Cochlear implants... a successful history with a bright future ahead

A friend of mine said to me few days ago: cochlear implants are one of those things of medicine and technology which actually looks like "magic" or "a miracle". Indeed, cochlear implants made possible to connect deaf people with the world of sound, allowing them to converse with others and even to listen to music. A dream for deaf people which started to take shape for the first time in Dr. Graeme Clark's mind, an Australian otolaryngologist pioneer in the field. He was the first person to develop the multi-channel cochlear implant and to have successfully performed the world’s first implant procedure on Mr Rod Saunders in August 1978, at Melbourne’s Royal Victorian Eye and Ear Hospital.

 

But explaining the whole history of this hearing implants is not the purpose of today's post. I would ike just to mention some of the new technologies currently developped in this interesting field, just to show that there is still big room for improvement and that deaf people can hope for the best in upcoming years. Among others: 

- DACS: Direct Acoustical Cochlear Stimulation: implantable hearing device which bypasses the middle ear and applies powerful vibration directly at the oval window in order to stimulate the cochlea without significantly entering it. It replaces the function of the ear drum and ossicular chain with direct vibration at the oval window (take a look here for more information: http://www.acousticimplants.com/en/product/how-it-works.php)

- Increase number of electrodes: "hi fi" cochlear implant featuring 50 electrodes. It is hoped that the increased number of electrodes will enable users to perceive music and discern specific voices in noisy rooms.

- Laser stimulation: The laser stimulation produced more precise signals in that brain region than the electrical stimulation commonly used in cochlear implants. Laser stimulation is a promising technology for improving the auditory resolution of implants.

- Fully internal cochlear implant with an internal microphone system: a fully implanted system which can be worn all the time (sleeping, having a shower…). The ability to hear 24/7! As of April 2011, four people have undergone a trial of an internal microphone system, with two more yet to come. More information in this article: http://www.newscientist.com/article/mg21028064.800-ear-implants-for-the-deaf-with-no-strings-attached.html

- Liquid transmission means for transmitting acoustical energy to the cochlea, using a liquid filled tube which is surgically inserted through the middle ear to an orifice in the cochlea. The liquid filled tube acts as a transmission line with little losses because the liquid can be similar in acoustic properties to the perilymph in the cochlea and the impedance of the transmission line can be more closely matched to the acoustic impedance of the cochlea at the termination of the tube at the cochlea.

- Improvement speech processing strategies: In the n-of-m sound coding strategy, the signal is processed through m bandpass filters from which only the n maximum envelope amplitudes are selected for stimulation (m>n). While this maximum selection criterion, adopted in the advanced combination encoder strategy, works well in quiet, it can be problematic in noise as it is sensitive to the spectral composition of the input signal and does not account for situations in which the masker completely dominates the target. A new selection criterion could be based on the signal-to-noise ratio (SNR) of individual channels.
- Possibility of delivering drugs to the cochlea by means of the cochlear implant to develop a range of local pharmacologic interventions to prevent hearing degeneration.

I hope this is enough to arouse curiosity... see you in the next biomedipost.

If you want to know how the natural process of hearing works, click here... And also a nice video about cochlear implants from Cochlear Limited:

The engine of life

As hard as it is to find nowadays anything that can last more than just a few years, our heart is there to prove that nature is capable of creating the most amazing and reliable things. The muscle that never rests, pumping and beating to keep every part of our body oxygenated, starting as soon as 22 days after we are conceived, just until the day we leave this world.  It beats more than 30 millon times per year and more than 2000 million times during a whole life in average. With each heart beat, it pumps 80ml of blood, making 8000l a day, the power enough to push a car over 32kms. And all this in a muscle with the size of a fist.

CT Scan of a human heart

Heart keeps representing a challenge to medicine, as cardiovascular disease is still the leading cause of death in the world, even above cancer or traffic accidents. An estimated 17 million people die of CVDs, particularly heart attacks and strokes, every year. Many of this deaths are related to blocked arteries problems, and today I would like to present two promising technological advances to fight heart disease.

The first is a new application in transmyocardial revascularization (TMR) laser technology that may offer an alternative method of treatment to patients with severe heart disease who are not candidates for coronary bypass surgery or balloon angioplasty. A normal heart depends primarily on the coronary arteries to deliver its blood supply from the left ventricle cavity, the pumping chamber of the heart. In patients with heart disease, the coronary arteries are blocked preventing normal blood flow to the heart muscle. However, they still have a large supply of oxygenated blood in their left ventricular cavity. For a subset of patients who are not candidates for traditional cardiac surgery, which bypasses blocked arteries, surgeons have to create new pathways for the blood flow. TMR uses laser energy to create these pathways through a series of 1mm channels from the outer surface of the heart through the heart muscle into the left ventricular cavity, allowing for an increased blood flow directly from this "blood-filled" chamber to the oxygen-starved areas of the heart muscle.

The second is related to something that has already been discussed in the blog: nanotechnology. Concretely, targeted nanoparticles callled nanoburrs that can reach damaged vascular tissue and may be used to deliver drugs that help clear arteries. This new particles have been designed by MIT and Harvard researchers with the aim of treating cardiovascular disease. The nanoburrs are coated with tiny protein fragments that allow them to stick to damaged arterial walls. Once stuck, they can release drugs such paclitaxel, which inhibits cell division and helps prevent growth of scar tissue that can clog arteries. Moreover, drugs are delivered over a longer period of time, and can be injected intravenously, preventing patients from enduring repeated and surgically invasive injections directly into the area that requires treatment.

In the next posts we will see what is going on with pacemakers, apart from other curiosities about the heart. In the meantime, take well care of your heart by doing regular exercise, cutting down on cigarettes and eating healthier. Surely it will make the difference.