CERVICOTHORACIC JUNCTION: BRACHIAL PLEXUS INFLAMMATORY CONDITIONS

ANTHONY A. MANCUSO

KEY POINTS

A cervicothoracic junction inflammatory condition acutely threatening the brachial plexus is relatively uncommon.
Imaging can most often provide a very likely diagnosis and establish whether the process is primarily or secondarily affecting the brachial plexus and assess any immediate threat of functional loss.
Imaging can help to identify complications, such as brachiocephalic vaso-occlusive disease, that might threaten immediate and/or permanent ischemic injury.
Imaging can help to differentiate radiation plexopathy from tumor recurrence but is not absolute in this regard.
Imaging is often critical to proper triage and medical decision making.

Inflammatory conditions that involve the cervicothoracic junction (CTJ) and brachial plexus are unusual. They are a possible source of symptoms of a mass lesion, and an inflammatory etiology must be considered when a mass is accompanied by swelling, tenderness, and/or fever or an appropriate clinical circumstance such as prior CTJ-region radiotherapy. Such conditions may be often lumped under the term thoracic outlet syndrome (TOS); however, TOS, in the vast majority, manifests only neurologically in the form of a brachial plexopathy.^1,2

ANATOMIC CONSIDERATIONS

The overall anatomy of the CTJ is discussed in Chapter 149 for the infrahyoid neck in general and more specifically in Chapter 163 for the CTJ region. The specific anatomy zones of anatomy^1,2 along the brachial plexus that must be considered in all patients with possible compressive brachial plexopathy are considered in Chapter 165.

IMAGING APPROACH

Techniques and Relevant Aspects and Imaging Pros and Cons

These techniques are discussed in Chapter 149 for the infrahyoid neck in general and more specifically in Chapter 163 for the CTJ and are presented in Appendixes A and B.

Urgent vascular ultrasound and/or catheter arteriography may be necessary in presentations strongly suggesting acute ischemia. These tools are also useful in more routine selected cases.

The use of computed tomographic angiography and/or magnetic resonance angiography positional and standard imaging has not been systematically investigated for TOS but is a reasonable option in selected patients.^1,2

DIAGNOSTIC CONSIDERATIONS IN INFLAMMATORY CONDITIONS OF THE BRACHIAL PLEXUS AND CERVICOTHORACIC JUNCTION

This chapter will follow an etiology-based approach to the diagnostic process regarding its involvement with inflammatory or infectious disease. The general diagnostic approach to conditions of the brachial plexus and CTJ is presented in Chapter 163.

Clinical Presentation

The primary presentation of interest in this chapter is a brachial plexopathy that may be accompanied by a mass and signs and symptoms of inflammation including pain, tenderness, fever, and possible vascular congestion or occlusive disease. There may also be a history of a mass or fullness changing size or other intermittently fluctuating symptoms (Fig. 166.1). A history of an inciting event or prior irradiation may be available. Chronic repetitive trauma might suggest inflammation due to mechanical compressive TOS, which is discussed in Chapter 165.

Neurologic dysfunction (Figs. 163.1 and 163.5) may include not only the brachial plexus but also the cervical sympathetics, vagus nerve, recurrent laryngeal nerve, and phrenic nerve.

Specific Conditions and Imaging Appearance

Inflammatory conditions generally cause the segments of the plexus involved to enlarge slightly and enhance. The surrounding tissue planes may be preserved but tend to be obscured by reactive changes during the most active phase of the disease. The surrounding planes typically return to normal. The nerves themselves may show persistent swelling and enhancement or evidence of atrophy depending on the cause and evolution of the process.

Compression syndrome/Mechanical irritation TOS: The compression in TOS can be aggravated by a localized tissue reactive response due to mechanical irritation (Fig. 166.1A–E) and/or and associated vasculitis (Fig. 165.1). The inflammation can also be due to other pathologic conditions or the healing process related to these conditions discussed here and in Chapters 163 through 168 (Fig. 168.6D,E) and anatomic variations, with the latter most commonly related to the presence of a first rib or fibrous bands.
Post radiation (Fig. 166.2): In this situation, the trunks and perhaps roots of the brachial plexus tend to enlarge slightly and enhance. The surrounding tissue planes may be preserved but tend to be obscured by reactive changes at the time of the more active phase of the condition, usually close to the time of the initial study. The nerve bundles may eventually atrophy and show brighter than usual signal on T2-weighted images; the surrounding tissue planes return to normal. Even when the tissue planes return to normal, the roots may remain swollen and edematous and persistently enhance in a chronic active phase of this condition.
Infectious (Fig. 166.3): The morphology of infectious disease is described in Chapter 13.
Inflammation of the spinal cord (Fig. 166.4) may mimic plexopathy.
Other noninfectious inflammations (Fig. 166.1F): Inflammation of the spinal cord (Fig. 166.4) may mimic plexopathy. The fibromatoses can mimic an inflammatory condition (Fig. 166.5).

MEDICAL DECISION MAKING AND TREATMENT OPTIONS

Medical

Once the diagnosis of an inflammatory etiology is suspected, medical therapy can be directed at the cause with the use of anti-inflammatory (Fig. 166.1) and antimicrobial medications (Fig. 166.3).

FIGURE 166.1. Two patients with an uncomplicated inflammatory brachial plexopathy A–E: Patient 1. T1-weighted (T1W) (A) and T2-weighted (B) axial images through the proximal brachial plexus in a patient with a waxing and waning right-sided brachial plexopathy of uncertain etiology. There is slight thickening of the brachial plexus trunks and infiltration of the surrounding fat on the right side (arrows in A and B) compared to normal left side (arrowheads in C and D). In (E), contrast-enhanced T1W coronal images show slight thickening and enhancement of the trunks on the right (arrow) compared to the normal left side (arrowhead). F: Patient 2. Computed tomography study showing abnormal thickening of the plexus and loss of surrounding tissue planes (arrow) and edema in the subscapular musculature (arrowheads). This was eventually attributed to an “autoimmune” etiology. (NOTE: The plexopathy in both patients resolved on anti-inflammatory medications and was believed to be due to compressive thoracic outlet syndrome.)