An estimated 1.7 million people in the U.S. sustain a traumatic brain injury (TBI) annually, and about 52,000 people die from TBIs each year, according to the Centers for Disease Control and Prevention (CDC). Not every blow to the head results in TBI, but intracranial hypertension is common in patients with TBI.

Now, researchers have developed wireless brain sensors capable of monitoring intracranial pressure and temperature before full absorption by the body, thereby eliminating the need for a subsequent surgery to remove the devices. The team of neurosurgeons and engineers published their findings online in the January issue of the journal Nature.

Accurate intracranial pressure (ICP) readings help direct treatment to reduce further brain injury, as brain scans and clinical features do not accurately reflect pressure inside the skull. Continuous monitoring of intracranial pressure and temperature illustrates brain functionality to help clinicians manage TBIs.

Raised ICP is a life-threatening condition, which can potentially result in brain stem compression and compromised brain circulation. Increased ICP is the most common cause of death in patients with severe TBI.

Neurosurgeons administer medications as the first course of treatment to reduce ICP but resort to decompressive craniectomy surgery if medications do not adequately reduce pressure. In the future, neurosurgeons could place these wireless, dissolvable devices into multiple locations in the brain during the craniectomy.

Electronic implants are an essential part of modern clinical medicine, helping clinicians treat acute coronary events, traumatic injuries and more. Advancements in electronic implants lag behind other point-of-care monitoring systems. In a press release, Dr. Rory K. J. Murphy, study author from Washington University School of Medicine, says doctors still rely on devices "based on technology from the 1980s."

While the standard permanent electronic hardware is accurate and helpful, it presents an increased risk for infection and is often large and cumbersome. Today's sensors also require surgical retrieval, which subjects patients to the additional stress of a second surgery and its associated risks for complications. Furthermore, implanted devices often trigger an immune response.

To overcome these hurdles, Murphy and his colleagues developed devices that use polylactic-co-glycolic acid (PLGA) and silicone capable of transmitting pressure, temperature readings and other information accurately. The team of researchers first tested the sensors in saline solution baths, where the devices dissolved in a few days. Next, they showed the devices were accurate and fully dissolved in rat brains. Testing in human patients is next.

Modifications could allow the devices to sense fluid flow, motion, pH or thermal characteristics and in formats compatible with the abdomen and extremities. The promise of adaptability suggests that, in addition to acting as a wireless, dissolvable sensor for brain injuries, the sensors could someday meet a variety needs in clinical medicine.

The performance of this absorbable device compares favorably with its nonabsorbable counterparts. The goal is to create an implantable device that doctors can use to monitor an organ. Then, once the patient has passed through the critical period, it will completely dissolve and disappear from the patient's body.