Parsonage-Turner syndrome is also known as neuralgic amyotrophy, paralytic brachial neuritis, idiopathic brachial plexopathy or acute brachial radiculitis . It is described in both children and adults and consists of a sudden, rather abrupt, unilateral shoulder or upper extremity pain that may begin rather insidiously but quickly amplifies in severity and intensity. It was first reported in 1948 by the Parsonage and Turner, but similar clinical presentations were described as far back as 1897.
Image 1. Labeled diagram of the brachial plexus
Evaluation for PTS can also be challenging due to its variable nature. It is mainly a clinical diagnosis but examination can aid in the diagnosis. A thorough cervical examination can show weakness in musculature, especially once the acute phase of pain has subsided. Atrophy can occur in a multitude of muscles, but the shoulder musculature should be evaluated closely for atrophy. Observing for scapular winging and wall push ups should be performed due to the possibility of long thoracic nerve involvement. Electromyography is typically a very important diagnostic modality.
Image 2. Scapular winging seen in parsonage turner syndrome (courtesy of bangaloreshoulderinstitute.com)
Electromyography is typically a very important diagnostic modality. Electromyographers need to be extremely detail-oriented in the systemic approach to testing muscles of the upper limb . EMG studies should typically be performed after 3-4 weeks of symptom onset and are normal many times if tested before 3 weeks. Since PTS is an axonal disorder commonly affecting proximal muscles of the upper limb, the motor and sensory nerve conduction velocities and distal latencies routinely tested on the distal upper limb are usually normal. Because of the involvement of the lateral antebrachial cutaneous nerve in many cases, some providers order a comparison of the unaffected limb. EMG studies 4 to 12 months after the onset of symptoms may show old denervation and reinnervation with polyphasic motor unit potentials .
Table 2. Electrodiagnostic findings for parsonage turner syndrome (adopted from Smith and Belevaqua 2015)
Image 3. MRI findings of parsonage turner syndrome which here demonstrate diffuse increased signal in rotator cuff muscles (courtey of orthobullets)
In summary, Parsonage Turner Syndrome is a rare and underrecognized condition with limited high-quality evidence in regards to treatment. Diagnosis should be considered in patients with abrupt onset of upper extremity pain that is non-traumatic in most cases. Muscle weakness and atrophy may follow an acute painful phase. An antecedent event occurs in around half the cases. Although many theories exist in regards to pathophysiology, a common unifying cause has not been established. EMG studies after three weeks can show specific abnormalities that can aid with diagnosis. No specific treatments have been proven to reduce neurologic impairment and most modalities are to control symptoms or maintain functionality. Most patients are treated with a multidisciplinary approach including physical therapy and pharmacologic treatments.
Read More: https://wikism.org/Parsonage_Turner_Syndrome