In-vivo

demonstration

of

the

effectiveness

of

thoracoscopic

anterior

release

using

the

fulcrum-bending

radiograph

a

report

of

five

cases

Thoracoscopic

anterior

release

of

stiff

scoliotic

curves

is

favored

because

of

its

minimally

invasive

nature

Animal

and

human

cadaveric

studies

have

shown

that

it

can

effectively

improve

spinal

flexibility

in

non-scoliotic

spines

however

it

has

not

been

demonstrated

to

be

effective

in

actual

patients

with

scoliosis

The

fulcrum-bending

radiograph

has

been

shown

to

accurately

reflect

the

post-operative

correction

To

demonstrate

that

the

flexibility

was

increased

after

the

anterior

release

five

patients

with

idiopathic

thoracic

scoliosis

who

underwent

staged

anterior

thoracoscopic

release

and

posterior

spinal

fusion

were

assessed

using

the

fulcrum-bending

radiograph

The

average

number

of

discs

excised

was

four

Spinal

flexibility

as

revealed

by

the

fulcrum-bending

technique

was

compared

before

and

after

the

anterior

release

The

patients

were

followed

for

an

average

of

years

-LRB-

range

years

-RRB-

Fulcrum-bending

flexibility

was

increased

from

before

the

thoracoscopic

anterior

spinal

release

to

after

the

release

-LRB-

P

-RRB-

The

average

Cobb

angle

before

the

anterior

release

was

on

the

standing

radiograph

and

with

the

fulcrum-bending

radiograph

This

reduced

to

on

the

fulcrum-bending

radiograph

after

the

release

and

highly

corresponded

to

the

measured

at

the

post-operative

standing

radiograph

and

at

the

latest

follow-up

Previous

animal

and

cadaveric

studies

demonstrating

the

effectiveness

of

thoracoscopic

anterior

release

did

not

have

scoliosis

We

are

able

to

demonstrate

in

patients

with

adolescent

idiopathic

scoliosis

that

thoracoscopic

anterior

spinal

release

effectively

improves

the

spinal

flexibility

Introduction

In

the

management

of

patients

with

stiff

thoracic

scoliosis

and

kyphosis

anterior

spinal

release

is

helpful

in

increasing

the

spinal

flexibility

and

therefore

the

result

of

deformity

correction

Excision

of

intervertebral

discs

through

open

thoracotomy

is

the

preferred

method

in

the

past

However

cutting

of

the

chest-wall

muscles

is

associated

with

complications

such

as

reduced

ventilation

post-operative

atelectasis

extensive

and

painful

scars

blood

loss

and

prolonged

hospital

stay

-LSB-

-RSB-

Video-assisted

thoracoscopic

surgery

-LRB-

VATS

-RRB-

for

anterior

release

of

the

spine

is

becoming

increasingly

more

popular

due

to

its

minimally

invasive

nature

-LSB-

-RSB-

However

opponents

do

not

believe

that

VATS

is

effective

in

improving

the

spinal

flexibility

as

it

is

difficult

to

perform

a

radical

discectomy

and

to

a

lesser

extent

rib-head

excision

by

thoracoscopy

-LSB-

-RSB-

While

VATS

supporters

have

used

animals

and

cadavers

to

demonstrate

the

effectiveness

of

thoracoscopic

spinal

release

-LSB-

-RSB-

these

studies

were

performed

in

spines

that

did

not

have

scoliosis

The

fulcrum-bending

radiograph

obtained

with

the

patient

lying

sideways

hinging

over

a

fulcrum

provides

a

simple

and

reproducible

technique

for

the

in-vivo

assessment

of

spinal

flexibility

It

can

accurately

predict

before

surgery

the

amount

of

correction

that

can

be

achieved

by

modern

segmental

spinal

instrumentations

-LSB-

-RSB-

Using

this

method

one

can

assess

the

effectiveness

of

an

anterior

release

by

either

directly

comparing

the

spinal

flexibility

-LRB-

as

reviewed

by

the

fulcrum-bending

radiograph

-RRB-

before

and

after

an

anterior

release

or

indirectly

by

comparing

the

predicted

correction

by

the

pre-release

fulcrum-bending

radiograph

and

the

actual

correction

achieved

by

the

anterior

release

and

posterior

fusion

Either

way

differences

in

the

measured

Cobb

angle

would

be

attributable

to

the

effect

of

the

thoracoscopic

release

In

our

institution

a

number

of

thoracoscopic

anterior

release

and

posterior

fusion

surgeries

for

thoracic

idiopathic

scoliosis

were

staged

This

gave

the

opportunity

to

perform

the

fulcrum-bending

radiograph

before

and

after

the

anterior

release

thereby

allowing

direct

assessments

of

flexibility

changes

as

a

result

of

the

thoracoscopic

procedure

Materials

and

methods

Between

and

five

patients

with

idiopathic

scoliosis

requiring

anterior

release

for

stiff

thoracic

curves

were

prospectively

investigated

The

authors

define

stiff

curves

as

those

which

have

a

Cobb

angle

of

more

than

with

the

fulcrum-bending

radiograph

this

was

arbitrarily

used

as

we

felt

that

the

residual

curves

of

over

gave

unacceptable

cosmetic

results

and

therefore

a

flexibility-modifying

procedure

would

be

indicated

The

mean

age

at

the

time

of

operation

was

years

-LRB-

range

-RRB-

According

to

the

King

's

classification

-LSB-

-RSB-

there

were

one

type

I

two

type

II

and

two

type

III

curves

For

the

patient

with

type

I

curve

both

thoracic

and

lumbar

curves

were

corrected

and

fused

and

for

the

type

II

and

III

curves

only

the

thoracic

curves

were

instrumented

According

to

Lenke

's

classification

-LSB-

-RSB-

there

were

three

type

I

one

type

III

and

one

type

V

curve

All

the

patients

underwent

an

anterior

thoracoscopic

release

followed

by

a

second-stage

posterior

instrumented

correction

and

fusion

week

later

The

instrumentations

used

for

the

posterior

spinal

fusion

were

Texas

Scottish

Rite

Hospital

-LRB-

TSRH

n

Sofamor-Danek

Memphis

TN

USA

-RRB-

ISOLA

-LRB-

n

Acromed

Corp.

Cleveland

OH

USA

-RRB-

and

CD-Horizon

-LRB-

CD-H

n

Sofamor-Danek

Memphis

TN

USA

-RRB-

systems

The

mean

number

of

thoracic

discs

resected

was

four

ranging

from

to

-LRB-

Table

-RRB-

Posterior

fixation

was

done

by

a

pre-dominant

hook

construct

using

one

upper

and

two

intermediate

hooks

and

either

a

hook

or

pedicle-screw

at

the

lowest

fusion

level

Table

patient

dataCase

's

typeIIIIIIIIIIIAge

-LRB-

years

-RRB-

at

Levels

of

discs

used

TSRHTSRHISOLACDISOLA

The

thoracoscopic

anterior

release

was

performed

with

the

patient

under

general

anesthesia

The

technique

involved

a

discectomy

by

making

a

large

annular

window

over

the

convex

side

of

the

scoliosis

the

whole

nucleus

and

cartilaginous

end-plates

were

removed

Excision

of

the

posterior

annulus

to

the

posterior

longitudinal

ligament

is

always

attempted

but

is

usually

successful

only

at

the

apical

discs

Rib-head

excision

was

not

performed

The

effectiveness

of

the

thoracoscopic

anterior

release

in

increasing

spinal

flexibility

was

investigated

by

two

methods

First

by

a

direct

comparison

of

the

Cobb

angle

measured

from

a

pre-release

fulcrum-bending

radiograph

with

that

of

the

post-release

fulcrum-bending

radiograph

Second

by

an

indirect

method

comparing

the

pre-release

fulcrum-bending

radiograph

with

the

final

post-operative

correction

As

the

pre-operative

fulcrum-bending

radiograph

has

been

reported

to

be

able

to

accurately

predict

the

post-operative

coronal

deformity

correction

for

posterior

surgery

-LSB-

-RSB-

the

difference

of

the

Cobb

angles

between

the

pre-operative

fulcrum-bending

radiograph

-LRB-

which

predicted

the

correction

for

the

posterior

surgery

alone

-RRB-

and

the

post-operative

standing

X-ray

-LRB-

which

shows

the

actual

correction

achieved

by

combined

anterior

release

and

posterior

instrumentation

-RRB-

will

indirectly

demonstrate

the

in

vivo

effect

of

the

anterior

thoracoscopic

spinal

release

Statistical

analyses

were

carried

out

using

the

Student

's

t-test

with

a

significance

level

of

-LRB-

P

-RRB-

The

fulcrum

flexibility

a

measure

of

the

spinal

flexibility

as

revealed

by

the

fulcrum-bending

radiograph

-LSB-

-RSB-

was

calculated

based

on

the

following

formula

where

FB

stands

for

fulcrum

bending

This

relationship

was

used

to

directly

assess

the

changes

in

flexibility

as

a

result

of

the

anterior

release

Results

The

patients

were

followed

for

an

average

of

years

-LRB-

range

years

-RRB-

The

mean

fulcrum

flexibility

before

the

anterior

release

was

it

increased

by

after

the

anterior

thoracoscopic

release

-LRB-

P

-RRB-

The

mean

pre-operative

Cobb

angle

on

the

postero

anterior

-LRB-

PA

-RRB-

standing

radiograph

was

the

mean

pre-operative

fulcrum-bending

angle

was

the

mean

post-release

fulcrum-bending

angle

was

and

the

actual

mean

Cobb

angle

after

combined

anterior

thoracoscopic

release

and

posterior

surgery

was

The

latter

correlated

with

the

post-release

fulcrum-bending

result

-LRB-

P

-RRB-

and

was

significantly

different

-LRB-

P

-RRB-

from

the

pre-release

fulcrum-bending

result

to

suggest

that

the

thoracoscopic

anterior

release

can

effectively

improve

the

surgical

correction

of

the

coronal

curve

On

an

average

four

discs

were

excised

per

patient

and

as

the

mean

improvement

in

correction

is

it

suggested

that

resection

of

one

disc

resulted

in

a

mean

improvement

in

correction

by

approximately

-LRB-

Table

Fig.

-RRB-

Table

Cobb

angles

for

each

case

-LRB-

For

case

it

was

not

possible

to

perform

a

post-release

fulcrum-bending

XR

because

of

wound

pain

-RRB-

Case

AP

standing

fulcrum

fulcrum

standing

latest

aPre-operative

anteroposterior

standing

radiograph

of

case

showing

a

curve

from

to

b

Pre-release

fulcrum-bending

radiograph

showing

a

correction

to

only

c

Fulcrum-bending

radiograph

taken

week

after

an

anterior

thoracoscopic

release

of

four

levels

showing

an

improvement

in

the

flexibility

to

d

Post-operative

standing

radiograph

taken

week

after

the

posterior

correction

showing

the

curve

correction

to

The

immediate

post-operative

Cobb

angle

of

-LRB-

data

not

shown

-RRB-

was

well

predicted

by

the

post-release

fulcrum-bending

radiograph

of

There

was

no

significant

change

in

this

correction

at

the

latest

follow-up

-LRB-

Table

-RRB-

Discussion

Anterior

spinal

release

by

open

thoracotomy

has

been

extensively

used

in

the

past

to

help

improve

spinal

flexibility

in

stiff

thoracic

scoliosis

Its

role

has

been

increasingly

taken

over

by

VATS

as

the

latter

is

associated

with

a

lower

morbidity

-LSB-

-RSB-

However

some

surgeons

feel

that

an

anterior

thoracoscopic

release

is

not

as

effective

as

an

open

release

This

is

because

they

believe

that

a

successful

anterior

spinal

release

requires

a

rib-head

resection

and

a

radical

discectomy

which

can

not

be

easily

performed

through

VATS

-LSB-

-RSB-

Although

studies

using

animals

and

cadavers

have

demonstrated

that

a

thoracoscopic

release

can

improve

spinal

flexibility

-LSB-

-RSB-

it

was

not

performed

on

actual

patients

with

scoliosis

Thus

there

is

no

definitive

proof

in

human

patients

with

scoliosis

that

the

thoracoscopic

spinal

release

is

effective

Although

some

clinical

studies

have

demonstrated

that

combined

VATS

and

posterior

spine

fusion

resulted

in

good

scoliosis

correction

-LSB-

-RSB-

they

did

not

assess

the

actual

flexibility

of

the

scoliosis

and

therefore

were

not

able

to

directly

demonstrate

that

the

thoracoscopic

release

added

to

the

spinal

flexibility

The

use

of

the

fulcrum-bending

radiograph

which

reflects

the

spinal

flexibility

and

accurately

predicts

the

post-operative

coronal

deformity

correction

provides

an

opportunity

to

assess

the

effectiveness

of

thoracoscopic

release

in

vivo

-LSB-

-RSB-

The

five

cases

included

in

this

study

had

stiff

curves

with

a

pre-operative

fulcrum-bending

angle

of

more

than

a

mean

pre-operative

fulcrum

flexibility

of

only

and

a

mean

Cobb

angle

of

As

these

cases

had

staged

surgery

we

were

able

to

obtain

a

post-release

fulcrum-bending

radiograph

for

comparison

with

the

pre-release

and

post-operative

Cobb

angles

After

anterior

thoracoscopic

release

flexibility

was

increased

from

to

thus

representing

a

direct

proof

that

the

procedure

can

improve

the

spinal

flexibility

in

our

cases

by

an

average

of

One

patient

-LRB-

Case

-RRB-

was

unable

to

lie

on

the

fulcrum

to

perform

a

post-release

fulcrum-bending

radiograph

due

to

wound

pain

Nevertheless

case

has

been

included

in

the

analysis

as

a

comparison

of

the

pre-release

fulcrum-bending

radiograph

with

the

post-operative

radiograph

will

still

provide

an

indirect

evidence

on

the

success

of

a

thoracoscopic

release

-LRB-

Table

-RRB-

For

those

who

were

able

to

lie

on

the

fulcrum

we

found

the

technique

reliable

In

this

limited

series

of

four

cases

the

post-release

fulcrum-bending

radiograph

correlated

well

with

the

post-operative

result

It

should

be

noted

that

the

previous

work

on

the

fulcrum-bending

radiograph

are

based

on

the

use

of

hooks

and

hybrid

systems

only

-LSB-

-RSB-

The

predictability

of

this

method

with

reference

to

the

use

of

pedicle-screw

fixation

is

not

known

It

is

widely

believed

that

pedicle-screw

systems

give

a

superior

degree

of

correction

when

compared

to

hook

systems

and

may

obviate

the

need

to

perform

anterior

releases

However

there

is

no

published

data

which

directly

compares

the

two

systems

taking

into

account

the

spinal

flexibility

The

authors

are

aware

of

two

different

ways

to

measure

Cobb

angles

before

and

after

surgery

One

method

is

to

determine

the

Cobb

angles

in

the

pre-operative

standing

radiograph

and

then

to

use

the

same

levels

throughout

although

in

the

post-operative

radiograph

the

same

measured

levels

may

no

longer

be

the

most

tilted

vertebra

The

alternative

method

is

always

a

measure

from

the

most

tilted

levels

even

though

the

levels

may

change

between

pre

and

post-operative

radiographs

While

the

authors

prefer

the

former

method

use

of

the

latter

method

would

not

alter

the

results

Using

the

presented

case

as

an

example

-LRB-

Fig.

-RRB-

the

pre-operative

Cobb

angle

from

to

was

the

pre-release

Cobb

angle

from

to

was

the

post-release

Cobb

angle

from

to

was

and

the

final

Cobb

angle

from

to

was

The

technique

of

anterior

spinal

release

is

different

amongst

different

surgeons

while

some

do

only

a

discectomy

others

routinely

remove

the

rib-heads

and

even

disrupt

the

posterior

longitudinal

ligament

The

use

of

VATS

limits

the

number

of

structures

that

can

be

easily

released

due

to

limitations

in

visualization

and

access

to

all

disc

levels

This

study

is

not

comparing

the

open

thoracotomy

and

release

with

the

thoracoscopic

anterior

release

this

is

because

no

data

is

available

for

the

former

Moreover

an

evaluation

of

open

release

versus

thoracoscopic

release

using

the

present

method

is

not

possible

as

patients

undergoing

the

open

release

would

still

have

a

painful

wound

which

would

prevent

them

from

lying

sideways

over

a

fulcrum

One

potential

pitfall

of

this

study

is

that

three

different

types

of

implants

were

used

while

the

original

study

on

the

fulcrum-bending

radiograph

was

based

on

TSRH

-LSB-

-RSB-

It

maybe

possible

that

different

implants

vary

in

their

ability

to

correct

scoliosis

and

therefore

invalidate

the

indirect

assessment

However

the

authors

feel

that

this

is

unlikely

because

it

has

been

demonstrated

by

the

same

group

that

there

was

no

significant

difference

in

the

ability

of

different

instrumentation

systems

to

correct

thoracic

scoliosis

-LSB-

-RSB-

Moreover

the

direct

comparison

of

fulcrum

flexibility

before

and

after

an

anterior

release

would

still

stand

This

study

was

performed

in

the

early

part

of

our

experience

with

thoracoscopic

anterior

release

hence

relatively

few

discs

were

released

and

the

surgeries

were

staged

However

it

did

serve

the

purpose

of

demonstrating

that

thoracoscopic

anterior

release

does

result

in

an

improvement

in

spinal

flexibility

With

increasing

experience

the

authors

tend

to

release

five

to

six

discs

per

patient

and

the

posterior

surgery

is

performed

on

the

same

day

With

the

advent

of

new

techniques

and

instrumentation

the

indications

for

a

thoracoscopic

release

may

change

in

time

In

particular

pedicle-screw

systems

appear

to

provide

a

better

correction

of

large

magnitude

curves

-LSB-

-RSB-

However

to

date

there

are

no

randomized

studies

comparing

hooks

versus

screw

systems

nor

a

correlation

of

the

correction

to

spinal

flexibility

assessment

such

as

the

fulcrum-bending

correction

index

-LSB-

-RSB-

Additionally

the

use

of

anterior

instrumentation

systems

may

mean

that

such

surgeries

are

carried

out

as

a

single-stage

anteriorly

avoiding

the

need

for

posterior

surgery

-LSB-

-RSB-

In

summary

this

is

the

first

study

to

provide

a

direct

in

vivo

evidence

demonstrating

the

effectiveness

of

thoracoscopic

anterior

release

in

improving

the

spinal

flexibility

in

patients

with

scoliosis

O O O O O O O B I O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O B I I O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O B I O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O B I O O O O O

adolescent idiopathic scoliosis
thoracoscopy
spinal flexibility
anterior release


Os odontoideum with bipartite atlas and segmental instability : a case report We report on the case of a 15-year-old adolescent who presented with a transient paraplegia and hyposensibility of the upper extremities after sustaining a minor hyperflexion trauma to the cervical spine . Neuroimaging studies revealed atlantoaxial dislocation and ventral compression of the rostral spinal cord with increased cord signal at C1/C2 levels caused by an os odontoideum , as well as anterior and posterior arch defects of the atlas . The patient underwent closed reduction and posterior atlantoaxial fusion . We describe the association of an acquired instability secondary to an os odontoideum with an anteroposterior spondyloschisis of the atlas and its functional result after 12 months . The rare coincidence of both lesions indicates a multiple malformation of the upper cervical spine and supports the theory of an embryologic genesis of os odontoideum . Introduction The craniovertebral junction is a common site for malformations -LSB- 10 -RSB- . Clefts of the anterior and posterior arch of the atlas are rare , but well-documented congenital anomalies -LSB- 1 , 2 -RSB- . Several reports attributed the aetiology of os odontoideum to an either embryologic , traumatic or vascular basis -LSB- 3 -- 5 , 8 -RSB- . We describe the unusual case of a combined midline cleft of the anterior and posterior arch of the atlas associated with os odontoideum leading to atlantoaxial instability with acute myelopathia after a minor trauma . We presume an embryologic genesis of our findings . Case report A 15-year-old male patient injured his cervical spine in a hyperflexion trauma when performing a somersault on a trampoline . He presented with transient numbness and weakness of both arms . Initial X-rays and computed tomography demonstrated a displaced os odontoideum which reduced on extension and a rostral compression of the cervical spinal cord due to a subluxation of C1 over C2 with narrowing of the spinal canal to 50 % . Additionally midline clefts of the anterior and posterior arch of the atlas became evident -LRB- Figs. 1 , 2 -RRB- . MRI scans revealed increased cord signals at C1/C2 levels on T2-weighted images and a persistent subdental synchondrosis was visualized on T2-weighted turbo spin echo sequences -LRB- Fig. 3 -RRB- . The patient underwent closed reduction and posterior atlantoaxial fusion by sublaminar tension band wiring with autologous bone grafting and transarticular lag screw fixation . Postoperatively all symptoms improved significantly . Radiographs taken 1 year after the trauma showed a stable fusion of C1/C2 -LRB- Fig. 4 -RRB- . The patient presented with a range of motion at 30 ° of extension , 40 ° of flexion and 50 -- 0 -- 40 ° of rotation . He was free of symptoms and had returned to his pre-injury status regarding work and leisure activities . Fig. 1X-rays of the cervical spine in neutral position -LRB- a -RRB- , flexion -LRB- b -RRB- and extension -LRB- c -RRB- . Ventral subluxation of C1 over C2 in flexion -LRB- b -RRB- , which reduces on extension -LRB- c -RRB- Fig. 2CT scans reveal midline clefts of the anterior and posterior arch of the atlas -LRB- a -RRB- . Displaced os odontoideum and subluxation of C1 over C2 with narrowing of the spinal canal -LRB- b -RRB- Fig. 3T2-weighted MRI images with increased cord signals at C1/C2 levels and a persistent subdental synchondrosisFig . 4Follow-up X-rays 12 months after trauma . Stable atlantoaxial fusion after sublaminar wiring and transarticular screw fixation in ap -LRB- a -RRB- and lateral -LRB- b -RRB- view Discussion The odontoid process and the atlas originate from the first cervical sclerotome . Body of the axis , lateral masses and posterior arch arise entirely from the second cervical sclerotome . The atlas is formed from three primary ossification centres , which develop during the seventh week of gestation . Two centres at the lateral masses extend posteromedially to form the posterior arch usually in the fourth year . Ossification of the anterior arch involves one or two ossification centres , which extend posterolaterally to fuse with lateral masses around the seventh year . The odontoid process separates from the atlas between the sixth and seventh week of intrauterine life and moves caudally to join the body of the axis -LRB- Fig. 5 -RRB- . Fig. 5Scheme of the embryologic development of atlas and axis Os odontoideum is an oval or round shaped ossicle of variable size with a smooth cortical border . Several reports attributed its aetiology to either an embryological , traumatic or vascular basis . Failure of fusion of ossification centres in the odontoid process has been considered to be the main aetiology -LSB- 8 -RSB- . Considerable evidence on cases of acquired os odontoideum indicates , that occult fractures with subsequent avascular necrosis might result in similar pathology -LSB- 5 -RSB- . O'Rahilly et al. -LSB- 9 -RSB- studied the cervical spine of 8-weeks-old human embryos and observed that axis consists morphologically of three parts . Two rostral parts form the odontoid process and a caudal part gives rise to the axis body , separated from the middle part by subdental synchondrosis . A segmentation anomaly of the two rostral parts , which never occurred in normal individuals , may result in bipartite dens -LSB- 3 -RSB- . Currarino -LSB- 3 -RSB- reported 11 cases with complete or partial segmentation defect in mid odontoid , suggesting an embryological anomaly characterized by a complete segmentation of two rostral parts of axis which may explain the congenital os odontoideum . Malformations of the atlas are very rare and include both clefts and aplasias -LSB- 1 , 2 -RSB- . Galindo and Francis -LSB- 6 -RSB- reported the incidence of anteroposterior spondyloschisis of the atlas in normal individuals as 0.3 % . Atasoy et al. -LSB- 1 -RSB- reported the first case of bipartite atlas with os odontoideum causing spinal stenosis . Garg et al. -LSB- 7 -RSB- presented a report of bipartite atlas with anterior arch aplasia associated to an os odontoideum . They found a small projection on the anterior surface of the dens and concluded that the ossification centre of anterior arch of atlas may fail to separate from future dens resulting in anterior arch aplasia with a small tubercle attached to the anterior surface of the dens . To our knowledge no other case of bipartite atlas with os odontoideum had been reported previously in the English literature . In our case , there was a malformation of the anterior and posterior arch of the atlas and a persistent subdental synchondrosis , both likely to be a result of a congenital failure of fusion of ossification centres . The associated os odontoideum was clinically silent until a traumatic instability occurred which resulted in acute myelopathy . Our findings support the theory of a congenital aetiology of os odontoideum . Both the combined anterior and posterior clefts of atlas and os odontoideum are either asymptomatic or , if cervical instability arises , may develop neurological symptoms . Conclusion We described a rare association of an anterior and posterior midline cleft of the atlas with an os odontoideum in an adolescent . An embryologic genesis is likely . Minor trauma is commonly the cause for the onset of symptoms , which may occur immediately after the injury , be transitory and experienced repeatedly or have a delayed progressive course . If the lesion is reducible , atlantoaxial fusion is recommended .

B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O


Dorsal

dumb-bell

melanotic

schwannoma

operated

on

by

posterior

and

anterior

approach

case

report

and

a

review

of

the

literature

The

schwannomas

are

benign

tumors

originating

from

Schwann

cells

which

constitute

the

nerve

sheath

The

dorsal

pigmented

type

of

schwannomas

is

relatively

rare

-LRB-

Goldstein

in

Am

J

Med

Genet

Kurtkaya-Yapicier

in

Histol

Histopathol

-LRB-

-RRB-

-RRB-

There

are

two

distinct

types

of

melanotic

schwannoma

the

sporadic

melanotic

schwannomas

and

the

psammomatous

melanotic

schwannomas

of

Carney

complex

We

report

a

case

of

a

patient

harboring

a

right

dorsal

dumb-bell

melanotic

schwannoma

and

left

adrenal

mass

The

patient

underwent

a

surgical

procedure

for

en

bloc

total

removal

of

the

mass

by

a

posterior

and

anterior

approach

Histopathological

examination

revealed

the

diagnosis

of

melanotic

schwannoma

At

present

we

have

no

reliable

marker

of

histopathological

malignancy

of

melanotic

schwannoma

so

the

follow-up

period

ought

to

continue

for

a

period

of

more

than

years

As

the

total

removal

of

the

melanotic

neurinomas

is

mandatory

to

prevent

possible

malignant

transformation

of

the

tumor

recurrence

or

regrowth

we

believe

that

the

posterior

and

trans-thoracic

approach

are

the

most

suitable

one

for

the

dorsal

dumb-bell

schwannoma

Introduction

Dorsal

dumb-bell

melanotic

schwannomas

are

very

rare

-LSB-

-RSB-

They

are

rather

frequently

associated

to

Carney

's

complex

-LSB-

-RSB-

They

present

problems

on

different

aspects

such

as

pre-operative

diagnosis

surgical

approach

and

post-operative

course

We

describe

the

case

of

a

man

who

presented

with

left

adrenal

hyperplasia

and

right

paravertebral

mass

suggesting

a

dumb-bell

schwannoma

Case

report

Presentation

and

examination

In

January

a

salesman

heavy

smoker

with

an

elevate

level

of

arterial

hypertension

began

to

complain

about

pain

in

his

right

chest

and

upper

limb

Chest

X-ray

and

thoracic

CT

scan

in

the

following

February

revealed

a

dumb-bell

mass

extending

into

the

intrathoracic

right

space

for

about

cm

The

patient

was

admitted

to

our

clinic

A

spinal

dorsal

MRI

confirmed

the

presence

of

the

voluminous

right

paravertebral

mass

-LRB-

Figs.

-RRB-

Abdomen

MRI

showed

an

almost

cm

swelling

of

the

left

suprarenal

gland

suggesting

a

pheochromocytoma

-LRB-

Fig.

-RRB-

The

neurologic

examination

and

brain

MRI

were

normal

The

renal

arterial

echodoppler

the

dosing

of

vanilmandelic

acid

alpha-fetoprotein

carcinoembryonic

antigen

urinary

catecholamine

and

cortisol

were

normal

The

renin

activity

and

the

plasmatic

level

of

aldosteron

resulted

normal

in

orthostasis

and

increased

in

recumbency

The

medullar

adrenal

gland

scintigrams

-LRB-

IIs

MBqs

e.v.

-RRB-

resulted

negative

for

pheochromocytoma

Therefore

we

excluded

a

pheochromocytoma

and

the

patient

underwent

a

surgical

procedure

for

total

removal

of

the

dorsal

mass

by

posterior

and

anterior

approach

in

collaboration

with

the

thoracic

surgeons

Fig.

images

demonstrating

a

right

dumb-bell

intra-extradural

mass

at

level

extending

into

the

intrathoracic

right

space

for

about

cm

Coronal

and

axial

images

with

Gd-DTPA

enhancementFig

MRI

showing

right

intervertebral

foramen

occupied

by

the

tumorFig

abdominal

spectral

fat

saturation

inversion

recovery

-LRB-

SPIR

-RRB-

MR

images

showing

left

suprarenal

swelling

Operation

A

laminectomy

after

radioscopic

control

was

performed

A

right

dumb-bell

intra-extradural

mass

of

blackish

aspect

was

seen

En

bloc

total

removal

of

a

markedly

melanotic

intradural

lesion

was

achieved

using

operating

microscope

Then

the

patient

was

placed

in

the

left

lateral

decubitus

and

by

trans-thoracic

approach

the

paravertebral

mass

was

radically

removed

en

bloc

also

freeing

the

right

intervertebral

foramen

from

the

black

and

well-encapsulated

neoformation

Accurate

plastic

of

the

paravertebral

pleural

wall

was

obtained

Histological

examination

revealed

melanotic

schwannoma

with

mitotic

index

not

superior

to

one

for

ten

fields

on

high

magnification

indicating

low

risk

for

malignancy

Postoperative

course

Post-operative

course

was

uneventful

with

marked

improvement

of

the

painful

symptomatology

and

good

healing

of

the

surgical

wounds

The

patient

was

discharged

from

our

ward

after

days

with

a

recommendation

for

ichnographic

controls

of

the

left

adrenal

gland

hyperplasia

During

a

follow-up

period

no

recurrence

was

evident

on

surveillance

MRI

Discussion

The

schwannomas

are

benign

tumors

originating

from

Schwann

cells

which

constitute

the

nerve

sheath

The

first

case

was

described

by

Bjornboe

-LSB-

-RSB-

in

in

a

patient

with

neurofibromatosis

type

I

There

are

two

distinct

types

of

melanotic

schwannoma

the

sporadic

and

the

psammomatous

melanotic

schwannomas

of

Carney

complex

-LSB-

-RSB-

In

Carney

described

a

syndrome

characterized

by

mixomas

-LRB-

heart

skin

and

breast

-RRB-

mucus-cutaneous

spotty

pigmentations

and

endocrine

overactivity

-LRB-

due

to

thyroid

dysfunction

or

hypophysial

adenoma

or

Cushing

syndrome

secondary

to

adrenocortical

pigmented

primary

nodular

hyperplasia

-RRB-

-LSB-

-RSB-

A

year

later

a

Mendelian

dominant

heredity

was

defined

responsible

for

the

symptomatologic

complex

-LSB-

-RSB-

About

of

patients

with

melanotic

psammomatous

schwannomas

are

affected

by

the

syndrome

of

Carney

and

one-fifth

of

them

are

carriers

of

multiple

lesions

-LSB-

-RSB-

Generally

melanotic

schwannoma

affects

the

spinal

nerves

the

central

nervous

system

and

the

autonomous

nerve

system

but

extra-nervous

locations

can

also

exist

The

dorsal

location

represents

of

the

spinal

melanotic

schwannoma

-LSB-

-RSB-

Until

today

we

were

able

to

find

spinal

cases

of

extramedullary

melanotic

neurinoma

in

literature

-LRB-

Table

-RRB-

-LSB-

-RSB-

The

clinical

presentation

is

not

specific

but

similar

to

that

of

other

extramedullary

spinal

tumors

-LRB-

radicular

pain

dysesthesias

progressive

sensorial-motor

deficits

-RRB-

Preoperative

diagnosis

is

based

on

magnetic

resonance

imaging

-LRB-

MRI

-RRB-

melanotic

schwannomas

appear

hyperintense

on

sequences

and

hypointense

on

sequences

compared

to

the

nonmelanotic

type

of

schwannomas

that

are

hypo-isointense

on

and

hyperintense

on

-LSB-

-RSB-

Table

of

cases

of

spinal

extramedullary

melanotic

schwannoma

reported

in

literatureReferencesAgeGenderLevelAprile

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

DorsalBosman

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

Gregorio

et

al.

-LSB-

-RSB-

SacralErlandson

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

Cam

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

et

al.

-LSB-

-RSB-

casesF

and

MC

T

L

SZhang

et

al.

-LSB-

-RSB-

casesF

and

MSpinal

nerve

rootZonenshayn

et

al.

-LSB-

-RSB-

and

The

histological

differential

diagnosis

with

the

other

spinal

pigmented

tumors

is

with

the

meningeal

melanocitoma

the

pigmented

neurofibroma

the

paraganglioma

the

ganglioneuroma

the

fibrous

form

of

meningioma

and

above

all

with

the

primitive

melanoma

or

relative

metastasis

-LSB-

-RSB-

Even

if

the

association

of

the

left

adrenal

swelling

and

arterial

hypertension

with

the

dumb-bell

thoracic

melanotic

schwannoma

can

be

correlated

to

the

Carney

complex

in

our

opinion

our

patient

did

not

harbor

such

a

syndrome

In

fact

only

the

adrenocortical

pigmented

primary

nodular

hyperplasia

is

a

characteristic

stigmata

of

Carney

complex

Moreover

our

patient

did

not

show

cutaneous

signs

of

neurofibromatosis

and

his

family

history

was

negative

for

Carney

complex

stigmata

The

total

body

CT

scan

showed

the

left

adrenal

mass

and

excluded

any

other

typical

lesion

of

the

syndrome

The

increased

plasmatic

level

of

renin

and

aldosteron

in

recumbency

in

our

patient

that

was

on

heavy

medical

therapy

for

high

level

of

arterial

blood

pressure

may

be

correlated

to

left

adrenal

hyperplasia

or

solitary

adrenal

adenoma

-LSB-

-RSB-

and

not

to

adrenocortical

pigmented

nodular

hyperplasia

which

is

the

cause

of

ACTH-independent

adrenal

Cushing

's

syndrome

-LSB-

-RSB-

and

normally

do

not

trigger

elevation

of

plasmatic

aldosteron

Moreover

in

our

case

the

histological

examination

of

the

neurinoma

did

not

show

the

most

common

psammomatous

aspect

of

Carney

complex

-LSB-

-RSB-

In

summary

we

did

not

perform

a

left

adrenal

biopsy

as

we

ruled

out

the

Carney

syndrome

and

malignancy

of

the

adrenal

mass

by

clinic

and

radiological

investigations

Hypertension

adrenal

mass

and

dumb-bell

melanotic

schwannoma

do

not

imply

Carney

complex

In

our

patient

the

hypertension

was

not

correlated

to

the

Carney

complex

but

to

the

hyperaldosteronism

caused

by

left

adrenal

hyperplasia

or

solitary

adrenal

adenoma

Nevertheless

neurosurgeons

ought

to

keep

in

mind

the

connection

between

the

melanotic

schwannoma

and

the

Carney

complex

since

more

than

of

the

cases

described

in

literature

have

been

related

to

such

syndrome

A

complete

endocrinological

evaluation

and

a

total

body

CT

should

always

be

performed

together

with

a

genetic

study

in

the

suspicion

of

Carney

complex

The

risk

of

possible

malignant

transformation

of

the

neurinoma

should

also

be

taken

into

consideration

as

cases

of

recurrences

or

metastases

have

been

described

even

years

after

surgery

-LSB-

-RSB-

It

is

not

possible

to

have

any

reliable

histopathological

indication

of

possible

malignant

transformation

after

the

first

surgical

operation

-LSB-

-RSB-

The

follow-up

ought

to

continue

for

a

period

of

more

than

years

We

have

both

to

check

the

primitive

tumor

regrowth

or

recurrence

and

the

possible

remote

locations

particularly

in

the

lungs

From

the

surgical

point

of

view

the

total

removal

of

the

melanotic

neurinomas

is

mandatory

to

prevent

possible

malignant

transformation

of

the

tumor

remnants

The

therapeutic

potential

of

radiotherapy

is

not

proven

-LSB-

-RSB-

The

prognosis

depends

therefore

almost

entirely

on

the

extent

of

surgical

removal

of

the

tumor

-LSB-

-RSB-

So

we

believe

that

the

posterior

and

anterior

approach

is

the

most

suitable

one

to

remove

the

dorsal

dumb-bell

schwannoma

completely

both

in

the

thoracic

cavity

and

in

the

intervertebral

foramen

and

to

avoid

possible

liquoral

leakage

O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O

dorsal dumb-bell melanotic schwannoma
thoracic nerve sheath tumor
spinal tumor