Craig Jerome, a nurse practitioner in North Carolina, contracted covid two years ago. He lost his sense of smell and continues to experience anosmia. “Emotionally, he has created pain,” said Jerome, who misses cherished scents like the Christmas tree that bring back fond childhood memories of him.
Richard Costanzo and Daniel Coelho hope that their neuroprosthesis, which they call a “bionic nose,” can help Jerome and others like him.
However, it will take five to 10 years for a fully developed prototype to be ready for implantation and testing in patients, said Costanzo, director of research at VCU’s Center for Taste and Smell Disorders in Richmond.
Costanzo said his idea for the device came long before the pandemic, and was born out of a desire to help people with permanent loss of smell.
He began collaborating with Coelho, a surgeon and professor of otolaryngology, because the olfactory implant they are creating is similar in concept to a cochlear implant used to help Coelho’s patients hear.
The need for the device is greater now because of covid, Costanzo said, citing his research with Coelho and others. In his study of patients who reported anosmia after contracting covid in early 2020, 7.5 percent said they have not regained their sense of smell two years later.
Covid has severely damaged the olfactory sensory cells in the nose of some patients, Costanzo said. “Without these cells, odors are not detected and signals are not sent to the olfactory region of the brain,” he said.
In other patients, some of these cells recover and their sense of smell is partially restored, “but they are often not normal, and people report distortions in the perception of smell, often unpleasant sensations,” he said.
Smell is important because it is intertwined with taste, which adds to the pleasure of eating. Smell helps detect dangers such as a gas leak or smoke from a fire. Emotions are also linked to smell; For example, we feel comforted by the unique smells of loved ones or joy by the fragrance of things like flowers.
We are able to smell because specialized olfactory receptor cells in the upper regions of the nose detect chemical vapors in the air, Costanzo said. The cells send olfactory information via nerve fibers that pass through openings in the base of the skull and connect to a part of the brain called the olfactory bulb.
“The olfactory bulb shares this information with the rest of the brain, resulting in the perception of smell, such as the aroma of an orange or the fragrance of a rose,” he said.
Duplicating how we smell is a unique challenge, Costanzo said.
For other sensory systems, he said, we know more about the stimulus and how the receptors encode it. For hearing, the stimulus is pressure waves; for touch, it is the mechanical deformation of the skin; and for vision, they are electromagnetic light waves.
“The problem with smell is that we don’t know what physical properties of chemical odors are important in encoding all the different odors that exist,” Costanzo said.
Costanzo and Coelho use microelectronics and computer processing, including artificial intelligence, to build their bionic nose.
Their strategy is to bypass damaged olfactory cells and stimulate the brain directly with an implanted electrode array.
A small external odor detection piece will send signals to a microprocessor chip that will generate “unique digital fingerprints for different odors,” Costanzo said. The chip will then transmit the information via special radio wave frequencies to a receiver inside the skull to stimulate specific areas of the brain that generate a particular odor sensation or perception.
In its current prototype, both the scent-detection piece and the microprocessor chip are attached to an eyeglass frame, but they could be on other objects such as a bracelet, Costanzo said.
Surgery would be required to insert the electrode array into the brain, although it’s too early to tell whether it would be placed by a neurosurgeon or by endoscopy through the nose, Costanzo said. The researchers believe that many people would accept this process, citing a small study of 61 patients with olfactory dysfunction, which showed that about a third said they were willing to undergo olfactory implant surgery to restore their sense of smell.
The research is funded through Lawnboy Ventures, a collaboration between Costanzo, Coelho and the VCU Intellectual Property Foundation, which have a minority stake, and private investor Scott Moorehead. The company licensed the patent associated with the VCU technology, Moorehead and the university said. Moorehead, who lost his sense of smell after a traumatic brain injury, said he joined the effort because he could potentially benefit from the device.
Studies to understand olfactory perceptions
An early version of the neuroprosthesis was tested in rats. The researchers cut the olfactory nerves of the rodents and surgically placed an array of electrodes in the area of the olfactory brain. Costanzo said they were able to bypass severed nerves and activate olfactory brain cells.
“The rat couldn’t tell us what it could smell, but we could record the electrical signals generated in the brain,” he said.
The researchers, in collaboration with a former student of Costanzo’s, Mark Richardson, are now conducting human studies to map specific regions of the brain that, if stimulated, could generate perceptions of odors.
Richardson, director of functional neurosurgery at Massachusetts General Hospital, is studying patients with epilepsy, who have electrodes attached to different regions of the brain to understand which areas are involved in seizures.
Those who agree to participate in the study of smell are presented with different odors. Using recordings from the electrodes, the researchers are mapping areas of the brain associated with odor perceptions to determine optimal sites for the olfactory electrode array.
“Discovering how odor perception arises from brain activity is a complex decoding problem,” Richardson said in an email, “but there may be multiple ways to recreate important aspects of smell for people with anosmia.”
The researchers are also planning studies to build a clinical version of their prototype that is safe and effective, they said.
“Hope comes,” Coelho said. “There are some important things we need to put in place, but there is very little reason to think this device shouldn’t work.”
That’s encouraging news for Gregory, a New York City resident in his 60s whose last name is withheld to protect his privacy. He said he lost his sense of smell after a traumatic brain injury in 2005 and contacted Costanzo for help.
When he found out about this device, he cried, Gregory said, adding that Costanzo “gave me hope that I could smell before I died.”
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