Diagnosing Erb’s Palsy
Since Erb’s palsy is usually caused by an injury at birth, the condition is difficult to be missed and is easily apparent. However, sometimes the extent of brachial plexus injury may not be clearly known for a few months after the baby’s birth.
Erb’s palsy is diagnosed by a thorough physical examination and medical history. An affected baby may hold its affected arm close to the body with the elbow flexed. In additional to a routine physical examination, some doctors may perform special imaging and diagnostic studies such as a nerve conduction study or magnetic resonance imaging (MRI).
During the physical examination to diagnose Erbs palsy a doctor usually looks for the following symptoms:
Normal forearm extension
Presence of biceps reflex
Normal power of the forearm
Normal hand grasp
Normal development and healthy arms
No sensory impairment on outer aspect of arm
Moro reflex absent on affected side (a reflex present in infants as a response to a sudden loss of support, for example, if the infant feels it is falling)
The diagnosis and assessment of the severity of brachial plexus injury are dependent on the physical examination and diagnostic testing, if indicated. Some doctors routinely support the use of nerve conduction study or MRI. In newborn infants, the injury is easily detected when the baby cannot actively move an upper extremity and shows a limited range of motion on the affected side. Doctors also examine other limbs in order to rule out tetraplegia ( paralysis of all limbs).
X-rays are sometimes taken to check for arm fractures or for paralysis of the hemidiaphragm, which indicates injury to the phrenic nerve. MRI of the brachial plexus and cervical cord is presumed to be the best imaging technique, if required.