I don’t want to repeat what was covered in my earlier blog on Tone Management but want to address more the symptom of Hypotonia which is abnormally low muscle tone or often referred to as “floppy baby syndrome”. This can be caused by a variety of conditions, including those that involve the central nervous system, muscle disorders, and genetic disorders. Some common causes included but are not limited to: Down Syndrome, Muscular Dystrophy, Cerebral Palsy, Prader-Willis Syndrome, Myotonic dystrophy, Marfan Syndrome, and Tay-Sachs.
Remember, Hypotonia is a symptom and not a condition. Preemies born before the 37th week have hypotonia because their muscle tone isn’t fully developed by the time they are born. But provided there are no underlying problems, this should gradually improve as the baby develops and gets older. Depending on the cause of Hypotonia, it can improve, stay the same, or get worse over time.
Some Hypotonias are not progressive and are of an unknown origin and may be called Benign Congenital Hypotonia. The central nervous system and intelligence is normal. It may not be associated with developmental delays. Some may acquire gross motor skills (rolling, sitting, crawling, walking, running, jumping, etc.) more slowly than most.
A good thing to remember is that tone lives in the brain but strength lives in the muscles. The earlier blog talked about how muscle tone is different than muscle strength. For a baby with hypotonia it feels like the weight of the world is holding their body against the floor. It is very hard for them to even lift their head up against gravity. It is similar to a rubber band that is stretched out and has lost its tension. This means that babies/children may have to exert 2-3 times more energy than a baby with normal muscle tone which can be very exhausting for them. Progress to help them develop muscle strength and endurance may be a slow progress and requires the skill of PT, OT, and ST to help improve overall muscle function for daily activities.
How Does Pediatric Physical Therapy Help Children With Hypotonia?
How a PT can help with the effects of Hypotonia is to 1) improve posture and coordination to compensate for the low muscle tone, and 2) strengthen the muscles around the joints of the arms and legs so they provide more support and stability. Hypotonia that is controlled by the central nervous system may not be changed but PT’s can help with improving muscle function needed for progression of gross motor skills and mobility. Problems involved with Hypotonia can be:
joint hyper-mobility
ligament laxity
decreased strength
Physical therapy needs to focus on minimizing the compensations that will lead to impairment of motor functioning and on building the posture, strength, and movement patterns that the child will need as he grows and develops. Postural control needs good alignment for good muscle activation. Remember, you need proximal stability to get distal mobility.
Ok, getting out of book work terminology, you may be asking how do I help my baby with Hypotonia? A baby with Hypotonia may have very poor head/neck control, poor lip closure with feeding difficulties and their mouth may hang open with tongue protruding, they may have a very slouched sitting position even when supported, and when standing, their ankles may be unstable with weak ankles/feet. Starting with their head control, they will need support as you begin to help them work on tummy time lifting their head and maintaining it up in midline while supporting their trunk in sitting either on your lap or on the floor. As you give them good trunk support, you can gradually help them lift their head up against gravity and maintain for longer periods of time to build strength in the front and back of the neck. Chin tucks are important for building this co-contraction of muscles and can be done with having them lying on an incline with their head and shoulders elevated and start with support from behind their shoulders/head and slowly pull them up to sitting helping them keep their head in midline and not falling back. You can gradually decrease the support needed from behind and progress to them being able to lift and maintain their head in midline as you gently pull up with their hands (this should not be started prior to 2-3 months of age). They will need lots of initial support for tummy time with either a blanket rolled under their shoulders or elbows on an inclined wedge with their hips lower than their shoulders as they strengthen lifting their head up against gravity to look at toys and turn to both sides equally.
Reaching for toys in different positions will help build coordination with postural control in different positions: supine, prone, side-lying, and eventually in sitting and standing.
I like to use multi-sensory approaches with babies and kids with Hypotonia especially the integration of vestibular, proprioception, and vision because they are important for building postural control. The vestibular system helps to organize sensory information and contributes to physical and emotional security. Working with the vestibular system will help build gravitational security so a baby can progress with movements on the floor such as rolling, crawling, and transitioning to kneeling and standing. A simple way to ensure your baby gets vestibular input is a technique called “Rock/Roll/Swing” where your cradle them in semi-lying or sitting and provide movements in different directions forward/back, side to side, and swinging to give them input and develop more of a tolerance to these kind of motions. A large, therapy or exercise ball can also provide good movements as well as proprioceptive feedback to their joints with rocking and gentle bouncing in different supported positions. This will also “wake up” their muscles and activate balance and righting reactions. Aquatic therapy or playing with your baby/toddler in the water is great for Hypotonia because it helps to reduce the effects of gravity on their muscles and they can move and strengthen their muscles easier.
Learning to sit in different floor positions without compensations is so important to building postural core strength. Normal sitting positions after they progress from prop sitting are in long, ring, and side sitting and then to progress to vertical sitting and short sitting on a small bench with their feet on the floor. Helping a child avoid and not develop the habit of W-sitting is crucial (as discussed in an earlier blog) to developing their postural strength needed to progress to crawling, pulling up to kneeling, and standing.
Side sitting is a great position to have them play in because their hands and feet are pulled in closer to their midline and will build postural strength as well and being an important position to start transitions moving down to their tummy, and moving in and out of hands and knees. Once they start pulling up to hands and knees and kneeling they may have difficulty keeping their knees under their hips and may slide out into a “frog-legged” position. They may need your hand support on the sides of their hips as they get used to these positions or having them wear a pair of compressive shorts may help to give them support until their muscles are strong enough to maintain on their own.
Once they are crawling on hands and knees (so important!!!!) they can progress by crawling on different types of surfaces or on and off of pillows on the floor to build more core and hip strength. I firmly believe that babies, especially those with Hypotonia, should not be placed in kneeling and standing too soon. Once they are able to pull up into kneeling and then standing by themselves, they have the postural support to work on kneeling and standing postures without causing abnormal strains on their spine and joints. Once in standing, their joint laxity and weakness in their ankles/feet may require supportive shoes or SMO’s (orthotics that cover their ankles and are worn inside shoes) may be needed to give them good alignment for muscle activation to work on cruising, standing balance, and walking forward with support.
Once they progress to independent standing and walking, kids with Hypotonia will continue to progress with postural control, coordination, and balance with learning to squat in play, transfer up into standing from the middle of the floor, and walk on different types of surfaces.
So, basically babies with Hypotonia will still be taken through the typical stages of motor development but it may take them longer and a PT can help you avoid the compensations that are easy for them to fall into and to work their muscles in optimal postural alignment!
