Straighten up for a few minutes only, then faint. This is what Nirina, 48, was experiencing since 2017 with multiple system atrophy of the Parkinson type. This rare neurodegenerative disease (estimated to affect between one in 10,000 and 50,000 people) causes, among other disabling symptoms, so-called “orthostatic” hypotension, i.e. a sudden drop in blood pressure that occurs when go from sitting or lying down to standing up. For a year and a half, Nirina could not live otherwise than in bed, until an electronic system was implanted in her spinal cord allowing her to get up, but also to walk a few hundred meters again.
This progress is due to Jocelyne Bloch, professor at the University of Lausanne (UNIL) and neurosurgeon at the Vaud University Hospital Center (Unil-CHUV), and Grégoire Courtine, professor of neurosciences at the Federal Polytechnic School of Lausanne ( EPFL) and UNIL, as well as their teams at the NeuroRestore research center. The results of this case study were published April 6 in the journal New England Journal of Medicine. They follow a previous work published in Nature in 2021, which had already demonstrated the possibility of treating orthostatic hypotension in tetraplegic patients through the placement of a similar implant. This is the first time that such an intervention has been performed on a person suffering from a neurodegenerative pathology.
“We applied exactly the same principle that we had put in place for individuals affected by a traumatic injury, explains Jocelyne Bloch. The objective is to use electrical stimulation at the level of the spinal cord in order to target the neural circuits that regulate blood pressure and thus reactivate the baroreflex. » It is a reflex triggered naturally during changes in blood pressure, for example when standing up and blood flow decreases in the head and increases in the legs. “In case of low blood pressure, we all have a sensor in the heart and carotid artery, which will immediately indicate that the pressure is too lowexplains the professor. This baroreceptor will then send the order to the sympathetic system to contract the arteries, which will raise the pressure. »
Rare cases
The disease affecting Nirina causes a loss of sympathetic neurons specialized in the regulation of blood pressure and therefore an alteration of the baroreflex, which resists, in her case, drug approaches. Coupled with a voltage sensor, the device used in this patient – electrodes and an electrical stimulation generator generally used in the treatment of chronic pain – detects abnormal drops in voltage and then sends a series of pulses to a specific location in the the spinal cord, which makes it possible to immediately increase the blood pressure to the desired level and thus to restore the natural hemodynamic system of the organism.
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