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Neuroanatomy, bullets and brain damage in ‘The Girl With the Dragon Tattoo’ [The Millennium Trilogy by Stieg Larsson]

April 3, 2010 1 comment

Like at least 27 million other people, I bought and read all three volumes of the late Stieg Larsson’s Millennium trilogy (The Girl with the Dragon Tattoo, The Girl who Played with Fire, and The Girl who Kicked the Hornet’s Nest). All three books are in the current top ten best sellers in Ireland. I’ve also been to see the first film of the series (in Swedish, with English subtitles). The books are all a bit daft, but hugely enjoyable and compulsively readable – Larsson must have had great fun dreaming up the cast of variously weird, wonderful, and way-out characters in these books. The film was enjoyable too, if you like stark, grey, colour-desaturated Swedish landscapes with the occasional ageing and semi-crazed nazi, vicious intrafamily feuds, intergenerational inheritors of murderous traditions and dreary, near-endless rain and snow (seems I do). The lead female character, Lisbeth Salander, something of a social misfit (perhaps with a mild case of Asperger Syndrome), is an accomplished computer hacker and is reasonably skilled in martial arts and the use of golfclubs to demotivate murderers from the object of their predatory desires.

Towards the end of second volume of the series, Lisbeth is shot in the head with a .25 calibre gun (she survives). Larsson describes the wound thus (p 550, Quercus paperback edition):

“The third bullet caught her about two centimetres below the top of her left ear… The lead came to rest in the grey matter about five centimetres beneath the cerebral cortex by the cerebrum.”

In volume three, two medics work to save her and remove the bullet. One operates, the other (who claims to have a certain amount of alcohol on board), observes and makes suggestions. On page 9 (again Quercus paperback edition), the bullet wound is now described as ‘Entry wound just above the left ear’ (hmm). On page 11, one asks the other for a diagnosis. The reply is: ‘It entered at the temple, and the stopped about four centimetres into the brain. It’s resting against the lateral ventricle’. A conversation ensues about bone fragments and their potential for damage. One medic says the bone fragments are the cause  for concern, as they might kill her, as they are embedded in brain tissue. The other then remarks they are in the part of the brain associated with ‘numbers and mathematical capacity’, eliciting a sceptical response. (However, a bullet this deep in the brain would surely give anyone pause for thought, even if they were somewhat under the influence of alcohol).

But, reading all this as a neuroscientist, makes me give a sceptical response too; the various descriptions of  where the bullet has travelled really make little sense at all. If she was shot two centimetres below the top of the ear (but presumably not through the pinna, the outer part of the ear), how does the bullet end up passing through the temple? The neuroanatomical description of the bullet trajectory makes no sense either. The bullet is described as ‘to rest in the grey matter about five centimetres beneath the cerebral cortex by the cerebrum’. However: the grey matter is what comprises the cerebral cortex; the cerebrum is merely the term for what is usually referred to as ‘the brain’ (excluding the brain stem and cerebellum).

Five centimetres into the brain is quite a distance into the brain, and would likely cause enduring damage to a variety of functions (depending on location – but the bullet location varies!). If the bullet is close to or above the ear, then it can’t be close to the lateral ventricle, which is in a distinctly different location. There is a part of the brain associated with numerical and mathematical capacity (well, there must be) – it is usually regarded as the left parietal lobe (and the subregion of the angular gyrus) in right-handed individuals. Damage to this region is associated with the syndrome of acalculia, the loss of the ability to use and manipulate numbers. Again, this all a bit of distance from the three different places in the brain that poor Lisbeth has been shot with the one bullet! If the bullet has travelled five centimetres into the brain (assuming the top of the ear description is the accurate one), then depending on the trajectory, it just might have passed through the angular gyrus, travelling in a straight line toward the corpus callosum, or perhaps up a bit to posterior cingulate or anterior retrosplenial cortex (all midline structures). If it travelled at a downward angle, then it gets a lot more complicated. It won’t get near the lateral ventricle in either case; there is, instead, a wide choice of structures (both thalamic and non-thalamic) for the bullet to compromise.

What’s the lesson here? I’ve no idea (except that I should get out more, perhaps).