On a sudden in the midst of men and day,
And while I walk'd and talk'd as heretofore,
I seem'd to move among a world of ghosts,
And feel myself the shadow of a dream.
Our great court-Galen poised his gilt-head cane,
And paw'd his beard, and mutter'd 'catalepsy'
- Alfred Lord Tennyson
A patient suffering an epileptic seizure might exhibit few symptoms. Most often children, the victims might suddenly stop what they're doing and stare blankly, unaware that the seizure is happening beyond a sense that they have lost time once the event is over. Patients sometimes describe the sensation as a series of brief electrical shocks.
To an observer, the event can seem violent and horrifying, and to the victim, it's as if parts of the mind were wiped clean or transposed entirely.
Caused by complex chemical changes tearing across nerve cells, some brain cells are either excited or inhibited from their business of sending messages. Of the six types of generalized seizures, the most dramatic is a convulsion known as a "grand-mal" event. Loss of consciousness and collapse, a stiffening of the body for up to a minute and then, the violent jerking of the clonic phase – often up to a full minute long – might end in injury, tongue biting and incontinence.
The treatment for the condition can seem mortifying as well. It commonly involves drilling straight through the skull to reach the brain and the tiny site inside responsible for the problem.
Now a team of engineers at Vanderbilt University think they've found a better way. They believe they've built a robotic device which can reach the hippocampus located at the base of the brain by operating through a patient's cheek to avoid disrupting the skull.
The working prototype of the device created by David Comber, a grad student in mechanical engineering at Vanderbilt, was recently demonstrated at the Fluid Power Innovation and Research Conference in Nashville. Comber and the team worked with medical 3D printing experts Vito Gervasi and Jonathon Slightam of the Milwaukee School of Engineering to print their device.
It consists of a 1.14 mm nickel-titanium needle which operates inside curved, concentric tubes to guide the MRI-safe needle using compressed air while robotics direct the path of the needle one millimeter at a time.
The problem is that to make it happen, they needed to develop a needle made of a "shape-memory alloy" which they can operate within the unforgiving magnetic field inside an MRI scanner.
The environment inside an MRI scanner uses energy from an oscillating magnetic field of a controlled resonant frequency to excite hydrogen atoms in the human body. The reaction of those atoms can then be detected via a radio frequency signal to form an image which doctors can use to assess the condition of the cerebral cortex, identify fatty tissue and characterize liver lesions and other tissue anomalies.
Many MRI systems use a superconducting magnet, coils or windings of wire through which a powerful current flows, and they can build up a magnetic field of up to 2.0 Tesla through the use of superconductivity which can lower resistance in the wires to nearly a zero state. Bathed in liquid helium at 450+ degrees below zero, the resulting powerful magnetic field allows for images of stunning quality.
Eric Barth, the Associate Professor of Mechanical Engineering at Vanderbilt who led the team, believes the device is less than a decade from use in operating rooms.
Working with Associate Professor of Neurological Surgery Joseph Neimat, the team found that neuroscientists regularly operate through a patient's cheek to implant electrodes in the brain to locate the source of epileptic seizures, but were prevented from operating in those areas by the lack of a precision device which could adequately direct the needle to the site in question.
"The systems we have now that let us introduce probes into the brain – they deal with straight lines and are only manually guided. To have a system with a curved needle and unlimited access would make surgeries minimally invasive," Neimat says. "We could do a dramatic surgery with nothing more than a needle stick to the cheek."