Idiopathic or Benign Congenital Hypotonia (BCH) in Babies and Children
Dr. Erica Martin PT, DPT, PCS
What does hypotonia mean?
Healthy muscles never fully relax. Muscles have a certain amount of resistance to passive movement and stiffness, which is called your muscle tone. Muscle tone is important for generating our reflexes, maintaining good posture and balance and controlling the proper function of several organ systems. The term hypotonia is used when a baby or child exhibits a reduction in this resistance to stretch or movement. Often times this somewhat abstract definition is poorly understood and leaves parents scratching their heads.
In order to bring more clarity, research has focused on developing an operational definition of hypotonia. A consensus has been developed among pediatric physical and occupational therapists identifying both motor and behavioral characteristics of children with hypontonia. These characteristics include decreased strength, decreased activity tolerance, delayed motor skill development, hypermobile joints/ ligament laxity, increased flexibility, a rounded back posture, and poor attention and motivation.
Idiopathic or Benign Congenital Hypotonia (BCH)
Hypotonia is an impairment that is commonly seen with many pediatric disorders. These disorders include pathologies of the central nervous system, genetic and metabolic disorders, and the motor unit (where the nerve and muscle meet). Well-known conditions in which hypotonia exist include Down Syndrome, cerebral palsy and spinal muscle atrophy. However, one of the more poorly understood groups of children are those in which no definitive cause for hypotonia is identified. Children diagnosed with hypotonia in which the cause remains unknown are referred to “benign congenital hypotonia” or idiopathic hypotonia. This makes diagnosing hypotonia challenging and often frustrating for parents.
How is Idiopathic or BCH diagnosed/ identified?
Diagnosis of idiopathic hypotonia is based on clinical signs of hypotonia when the hypotonia cannot be attributed to any other condition. Clinical signs of hypotonia in infancy include a significant head lag when pulled to sit, a very loose feeling of the extremities with excessive flexibility (floppy baby), decreased ability to accept weight into the arms or legs, and a slip-through. A slip through is the feeling a child would slip through your arms when holding them underneath their armpits.
Infants with hypotonia may also have difficulty with feeding and experience increased difficulty sucking and swallowing. Many experience difficulty latching for breastfeeding and have a weak cry. They will also exhibit limited anti gravity movements (ie, pushing up in tummy time and bringing their feet to their hands or mouth to play) and a desire to decrease movement by keeping their arms and legs out wide to their sides. There is also a greater incidence of positional plagiocephaly and/ or positional torticollis is infants with hypotonia.
Young children with hypotonia demonstrate delays in there motor development. Many will not crawl on all fours and will commando crawl or “scoot” instead. They may walk late (after 18 months) and maintain a wide base of support or prolonged high guard position of their hands when walking. They may also have delays in their speech or difficulty with articulation. Children with hypotonia will also have difficulty getting up from lying down or into a standing position without excessive use of their arms to push up. A child with hypotonia may prefer a “W-sit” position when playing on the floor so that they may limit the use of their postural/ core muscles. When standing, children with hypotonia frequently have very flat feet that may turn out (over pronation), a wide base of support (feet far apart), hyper extended knees and an increased arch in their backs (lumbar lordosis). This may give them the appearance of a big protruding belly.
Older children with hypotonia are described as clumsy and fall frequently. They will have a high degree of flexibility in their arms and legs. They tend to have poor endurance for physical activity and fatigue easily. They will often demonstrate slower running speeds and decreased agility. Older children with hypotonia tend to be less physical and prefer sedentary activities. They may also have trouble sitting for prolonged periods of time or will slump forward and rest their heads down on their desks. This can result in difficulty with attention in the classroom and with their handwriting skills. They will also demonstrate flat pronated feet and poor posture in both sitting and standing.
What should I do if my baby or child is diagnosed with hypotonia?
A child diagnosed with idiopathic or BCH will generally have hypotonia throughout their life. However, with early skilled physical, occupational and/ or speech therapy, their function and abilities can improve and deficits may be minimized. If your child was diagnosed with hyptonia or demonstrates the signs and characteristics identified, speak to a pediatric therapist. If you have any questions or to learn how we can help, email me at Erica@dynamicsolutionstherapy.com .
Look for our next blog on intervention strategies and orthotic management in children with hypotonia.