When it’s hard to swallow
A single act of swallowing is a symphony of perfectly timed events: muscles tightening and relaxing, holes opening and closing, signals flashing from brain to throat and back.
So when 2-month-old Hana Pitt vomited with every feeding and rasped with every breath, doctors were left to wonder: What in the complex sequence was going wrong?
“Swallowing problems can result in a disruption anywhere from the mouth to the stomach,” said Maureen Lefton-Greif, a speech-language pathologist at the Johns Hopkins Children’s Center who helped solve the mystery. “There is no one domain that swallowing belongs to.”
Specialists say they are seeing more children and adults who have trouble managing a task that most people never think about because it comes so naturally.
Although the reasons aren’t completely clear, the increase appears at least partly to be the price paid for the survival of premature babies and elderly stroke patients who might have died just a decade or two ago. Many survive with impairments that make swallowing difficult or impossible.
The Centers for Disease Control and Prevention recently estimated that as many as 10 million older Americans suffer from swallowing disorders. Most are victims of stroke, although some suffer from neurodegenerative disorders, including amyotrophic lateral sclerosis (Lou Gehrig’s disease), multiple sclerosis and Parkinson’s disease.
Head injuries, cancer and dementia are also sometimes to blame.
Among children, cerebral palsy -- a brain injury that interferes with the proper signaling of muscles -- is a leading culprit. Also, an estimated 40% of children with developmental problems, including autism and mental retardation, have trouble swallowing.
Children who are born prematurely are frequently at risk because myriad muscles and nerves required for swallowing haven’t had time to develop properly. But problems also arise in the neonatal intensive care unit, where breathing and feeding tubes that help babies overcome the tumultuous first weeks of life can cause damage.
Dr. Anil Darbari, a gastroenterologist at Baltimore’s Kennedy Krieger Institute, said the tubes could cause structural damage to muscles and tissue needed for healthy swallowing.
Mechanical life support can also deprive muscles of the exercise they need to work properly on their own. “The way we develop muscles is to use them,” Darbari said.
To understand what can go wrong when a person swallows, consider what must happen for everything to go right.
The first part is deliberate: As a person chews, the tongue pushes food from the center of the mouth to the side and back. When the food is sufficiently softened, the tongue rises and the palate presses down to force food into the throat.
“From the point where the bolus hits the back of the throat, the rest is involuntary,” said Darbari, using the term for a softened ball of food.
As soon as the food hits the back of the palate and begins its descent, a piece of elastic cartilage known as the epiglottis closes like a lid over the airway. A wrong turn into the windpipe can cause severe irritation or infection in the upper airway or lungs.
But with the lid properly closed, the food has nowhere to go but on its correct path into the esophagus, the passageway to the stomach.
The esophagus isn’t a simple tube, but a series of muscles that contract and relax in wavelike action called peristalsis. (Think of a snake digesting its prey.) When working properly, this ensures that the food is pushed, accepted and pushed again.
Finally, as the bolus approaches the stomach, a muscle called the lower esophageal sphincter opens and lets it drop inside.
None of this would happen without communication between nerves that sense the bolus’ progress along the way and the brain, which receives the information and signals muscles to contract and relax in a precise timing. Specialists use various tests to determine whether a patient is suffering from a swallowing disorder and, if so, what part of the anatomy isn’t functioning. One important tool is video fluoroscopy, which uses X-rays to produce a moving picture of a patient swallowing.
For Hana Pitt, fluoroscopy provided a quick answer.
The problem stemmed from a soft spot that caused her upper airway to collapse upon itself and produce a disturbing sound every time she exhaled. To make matters worse, she breathed rapidly during feeding and couldn’t hold her breath -- as people who swallow properly do -- with every gulp of formula.
For the little girl, the temporary solution was to attach a feeding tube directly through the abdominal wall into her stomach. This gave her anatomy additional time to mature while she received sufficient nutrition to help her grow.
To exercise her sucking muscles, Hana’s parents frequently gave her a pacifier dipped in milk. Later, they spoon-fed her moistened bits of cracker. Finally, when she was 13 months old, doctors withdrew her feeding tube.
Hana, now 4, is healthy. She was among the many babies who, although carried to term, needed extra time to mature.
Swallowing experts stress the importance of early intervention, which can prevent lung infections and help children grow. There might be a long-term reason too.
“Swallowing disorders in childhood might cause lasting damage that shows up in adulthood,” Lefton-Greif said.
