High Resolution Ultrasound detects the cause of residual limb pain

High Resolution Ultrasound detects the cause of residual limb pain in Amputees
Dr. Marian O’Reilly
Dr. Peter O’Reilly
Mr. John Sullivan
Ms. Helena O’Reilly
Departments of Radiology and Prosthetics,
Douglas Bader Centre, Queen Mary’s Hospital, Roehampton, London
SW15 5PN, UK.
MUSOC – Leuven Sept 2012
Introduction
An ever-increasing number of the amputations is being carried out globally.
These are related to medical complications due to diabetes, infection,
peripheral vascular disease, neoplasms and trauma - as a consequence of
war (landmines, explosions etc) and accidental injury due to road traffic
accidents.
Some well-documented forms of pathology affecting the amputated limb
include infection resulting in abscess formation, osteomyelitis, bursitis, and
cellulitis.
Other causes of pain in the residual limb are due to the formation of
neuromas, recurrence of the presenting pathology and recurrent cancers,
heterotopic new bone formation, haematoma, and foreign bodies.
This study describes how high resolution ultrasound can be used
to readily diagnose and assess the cause of pain in the residual limb of the
amputee.
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Patients and Methods
133 civilian patients with one or more amputations were included in
the study.
They were seen over a two year period, at the Douglas Bader Unit,
Queen Mary’s Hospital, Roehampton, Surrey, UK, in an outpatient
setting.
Patients were scanned using a Philips ATL/HDI 5000 ultrasound
scanner.
The main causes of pain in the amputated limb diagnosed by U/S
were documented.
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AE = Above Elbow
BE = Below Elbow
HQ = Hind-quarter
AK = Above Knee
BK = Below Knee
MF = Mid Foot
AE, n=4
CFA = Chopart foot amputation
TA = Through Ankle
BE, n=7
TW, n=2
HQ, n=1
TK = Through Knee
TW = Through Wrist
AK, n=46
TK, n=7
BK, n=66
TA, n=1
Chop FA, n=1
MF, n=2
A ‘stick-man’ diagram shows the site and number (n) of selective amputations in the
study population.
AE = above elbow, BE = below elbow, HQ = hind-quarter, AK = above knee,
BK = below knee, MF = mid-foot, CFA = Chopart foot amputation, TA = through ankle,
TK = through knee, TW = through wrist.
Results
There were 89 male and 44 female patients,
Age range 14-91 years,
with a total of 136 amputated sites.
80% of amputations involved the lower limb.
Neuromas were the most frequent source of pain in the
residual limbs
followed by inflammatory edema, soft tissue calcifications,
bony spurs, soft tissue infection, overuse injuries, bursa
formation and skin lesions.
Scar tissue, bony erosion, bone infection, aneurysm
formation, venous thrombosis and failure of the myodesis
were less frequent causes of pain.
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Morbidity
Number of cases
Causes of Pain: Neuromas (n) were by far, the most frequent cause of pain.
fm = failure of myodesis, vt = venous thrombosis, a=aneurysm, be =bone erosion, Bc= Baker’s cyst,
bi= bony infection, sc = skin cover, s = scar, sl = skin lesion, b = bursa,
o = overuse injury, sti = soft tissue infection, bs = bony spur, stc = soft tissue calcification,
i/o = inflammation /edema, n = neuroma.
Neuromas
Neuromas are the most common cause of residual limb pain among
amputees.
Typically, neuromas are the cause of considerable pain with
accompanying altered sensation along the course of the affected
nerve.
Transducer probe pressure was used to reproduce the patient’s
symptoms and distinguish between symptomatic and asymptomatic
neuromas reproducing the ‘Tinel Hoffman’ sign of compression
neuropathies.
Deciding which neuroma is symptomatic is of great clinical
significance, given the association an amputee may have with pain
related to neuromas and subsequent prosthetic design, fitting and
mobility.
In our study 80 patients had a total of 159 neuromas and 106 of
these were symptomatic neuromas.
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Ultrasound of a Nerve
In normal Nerves the nerve fascicles
appear as hypoechoic bands on
longitudinal ultrasound scans and as
bundles of uniformly hypoechoic dots on
transverse scans, surrounded by
echogenic connective tissue
Histology:
Epineurium
Echogenic on US
Nerve Fascicle
Hypoechoic on US
N
N
B
B
Striated appearance of 2 adjacent nerves on
longitudinal scans. N = Nerve, B = Bone
Follicular appearance of a nerve on
transverse scans.
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S
N
n
32yo man with above elbow amputation post electrocution incident.
Swollen nerve (N - thick arrows) more superficial to a normal nerve (n – thin arrows),
S = thickened skin/scar tissue
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Ultrasound of Neuromas
Neuromas result when an intact nerve is subjected to trauma. A
neuroma may be regarded as a form of repair in the proximal nerve.
In our study, 3 patterns of morphology were seen :
-The most common was a neuroma with fusiform/lobulated shape and
these neuromas could be symptomatic or asymptomatic.
-Small numbers of neuromas ( 12 out of a total of 159) were formed of
a radiating network of tiny nerves – these neuromas were all
associated with severe pain.
-Neuromas that were cylindrical in shape and maintained the
morphology of a normal but swollen nerve were associated with either
moderate or severe pain.
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Radiograph of a 32 years old man
with bilateral above-elbow
amputations due to an
electrocution incident.
The ultrasound scan shows a mushroomshaped neuroma (star) at the cut end of the
Median nerve (N). Normal nerve tissue (N) has
linear parallel hypoechoic dark fascicles. Deeply
the nerve is tethered to scar tissue (Sc) in
muscle (M).
Symptomatic vs Asymptomatic
Neuromas
In our study, 9 of the most painful neuromas
were tethered to other structures :
3 neuromas terminated in scar tissue
1 was tethered to the bony cortex
4 were tethered to bony spurs
1 was tethered to heterotopic new bone.
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A 7yo girl post meningitis required
disarticulation of knees and bilateral
trans-forearm amputations
C
N
LS
TS of the neuroma
Symptomatic neuroma (star) tethered to a scar (C) on the skin surface.
N = nerve
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A 44yo man has a Below Knee Amputation with an exquisitely sensitive neuroma.
He previously had a neuroma excised at this site.
n
n
n
n
n
S
Nerve roots (n) radiate from
the scar to a lobulated
neuroma (star) behind the
tiny bony spur (arrow) on
lateral aspect of tibia (T).
N
N
S
T
N
He has another
fusiform shaped
neuroma (star)
medially which is
Asymptomatic.
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Lateral radiograph of a below knee
amputation in a 42 years old lady
with a painful neuroma.
There is a bony spur (arrow) at the
cut end of the fibula (F). T = tibia.
Longitudinal ultrasound scan of the cut
end of the fibula (F) shows a nerve (N)
running along the bright bony cortex.
This nerve (N) terminates in a
neuroma (star).
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65yo man with Below Knee Amputation.
He is tender over a cylindrically thickened nerve running over cut end of fibula
TS and LS scans of a
Cylindrically shaped neuroma.
Star = neuroma
N=nerve
F=fibula
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38 yo man - Bomb blast victim with a Below elbow amputation
has 3 neuromas
Asymptomatic fusiform neuroma
Symptomatic fusiform neuroma with
heterogeneous echotexture
Symptomatic fusiform neuroma
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Bursae and skin lesions were equally a source of prosthesis-associated
discomfort. To a lesser extent, thinning of the overlying soft tissues and scar tissue
caused friction, irritation and inflammation.
Radiograph of a post-traumatic
below knee amputation in a 42 years
old man. The arrows point to
thickening of the soft tissues
overlying the tip of the cut end of the
tibia.
Ultrasound demonstrates that the
thickened tissue corresponds to
subcutaneous oedema (arrows) deep
to the skin surface (S). The edema has
a ‘cobble-stone’ appearance on
ultrasound
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Radiograph of a transarticular
amputation through the knee of
an 83 years old man. The bone
appears demineralized with
features of disuse osteopenia
present.
There is a soft-tissue mass (B)
on the posterolateral aspect of
the bone.
Ultrasound demonstrates
that the mass is a fluid-filled
bursa (B) which lies deep to
the skin (S) and superficial
to the femur (F).
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Inflammatory causes of pain
Inflammation of the distal stump and associated edema caused
problems with fit of prosthesis, especially with lower limb prostheses.
f
Myositis
m
ill-defined muscle fibres with
oedematous change and
neovascularity in the muscle
(m) and fascia (f).
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Soft Tissue
INFECTION
C
Above Knee
Amputation
m
m
Infected Ulcer Crater (C) in the skin with a sinus
(arrows) extending deeply through the
subcutaneous fat into echogenic muscle tissue (m)
displaying fatty infiltration.
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Calcification, Bony Spurs, Heterotopic New Bone
Soft tissue calcifications and heterotopic new bone were an obvious
impediment to prosthesis comfort. The presence of a bony spur at the
distal tip of the cut bone and soft tissue infection caused equal discomfort.
A high transfemoral amputation in
a 28 years old bomb-blast victim.
There is considerable heterotopic
new bone (arrows) at the cut end
of the femur.
Ultrasound shows the irregular
bright cortex (arrows) of the
heterotopic new bone (arrows).
There is a peripheral cuff (c) of soft
tissue along the surface of the new
bone. Colour Doppler demonstrated
neovascularity within this tissue.
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42yo man had a fall some14 months post above knee amputation for
vascular occlusion due to thrombophilia
Heterotopic ossification at
the cut end of the femur
(arrows)
H
There is a Haematoma (H) on
the anterolateral aspect of the
stump (F)
F
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Below knee amputee with a neuroma (star). This is growing along a bony spur (arrow)
on the distal fibula (F).
N = nerve.
F
There is posterior acoustic shadowing
behind the bony spur (arrows).
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Overuse injuries were common with lower limb prostheses and
infrequent with upper limb prostheses.
48yo male. Transfemoral amputation for compartment syndrome post drug overdose
has severe pain over adductors. He is unable to wear his prosthesis because of pain.
Palpable tender lump in groin – muscle tear (arrows) in Adductor longus.
LS
TS
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Conclusion
A wide spectrum of painful lesions affecting the fit of
limb prostheses can be diagnosed by ultrasound.
By facilitating direct communication with the patient,
ultrasound becomes the only imaging modality to allow
direct correlation between the appearance of the
underlying tissues and the patient’s symptoms.
Ultrasound can help to diagnose the many factors that
can delay prosthetic fitting and training which may, in
some instances, lead to inability or unwillingness to
wear the prosthesis.
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