Precision injections of Botox into migraine

It looks like a pistol in which the stock has been replaced by a long needle. The tool, called MultiGuide, has been developed by NTNU and is based on an invention made by Dr. Daniel Bratbak at St. Olav's Hospital. This high-precision instrument is currently being used on patients with great success.

However, in order to position the tip of the needle within one millimetre of its intended target, the guidance system must continuously be informing the surgeon of exactly where the tip is located -- and in an easily accessible way. SINTEF researchers were asked to look into this in 2014.

Accuracy is everything

SINTEF researcher Christian Askeland is demonstrating the equipment in his laboratory at the Medical Engineering Centre in Trondheim. This includes the 'pistol' -- pointed at the head of a test dummy lying on the bench. The image of a brain is displayed on a screen behind him. "During surgery, the surgeon must be guided by images. This is called image-assisted intervention," says Askeland. "It is vital to carry out the injection to an accuracy of 5 millimetres or less, and preferably within 1 millimetre of the intended target point. Access to a screen display is thus a prerequisite for using the instrument," he says.

Currently, a more universal system called BrainLab is used to obtain cross-sectional images of the head while the surgeon is performing the operation. The SINTEF researchers want to replace this system with their own research platform called CustusX, which will be user-adapted and more efficient.

"BrainLab can be used for all types of operation, but here we're talking about a very specific task involving accurate injection at a precise point by means of the insertion of a needle along a given path to a predefined migraine 'centre'. This is why we need the benefits of a more tailored system," says Askeland.

All in one

The inventor, Dr. Daniel Bratbak, works at the Neurosurgical Department at St. Olav's Hospital where one of his jobs is to alleviate symptoms suffered by migraine patients. There is a so-called 'centre' located between 5 and 6 centimetres beneath the skin that triggers impulses which in turn generate cluster headaches. The Botox is injected into this centre. The impulses are reduced or disappear between 3 and 9 months after the procedure is completed, after which the patient must return for a new injection.

"With the patient lying in front of me, I have to focus all my attention on guiding the tip of the needle to its target," says Bratbak. "If I have to shift my line of sight to get assistance from the screen display, my guidance of the needle is interrupted and I have to re-orient myself in order to continue," he says.

Bratbak thus saw the need for a miniature screen that could be positioned within his line of sight, and had the idea to install an iPhone on the MultiGuide instrument. His idea was that this display would allow him to operate using an all-in-one instrument without having to shift his line of vision.

Efficiency

Today, migraine patients are admitted to the Surgical Department for treatment. By using an improved needle guidance system, which is prerequisite if the images are to be displayed on an iPhone, patients need no longer occupy operating theatres, but can be treated at an out-patient clinic where a neurologist can perform the entire procedure. This may lead to dramatic improvements in efficiency.

Back at the laboratory at SINTEF, Christian Askeland tells us that he is now working on a screen visualisation system that will simplify the precise guidance of the needle tip to its intended target location. "Moreover, we aim to better visualise the path the needle takes to its target so that the surgeon won't accidentally encounter an obstruction such as a bone. We're now very familiar with the system and are tailoring our platform specifically to address migraine operations," he says.

Askeland goes on to say that he has no basis for claiming that the needle guidance system will be more accurate. However, by assembling all the necessary components into a single tool that allows the surgeon to avoid having to shift his line of sight, the system will undoubtedly be more user-friendly. "It is of little use developing a high-accuracy system if the user is unable to exploit it," he says.