Seating for Hypotonia

Pediatric considerations for children with low tone

Defining hypotonia — low muscle tone — might seem easy. Metaphors such as “rag doll” traditionally come to mind. But hypotonia’s presentation still varies from child to child.

Josh Tucker is the National Sales Manager for Leggero. “By definition, hypotonia is extremely low or decreased muscle tone,” he said. “This has resulted in it being called ‘floppy baby syndrome.’ Many people compare the body to a rag doll.

“Remember that hypotonia is a symptom and not a condition. One of the first signs is when a child has difficulty or is unable to hold their head up to look around. In infants and toddlers, the arms will hang straight down with little to no bend at the elbow. The child’s head will roll around front, back and side to side. Not because of lack of muscle control, but because of lack of muscle tone.”

Linda Bollinger, PT, DPT, ATP, Sunrise Medical, said, “From my experience, a child with hypotonia does present as ‘floppy,’ but what that means to everyone is different. A rag doll does not have bones and muscles that can rest on each other in their quest to find a stable position. These children struggle with achieving upright trunk positioning against gravity. tend to ‘collapse’ until all their bones are supported upon one another. This is what leads to their orthopaedic asymmetries. Since they have difficulty working against gravity to hold their trunk up, you may also find that they use distal extremities to gain this stability. They may utilize ‘fixing’ of their head, UEs [upper extremities] and LEs [lower extremities].”

And children with low tone don’t necessarily have low tone all the time, as Heather Roussel, OTR/L, ATP, Regional Manager for Stealth Products, pointed out. She said that while kids with spinal muscular atrophy (SMA) or muscular dystrophy could present with that classic “floppy” appearance, kids with other diagnoses might not.

“Kiddos with CP [cerebral palsy] are known for high tone, but it actually fluctuates,” Roussel said. “Sometimes, if they’re not active, you’ll actually see low tone. When they go to move, they’ll have that high tone kick in, so you have to accommodate for both. It just depends on diagnosis.”

Considerations for Head Positioning

While seating is typically thought of in terms of positioning the pelvis, for children with low tone, interviewees were also very concerned about optimal head positioning… perhaps because engaging with the world is so critical for developing children.

“Along with low muscle tone, children with hypotonia often have trouble sucking and swallowing,” Tucker said. “When sitting, they will oftentimes be slouched over with their head resting on the shoulders. So creating and maintaining an upright head position will not only allow them to make eye contact and increase social interaction; it will also improve breathing and feeding.”

“My goal,” Bollinger said, “is to provide proximal support with the head over neutral-positioned pelvis and level shoulders. Therefore, I try to facilitate a position or ‘sweet spot’ where the head is not too far forward and to try to create a chin tuck, while not having the orientation of the trunk so posterior that it interferes with social interaction. I think this gives the best opportunity for breathing, digestion, etc. Providing head alignment allows for safe swallowing. If the head is too far forward or back, it can lead to choking.”

Roussel pointed out that some children need to be accommodated because they’ve already developed functional — though not textbook-attractive — head positioning that works for them.

“Sometimes, their positioning is to compensate for how they get their visual references and how they can actually see things,” she said. “You don’t want to restrict their head movement, because then they can’t do functional activities. Sometimes their seating systems have to be designed to actually allow movement at times. Maybe if you’re moving or transporting, you have ways to strap them into place for safety. But if they’re doing functional activities, you have to allow that freedom of movement.”

Positioning Goals for Extremities

Reaching, grabbing and holding are critical to infants who are learning about their world, and continue to play an important part in performing activities for daily living.

“Hopefully, by providing proximal support, we have created opportunity for the child to reach, do tabletop activities such as feeding and coloring, and maybe self-propelling and or use of a joystick with their hand,” Bollinger said. “This is the old saying ‘Proximal stability for distal mobility.’

“Another priority is to position the hips in neutral to ensure that the femur is within the joint to address potential subluxation. A neutral hip position is approximately 5° to 8° of abduction. Often, we position the upper legs parallel to one another, and that can be an already adducted position. This affects hip joint position and stability.”

Potential dislocation is definitely a concern for this population, Tucker said. “They have joint hypermobility, which allows them to move in a range of motion most of us can’t. This will obviously put the child at risk for joint dislocation. So one thing we have to keep in mind is limiting that range. Depending on the seating and positioning, there are different factors to look out for. If the child is in tilt, are their arms secure and not falling off the armrests and behind the body? If upright, is the head comfortable and safe from falling forward or side to side?”

Upper-extremity positioning is also crucial for power wheelchair users: Children with hypotonia might find it difficult and tiring to use a standard joystick at the end of a power chair armrest.

“For most of these kids,” Roussel said, “we’re going to be thinking of alternative driving controls from the beginning.” That’s because specialty joysticks, for example, can require far less force to operate versus conventional models.

“For a typical joystick, it’s about 250 grams of force required to activate it when you deflect it,” Roussel said. “The lowest one that Stealth Products carries is 8.5 grams, so there’s very little movement required. For a lot of those kids, I would probably use something requiring 50 grams of force or so. We have a joystick in that range, and that’s usually the range I would pick for those kids.” When choosing a joystick, Roussel also considers the progression of that hypotonia — increasing weakness as the child ages, as well as increasing weakness as the child fatigues during the day.

“If we think there’s going to be progression, that’s something we’re going to look at,” she said.

“If they can’t [operate] it consistently throughout the day, it’s something we have to look at early on.”

Roussel referenced a recent client who benefited from a hybrid approach to driving controls.

“He couldn’t use a head array, because when his head fell forward, he couldn’t bring it back,” she said. “He couldn’t use his hands: He had some finger movement, but not enough to have fine motor control. We ended up doing a head array/sip-and-puff combo. He uses a sip-and-puff for forward and reverse, and does right and left with his head. You just have to get creative with setups for these kiddos. There are so many options out there.”

While Roussel said she aims to stabilize kids who present with very low tone and very minimal movement, she uses a different plan for kids who intermittently present with high tone: “If that tone fluctuates, I’ll probably have more dynamic pieces in the system, or pieces I can move in and out of place depending on what they’re doing.”

Dynamic backrests, footplates, etc., reduce the risk of equipment breakage, Roussel noted, while also reducing the risk of injury, unsafe pressure levels, and pain.

Conserving Energy Through the Day

For children with low tone, conserving energy throughout the day is an important goal. It might look as if a toddler leaning back in his stroller is just relaxing, but actually, staying upright with your head in a functionally upright position is hard work.

It’s the kind of energy, effort and strength that kids with low muscle tone often don’t have or can’t sustain.

“Definitely, energy conservation is a number-one goal for those populations,” Roussel said. She added that teaching that point to caregivers is also crucial, “because sometimes they have the idea that the harder [children] work, the better it is for them. But you want them to be able to use their energy for tasks that are important, not just for staying upright. If they’re spending that much energy just on keeping their head upright, can they do other school tasks? So it’s trying to educate the parents, as well: ‘I know you want your kid to work hard, but that’s not the goal of the seating system.’ I think a big part of our job is educating, so they know the reasons why we’re putting some of that [equipment] in place.”

While children with low tone can fatigue simply from fighting gravity to stay upright, adding tilt to a seating system can actually make gravity a kid-friendly force.

“Pediatric upright wheelchairs like the [Sunrise Medical] X-cape or Zippie are a perfect choice for children with hypotonia, as they can be configured with an incline to allow gravity to assist in upright positioning,” Bollinger said. “However, a tilt wheelchair such as the Zippie Iris may be indicated for the child who is demonstrating forward head and trunk, posterior pelvic tilt, or asymmetries. When the child becomes fatigued, this wheelchair can provide alternative positions throughout the day. Tilt wheelchairs also use gravity to assist with trunk control; however, it is often a good compromise between a gravity-eliminated and gravity-dependent position.”

“Vests and harnesses always come in handy to keep the child from falling forward,” Tucker said. “Thigh guides, knee adductors and adductor positioning straps are all very helpful with the lower extremities. These protect the hips from extending too far and avoiding any dislocation.”

The ability to add significant positioning options, incidentally, is an important point to make to parents who are wondering if a traditional stroller will suffice.

“Leggero makes growable strollers and wheelchairs that not only grow as the child does, but allows you to change the seating and positioning of the child as they progress,” Tucker said.

“If I’m thinking about basic spinal and pelvic support, a basic stroller that you’re going to get at Toys R Us is going to collapse that system, and [children with low tone] don’t have the ability, muscle tone wise, to overcome that,” Roussel said. “They can start developing bad postural habits early on if they’re in that kind of system, where they’re getting curving of the lumbar spine and sacral sitting from sitting in that system versus something that’s actually going to support their back and support their pelvis in the correct posture.

“Again, there’s that fatiguing factor: If they’re having to work that hard just in that position, and they’re collapsing — then there’s difficulty breathing and interacting with the world because they’re not able to get that upright posture to see the environment. It can have a pretty significant impact long term.”

Early Intervention for Long-Term Impact

Roussel added that a positioning stroller can also help to prevent pressure injuries: “A regular stroller isn’t going to give you any kind of pressure relief system, where I could potentially put a backrest on there or a cushion on [a positioning stroller] that will provide some kind of support to lower the risk of pressure injuries.”

Early intervention in the form of optimal seating and positioning is critical to give children with low tone the best start possible.

“We often don’t see them until they’re school aged,” Roussel said of children with low tone, “and they already have some tightness in some areas. If they’re low tone as their body is developing, you’re going to potentially get contractures, even when they’re fairly young, where they don’t have the ability to stretch out, versus having a supportive system.

“If you can get the positioning of the pelvis and the spine early on, it’s preventive for later on down the road.”

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