For 35 years, Linda Castillo couldn’t figure out what was going on with her legs.

If she stood in place for long, she felt shaky and weak―and thought she might fall. Struggling for balance, she curled her toes, folded her arms or placed her hands on hips.

Sometimes, when she was out shopping, the fear of falling became so intense she hyperventilated. She had to sit down and breathe into a bag.

“I would go to a doctor and tell him about it, and he would think it was all in my head,” she said. “He would want to give me Valium to calm me down.”

She was 72 years old before she finally discovered the reason for decades of unsteadiness. She suffers from primary orthostatic tremor―a rare movement disorder characterized by a rapid tremor in the legs. A key feature of the disease―the tremor occurs when standing, not while in motion.

“The tremor usually starts in the legs and it may gradually ascend upwards to the trunk and the arms while they are standing still,” said Ross Coleman, MD, a Spectrum Health neurologist who specializes in movement disorders. He did research on primary orthostatic tremor during a fellowship at University of California-San Francisco.

“What the patient experiences is after they are standing still they will start to feel unstable, feel like they are going to fall. Some patients may realize they have a tremor and some may not. Some describe almost a discomfort. The feelings get better when the patient walks, shifts their weight or sits down.”

Castillo learned her diagnosis in July 2016, after her family medicine doctor referred her to Dr. Coleman.

Just hearing the name of the condition that plagued her for years brought immense relief.

“It was like a release from my shoulders. It was just like, “Poof! Ok, this is what I have,’” she said.

Like Castillo, many patients with primary orthostatic tremor search a long time before they learn the cause of their symptoms.

The condition can be difficult to diagnose, in part because of a lack of awareness about it. Also, the condition often does not show up on a physical examination.

“When they’re standing still you may see a fine tremor. If they’re in a hospital gown, you may see the hospital gown rippling,” Dr. Coleman said. “But it’s not usually a pronounced tremor.”

Because the disabling symptoms don’t match up with a physical exam, patients often are misdiagnosed with a psychological condition.

“The average time to diagnosis is five and half years,” Dr. Coleman said. “That is a long time for disabling symptoms.”

Although no cure exists for it, medications may help patients stand still longer without shakiness. That allows patients to more easily navigate daily tasks that involve standing in one place.

Measuring the tremor

Aiding the diagnosis of the tremor is a new electrophysiology lab for movement disorders at Spectrum Health, led by neurologist Emily Ruether, MD.

While doing her neurology residency and movement disorders fellowship at the Mayo Clinic, Dr. Ruether had the rare opportunity to train in their advanced movement disorders neurophysiology laboratory,  learning how to better test and characterize tremors using electrical activity.

“This really enhanced my understanding of movement disorders,”  she said.

After she joined Spectrum Health in 2016, the hospital system became one of the few centers in the country to have advanced testing in the evaluation and treatment of movement disorders.

Dr. Ruether conducts an electromyogram test, called a surface EMG, which detects abnormal muscle electrical activity.

“A tremor is a rhythmic oscillation of a body part,” Dr. Ruether said. “It is rhythmic in that each movement or shake occurs at very regular intervals, like if listening to a beat.”

Nobody knew I had an issue. Nobody said anything to me about it.

Roxann Rentsman

The test can detect the tiny movements―which can occur at frequency of around 16 oscillations per seconds in orthostatic tremor.

Dr. Ruether puts surface electrodes, or “stickies” on the patients’ legs, trunk and arm regions and observes them in different positions―sitting, standing, leaning against a chair, and with other maneuvers.

“Often it’s very quickly on standing that we can see the changes,” she said. “You can see this very fast rhythmic tremor on the screen. A lot of times, we see it before they feel the shaking coming on.”

Castillo’s tremor “was going at a frequency of about 16 oscillations per second―so, really fast,” Dr. Ruether said.



Roxann Rentsman, a 64-year-old retired teacher, can sympathize with Castillo’s experience.

She first noticed shakiness in her legs 20 years ago, in her early 40s, when she taught third grade in Greenville, Michigan.

“As long as I was teaching and walking, I was fine,” she said.

But if a parent or another teacher stopped her for a conversation in the hall or classrooms, her legs soon would feel weak and unstable. She would move to a spot where she could lean on something―a locker, table or desk. Or she would find a place to sit.

“Nobody knew I had an issue. Nobody said anything to me about it,” she said.

I would say I’m 75 percent better. A lot of days, I feel pretty normal.

Linda Castillo

For a long time, she chalked the experience up to nerves. But a few years ago, with the problem becoming more noticeable, she worried that the tremors could be a sign of multiple sclerosis. She told her family doctor, who referred her to Dr. Coleman for evaluation.

When she heard the diagnosis, Rentsman said her first reaction was “Relief. Because it was not MS.”

“It could be much worse,” she added. “There are things I can do to adapt to this.”

Medication helps. Taking clonazepam has boosted the length of time she can stand in place.

She continues to struggle in situations where she must walk slowly or stand still. Stuck in a check-out line at the grocery store, a buffet line or a crowd shuffling toward an exit, she quickly looks for a way to lean, sit or escape.

But she has found ways to make life manageable.

Walking through the old farmhouse where she has lived for 44 years, Rentsman showed how she gets brief rest holding on to chairs, tables and a wall post.

She stood at the kitchen sink and demonstrated how she leans against the counter as she washes dishes. When her legs feel too shaky, she takes a break and walks laps around the kitchen table.

At the grocery store, the cart is her friend. She leans on it, getting support as the cashier scans her purchases and as she pays the bill.

She remains determined to stay active. She works in her garden, takes vacations with friends and plans to go to Europe next spring with her children.

“I haven’t let it take me back,” she said. “Traveling is difficult, but I’m not going to turn anything down.”

Sharing tips

Castillo also has found ways to accommodate her condition. A decade ago, before she knew her diagnosis, she bought a walker with a seat. She can lean on it when she walks and sit down whenever she feels shaky. In stores, she rides an electric scooter.

At home, she placed rolling, adjustable-height chairs in the kitchen, bathroom and laundry room. She uses them for tasks that involve standing still, such as brushing her teeth and preparing food.

Her husband, Gil, helps her with some of the tasks, such as transporting her walker and bringing groceries in from the car.

She tries to pace herself as she does chores during the day. In the evening, she enjoys computer games and watching television.

The medication gabapentin also has helped ease the tremors.

“I would say I’m 75 percent better,” she said. “A lot of days, I feel pretty normal. Then there are days when I’m under stress, and it goes back to weakness and unsteadiness.”

Since learning her diagnosis, she has connected with other people who have primary orthostatic tremor through a Facebook group. They share experiences and information about symptoms, coping mechanisms and medication. Just knowing that others understand the condition has been invaluable.

“It’s like an affirmation of what I have had all these years,” she said.