The implant stimulates nerves in the spinal cord. A rare disease caused a woman to faint every time she sat up or stood. Now, with a new device implanted in her spinal cord, she can stand and walk the length of two and a half football fields with a walker. Researchers recently used the same implanted device to treat three men with paralyzing spinal cord injuries, Live Science previously reported. In these patients, the implant stimulated specific nerves in the spinal cord that then activated muscles in the trunk and legs. This allowed the men to stand, walk and even cycle on a stationary bike. In the woman's case, the implant instead stimulates spinal nerves that cause arteries in the trunk and legs to constrict when activated. Normally, when she sits up or stands, the woman's blood pressure plummets and this often causes her to faint, due to inadequate blood flow and oxygen supply in the brain. By telling arteries in the lower body to constrict, the spinal implant prevents this drastic dip in blood pressure and thus prevents her from losing consciousness. Prior to receiving the implant, the patient "fainted every day, many times … each time she went to the bathroom, she fainted," said Dr. Jocelyne Bloch, a neurosurgeon at Lausanne University Hospital and an associate professor at the University of Lausanne in Switzerland, who treated the woman and co-authored the report of her case. "It was striking … to see her verticalized and not fainting immediately, and then walking" after the implant was placed, Bloch told Live Science. The researchers published a report describing the woman's case Wednesday (April 6) in The New England Journal of Medicine. Based on their evaluations of the patient, "these are, undoubtedly, clinically relevant benefits," said Dr. Jose-Alberto Palma, a research associate professor of neurology at the New York University Grossman School of Medicine who was not involved in the woman's case. That said, the results "must be interpreted with extreme caution, as [this] was a single case, without any type of blinding or control group, so there is a high possibility of bias," Palma told Live Science in an email. It's also important to note that, although the implant has improved the patient's quality of life, it does not address her underlying neurodegenerative disease, which is fatal, he said. Closing the loop The woman's blood pressure issue, known as orthostatic hypotension, emerged as a consequence of a relatively rare neurodegenerative disease called multiple system atrophy (MSA). The progressive disease causes nerve cells in the brain and spinal cord to malfunction and eventually die, and it also causes abnormal clumps of protein to appear in certain brain cells, according to the National Institute of Neurological Disorders and Stroke. MSA affects the part of the nervous system that controls involuntary bodily functions, such as blood pressure and bladder control, and also damages key areas of the brain involved in motor control and coordination. "Orthostatic hypotension affects approximately 80% of patients with MSA and is a cardinal feature of the disease," Palma said. Medications, including those that cause blood vessels to constrict or trigger water and salt retention, can help relieve the symptoms, he noted, but in this patient's case, drugs did not stop the fainting spells. Before receiving the new implant, the patient consistently felt dizzy the moment she tried to stand, and she fainted about three to four times a day. After one fainting episode that occurred within seconds of her standing, the patient became bedridden and remained so for about 18 months. Normally, when blood pressure falls, sensory cells in the heart detect the change and shoot a message to the brain, Bloch said. The brain then sends signals through nerves in the spinal cord to constrict arteries and make the heart beat faster, thus driving blood pressure back up. In the patient, however, this feedback loop — called the baroreflex — had been broken, she said. Bloch and her colleagues had previously repaired this feedback loop in people with paralyzing spinal cord injuries, so they thought the same treatment might work in the MSA patient. The implant includes a device that generates electrical impulses and has an embedded accelerometer, which detects changes in the patient's body position. This impulse generator then connects to a soft, paddle-shaped lead, which carries 16 electrodes that deliver the impulses to nerves in the spinal cord. The patient underwent surgery to have the impulse generator placed in her abdomen and the electrode-carrying paddle placed directly on top of nerves in her thoracic spine, beneath the vertebrae. Such a procedure carries some risk of infection and injury to the spinal cord, Bloch noted. Once implanted, the device can be switched on or off with a software operated on a tablet, outside the body. Promising results Following the procedure, the patient underwent seven days of so-called tilt table tests, in which her doctors monitored her blood pressure while moving her from a horizontal to a vertical position. The device prevented the patient's usual dizziness and blood pressure drops. The woman also completed six weeks of neurorehabilitation in the hospital and was allowed to practice using the device at home after three weeks. After the training, she no longer fainted or experienced the symptoms that preceded these spells, such as ringing in the ears and dizziness while standing or urinating. Before the procedure, the patient could only walk about 16 feet (5 meters) before needing to lie down. Within a few weeks of having the implant, she could walk about 10 times that distance with a walker, and after three months, she could walk about 50 times that distance. After eight months, "the patient reported that she was still using stimulation all day and that she no longer had syncope [loss of consciousness]," the researchers reported. "She could train, walk, go at home from her bed to the bathroom without fainting … We clearly saw a difference," Bloch said. The new implant does not address the patient's underlying condition; as the weeks have progressed, so too have the various symptoms of her MSA-P. "The surgery … will do nothing to stop the rapidly progressive nature of the disease," Palma said. Patients with MSA typically must use a wheelchair within three to four years of disease onset and die within five to eight years, he said. "We know that we are not going to stop the disease," Bloch said. "But … at least this symptom is still OK. It's not perfect, but it's much better than it used to be before the treatment." Bloch said she expects they'll identify other diseases for which such a spinal implant could improve patients' mobility and quality of life. In the meantime, Bloch and her co-senior author Grégoire Courtine, a professor of neuroscience at the Swiss Federal Institute of Technology Lausanne (EPFL), are working with a company called Onward Medical to develop new spinal implants specifically designed to treat patients with compromised mobility or issues with blood pressure regulation. The first of these newly designed devices will be implanted later this year, likely in May, Bloch said. Source
