Acute brachial neuritis overview

# Overview
Acute brachial neuritis (also known as Parsonage-Turner syndrome) is a rare syndrome of unknown etiology affecting mainly the lower motor neurons of the brachial plexus and/or individual nerves or nerve branches. Acute brachial neuritis usually is characterized by the acute onset of excruciating unilateral shoulder pain, followed by flaccid paralysis of shoulder and parascapular muscles after several days.

# Historical Perspective
-  was first discovered by , a , in  during/following .
- In ,  mutations were first identified in the pathogenesis of .
- In , the first  was developed by  to treat/diagnose .

# Classification
-  may be classified according to  into  subtypes/groups:
- Other variants of  include , , and .

# Pathophysiology
- The pathogenesis of  is characterized by , , and .
- The  gene/Mutation in  has been associated with the development of , involving the  pathway.
- On gross pathology, , , and  are characteristic findings of .
- On microscopic histopathological analysis, , , and  are characteristic findings of .

# Causes
Acute brachial neuritis is a form of peripheral neuropathy. It occurs when there is damage to the brachial plexus, an area where a nerve bundle from the spinal cord splits into the individual arm nerves.

# Differentiating  from other Diseases
-  must be differentiated from other diseases that cause , , and , such as:

# Epidemiology and Demographics
In the USA each year, there are approximately 1 to 2 cases per 100,000 people. The reported incidence in the UK is 3 cases per 100,000 people.

# Natural History, Complications and Prognosis
The likely outcome depends on the cause. A good recovery is possible if the cause is identified and properly treatment. In some cases, there may be a partial or complete loss of movement or sensation. Nerve pain may be severe and may persist for a long time.

# Risk Factors
- Common risk factors in the development of  are , , , and .

# Natural History, Complications and Prognosis
- The majority of patients with  remain asymptomatic for .
- Early clinical features include , , and .
- If left untreated,  of patients with  may progress to develop , , and .
- Common complications of  include , , and .
- Prognosis is generally , and the  of patients with  is approximately .

# Diagnosis

## Diagnostic Criteria
- The diagnosis of  is made when at least  of the following  diagnostic criteria are met:

## Symptoms
-  is usually asymptomatic.
- Symptoms of  may include the following:

## Physical Examination
- Patients with  usually appear .
- Physical examination may be remarkable for:

## Laboratory Findings
- There are no specific laboratory findings associated with .
- A    is diagnostic of .
- An  concentration of   is diagnostic of .
- Other laboratory findings consistent with the diagnosis of  include , , and .

## Imaging Findings
- There are no  findings associated with .
-  is the imaging modality of choice for .
- On ,  is characterized by , , and .
-  may demonstrate , , and .

## Other Diagnostic Studies
-  may also be diagnosed using .
- Findings on  include , , and .

# Treatment

## Medical Therapy

## Surgery
Some patients with brachial plexopathy may benefit from surgery if nerve compression is the cause of the symptoms.

## Prevention