More Information on Brain Injury of Giffords
Yesterday's press release and press conference from the University of Arizona Medical Center provide more clues to the nature of Rep. Giffords's injury. In addition to performing a tracheotomy* and inserting a percutaneous feeding tube on Saturday, neurosurgeon Lemole and other physicians also performed a "minor" 2-hour repair of a right "orbital roof fracture" on Giffords. (Giffords sustained bilateral orbital roof fractures, but the left-sided injury, according to Lemole, did not require surgical repair.)
Lemole said that bone fragments from the right-sided fracture were "pushing down enough on the eye and the contents of the eye socket," so that an oculoplastic surgeon (Lynn Polonski) needed to perform a "quick releasing-and-incision operation" on the day of Giffords's injury. On Saturday, the full extraction procedure was performed, which necessitated a craniotomy (ie, an opening "just above the [right] eyebrow"). Once the bone fragments were removed, a metal mesh was placed in the roof of Giffords's right orbit. Lemole emphasized that, postoperatively, Giffords returned to her preoperative level of consciousness and functioning.
Given the description of orbital roof fractures, it appears that Giffords probably sustained significant injury (via the bullet exit entry wound) to her left (and possibly right) inferior frontal lobes. If previous descriptions of Giffords's brain injury are correct—namely that the bullet did not cross the hemispheric midline—the right-sided orbital injury may merely be collateral damage from the bullet exiting entering her left forehead.
The roof of the orbital socket, largely composed of the orbital plate of the frontal bone (of the skull), is relatively thin and therefore vulnerable in cases of traumatic injury—like a gunshot wound to the head.
Ophthalmologists are encouraged—nay, urged—to weigh in.
* At the press conference, Dr. Randall Friese, who performed the tracheotomy, indicated that Giffords cannot produce audible speech because the tracheostomy that she has in place "does not allow air to get past her vocal cords." But, he added, "she could certainly mouthe words...when she's ready to do that." Friese did indicate, later in the Q&A portion of the conference, that Giffords hasn't attempted speech.
Images of branded orbital meshes or plates in the inferior aspect of the orbit from Synthes.
Ophthalmologist here. Funny, all day I've been feeling this...this strange urgency to weigh in on something, anything. To think I almost posted on Gary Busey's blog instead.
The bony orbital walls are quite literally paper-thin in many areas. A bullet blasting through the frontal cranium easily transmits enough force to splinter and crack those bones---in this case, a "blow in" fracture, rather than the usual "blow out" fracture when the eye is hit with a blunt object and, along with the orbital contents, is slammed against the orbital wall.
Here's some reasoned guessing (or irresponsible speculation---take your pick) re/ the "quick releasing-and-incision" [sic] done when she was admitted. Clearly impingement from orbital bone fragments, and /or orbital hemorrhage, was jeopardizing either the optic nerve or the globe itself. The relaxing incision might be describing a lateral canthotomy (incision through the soft tissues where the two eyelids meet laterally). Generally this is done if a posterior force (such as a orbital hemorrhage) is pushing the eye forward. Cutting the lateral canthal tendons permits the eye to protrude further, diminishing intense pressure on the globe. Less likely, the initial procedure might have been a decompressive orbitotomy (i.e., surgically opening a hole through another orbital wall). This would permit orbital contents to prolapse somewhat, which might also relieve pressure or bony impingement. However, an orbitotomy is not a very "short" procedure, and decidedly more invasive than a simple canthotomy.
Thanks for the speculation and directing your energy away from Busey.
Descriptions of the Safeway surveillance videos (for instance, here: http://www.washingtonpost.com/wp-dyn/content/article/2011/01/18/AR2011011804266_2.html ) indicate that Giffords was shot once in the left forehead at a range of about 2-3 feet. (Some news sources [eg, the LA Times] had falsely indicated that Giffords was shot in the back of the head.) A close-range GSW to the forehead would certainly transmit enough force to fracture, by proxy, some part of the left and right orbits--and probably other fragile bones in the area, like the cribiform plate, etc.
Video clips of a lateral canthotomy--which you speculate may have been performed on the day of injury--can be seen on the web, courtesy of eMedicine/WebMD: http://emedicine.medscape.com/article/82812-media.
Generally speaking (and for what it's worth in Giffords's case), entrance wounds from gunshots are typically smaller than exit wounds. But it's really difficult to guess what type of brain damage she may have sustained near the exit wound (or where the exit wound even is*), given the probability that the bullet trajectory was not linear.
* Other than somewhere in the left parietal-occipital area.