Author: vaughanbell

Many thanks to Alex and the Neurophilosopher, who sent in the article I had no luck getting hold of in the previous post on trepanation – the surgical technique of putting a hole in the skull.

The brief article is from the 1923 edition of the anthropology journal Man and describes ninth century brain surgery on a 22-year-old man.

If you’re wondering why it describes the operation as trephination, it’s an alternative word for trepanation. Click on the image for a larger version.

A Trephined Irish Skull
Man, Vol 23, (Nov 1923), p180
Thomas Walmsley

Cennfaelad, a young Irish chief, had his skull fractured by a sword-cut at the Battle of Moyrath AD 637. He was under treatment for a year afterwards at the celebrated school of Tomregan (now in Co. Cavan), where the injured part of his skull and a portion of his brain were removed. He recovered and afterwards became a great scholar and a great jurist. Such is one record of early Irish surgery.

The skull reproduced here (Fig. 1) is that of a young male about twenty-two years of age, which was obtained, along with a number of other skulls, from early Christian (ninth century) graves at Nendrum Monastery in Island Mahee, Strangford Lough. The other skulls, with a few more of the same period from another locality, I hope to describe at a later date, but this one is of sufficient interest to be described separately.

For on the left side, towards the anterior-inferior angle of the parietal bone and just within the temporal line, there is a trephined opening. The diameter of the opening is 8mm, but it originally must have been more, for the edges have healed all round; this can be seen better on the inner surface. Round the opening, on the outside of the skull, for a distance of 3mm, the bone is bevelled as if it had been scraped away. On the inside there is no such bevelling; rather the bone is slightly raised and tuberculated round the original margin of the opening.

There are no marks of injury on the skull, and there is no evidence of disease. The deficiency above the mastoid is due to the falling out of a sutural element.

Neurophilosopher has written an absolutely fantastic post on the history of trepanation – the surgical procedure that has been carried out since prehistoric times and involves drilling a hole in the head.

Neurophilosopher always has great articles but this is also wonderfully illustrated and has all the gory details of this fascinating procedure.

The trepanned skulls found at prehistoric European sites contained round holes, which varied in size from just a few centimetres in diameter to nearly half of the skull. They are most commonly found in the parietal bone, and also in the occipital and frontal bones, but rarely in the temporal bone. In the earliest European skulls, the holes were made by scraping the bone away with sharp stones such as flint or obsidian; later, primitive drilling tools were used to drill small holes arranged in circles, after which the piece of bone inside the circle was removed. The late Medieval period saw the introduction of mechanical drilling and sawing instruments, whose sophistication would continue to increase for several hundred years.

The article takes you through the prehistoric origns of the procedure, to how it developed around the world, to its modern uses for surgery and recreation (yes, recreation!).

The picture at the top is from a trepanned skull from the Hunterian museum in London that also showed signs of neurosyphilis infection. There’s more about it in a previous post.

I also found a good example of a trepanned skull in the National Museum of Ireland but unfortunately they don’t allow pictures and don’t have images of it available.

However, this article has an interesting snippet about the various examples of the procedure discovered in the country:

From Ireland several interesting examples are available. A trepanned skull of a thirteen-year-old child, probably early Christian, was recovered from Collierstown in Co. Meath (Martin, 1935). Two further trepanations each of late Mediaeval date, one from Ballinlough (Co. Laois) and the other from Maganey Lower (Co. Kildare), were found during recent excavations.

A fourth specimen was discovered in a stone-lined grave at the Abbey of Nendrum on Mahee Island in Strangford Lough (Martin). The abbey was destroyed in 974 A.D. by fire. It is highly likely that in those days “major surgery” was performed in monastic institutions (Fleetwood, 1951). Legend has it that Cennfaeladh, whose skull was fractured by a blow from a sword during the battle of Moyrath in Co. Down (637 A.D. ), was operated upon by St. Bricin, the Abbot of Tuaim Drecain, an accomplished surgeon and scholar (Fleetwood).

And this page has an image of a 7th century gargoyle-esque carving of St Bricin with trepanning tools in one hand and a skull in the other.

Apparently, the treatment worked so well that Cennfaelad, an Irish chieftan, recovered his intellect and improved his memory so that on his recovery he became a great scholar, whose name ‘Kennfaela the Learned’ is known in Irish literature to this day.

There’s more about this case, and about trepanning in Ireland, on this page, and, if you’ve got a subscription to JSTOR, which I don’t have unfortunately, there’s an academic article here. Do let me know if you can get hold of a copy!

Link to Neurophilospher on ‘An Illustrated History of Trepanation’.

ScienceDaily reports that the first images from a new type of brain scanner that combines both magnetic and radiation-based imaging have been shown at a recent medical conference.

The new technology is called MR/PET because it allows magnetic resonance and positron emission tomography scans to be conducted at the same time.

MRI uses very strong magnets that align the spin of the atoms in your body. It then sends a radio pulse which knocks the atoms out of alignment.

After the knock, the atoms return to their previous alignment but the time taken will differ, depending on the body tissue. As they return, they send off their own pulse, and this can be picked up and turned into an MR image of the tissue by computer software.

PET involves adding a small amount of oxygen or glucose into the body that the brain uses to do its work. Crucially, the substance has been altered so it is slightly radioactive.

As the brain works, the areas that are most active will be slightly more radioactive, and this can be measured to generate a map of brain activity.

You can create similar maps using functional MRI, but one advantage of PET is that it is especially good at ‘resting PET’, meaning you’re not asked to do any tasks. It just gives a general picture of which brain areas are most active.

This is particularly useful if the medical team think your brain might be structurally intact but may have areas which are under or overactive, or want to know the effects of structural damage in one area on function in the rest of the brain.

PET can also be used to track the effects of specific chemicals in the brain (by making them slightly radioactive and injecting them), which is something that fMRI currently can’t do very well.

Previously, to combine the two scans, someone would have to go into a MR scanner to get a structural image, and then go into a PET scanner to get a measure of activity, and computer software would impose the PET image onto the MR image.

This causes problems because the two images aren’t perfectly aligned and so information gets lost.

Imagine you are trying to fit a photo you took from an airplane onto a street map. You might need to stretch or edit the photo to make it fit properly, and in doing so, you might miss bits out or blur important details.

The reason the combined MR/PET will be useful is that the two scans are taken at exactly the same time, so no information is lost.

It also means patients with fragile brains won’t need to be moved between scanners.

One of the difficulties with combining the types of scanning before is that PET normally uses photomultiplier tubes to detect the effects of radiation, which don’t work in magnetic fields, but now new sensors have been developed which are MR safe.

Unfortunately, I can’t seem to find any images of the new scans online (please let me know if you find or have any!).

However, if you want to know more, Radiology Today magazine has a more in-depth article and Siemens, the creator of the technology, has some information as a webpage and pdf.

Also there’s an image of the scanner from a Cambridge University team also working on the technology.

Link to ScienceDaily on new MR/PET images.
Link to Radiology Today article on the technology.

Brain injury resource site Neuroskills has a nifty page of brain animations, including a selection showing how various types of brain injury occur.

They’re a bit clunky in places and the point of injury seems to be illustrated with a small science-fiction-like stellar explosion, but they’re genuinely informative and quite fun to watch at times.

They include the effect of a bullet to the head, stroke, shaking injuries, animations highlighting the main anatomical areas, the functioning of healthy and damaged neurons and a few others thrown in for good measure.

Link to Neuroskills animations gallery.

Wired has a good break down of theory that says that nerve cells don’t work on electricity as we assume, but instead transmit signals using pressure waves, and crucially, this might explain how anaesthetics work.

The idea that nerve cells send their signals as pressure waves is not brand new. Known as the Soliton model, it was first published in 2005 by Drs Andrew Jackson and Thomas Heimburg and was thought a bit of a curiosity.

It challenges the model of nerve cell functioning that was developed by Alan Hodgkin and Andrew Huxley, both of whom won the Nobel prize for their work.

Their discovery was that nerve cells can be understood as electrical circuits and that the transmission of nerve signals or action potentials can be described using a simple elegant mathematical formula.

This formula describes how nerve cells work remarkably well and is still the basis of much modern neuroscience.

So suggesting that the Hodgkin-Huxley model is wrong is likely to piss a lot of people off, and that’s exactly what the Soliton model has done.

However, this new paper suggests it could explain how anaesthetics work, which is one of the mysteries of modern neuroscience.

It’s a totally left-field idea, but if it works out, it would be a revolution in both neuroscience and medicine.

Link to Wired article on application of the Soliton model to anaesethics.
Link to 2005 scientific paper on the Soliton model.

BBC Radio 4 science programme Frontiers just had a special edition on using brain scans to read the mind.

There’s been various reports in the media about research studies that have been able to identify subjective mental states or intentions from patterns on brain scans, mainly reported as a sort of ‘mind reading’ technology.

While these are genuinely interesting studies, they’re really not at the stage of being able to ‘read’ anyone’s thoughts.

The first thing to ask yourself when you hear this sort of claim is ‘has the effect been shown to work on individuals, or only as an average over a group?’. The next is ‘what task was the effect demonstrated on?’ and finally think about how reliably the effect could be demonstrated.

For example, on a recent brain imaging study that attempted to predict intentions, the prediction was made for individuals, but only between one of two possible options and the best reliability was 71%.

In other words, this study found that for each individual, when looking back at the data, with a choice deliberately designed to be predictable, their choice could be worked out before they made it about two-thirds of the time.

It’s hardly likely to concern anyone worried about the privacy of their thoughts.

It is a start though, and the implications of how the technology might be used as it becomes more accurate are certainly thought provoking.

The special edition of Frontiers talks to some of the researchers involved in this work and tackles the ethics of the technology.

Link to Frontiers on ‘Mind-reading’ (with audio).