Low muscle tone is a common finding. Remember the following points
Causes of Hypotonia
- Anterior Horn cell disorders like Hypoxic-ischaemic myelopathy, Spinal muscular atrophy
- Congenital myelopathy like Charcot Marie Tooth disease
- Neuromuscular junction disorders like Congenital myasthenia
- Congenital myopathy like Nemaline myopathy
- Muscular dystrophy
- Syndromes- like Downs syndrome, Prader Willi syndrome, Hypothyroidism, Tay Sachs disease, Marfan’s disease
In older children along with the above
- Multiple sclerosis
- Cerebral palsy
- Post meningitis, encephalitis
Examination of Hypotonia
Feeding difficulty at birth
Delay in gross development, like delayed walking
The attitude of the patient in the bed
- The position of the child tells you about the tone.
- Like frog-like position in infants.
- Look for the degree of abduction at the shoulders and hip. The more hypotonic the child, the more the limb lies on the bed
- Standing on the right side of the patient’s bed, ask the child to relax while lying supine.
- You need to assess the passive movements at each joint – the ankle, knee, hip and similarly on the upper limba t the wrist, elbow, shoulder
- Keep your left hand proximal to the joint where the muscle mass is maximum. For example- Keep your hand on the calf muscle when assessing the ankle joint
- Make the whole range of movement and assess the tone. If floppy you may shake the limb to make it obvious.
- The muscles may be soft and flaccid to touch