University of Pittsburgh

Invisible Harm

We live in a world of vibrations that flow in and around us. Increasingly, in the modern world, that’s not always a good thing. A new center at Pitt is exploring what happens to humans assaulted by not-so-good vibrations—and how science can help.

Written by Ervin Dyer



Under a blistering desert sun, a tank rumbles along, jerking through sand dunes. A Marine is on patrol, not far from his base, in an oven called Iraq. Without warning, a homemade bomb detonates nearby. The blast instantly spawns a tsunami of vibrations, waves of pressure that spin outward at speeds greater than 1,000 mph. Moving faster than sound, the vibrations slam into the tank.

By the time he hears the explosion, the Marine has already been jolted, shaken, and shoved against the innards of the tank. For a moment, he loses consciousness. He feels groggy. His head hurts. Within minutes, he’s able to stand in the turret, but he’s wobbly. The armor of the tank seems to have shielded him from serious physical wounds. He tells his fellow soldiers he’s OK. Or so he thinks.

What researchers are now discovering is that such violent vibrations can shatter someone’s very core, damaging hearing, bruising blood vessels, thrashing neurons, and traumatizing the brain. The battered Marine doesn’t know there’s an ensuing problem until a few months later, after he returns home. He begins to experience constant dizziness, nausea, memory loss, and ringing in his ears.

Thousands of service members deployed in Iraq and Afghanistan have come home with blast-related injuries similar to those experienced by the tank Marine. Now, an unusual area of research holds promise for these soldiers and may offer intriguing medical insights for the rest of us, too. Pitt’s Carey D. Balaban is leading a venture to examine the fallout that occurs when bad vibrations happen to healthy people. He’s the director of the newly established University of Pittsburgh Center for the Biology of Vibration and Shock Exposure.

It’s a gray, blustery day as Balaban—a professor of otolaryngology and neurobiology in the School of Medicine—takes a short walk from his University office building on Lothrop Street and heads downhill to a coffee shop on Atwood. To protect himself from the elements, he’s put on a black trench coat and tucked his shock of gray hair under a black wool cap. As he walks across Oakland, he steps through a sphere of vibrations, a world that, though omnipresent, remains invisible to most people.

Vibrations are like the wind. They are frequencies or movements of energy and pressure that flow from natural or mechanical sources and are emitted by all kinds of things. They bobble through the air as sound waves with varying degrees of physical force. Music. Laughter. Sirens. Car horns. Voices. Our ears receive the frequencies and ferry them through narrow tunnels and over a stream of sensory cells to our brain, which translates them into sound, allowing us to distinguish a Beethoven concerto from a chihuahua’s bark.

Balaban knows that parts of the brain, the ear, and other sensory organs are control centers for vibrations, absorbing them and using them to help the body cope with gravity, move through space, communicate, and react to threats. In addition to his medical-school roles, he also is a professor of communication sciences and disorders in Pitt’s School of Health and Rehabilitation Sciences, as well as a professor of bioengineering in the Swanson School of Engineering.

During his short walk from his office to the coffee shop, Balaban passes plenty of signs that the world of vibrations is increasingly oscillating in ways that aren’t within the human comfort zone: The brakes of an oversized truck screech at a traffic light; a construction worker lurches from the impact of a jackhammer; everywhere, students listen to iPods that rattle in their ears. In the 21st century, more humans than ever are exposed to vibrations at levels that are too loud, for too long, and too violent. Such levels can distress and wound, or worse.

To look more closely at the biological effects of vibrations, Balaban is gathering physicians, neuroscientists, therapists, and military doctors at the University of Pittsburgh’s new Center for the Biology of Vibration and Shock Exposure. Even physicists are involved in this research, using their knowledge about matter and energy to examine how vibrations permeate human tissue and may create trauma, compromising brain cells and sensory systems.

The scientists are studying the most extreme cases of people who have been affected by vibrations, namely soldiers who have been shaken in bomb blasts. The intriguing work at Pitt’s new center is being conducted in collaboration with the National Institutes of Health, as well as with the Uniformed Services University of the Health Sciences, the nation’s federal health sciences university in Bethesda, Md. Together, the researchers are revisiting tantalizing evidence from previous studies, which suggest that more and more service members, and perhaps millions of civilians, are living with blast and vibration injuries.

A blast exposure is defined as any incident in which individuals feel or are exposed to a pressure wave before they hear a noise. Such exposure is regarded as a primary cause of much of the brain injury seen in soldiers. More is known now because, in recent years, improvements in body armor have increased the chances for survival. Soldiers in Iraq or Afghanistan—who, in an earlier era, might have died from bullets and shrapnel—are now coming home. The improved survival rate has led physicians to discover that up to 80 percent of all survivable injuries in the Iraq and Afghanistan battlefields involve vibration-related brain trauma. This category of blast injuries was once unnoticed, says Balaban, but is now coming to light.

For 14 years, Balaban has worked with naval researchers and officials, seeking methods to treat and prevent such injuries. One of his longest alliances has been with Michael Hoffer, a navy captain at the Naval Medical Center San Diego. Because of Pitt’s diverse legion of researchers—many looking for healing solutions—Hoffer considers the University to be a “brain trust” to U.S. service members.

So far, the collaborative research of Balaban and Hoffer has shed light on how vibrations are amplified in the body. When frequencies resonate too long or too violently against the thorax, sinuses, and intracranial cavities, they can injure cell membranes and cause a flood of free radicals. These free radicals can destabilize cells and eventually cause cellular injury or death. Once brain cells die, they are hard for the body to recover. The loss of sensory neuronal cells, including those in the ears, can weaken the ability to mediate vibrations, causing problems with hearing, equilibrium, migraine headaches, and other health issues.

Researchers in this field contend that trauma from harmful vibrations is just as serious as concussion injuries that plague athletes and accident victims.  And because of the numbers of people debilitated by vibrations, Hoffer says, it’s important “to prove to the world that we must treat these injuries.” The latest center studies have focused on 113 Marines who suffered blast injuries while in Anbar Province of Western Iraq. The findings suggest that mild traumatic brain injuries can lead to migraine headaches, short-term memory loss, mental processing difficulty, or dizziness.

The work to protect humans from bad vibrations puts Balaban and the Center for the Biology of Vibration and Shock Exposure on the cusp of ground-breaking scholarship. What the neurobiologist has learned about vibrations during his career has broader implications for the general population, too.

Balaban, a national merit finalist in high school, entered the Honors College at Michigan State University in 1971. His father was a zoologist who began a neuroscience program at the University of Michigan and raised his children in an environment that nurtured traditional intellectual values. Deeply interested in human motivation and behavior, Balaban sprinted toward a history degree. But he also was attracted to data analysis and logic, so, in his free time, he explored other academic areas. He studied math. He studied linguistics. He studied the emerging field of cognitive psychology. He studied neuroscience. Along the way, he discovered that he wanted to know more about the brain.

He graduated with high honors and pursued graduate studies at the University of Chicago, where he initially focused on psycholinguistics. After receiving a graduate fellowship from the National Science Foundation, he changed disciplines and earned a PhD degree in anatomy, specializing in the sensory systems of mammals and reptiles. He then crossed continents and, supported by a fellowship from the National Institutes of Health, attended the University of Tokyo for postdoctoral work with Professor Masao Ito, who had been trained by Nobel Laureate Sir John Carew Eccles, a pioneer in neurophysiology. Ito’s guidance helped Balaban to hone the intellectual tools needed to cross disciplines, and he began to examine the intricacies of balance, controlled eye movement, and posture. All of these disparate studies led him to the effects of vibrations, which encompassed his knowledge of nerves, the brain, and biochemical circuits that arbitrate mind and body responses.

Balaban learned that, like the vibrations in the external world, there are inner vibrations echoing inside our bodies—the heart pumping blood, breath resonating through the lungs, the voice box reverberating to create the noise of speech. At the tip of our fingers, there are receptors sensitive to vibrations, enhancing our sense of touch. There are even vibrations associated with our digestive functions, which are sensed by internal receptors. The body is alive with pulsing movement, with cause and effect, constantly responding to the tangle of frequencies that happen in us and around us.

Vibrations, he says, are pervasive—and that can have a downside. Sensors in the ear, internal organs, and the brain coordinate our balance, breathing, and hearing. These neurological pathways filter and react to all incoming vibrations. They even contribute to a process called interoception, a “gut feeling” about whether we are healthy or perhaps have a serious internal problem. Intriguingly, such stirrings of vibrations can affect our beliefs about our own safety and even trigger panic attacks.

Several years before Balaban joined Pitt’s faculty in 1988, two other School of Medicine researchers, Rolf Jacob and Joseph Furman, were studying the relationships between balance disorders and anxiety disorders. They noticed that there were many patients with panic disorders accompanied by agoraphobia (fear of public spaces) who also had evidence of previously undiagnosed balance disorders. The converse also seemed to be true: Many patients with balance disorders also showed symptoms of panic disorders accompanied by agoraphobia. The researchers’ further studies suggested that some migraine patients also share many of the same characteristics. In their search for the possible mechanisms behind these clinical observations, Jacob and Furman used a combination of basic research and clinical research to explore, for instance, the neurology and psychology underlying the patients’ symptoms.

One insight was that many patients compensate for damage to their balance systems by becoming dependent on their vision to maintain their balance.  These patients also protect themselves by avoiding situations where the information from vision is less reliable, which is termed “space and motion discomfort.”

Not long after Balaban came to Pitt, he teamed up with Jacob and Furman, who are also professors in the School of Medicine’s otolaryngology department. They combined many areas of expertise. Jacob also has an appointment in the medical school’s psychiatry department, and Furman has an appointment in the school’s neurology department, as well as in the bioengineering department in the Swanson School, and the physical therapy department in the School of Health and Rehabilitation Sciences.

Their collaboration has led to more than a decade of translational cross-disciplinary research in the laboratory and the clinic to relate these changes to brain pathways and help guide clinical management. What they learned is now helping to advance the center’s research, as is the latest data coming from high-impact injuries. Extreme examples of harmful vibrations typically originate outside our bodies—the roadside bomb in Iraq or the loaded backpack of a suicide bomber. Upon detonation, the blast itself is violent and explosive. The shrapnel, debris, and heat from the attack can maim and destroy. But the supersonic pressure waves that radiate from the blast—some with the force of a hurricane—can rattle the body with such ferocity that they severely damage fragile tissues such as those in the lungs and brain. In such extreme situations, people can die simply from the energy of vibrations. In acute mild traumatic brain injury after blast exposure, though, Balaban and his research partners in the military have recognized familiar culprits—combinations of dizziness and headaches that were reminiscent of the balance-migraine-anxiety disorder phenomena discovered earlier by Jacob and Furman.

In recent years, as more soldiers have returned from the battlefield, Balaban and other researchers in the field have recognized that the vibration-impact injuries occurring in Iraq and Afghanistan may involve the same neurological pathways associated with vibration injuries related to anxiety. The severity of the injuries is a matter of degree; but the fundamental nature of the biological disruption appears to be similar, whether generated by the vibrations of a roadside bomb or associated with chronic anxiety/balance disorders.

This insight helped to launch the Center for the Biology of Vibration and Shock Exposure, which is engaged in exploring how and why such different conditions are related in the ever-pulsing world of vibrations. “Finally,” says Balaban, “the little pieces seem to be coming together.” The gathering of these pieces and the answers they reveal will give scientists the knowledge to develop healing treatments and preventive measures.

Right now, the center is engaged in multiple layers of studies, including monitoring cell responses to vibrations using mathematical and simulation models. The center also is involved in field and clinical trials with the military. Significantly, a recent study suggests that, if not treated, more than 80 percent of mild traumatic blast injury patients will have long-term symptoms.

The center’s initial collaborative research with the military shows that connecting soldiers with proper health services for these injuries is, in fact, critical. Early therapy—a combination of medications and physical rehabilitation—can reduce short, intermediate, and long-term symptoms of vibration impact, and future research is bound to yield improved treatments.

This is good news not only for those on patrol in combat zones, but for all of us who, more and more, live in a world of not-so-good vibrations.