Download Importance and timing of MR Imaging in obstetric brachial plexus

Importance and timing of MR Imaging in obstetric brachial
plexus injury
Poster No.:
C-3326
Congress:
ECR 2010
Type:
Educational Exhibit
Topic:
Head and Neck
Authors:
A. Aralasmak, K. Karaali, C. Cevikol, O. Duman, H. Uysal, U.
Senol; Antalya/TR
Keywords:
obstetric brachial plexus injury, subtypes, MRI, timing of imaging,
preganlionic, postganglionic, traction
DOI:
10.1594/ecr2010/C-3326
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Learning objectives
To discuss MRI findings in acute and chronic obstetric brachial plexus (BPL) injury based
on 35 BPL MRI from 31 subjects, emphasizing on imaging techniques, subtypes of
injuries and importance of early MRI.
Background
BPL is is a part of the peripheral nervous system in cervicothoracobrachial region (Fig 1),
on page
responsible for innervation of shoulder, upper extremity and upper chest
muscles and skin with branches to phrenic nerve (C3-C5) for diaphragm movement and
to the sympathetic ganglia via C8 and T1 nerves.
At each vertebral level, anterior-motor and posterior-sensory roots exit from the spinal
cord merging at the dorsal root ganglion within the neural foramina, thereafter anterior and
posterior rami come out. Both rami include a mixed of motor and sensory fibers. Anterior
rami form the BPL. Posterior rami do not form the BPL but innervate the paraspinal
mucles.
Roots
-anterior rami of C5, C6, C7, C8, T1 nerves w/wo minor branches from C4 and T2
Trunks
- Superior (C5, C6), middle (C7), inferior (C8, T1)
Divisions
-anterior, posterior
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Cords
-medial (anterior divisions of inferior trunk )
-lateral (anterior divisions of superior and middle trunks)
-posterior (posterior divisions of superior, middle and inferior trunks) Peripheric
Branches
-Axillary nerve (C5, C6)-Deltoid muscle
-Musculocutenous nerve (C5, C6, C7)
-Biceps muscle
-Radial nerve (C5, C6, C7, C8, T1)-Triceps muscle
-Ulnar nerve (C8, T1)-Abductor Digiti Minimi muscle
-Median nerve(C5, C6, C7, C8, T1)- Abductor Pollicis Brevis muscle
Supraclavicular plexus: Roots and trunks
Roots within the interscalene triangle between the anterior and middle scalene mucles
Trunks form at the lateral border of middle scalene muscle.
Retroclavicular plexus: Divisions costoclavicular space posterior to clavicle and above
the subclavian artery and vein
Infraclavicular plexus: Cords and terminal branches retropectoralis minor space lateral
to the first rib, posterior to pectoralis muscles and above the axillary artery and vein.
Lateral to the first rib, subclavian artery and vein take the name of axillary artery and vein.
Obstetric Traumatic Brachial Plexopathy
• Prevalance: 0.38-1.56/1000
• Mostly right sided
• Mostly supraclavicular BPL (C5, C6 ± C7).
Erb-Duchenne paralysis
• Less often whole BPL (C5-T1)
• Very rarely infraclavicular BPL (C8 vand T1)
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Klumpke's paralysis/ Horner's syndrome /diaphragm paralysis.
• Supraclavicular injuries are mostly postganglionic injury
• Infraclavicular injuries are mostly preganglionic injury
• Stretching (neuroapraxia or traction) injury the least severe and most common form,
typically heals on its own
• Root avulsion (preganglionic separation of the root from the spinal cord - intraforaminal)
nerve transfers to the denervated muscle (neurotization) is recommended within 3
months of injury for the optimal recovery.
• Postganglionic rupture (separation of BPL distal to the ganglion -extraforaminal)
varying degree of recovery possible so that microsurgery is usually performed between
3 and 9 months of injury (end to end anatomosis, nerve grafting, microsurgical removal
of perineural scar tissue and adhesion (neurolysis))
• Pseudomeningocele (a tear in the meningeal sheath around the nerve roots with
extravasation of CSF in the neighboring tissue)
• Postraumatic neuroma (tangles of regenerating nerve fibers at the site of
postganglionic seperation)
PREGANGLIONIC-POSTGANGLIONIC DIFFERENTIATION
Injury of nerves close to dorsal root ganglion supports the presence of preganglionic injury
• Horner's sydrome (sympathetic system)
• Hemidiaphgram elevation (phrenic nerve);
• Winged scapula (long thoracic nerve);
• Loss of muscle functions
Rhomboid muscle (dorsal scapular nerve),
Rotator cuff muscles (suprascapular nerve),
Latissimus dorsi muscle (thoracodorsal nerve)
MRI
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• Most valuable technique for lesion identification and differentiation between pre and
postganglionic lesions which is crucial for surgical management
• Contrast enhanced BPL MRI in multiple planes
Fat saturated T2 TSE or STIR (MR neurography)
3D heavily T2W (MR myelography)
• Root avulsion,
Pseudomeningocele,
Postganglionic separation,
Post-traumatic neuromas,
Hematoma, Fibrosis,
Intrinsic and extrinsic masses of BPL,
Inflammatuar plexitis (idiopathic, infectious, radiation -induced, immune mediated, toxic).
Imaging findings OR Procedure details
Contrast enhanced MRI with STIR and MR myelography are essential.
CT myelography is still gold standard for root avulsion because of spatial resolution.
However, MR myelography is noninvasive, easily applied to newborns and more
successful in demonstration of pseudomeningocele since if there is no relation to dural
sac, pseudomeningocele cannot fill on CT myelography.
MRI Findings in Traction (stretching, neuroapraxia) injury
In acute cases: asymetric thickening, irregularities,T2 hyperintensity and diffuse contrast
enhancement seen along the BPL (Fig 2). on page
In mild injury, T2 hyperintensity
is noted only on STIR images without thickening and contrast enhancement (Fig 3). on
page
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In chronic cases: Findings resolve to normal or cicatricial changes-(irregularities,
adhesions, T2 hypointensity along the BPL without T2 hyperintensity and contrast
enhancement) (Fig 4).
MRI Findings in Preganglionic injury
In acute cases (Fig 5):
•root avulsion
•pseudomeningocele
•enhancement of paraspinal or BPL-innervated muscles
•enhancement of the root stump or intradural roots
•spinal cord edema at the level of root avulsion
•spinal cord avulsion
•displacement of spinal cord to the avulsion site
In chronic cases (Fig 6 and Fig 7),
•pseudomeningocele sacs become smaller,root enhancement and edema and contrast
enhancement of BPLs resolve to normal or cicatricial changes, muscles becoming normal
or atrophic.
Indirect signs of Preganglionic injury
• Pseudomeningocele
occur alone without root avulsion in 15 % of the cases
20 % of avulsed roots will not have a pseudomeningocele
• Spinal cord signal changes
only in 20 % of cases with preganglionic injuries.
Acute phase edema (T2 hyperintensity with expansion) hemorrhage (T2 hypointensity)
Chronic phase myelomalacia (T2 hyperintensity with volume loss)
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• Paraspinal muscle signal changes
Root avulsions mostly occur without paraspinal muscle denervation because of
multisegmental innervation of paraspinal muscles
Paraspinal muscle
• Innervated by posterior rami of cervical spinal nerves
• Denervated with injuries to the anterior root or spinal nerve proximal to origin of posterior
ramus
• Mostly multifidus muscles affected
• Contrast enhancement is early and most sensitive imaging sign of paraspinal mucle
denervation
• Enhancement of the denervated muscle occurs as early as 24 hours after nerve injury
possibly due to dilatation of vascular bed and enlargement of the extracellular space
within the muscle.
• High signal changes on T1W and T2W images and volume loss of the paraspinal
muscles are others but less sensitive findings of denervation.
MRI Findings in Postganglionic injury
In acute cases, hematoma or enhancing nodular thickening (posttraumatic neuromas)
can be seen at the separation site.
Posttraumatic neuromas continue to be present in chronic cases (Fig 7) .
Conclusion
In obstetric BPL injury, MRI is essential for differentiation of subtypes of injuries and
surgical planning. Early MRI is necessary as imaging findings may fade out over time.
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Personal Information
Ayse Aralasmak, M.D. Akdeniz University, Department of Radiology, Antalya,
Turkey
Kamil Karaali, M.D. Akdeniz University, Department of Radiology, Antalya, Turkey
Can Cevikol, M.D. Akdeniz University, Department of Radiology, Antalya, Turkey
Ozgur Duman, M. D. Akdeniz University, Department of Pediatric Neurology,
Antalya, Turkey
Hilmi Uysal, M. D. Akdeniz University, Department of Neurology, Antalya, Turkey
Utku Senol, M. D. Akdeniz University, Department of Radiology, Antalya, Turkey
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Images for this section:
Fig. 1: Fig 1: Oblique sagittal T1 W MRI views (A, B, C from medial to lateral) demonstrate
three parts of the BPL. Supraclavicular plexus is composed of roots and trunks. Roots
are seen at the interscalene triangular space (IS) between anterior and middle scalene
muscles. Subclavian artery forms the floor of the interscalene triangle (B). Roots then
form the trunks at the lateral border of middle scalene muscles. Retroclavicular plexus
is composed of divisions situated in the costoclavicular space (CC) between the first rib
and clavicula and BPL is seen in superior and posterior aspect of the subclavican artery
(C). Infraclavicular plexus is composed of cords and terminal branches located in the
retropectoralis minor space (RP), BPL is situated in the posterior and superior aspect
of axillary artery (D). Subclavian artery and vein take the name of axillary artery and
vein at the lateral border of first rib. AA:axillary artery, ADs:anterior divisons, AS:anterior
scalene muscle, AV:axillary vein, CL:clavicula, I:inferior trunk, LC:lateral cord, M:middle
trunk, MC:medial cord, MS:middle scalene muscle, PC:posterior cord, PDs:posterior
divisions, PMA:pectoralis major muscle, PMI: pectoralis minor muscle, S:superior trunk,
SA:subclavian artery, SV:subclavian vein.
Page 10 of 25
Fig. 2: Fig 2: Axial T1W (A), T2W (B) and postcontrast T1W (C) images of an 8 day old
newborn having right arm weakness, there is asymmetric thickening and enhancement
and T2 hyperintensity of the right BPL (long arrows) compared to that of the normal left
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side (short arrows). There is no root avulsion nor other indirect signs of preganglionic
injury. Findings are suggestive of traction injury. Follow up MRI after 10 months was
normal.
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Fig. 3: Fig 3: Coronal STIR (A) and axial T2W-TSE (B) images of 3 months of baby
with birth trauma and left arm weakness, T2 hyperintensity of the left BPL (arrows on
A) is seen only STIR image without thickening and signal changes on axial T2W TSE
view. There is no contrast enhancement of the left BPL (not shown here). Findings are
suggestive mild traction injury of the left BPL.
Fig. 4: Fig 5: Coronal STIR (A), axial fat-sat post-contrast T1W (B) and 3D MR
myelography (C) of a 2 month old baby shows edema and enhancement of right BPL
(white arrows on A and B) and shoulder muscles and no anterior C7 root visualized
within the pseudomeningocele extending ino the right C6-7 foramina (C). Findings are
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suggestive of preganglionic injury of the right BPL. In another patient with left sided
preganglionic injury, there is enhancement of left anterior root stump (arrow on D) at
one level and left anterior and posterior roots coming off the spinal cord at another level
(arrows on E).
Fig. 5: Fig 4: In a 6 months years old infant with a history of obstetric BPL injury, there
is thickening of right BPL on axial T2 (A) and T1W (B) MRI views without associated
contrast enhancement (C). There is obliteration of normal fat signal between the anterior
and middle scalene muscles on the right, supporting thickening of the right BPL. T2
hypointensity of the right BPL compared to that of the left side (A) suggests fibrosis of the
right BPL. MR myelography views show pseudomeningocele within the spinal canal at
C6-7 ve C7-T1 level (not shown) extending into C6-7 foramen with roots visualized within
the pseudomeningocele (D). Findings are consistent with chronic traction injury with no
evidence of preganglionic injury.
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Fig. 6: Fig 4: In a 6 months years old infant with a history of obstetric BPL injury, there
is thickening of right BPL on axial T2 (A) and T1W (B) MRI views without associated
contrast enhancement (C). There is obliteration of normal fat signal between the anterior
and middle scalene muscles on the right, supporting thickening of the right BPL. T2
hypointensity of the right BPL compared to that of the left side (A) suggests fibrosis of the
right BPL. MR myelography views show pseudomeningocele within the spinal canal at
C6-7 ve C7-T1 level (not shown) extending into C6-7 foramen with roots visualized within
the pseudomeningocele (D). Findings are consistent with chronic traction injury with no
evidence of preganglionic injury.
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Fig. 7: Fig 5: Coronal STIR (A), axial fat-sat post-contrast T1W (B) and 3D MR
myelography (C) of a 2 month old baby shows edema and enhancement of right BPL
(white arrows on A and B) and shoulder muscles and no anterior C7 root visualized
within the pseudomeningocele extending ino the right C6-7 foramina (C). Findings are
suggestive of preganglionic injury of the right BPL. In another patient with left sided
preganglionic injury, there is enhancement of left anterior root stump (arrow on D) at
one level and left anterior and posterior roots coming off the spinal cord at another level
(arrows on E).
Fig. 8: Fig 6: In a 2 month old baby with right sided Erb Duchenne paralysis and
partial Horner's syndrome, there is thickening and T2 hyperintensity of the right BPL
on T2W image (A). Contrast enhancement of the right BPL is not shown here. 3D
MR myelography views show pseudomeningocele in the right posterolateral aspect
of the central canal extending from C5-6 to T2-3 and no visualization of roots within
C5-6, C6-7 and C7-T1 foramina. Findings are suggestive of preganglionic injury. 16
month later, coronal T1W (C), coronal STIR (D), post-contrast axial T1W (E) images
show resolution of enhancement, thickening and T2 hyperintensity of the right BPL.
Pseudomeningocele becomes smaller and only seen at the right posterolateral aspect of
the central canal extending from C7-T1 to T1-2 on coronal reformatted 3D myelography
views (F). Pseudomeningocele extends into C7-T1 foramen with no visualization of
anterior and posterior roots of the right C8 nerve. Probably fibrotic band gives false
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images of presence of roots at other levels of avulsion that were described in the previous
MRI.
Fig. 9: Fig 6: In a 2 month old baby with right sided Erb Duchenne paralysis and
partial Horner's syndrome, there is thickening and T2 hyperintensity of the right BPL
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on T2W image (A). Contrast enhancement of the right BPL is not shown here. 3D
MR myelography views show pseudomeningocele in the right posterolateral aspect
of the central canal extending from C5-6 to T2-3 and no visualization of roots within
C5-6, C6-7 and C7-T1 foramina. Findings are suggestive of preganglionic injury. 16
month later, coronal T1W (C), coronal STIR (D), post-contrast axial T1W (E) images
show resolution of enhancement, thickening and T2 hyperintensity of the right BPL.
Pseudomeningocele becomes smaller and only seen at the right posterolateral aspect of
the central canal extending from C7-T1 to T1-2 on coronal reformatted 3D myelography
views (F). Pseudomeningocele extends into C7-T1 foramen with no visualization of
anterior and posterior roots of the right C8 nerve. Probably fibrotic band gives false
images of presence of roots at other levels of avulsion that were described in the previous
MRI.
Fig. 10: Fig 6: In a 2 month old baby with right sided Erb Duchenne paralysis and
partial Horner's syndrome, there is thickening and T2 hyperintensity of the right BPL
on T2W image (A). Contrast enhancement of the right BPL is not shown here. 3D
MR myelography views show pseudomeningocele in the right posterolateral aspect
of the central canal extending from C5-6 to T2-3 and no visualization of roots within
C5-6, C6-7 and C7-T1 foramina. Findings are suggestive of preganglionic injury. 16
month later, coronal T1W (C), coronal STIR (D), post-contrast axial T1W (E) images
show resolution of enhancement, thickening and T2 hyperintensity of the right BPL.
Pseudomeningocele becomes smaller and only seen at the right posterolateral aspect of
the central canal extending from C7-T1 to T1-2 on coronal reformatted 3D myelography
views (F). Pseudomeningocele extends into C7-T1 foramen with no visualization of
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anterior and posterior roots of the right C8 nerve. Probably fibrotic band gives false
images of presence of roots at other levels of avulsion that were described in the previous
MRI.
Fig. 11: Fig 7: Axial T2W (A) and T1W (B) and fat saturated postcontrast axial T1W (C)
MRI views of a 27 years old male patient having a short left arm with a history of left
sided birth BPL injury shows enhancing noduler lesions (thin white arrows) along the
left BPL compatible with posttraumatic neuromas. Other than postraumatic neuromas,
there is no enhancement nor T2 hyperintensity of left BPL, suggesting chronicity of
the injury. Sagittal reformated views from 3D MR myelography (D) shows thickening,
irregularites, adhesive changes of the left BPL compared to that of the normal right side.
BPL fibers (black arrows) are seen in posterior and superior aspect of subclavian artery
(short thick white arrows). Postraumatic neuromas along the left BPL are noted within
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the costoclavicular space (dashed white arrow). There is no nerves seen within the left
C7-T1 and T1-2 foramina (long thick white arrows). Axial 3D MR myelography view (E)
shows adhesion of the spinal cord to the avulsion side. Findings are consistent with
chronic traumatic injury with pre and postganglinic seperations, C8 and T1 root avulsions
and posttraumatic neuromas in costoclavicular space. EMG revealed chronic left BPL
lesion affecting whole plexus with avulsed C8 and T1 roots. IS: Interscalene triangle,
CC:Costoclavicular space, RP: Retropectoralis minor space.
Fig. 12: Fig 7: Axial T2W (A) and T1W (B) and fat saturated postcontrast axial T1W (C)
MRI views of a 27 years old male patient having a short left arm with a history of left
sided birth BPL injury shows enhancing noduler lesions (thin white arrows) along the
left BPL compatible with posttraumatic neuromas. Other than postraumatic neuromas,
there is no enhancement nor T2 hyperintensity of left BPL, suggesting chronicity of
the injury. Sagittal reformated views from 3D MR myelography (D) shows thickening,
irregularites, adhesive changes of the left BPL compared to that of the normal right side.
BPL fibers (black arrows) are seen in posterior and superior aspect of subclavian artery
(short thick white arrows). Postraumatic neuromas along the left BPL are noted within
the costoclavicular space (dashed white arrow). There is no nerves seen within the left
C7-T1 and T1-2 foramina (long thick white arrows). Axial 3D MR myelography view (E)
shows adhesion of the spinal cord to the avulsion side. Findings are consistent with
chronic traumatic injury with pre and postganglinic seperations, C8 and T1 root avulsions
and posttraumatic neuromas in costoclavicular space. EMG revealed chronic left BPL
lesion affecting whole plexus with avulsed C8 and T1 roots. IS: Interscalene triangle,
CC:Costoclavicular space, RP: Retropectoralis minor space.
Page 23 of 25
Fig. 13: Fig 7: Axial T2W (A) and T1W (B) and fat saturated postcontrast axial T1W (C)
MRI views of a 27 years old male patient having a short left arm with a history of left
sided birth BPL injury shows enhancing noduler lesions (thin white arrows) along the
left BPL compatible with posttraumatic neuromas. Other than postraumatic neuromas,
there is no enhancement nor T2 hyperintensity of left BPL, suggesting chronicity of
the injury. Sagittal reformated views from 3D MR myelography (D) shows thickening,
irregularites, adhesive changes of the left BPL compared to that of the normal right side.
BPL fibers (black arrows) are seen in posterior and superior aspect of subclavian artery
(short thick white arrows). Postraumatic neuromas along the left BPL are noted within
the costoclavicular space (dashed white arrow). There is no nerves seen within the left
C7-T1 and T1-2 foramina (long thick white arrows). Axial 3D MR myelography view (E)
shows adhesion of the spinal cord to the avulsion side. Findings are consistent with
chronic traumatic injury with pre and postganglinic seperations, C8 and T1 root avulsions
and posttraumatic neuromas in costoclavicular space. EMG revealed chronic left BPL
lesion affecting whole plexus with avulsed C8 and T1 roots. IS: Interscalene triangle,
CC:Costoclavicular space, RP: Retropectoralis minor space.
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