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Clinical case: Brachial plexus injury

This is an educational article based on a real life case report of injury sustained as a result of suicide attempt. The greatest focus in the case of a suicide attempt should undisputedly be put on providing immediate psychological support. However, it is important to be aware that such attempts can also have serious physical implications, as are outlined in this case. 

You may find this information triggering or upsetting. If you are experiencing feelings of extreme low mood or have been considering suicide, please contact your local mental health facilities. Help is available for you. 

If you're interested in pathology of the upper extremity neurovasculature, you might prefer to read our clinical case on Ulnar Nerve Subluxation. Or, you can browse our full collection of gross anatomy case reports.

After reviewing this case you should be able to describe the following:

  • Electrodiagnostic testing and why was it used in this case.
  • The fatal components of hanging.
  • Why this patient was believed to have had a lower, and specifically, not an upper motor nerve lesion (how it was possible to rule out brain damage due to hypoxia).
  • How and why brachial plexus injury is common obstetrical injury.
  • The anatomical and clinical differences between a dermatome and a cutaneous area innervated by a peripheral nerve. Why this difference is important in this case.

This article is based on a case report published in the Journal "World Journal of Clinical Cases" in 2015, by Ashley Dawson et al. 

It has been modified and reviewed by Joel A. Vilensky PhD, Carlos A. Suárez-Quian PhD, Aykut Üren, MD.

  1. Case description
    1. History
    2. Physical exam
    3. Paraclinical investigations
    4. Diagnosis and causes
    5. Management and evolution
  2. Anatomical and medical considerations
  3. Upper/lower brachial plexus roots injury
  4. Objective explanations
    1. Objectives
    2. Electrodiagnostic testing
    3. Fatal components of hanging
    4. Lower vs. upper motor nerve lesions
    5. Brachial plexus injuries in obstetrics
    6. Dermatome vs cutaneous area innervated by a peripheral nerve
  5. Sources
+ Show all

Case description


The patient was a young man with a history of weakness and numbness in his left arm. A complaint of shortness of breath occurring several months prior to the current clinic visit had prompted a radiographic workup that showed a slightly elevated left hemidiaphragm at the time. However, detailed MRI and MRA neuroimaging at the time failed to show a cause for the elevation.

Physical exam

Physical exam at the current visit to the clinic showed that the young man had difficulty raising his left arm against resistance above the horizontal plane. The patient also showed slight atrophy of both the left deltoid and supraspinatus muscles, and atrophy and weakness of the intrinsic muscles of the left hand. Full strength and normal muscle mass were, however, demonstrated in the left biceps and triceps brachii muscles.

The sensory exam showed reduced sensation to light touch and pinprick along the upper lateral shoulder, suggesting left C5 ramus nerve compromise. In addition, sensory deficits along the medial aspect of the forearm, hypothenar eminence and the fifth digit, and the hand muscle weakness suggested that the left C8 and T1 spinal nerves were also affected.

Paraclinical investigations

In support of these three nerves (C5, C8, and T1) being involved in the young man’s condition, an electrodiagnostic study found denervation and early regeneration potentials for the left C5, C8 and T1 nerves at the trunk level of the brachial plexus (Figure 1-2).

Diagnosis and causes

The patient was initially evasive pertaining to the events preceding his neurological deficits. He repeatedly denied any trauma, and a serological exam failed to reveal evidence of an inflammatory process that could account for his motor deficits. With persistent inquiry, however, the patient finally disclosed that several months ago he had attempted suicide by hanging.

He had used a rope and jumped with it around his neck from a significant height to cause injury. The patient stated that just when the noose tightened, his neck was stretched upward. But having a change of mind, the patient then reached up and grabbed the rope. Nevertheless, he remained suspended on his abducted upper limb before he was able to support himself on his feet and remove the noose.

Management and evolution

Conservative treatment, including physical therapy, resulted in gradual improvement over several months of the deficits. Psychiatric care was also initiated. 

Anatomical and medical considerations

Figure 1. The main photograph (cadaver) shows the roots and trunks of the brachial plexus. The inset shows the area magnified in the larger image. UT, upper trunk; MT, middle trunk; LT, lower trunk.

The brachial plexus is a complex of nerves from C5-T1 that provide motor and sensory innervation to the upper extremity (Figure 1). Injury to the brachial plexus usually results in a pattern of functional deficits that implicates the roots or nerves of the brachial plexus that are compromised.

Erb, or Erb-Duchenne palsy, is the name given to a typical upper brachial plexus injury involving spinal nerve roots C5 and C6. In contrast, Klumpke’s, or Klumpke-Dejerine palsy, affects the lower roots of the brachial plexus (C8, T1). Both these types of lesions usually involve a specific injury mechanism that results in the excessive stretching of either the upper plexus (due to an increase of the angle between the shoulder and head) or the lower plexus (associated with hyper abduction of the arm (Figure 3).

Figure 3. Mechanism of brachial plexus injury. The image on the left shows the mechanism of the left upper brachial plexus injury, whereas the one on the right shows the mechanism for the left lower brachial plexus injury.

In the case described here, the patient had a puzzling neurological deficit consisting of apparently both upper and lower brachial plexus injuries. Based on the radiographic findings and patient history, clinical interpretations led to the reasoned response that initial partial diaphragmatic paralysis was responsible for the shortness of breath experienced by the patient. This paralysis was likely associated with some injury to the C3, C4 and C5 spinal nerves, phrenic nerve (Figure 4).

Figure 4. An illustration showing the left phrenic nerve origin in addition to its path through neck and thorax before reaching the dome of the left hemidiaphragm.

Physical examination of the patient found atrophy of the intrinsic muscles of the hand and also ipsilateral weakness of the supraspinatus and deltoid muscles. 

The hypothenar and intrinsic muscles of the hand are innervated by branches of the median and ulnar nerves that contain elements from the ventral roots of C8-T1. C5 and C6 innervate the supraspinatus muscle via the suprascapular nerve. The axillary nerve, formed also from roots of the C5-C6 spinal nerves, innervates the deltoid muscle. 

This pattern of involved nerves and the electrodiagnostic findings suggest injury to the C5, C6, C8 and T1 nerve roots. Apparently the C7 and possibly C6 nerve roots were spared in this patient. It seems likely the damage occurred due to successive movements during the attempted hanging episode that initially stretched the upper, and then later the lower components of the brachial plexus. Natural recovery from brachial plexus injuries usually occurs within six months. However, the patient in this case was very non-compliant and thus the authors were unable to determine the degree of recovery in him.

Upper/lower brachial plexus roots injury

In Erb’s palsy, the most commonly affected nerves are the suprascapular, musculocutaneous, and axillary nerve. The patient typically presents with loss of sensation in the arm and paralysis and atrophy of the deltoid, biceps, and brachialis muscles. The position of the limb in Erb’s palsy is characterized by: 

  • the arm hangs loosely by the side and is rotated medially
  • the forearm is extended and pronated
  • the arm cannot be elevated from the side
  • the elbow cannot be flexed
  • the forearm cannot be supinated voluntarily

The position of the upper limb is referred to as a "waiter's tip position" (Figure 5).

Quite a few muscles are affected in a patient suffering from Erb's palsy. Remember them easily using a mnemonic!

'SUzy and SUzane IN BRAs Drinking Beers'

  • Supinator
  • Supraspinatus
  • Infraspinatus
  • Brachialis
  • Deltoid
  • Biceps
Figure 5. An illustration showing Erb’s palsy characteristics, which is a common presentation of the upper brachial plexus injuries,.

In lower brachial plexus injuries, the paralysis affects, principally, the intrinsic muscles of the hand, specifically, the interossei, thenar and hypothenar muscles (Figure 6) and the flexors of the wrist and fingers (notably flexor carpi ulnaris and ulnar component of the flexor digitorum profundus).

Figure 6. Cadaver photograph showing intrinsic hand muscles (interossei are not shown because they are deeper to the plane of this dissection). The ulnar nerve innervates these muscles, although the median nerve innervates the thenar muscles via its recurrent branch.

Forearm pronators and wrist flexors may be involved. The classic presentation, known as Klumpke-Dejerine palsy (Figure 7), is the “claw hand,” in which:

In the case of the patient presented here, he did not show all the signs of either complete upper or lower brachial injury because not all of the spinal nerve roots were affected by the injury (C7 and possibly C6 were spared).

Figure 7. An illustration showing Klumpke-Dejerine palsy characteristics, which is a common presentation of the lower brachial plexus injuries.

Clinical case: Brachial plexus injury: want to learn more about it?

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