Radiology point of view for brachial plexus .

1. IMAGING OF THE BRACHIAL PLEXUS
Hanan Eid, MD
ASS. LECTURER OF RADIOLOGY
AL-AZHER UNIVERSITY FACULTY OF MEDICINE FOR GIRLS.

2. Objectives:
 Introduction.
 Anatomy notes.
 Imaging modalities.
 Normal imaging findings.
 Pathological conditions.
 Radiological appearance of pathological conditions.

3. INTRODUCTION:
 Brachial plexus a neural network , motor and somatosensory innervation of the arm, shoulder, and upper
chest.
 Evaluation of disease begins with :
 patient history,
 physical examination,
 electro physiologic testing.
 Imaging , important role in:
 lesion localization
 Lesion characterization.
 management of traumatic and nontraumatic brachial plexopathies.
 Imaging:
 can be included in the field of view at nondedicated imaging.
 Dedicated advanced imaging.
 Review clinical data in each case to understand how imaging may affect patient care.

4. Brachial Plexus Anatomy
 Formation: ventral rami of the C5–T1 spinal nerves.
 Variant anatomy, contribution of C4 +/- T2 spinal nerve roots:
 Pre-fixed plexus C4 nerve without T1
 Post-fixed plexus T2 nerve Without C5
 Subdivisions:
 Roots: ventral rami of C5- T1 spinal nerves.
 Trunks: Upper, middle and lower.
 Divisions: 2 divisions of each trunk, anterior and posterior.
 Cords: medial, lateral and posterior.
 Branches: Mainly, the median, radial, ulnar, and axillary n.

5.  5 anatomic landmarks for better assessment:
 The neural foramen: roots.
 Interscalene triangle: roots and trunks.
 Lateral border of the first rib (costo-clavicular ): divisions.
 Medial border of the coracoid process (retro-pectoralis minor): cords.
 Lateral border of the pectoralis minor muscle: branches.

6.  Neural foramina:
- The roots 5 stacked points on sagittal images.
- The proximal aspect of the first rib a useful landmark , locating the roots in
sagittal plane, T1 root is below while C8 root is above the rib.

7.  The interscalene :
 The subclavian artery a
landmark.
 Medially:C5–C7 roots
superior, C8 & T1 roots
posterior.
 Laterally: upper &middle
trunks superior, lower trunk
posterior.

8.  The lateral border of the first rib:
 3 anterior & posterior divisions
form a triangular cluster of six
points just superior to the artery
and posterior to the mid-clavicle

9.  The medial border of the coracoid process:
 cords named for their relation to axillary artery.
 posterior cord between lateral & medial cords.
 3 cords, and the artery, form a 3 -toed “paw-
print” configuration on sagittal images.

10. Imaging Modalities:
 goal of imaging :
 visualize the entire course of the neural network (clear structural analysis , its
intraneural integrity).
 provide a causal diagnosis for brachial plexopathies.
 Assessment of surrounding structures.
 Effects of nerve injury on MSK.
 Modalities:
 Conventional radiography.
 US.
 CT conventional CT.
CT myelography.
 MRI/MRN .

11. Radiography:
 Of limited use.
 Indirect evidence of BP pathology rather than its actual demonstration.
 X-ray of cervical spine, shoulder, or chest in trauma / pain.
 Relevant findings of musculoskeletal disease compressive neuropathy:
 cervical rib.
 elongated C7 transverse process,
 structural lesions between the clavicle and first rib: hypertrophic callus in clavicular #.
 Tumours of thoracic apex, a Pancoast tumor, as a pulmonary mass / osseous
erosion.

12. U/S:
 Non-invasive, well-tolerated.
 A unique advantage dynamic imaging across a spectrum of neck and
shoulder movements.
 US guided peripheral nerve or intra muscular blocks.
 identification of “Typical characteristics of peripheral nerves :”
 More echogenic than muscles, less echogenic than tendons.
 Honeycomb appearance.
 Less mobile than tendons.
 Characteristics of diseased nerves :
 Nerve enlargement.
 Hypoechoic , nerve edema.
 Discontinuity of nerve fascicles- Complete /Partial.

16. Conventional CT:
 initial cross-sectional imaging study, emergency & spine.
 individual nerves & microstructural nerve abnormalities not
possible.
 improved spatial resolution & MPR of MDCT : portions of BP are
evident, even at routine CT of the neck, chest, and shoulder.
 excellent for osseous anatomy, rib and vertebral body erosion.
 gross abnormalities: hematoma, perineural scarring, & tumor
involvement can be identified.
 Dynamic CTA & CTV protocols (arms-up & arms-down): vascular
TOS.

17. CT Myelography
 outline the spinal cord and exiting nerve rootlets.
 evaluating possible preganglionic brachial plexus injury.
 In indeterminate MRI findings
 suspected brachial plexus injury in neonates, evaluation of such small structures
limited with MRI.
 root avulsion:
 spinal nerve discontinuity near the rootlet-cord interface
 Pseudo-meningocele, implying meningeal rupture.
 performed 3–4 weeks after injury: hematoma resolve, Pseudo-meningoceles
develop.
 invasive nature & exposure to iodinated contrast material and ionizing radiation.

19. MRI Evaluation:
 Advantages:
 detailed evaluation of all components of brachial plexus.
 excellent soft tissue contrast.
 Multiplanar imaging.
 identification of structural and microscopic changes: nerve edema, degeneration, and
inflammation T2 signal intensity change or abnormal enhancement.
 In addition to depicting direct nerve injury, end-organ skeletal muscle denervation
 localize nerve involvement and characterize the chronicity of injury.
Acute: muscular edema.
Chronic: muscle atrophy & fatty change.

20. MRI Evaluation:
 Technique:
 Orientation :
 Direct coronal & Oblique sagital BP runs in a coronal plane from medial-superior to
lateral-inferior direction.
 Individual nerve roots Axial & sagital views of the exiting nerve roots.
 Sequences:
 Coronal T1 and STIR.
 Sag T1
 Axial T1
 T2 fat sat / STIR images.
 3D STIR SPACE images with reconstruction & post-processing (MIP).
 Post contrast T1fat sat if required.

21. Normal Imaging Findings:

24. Normal brachial plexus.
Coronal MIP 3D STIR SPACE
image focused on the left
side shows the anatomy of
the brachial plexus

25. A recommended search pattern, Structures to
assess at MRI/CT of the BP:

26. Pathologic conditions:
Traumatic plexopathy :
 broad spectrum of severities
 imaging assess severity of injury for
prognostication
 guide potential surgical intervention.
Nontraumatic plexopathy :
 neuritis of various causes:
 radiation
 inflammation
 infection,
 metabolic condition,
 compression or entrapment
 Vascular abnormalities.
 neoplasias:
 benign
 Malignant: 1ry, 2ry.

27. Pathologic conditions:
 According to their location in relation to the clavicle:
 Supraclavicular nerve roots & trunks in scalene
 Retroclavicular divisions.
 Infraclavicular cords and terminal branches.
 Less commonly, panplexus lesions from severe trauma or radiation
neuropathy.

28. Abnormal MRN Findings in the Brachial Plexus:
 1ry nerve findings:
 asymmetric T2 hyperintensity.
 Enlargement.
 kinking by fibrosis.
 flattening by intramuscular course.
 entrapment by mass lesion.
 discontinuity/focal neuroma in injury
 +/-Cause of plexopathy:
 anatomic variation, e.g.: accessory scalene muscle belly or intramuscular course.
 surrounding fat plane changes.
 perineural space-occupying lesions.
 cervical spondylosis or injury.
 +/- Regional denervation muscle changes.
 combination of all these.

29.  Sometimes, it may be difficult to differentiate stretch
injury/brachial plexitis–related internal nerve root changes
from underlying long-standing cervical spondylotic changes
in middle-aged and elderly subjects.
 Generally:
 Brachial plexopathy asymmetric T2 hyperintensity in the
scalene , sparing most proximal nerve root & DRG.
 Cervical spondylosis–related nerve impingement most
proximal portion of the nerve within and immediately distal to
the neural foramen.
 abnormality in the latter case is usually restricted to the nerve
corresponding to the most narrowed foramen.

30. isolated C6 radiculopathy. A 51-year-old woman with right arm pain and a tingling sensation, clinically
suspected of having brachial plexitis versus radiculopathy. Sagittal STIR (A), axial T2 SPACE (B), and
coronal 3D MIP STIR SPACE (C) images show an asymmetrically hyperintense and diffusely enlarged
isolated C6 nerve root (arrows), corresponding to the markedly narrowed right C6 neural foramen. The
findings are in keeping with cervical radiculopathy, in the setting of cervical spondylosis.

31. Pathologic Imaging Findings, Traumatic injury:
differentiate pre and post ganglionic injury.
preganglionic injury:
Direct signs
 High-resolution 3D T2- and CT
myelography
 anatomical discontinuity or lack of
intradural nerve rootlets.
Indirect signs
 Pseudo-meningocele on T2WI.
 Contralateral deviation of the
spinal cord.
 Denervation changes involving
ipsilateral paraspinal muscles.

33. Postganglionic lesions
 in continuity:
 requiring:
rehabilitation/neurolysis.
 Neuropraxia/stretch injury
(most common).
 Axonotmesis.
 Partial neurotmesis with
neuroma in continuity
formation.
 nerve discontinuity :
 requiring :
nerve repair/grafting.
 complete nerve lacerations
(neurotmesis).
 nerve root avulsions, the most
severe injury.

34. Postganglionic traumatic injuries:
 Focal edema ( T2 signal) involving any part of the plexus distal
to the DRG.
 Nerve thickening/loss of fascicular architecture.
 In-continuity/ end bulb neuroma.
 Anatomic discontinuity +/- clumping/retraction.
 A peri-plexus hematoma.
 Denervation changes limited to distal end organ muscles.
 Perineural scarring.

37. Nontraumatic Brachial Plexopathy, Irradiation:
 T2 signal.
 Thickening without focal mass.
 Longitudinal thin enhancement.
 If prior malignancy & local radiation to the brachial plexus
differentiate tumor progression/recurrence Vs benign radiation-
induced plexopathy:
 Time course : radiation induced plexopathy occurs between 5 and 30
months post radiation (peak incidence 10-20 months).
 details of clinical presentation aid in diagnosis, e.g.:
 increasing/new pain or new Horner syndrome tumor
recurrence/progression.
 unilateral edema or parasthesia radiation-induced plexopathy.

39. Acute Brachial Neuritis, Parsonage Turner Syndrome :
 intrinsic nerve abnormality:
 T2 hyperintensity
 thickening
 variable enhancement
 Muscular denervation changes, acute/subacute:
 muscle edema, T2 signal.
 Variable enhancement.

41. Polyneuropathy
 intrinsic nerve abnormality:
 T2 hyperintensity
 thickening
 variable enhancement
 CIDP, type of inflammatory demyelinating neuropathy:
 smooth fascicular or fusiform nerve enlargement
 marked T2 signal.
 minimal peripheral enhancement.
 Although the mass-like nerve enlargement may resemble plexiform
neurofibroma, it can be distinguished by the relative lack of
enhancement.

42. Thoracic Outlet Syndrome
 neurovascular impingement within the thoracic outlet.
 three spaces :
 interscalene triangle neurogenic or arterial TOS
 costoclavicular space venous TOS
 pectoralis minor /retropectoral space neurogenic/venous
TOS.
 neurogenic TOS: most common compressive B.
plexopathy.

43. Neurogenic TOS
 X ray chest and cervical spine cervical rib.
 US and MRI : support the diagnosis & localize sites of
compression.
 Dynamic US assess brachial plexus compression.
 MRI evaluating soft-tissue structures contribute to compression,
e.g. fibrous bands, abnormal scalene muscular attachments &
supernumerary muscles
 Dynamic MRI, arm imaged in a neutral position & in overhead
positions brachial plexus impingement ( loss of normal
perineural fat & nerve T2 hyperintensity.

44. Thoracic outlet syndrome. A 55-year-old woman with weakness of the left upper extremity with
tingling in the hand. Coronal T2 SPACE image shows the deviated path of the C8 nerve root with
abnormal flattening (arrow) due to pseudoarthrosis between the left cervical rib and first rib,
which was subsequently proved on the surgery. The patient improved after surgery.

45. Brachial Plexus Tumors:
 Primary:
Benign Malignant.
 Secondary
 precise description of the suspected tumour including:
 lesion size,
 nerve(s) involved,
 nerve location,
 soft-tissue involvement, to guide the surgical approach and assess
resectability.

47. Take home message:
 Imaging confirm physical examination and electrodiagnostic findings
 localize sites of involvement, assist in preoperative planning, and assess for
underlying structural or neoplastic lesions.
 US a valuable tool for evaluating the superficial components of the brachial
plexus.
 CT images limited soft tissue contrast resolution, but may show initial evidence
of disease, and CTA or CTV to evaluate cases of vascular TOS.
 CT myelography useful for assessment of preganglionic injury, particularly in
neonates.
 MRI the best modality overall for assessing the brachial plexus, and used as a
biomarker for assessment of demyelinating and inflammatory conditions.
 Familiarity with anatomy, distributions of brachial plexus and spectrum of
associated imaging appearances is important for radiologic evaluation.

48. References:
 https://pubs.rsna.org/doi/full/10.1148/rg.2020200012.
 https://appliedradiology.com/articles/mri-of-the. MRI of the brachial plexus: A practical
review.
 https://www.bing.com/ck/a?!&&p=c7c9c668c99b5f92JmltdHM9MTcwMjI1MjgwMCZpZ3VpZD0
zMzQzYjZkMi05NWU1LTYxNTQtM2RjMC1hNmFhOTQzZTYwNzcmaW5zaWQ9NTAwNg&ptn
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a6aa943e6077&u=a1aHR0cHM6Ly9yYWRpb2xvZ3lrZXkuY29tL21yLWltYWdpbmctb2YtdGhlL
WJyYWNoaWFsLXBsZXh1cy8&ntb=1.
 https://www.ajnr.org/content/34/3/486.

49. Thankyou