubica's terrifying 140mph-into-the-wall crash in 2007 was a mere 75g.
AMuS points out that Bianchi was brought to a complete stop in under five meters, that the crash was so violent that the neck protection holding the driver's head softly in the cockpit was found in the engine compartment.
It is indeed incredible that Bianchi has survived the critical first 24 and 72 hour periods after the wreck.