Neuralgic Amyotrophy is an uncommon condition affecting the shoulder and upper arm. The exact cause is not known, therefore it is known by numerous different names such as:
- Parsonage-Turner Syndrome
– Brachial neuritis
– Patchwork amyotrophy
- Localised neuritis of the shoulder girdle
- Seratus magnus paralysis
- Multiple neuritis of the shoulder girdle
- Acute brachial radiculitis
- Shoulder-girdle syndrome
- Paralytic brachial neuritis
- Acute shoulder neuritis
- Acute scapula-humeral palsy
- Brachial plexus neuropathy
Despite the confusion in naming the condition it is a well-recognised and well-identified clinical entity.
The typical history is sudden pain followed by marked muscle-weakness and wasting of the shoulder girdle and upper arm. Pain starts suddenly across the top of the shoulder-blade and lasts from a few hours to a fortnight. The degree of pain may be variable and some patients don't recall a significant painful episode.
Then, a weakness of some of the muscles of the shoulder girdle and often of the arm develops. When the weakness appears, the pain usually stops. There is usually no loss of sensation associated with the weakness.
It may give rise to secondary shoulder impingement due to the muscle imbalance. Patients also develop a fatigue of the shoulder, particularly with overhead activities.
In the acute phase the condition may resemble an acute frozen shoulder, calcific tendonitis or arthritis. In the chronic, weak phase it often resembles rotator cuff tears of the shoulder or nerve root compression.
Nerve conduction studies (EMG) and imaging studies are useful in distinguishing the above conditions from Neuralgic Amyotrophy.
No specific treatment has yet been proved efficient in Neuralgic Amyotrophy. In the early stages, pain may require treatment. Common pan-killers are usually sufficient.
As pain subsides, physiotherapy is recommended. Passive range of motion exercises of the shoulder and elbow are suggested to maintain full range of motion. Active rehabilitation is undertaken only when some recovery of the affected muscle(s) is already obtained. Furthermore, all the upper body muscles should undergo rehabilitative exercises, and not only those presenting clinical weakness. It is also recommended that strength recovery reaches a plateau before patient returns to sports.
The prognosis is generally good, since recovery of strength and sensation usually begins spontaneously, as early as 1 month after symptoms onset, with about 75% of complete recovery within 2 years. However, the period of time for complete recovery is very variable, ranging from 6 months to 5 years. It seems that the delay in recovering strength depends on the severity and duration of pain, weakness, or both.
Patients with involvement of proximal and upper trunk lesions have the most rapid recovery. In general, complete restoration to normal strength and function usually occurs within five years.
M. J. Parsonage, J. W. Aldren Turner:
Neuralgic amyotrophy. The shoulder-girdle syndrome.
The Lancet, London, 1948, I: 973-978.