Cerebral Palsy (CP) in a child is often known for its varying degrees of movement disorder, positional or mobility issues. However, impaired thoracic mobility causing respiratory issues in the child with CP is one of the major and life threatening problems. The biomechanically coordinated motion of the thorax that occurs during a breathing cycle is affected by various reasons such as weak or spastic thoracic or trunk muscles, poor posture, and decreased mobility among many others.
The ability to breathe properly, cough effectively and management of respiratory infections timely are the key factors to improve or maintain respiratory health. A strong and effective thoracic mobility is warranted for the healthy lung function which is the key factor to ensure enough oxygen supply in the body systems. Poor lung function (breathing cycle) with oral-motor dysfunction (weak facial and neck muscles), which is very common in a child with cerebral palsy, can lead to a number of serious and some life threatening issues such as:
What causes impaired or reduced thoracic movement in CP?
A. When breathing cycle is impaired or labored, it predisposes a child with Cerebral Palsy to respiratory dysfunctions, infections, lack of oxygen in the circulation and in some severe cases, a respiratory failure. Typically, when a child begins to develop a more upright position from 6 months of age, there is a change in the mechanical development of the thoracic cage. There is a development of posterior-to-anterior downward gradient or incline to the ribs in relation to the spine. This mechanical gradient is developed due to both gravity and the forces of the axial musculature in resisting the gravity. The development of this gradient relationship enhances the expansion of the diameter of the thorax in both an anterior-posterior (pump handle movement) and a lateral direction (Bucket-handle movement).
This downward slant of ribs is severely hindered or never fully develops in the child with CP. Therefore, there is a compromise in the mechanical advantage of the pump-handle and bucket-handle motions of inspiration.
In addition to maintaining the gradient relationship between the ribs and spine, the thoracic (external intercostals) and abdominal (oblique) muscles also act to fix the rib cage. This fixation is a key to ensuring the complete and effective contraction of the diaphragm. And thus to increase lung volume. In Cerebral Palsy due to weak muscles, the fixation of rib cage is compromised. Hence, the contraction of the diaphragm is weaker, which in return compromises the quality of respiration.
C. On the other hand, weaker muscle tone to stabilize the thoracic cage can pull down the xiphoid process and the sternum during inspiration. This paradoxical movement is mainly due to the pull of diaphragmatic fibers, particularly the sternal fibers. Impaired thoracic expansion in conjunction with sternum depression causes shallow respiratory motions. So, there will be reduced lung volumes, including vital capacity and total lung capacity which in turn contribute to a failure of pulmonary system to adequately oxygenate the mixed venous blood. Reduced oxygen available for circulation means the reduced energy available for activities, leading to reduced level of physical fitness and hence further complications.
D. Also, due to poor postural muscular system weakness such as decreased active balance of trunk flexors and extensors, compromise the proper postural alignment during activities and rest. As a result there are differences in motion of the chest wall during inspiration and expiration cycle. Poor respiratory efforts or poor breathing cycles negatively impacts several mechanisms like vocalizations, swallowing and coughing
The detailed assessment of thoracic mobility during respiration is the critical part of motor assessment for the child with CP. This assessment should be done with child in various functional positions and plan the therapy protocol accordingly to address all the issues.
Strengthening exercises for the postural system muscles to facilitate postural control throughout the trunk. It is important to focus on both axial extensor and flexor muscles. Especially, strengthening the oblique abdominal muscles that aid in forceful expiration needed for coughing and sneezing is important.
Strengthening exercise for thoracic cage musculature such as intercostals, to improve chest mobility.