Axillary nerve injury is also referred to as axillary nerve compression and quadrilateral space syndrome. It is not a particularly common injury and usually occurs as a result of a direct impact to the outer arm, or from throwing. Here we explain the symptoms, causes and treatment of Axillary nerve injury.
Symptoms of an Axillary nerve injury
- Numbness over the deltoid muscle on the outside of the upper arm.
- Pain at the back of the shoulder. This is likely to be poorly localized, or difficult to pinpoint exactly where the pain is.
- Difficulty raising the arm out to the side. This is because of weakness in the deltoid and teres minor muscles.
- As a result, the deltoid muscle will appear smaller or wasted away, especially in long-term chronic injuries.
What causes Axillary nerve injury?
Injury to the Axillary nerve may be from a traumatic injury such as a shoulder dislocation or a direct impact to the outside of the upper arm. In this case, the damage is done to the nerve. Either the myelin sheath (which surrounds the nerve) or the axon (the nerve itself) is injured. It may heal but also may cause permanent disability, depending on the extent of the damage.
The Axillary nerve may also be compressed. This causes more temporary symptoms, rather than permanent damage. A common example of this is using crutches incorrectly, especially with the very old-fashioned axillary type crutches which apply pressure into the armpit.
Quadrilateral space syndrome
Another condition to be aware of is Quadrilateral Space Syndrome. This occurs when the Axillary nerve is compressed within the quadrilateral space at the back of the shoulder. This is seen more often in throwers. As well as the common Axillary nerve injury symptoms listed above, the patient may also complain of pain in the back of the shoulder.
The patient should be referred to a neurologist.
An EMG may be taken to confirm the diagnosis.
In most cases, treatment is not necessary as the symptoms will gradually clear on their own as the nerve heals.
Anti-inflammatories may be prescribed to ease pain and swelling around the nerve, which helps to reduce compression.
Physical therapy may be recommended to maintain muscle strength as much as possible. Read more on shoulder exercises.
Timescales vary massively for recovery from this injury. It could be anywhere from 6 weeks to 6 months or more.
If symptoms do not clear or the problem gets worse, surgery may be required to further investigate the problem.
References & further reading
- Lee S, Saetia K, Saha S et al. Axillary nerve injury associated with sports. Neurosurg Focus 2011;31(5):E10.
- Galvin JW, Eichinger JK. Outcomes Following Closed Axillary Nerve Injury: A Case Report and Review of the Literature. Mil Med 2016;181(3):e291–7.