Neuroradiology Alessandro Bozzao, Antonio Barile, MD

MD #{149}Massimo Gallucci, MD #{149}Roberto Passariello, MD

Carlo

#{149}

Masciocchi,

MD

Italo

#{149}

Aprile,

MD

Lumbar Disk Herniation: MR Imaging Assessment ofNatural History in Patients Treated without Surgery’ The aim of this study was to evaluate the evolution of lumbar disk herniation in patients treated without surgery. Sixty-nine patients with a lumbar disk herniation proved at magnetic resonance (MR) imaging underwent

a follow-up

MR

imaging

study. The disk herniations evaluated during both MR imaging examinations were measured and classified into four categories according to the change in size that occurred. The patients were also divided into three clinical classes on the basis of the clinical outcome. Sixty-three percent of the patients showed a reduction of disk herniation of more than 30% (48% had a reduction of more than 70%),

while

only

8%

demonstrated

worsening of the clinical picture. These findings suggest that lumbar disk herniation may be primarily a medical (nonsurgical) disease and that MR imaging could play an important role in management of and research into the disorder. Index

terms:

intervertebral 33.1214 Radiology

Spine, disks,

1992;

diseases, 33.7831

33.7831 #{149} Spine,

a.

b.

Figure 1. Evaluation herniation

MR images from evaluation was performed by means was present. Volume was

of volume of spinal canal (a) and disk herniation of surface measurements at the level at which the then obtained by means of dedicated software.

(b). disk

#{149} Spine,

MR.

185:135-141

I From the Department of Radiology, University of Rome “La Sapienza,” Policlinico Umberto I, Viale del Policlinico 155, 00161 Rome, Italy (A. Bozzao, R.P.); and the Department of Radiology, University of L’Aquila, L’Aquila, Italy (MG., CM., IA., A. Barile). From the 1991 RSNA scientific assembly. Received December 10, 1991; revision requested January 30, 1992; final revision received May 11; accepted May 14. Address reprint requests to A. Bozzao. C RSNA, 1992

S

reduction of disk herniation (RDH) in the lumbar spine has been described (1-8). Reduction or disappearance of acute back pain or sciatica after nonsurgical treatment of lumbar disk lesions is known to occur (9-13). Nevertheless, to our knowledge, no investigators have correlated-on the basis of a

ties in restudying patients considerable period has initial diagnosis.

prospective

these findings are not supported by statistically significant data. Studies concerning the clinical evaluation of patients treated nonoperatively define a good outcome as an RDH of 70%-90% (2,8,10-12). We performed a prospective follow-up MR imaging study of 69 patients with diagnosed disk herniation. They all had radicu-

PONTANEOUS

study-the

evolution

of disk herniation with the clinical course of the disease. Since there have been no studies of large series of patients undergoing conservative treatment after radiologic diagnosis of disk herniation, to our knowledge, an indepth analysis of the natural evolution of this disease has not yet been made. This has probably been due to use of invasive procedures before the advent of computed tomography (CT) and magnetic resonance (MR) imaging and also to the practical difficul-

Perithecal

fibrosis

when elapsed

is thought

a since

to be a

common complication of disk herniation; moreover, the worse neurologic outcome is considered to be related long compression of nerve roots by

nuclear

Abbreviation:

material

RDH

(13,14).

=

reduction

to

However,

of disk

herni-

ation.

135

Figure 2. RDH of more than (b) Follow-up image obtained

70% (arrows). (a) Initial 9 months later.

proton-density

sagittal

image.

a.

#{149}-.:

b.

4.

Figure itial

I-

a. 3. RDH of more than 70% (arrows). obtained 11 months later.

(a) Initial

axial TI-weighted

image.

(b) Follow-up

lar

or lumbar

conservative

pain

and

were

given

is no longer

while the remaining 98 (82%) gone conservative treatment. treat patients surgically were

treatment.

basis

PATIENTS

AND

of severity

of radicular myography,

METHODS

Among 978 lumbar MR imaging examinations performed at our institution during the past 2 years, diagnosis of disk herniation was made in 253 patients. Of

sent. Most

these,

The

tacted;

136

120

were

22 (18%)

#{149} Radiology

randomly

had

chosen

undergone

and

surgery,

con-

obtained

high intensity Also

of clinical

than

majority

signs,

presence

distress as shown with and granting of patient

of the patients

vatively were confined after the acute event; manipulation

had underDecisions to made on the

or therapy

of them

one therapeutic

treated

electrocon-

conser-

to bed for 2 weeks others underwent for

underwent

procedure.

symptoms.

more

of 30%-70%

T2-weighted

up image

V.

Figure image

RDH

sagittal

note

13 months

inside evident

on

L4-5

to undergo then offered

without

Note

in a; this

follow-up

of the

The opportunity MR imaging was

treated

later.

the

(a) In-

(b) Follow-

disk herniation

dehydration

patients

(arrows).

image.

image. disk.

follow-up to the 98

surgery.

Twenty-

nine refused, mostly because they were in good clinical condition; 69 accepted. Forty-three subjects had been referred for leg pain that started 1-3 months before the

pain time

was

first

examination

and

or lumbodynia

lasting

(up to I year). made:

The

26 for

No age-based

youngest

lumbar

for a longer patient

selection was

October

23

1992

months) after initial MR imaging of the same 0.5-T superconducting

Table 1 Relationship

between

Morphologic

Groups

and Clinical

Clinical Morphologic Group

Classes

ment

A

B

C

19(61) 0(0) 0(0)

9(29) 7(70) 11(58)

3(10) 3(30) 8(42)

31(48)

4

0(0)

0(0)

5(100)

All

19 (29)

27 (42)

5(8) 65(100)

Note-Numbers Numbers t Numbers *

are numbers

in parentheses in parentheses

of patients.

are percentages are percentages

of morphologic of total study

MIt

10(15)

19(29)

19 (29)

group. population.

between

Morphologic

Clinical

and Location

Groups

of Disk

Herniation

(period

Location*

Morphologic Group

Posterolateral

1 2

17(55) 5 (50)

3

11(58)

4

3 (60) 36 (55)

All Note-Numbers *

are numbers

Numbers

in parentheses

Median

Intraforaminal

11(35) 3 (30)

6(32) 1 (20) 21 (32)

of patients.

are percentages

of morphologic

are percentages

of total

group.

in parentheses

study

evaluation

was performed

at

of rest in bed or absence

from

work), and working capacity (unchanged or diminished), with use of a method described by Pearce and Moll (II). For each

MIt

3(10) 2 (20)

31(48) 10 (15)

analysis,

2(11)

19(29)

clinical

1 (20) 8 (12)

(8) 6(100)

were considered: complete regression (class A), partial remission or stable picture (class B), and progression of cal symptoms (class C). Both parametric and nonparametric tistics were used. This decision was because some of the variables were

(Percentages

may

not add

used.

up to

of rounding.)

100% because t Numbers

Genoa,

the time of the second MR study by using parameters such as physical signs (limitalion of spinal flexion and straight leg raising, motor or sensory dysfunction, tendon reflex change, and muscle wasting), severity of recurrence or acute exacerbation

Table

2 Relationship

MR 5000; Esaote,

Italy) and technique. According to the volumetnc values and the relative modifications shown on the two sets of MR images, we divided the patients into four groups: those with an RDH of more than 70% (group 1) (Figs 2, 3), those with an RDH of 30%-70% (group 2) (Fig 4), those with no change in amount of disk herniation (group 3), and those with an increase in disk herniation (group 4).

Class*

1 2 3

(Esatom

with use equip-

population.

a threeThis

or four-level

resulted

classes

normally

score

in formation

when

the

distributed

overall

and

results

others

Groups

Morphologic

and Size of Disk

Herniation

Size*

Package

Morphologic

used

Group

Small

MIt 31(48) 10(15) 19(29)

6(19) 4(40) 15(79)

19(61) 5(50) 3(16)

6(19) 1(10) 1(5)

4

2 (40)

3 (60)

0 (0)

Note-Numbers

27(42) are numbers

Numbers

100% because t Numbers

Large

1 2 3 All

*

Medium

30(46)

of patients.

in parentheses of rounding.)

are percentages

of morphologic

group.

in parentheses

are percentages

of total study population.

(Percentages

for

Of the

65 (100)

may not add up to

this

reason,

the

statistical

out in 41 cases, in 32 of which signs of radicular distress were demonstrated. Sagittal (1,800/30-120 and 500/30 [repetition time msec/echo time msecj, with two

echo

excitations)

and

axial

(500/30)

sequences were used. The was 256 x 256, with a 5-mm

spin-

image masection

parallel

to the inferior

verte-

bral plate. Only when a focal protrusion in the disk (best evaluated on the axial image) or a detached fragment was shown was the patient admitted to the study. The combined evaluation of axial and sagittal images allowed us to exclude bulging

disks.

ages and a 3-mm section thickness with a I-mm gap for axial images. Sagittal images were acquired by placing the central seclion in the midline of the spinal canal, as visualized on a low-quality axial image used as a reference. This axial image was acquired at L4-5 only after correct alignment of the lumbar spine was shown on a low-quality coronal image used as a reference. Axial images were acquired by using

Volumetric evaluation of disk hernialion was performed in the sagittal and axial planes with use of the dedicated software of the imager (Fig 1). The size of the disk herniations was related to that of the spinal canal at the same level as the disk herniation. This allowed us to classify them as small when they ifiled 25% or less of the spinal canal, as medium when they filled 26%-50% of the spinal canal, and as large when they filled more than 50% of the spinal canal. Follow-up MR imaging

the midsagittal

was performed

trix

thickness

Volume

with

185

a 1-mm

image Number

#{149}

gap for sagittal

as a reference; 1

im-

they

6-15 months

(average,

Sciences

69 patients

Ii

they

(SPSS)

admitted

were

was

to the

excluded

analysis.

were

Disk

posterolateral

median

involved placed

Social

final protocol, four had new disk herniations located at a different level than the original disk herniation. For

lions

were

the

in the analysis.

and

years and the oldest 65 years (average age, 52 years). Electromyography was carried

as

were

RESULTS

(8)

8(12)

stamade not

scored on an ordinal scale. The Pearson R and x2 tests were used to evaluate correlalions between variables. The Statistical

Table

between

clinical clini-

such

RDH and size of disk herniations 3 Relationship

was

of three

in 21;

the

neural

from

hernia-

in 36 cases

in eight

cases,

foramen.

they

There

were

27 small,

large RDH

herniations. Results concerning and symptoms, RDH and loca-

tion,

are

and

given

30 medium,

RDH

and

in Tables

lively. Thirty-one an RDH higher

and

size

eight

of herniations

1, 2, and

patients than 70%

3, respec-

(48%) (group

had 1),

10 (15%) had an RDH of 30%-70% (group 2), 19 (29%) showed no change in amount of disk herniation (group 3), and five (8%) had an increase in disk herniation (group 4). Statistically significant correlations (P < .05) were found between changes in size and amount of herniation (Pearson R = .40953, P = .0004); no correlations were found between

RDH

(x2

and =

location

1.39010,

P

of disk =

.9665).

herniation The

Radiology

distribu#{149} 137

b.

Figure

(a) Sagittal

6.

hypenntense

disk

L4-5. (b) Follow-up later. intensity

d.

C.

Figure

5.

(a, c) Sagittal

(a) and

at L5-S1. (b, d) Sagittal evident unlikely.

in b and

axial

(c) Ti-weighted

(b) and axial (d) follow-up

d (arrows);

however,

regression

RDH

images

images

of large

obtained

of this

large

disk

herniation

12 months

herniation

the

is evident is reduced

RDH

disk

study

have

performed

of patients’

logic

groups

not show differences.

ages

and any

in the

clinical

statistically

morpho-

classes

did

significant

tion who received ment. Nevertheless,

patients

(3,4). tion

Spontaneous regression of disk herniation at repeat epidurography has been described since 1945 (6). CT has proved to be an excellent tool for fol-

138

of patients Radiology

#{149}

with

disk

hernia-

has

been

examinations imaging. studies, follow-up

been

MR

up with therapy

change in size after chemonucleolysis. However, in these studies, the timing

prospective hernia(1,2,8). In

of disk

done

have been knowledge,

found. in no

performed (15-18). suggest herniations

evalua-

followed

knowledge,

RDH to our

both

with

treatstudies,

studies in which follow-up evalualions were performed, a high success rate for conservative treatment and

substantial However,

as well.

conservative in most

evaluation

not been

8 months the high

lions have been chemonucleolysis cases, the results majority of disk

because of persisting after conservative

To our

follow-up

DISCUSSION

low-up

have

CT mostly symptoms

image obtained in b (arrows);

of

at

is

seems

In other tion

image

(arrows)

(arrows)

later.

into

T2-weighted

herniation

after In most that the do not

of follow-up after therapy was usually considerably shorter than in our study (only 3 months); when this interval was longer, the size of disk herniations was found to decrease (16).

In our study, we performed MR imaging in a large series of patients with

disk

herniation.

The

population

October

1992

d.

C.

Figure 7. herniation

(a, c) Sagittal (arrowheads)

proton-density surrounded

(a) and by epidural

(possibly

axial Ti-weighted tissue (arrows)

from the disk itself. (b, d) Sagittal proton-density ages obtained 6 months later. Reduction of the

epidural

arrows

but much

in d); the disk herniation

Note presence

of a new hyperintense

son, the patient

contacted study

patients

was not included

in the was

is unchanged,

first

narrowed

treated

phase

of the

to the

group

conservatively.

of

This

introduced a bias into the study, since it restricted our findings to the group of patients treated without surgery. However, the selection of these patients was done randomly and without considering the clinical outcome of the conservative treatment. Moreover, the same procedure (O.5-T MR

Volume

185

Number

#{149}

1

(b) and axial Ti-weighted

disk herniation in the protocol

(c) images of L5-S1 disk that is clearly differentiable

tissue

is evident

less dural

(top arrow

(d) follow-up (bottom

compression

arrow

imin b,

is evident.

representing

ices) are evident. tamed 5 months associated with

vessels

or venous

var-

(b) Follow-up image oblater. There is mild RDH substantial reduction of dural

compression by the epidural no longer evident.

tissue,

which

operated follow-up

on MR

is

in b) at L4-5. (For this rea-

study.)

imaging) sequences) the initial thus

(other volume ences

and technique (the same were employed in both and follow-up evaluations,

avoiding

methodologic

than those averaging in image

patients and did

biases

related to partial and subtle differalignment).

who were not undergo

imaging were in good clinical condilion (this was the main reason why they did not undergo follow-up), the rate of RDH could have been even higher.

The study demonstrated a high rate of RDH (63% [groups 1 and 2]) and a

The clinical disk herniation

low prevalence niation (8%

ing nonsurgical described (8-11).

of increased

[group

4]). Since

not

disk

most

her-

evolution of lumbar in patients undergotreatment has Most studies

Radiology

been report

139

#{149}

a satisfactory

response

in over

70%

of

cases. These results were confirmed our study, with a good clinical outcome

(classes

A and

lients

treated

conservatively.

lief

of pain

subsidence

occurs acute lions

within event. between

To

should (This

since

it was

The

exact

anulus,

(1,7,19).

by means of tears fragmentation

and

When

nuclear

outside

the

different desiccation, material

resorption

of disk

phase there

of the

that supported sible causes.

On

a.

epi-

events such as and phagocymay occur. The

material

no

by the lack and the inin the

In our

any one of these the basis of our

images

and

b. 9.

Reduction

Ti-weighted

of more

image.

a decrease

than

(b) Follow-up

70%

of posterolateral

image

obtained

no

data

to support

posfind-

in

to a tranother such high

signal intensity in up to 80% of sequestered intervertebral disks. Idenlification of epidural granula-

the

theory

that this tissue is related to granulalion rather than fibrosis and that it has a role in RDH. A prospective MR imaging study that used gadolinium this

signal intensity was observed at follow-up MR imaging (Figs 4, 6). The high intensity of the herniated frag-

ment is thought to be due sient gain in water content; studies (20) have reported

have

enhancement

observations

ings, regression of large herniations into the anulus seems unlikely (Fig 5). Dehydration may have occurred in those cases in which the disk fragment was hyperintense on T2-

weighted

Figure

LS-Si

iO months

to show

the

details

of

would

found between size of disk herat initial MR imaging and at follow-up MR imaging. These

correlations

indicate

disk most

herniations frequently

size

(Fig 5). A possible

that

medical

explanation

for

Bolognese,”

we did hancement

140

not

or absorbing

reduced (Figs

at fol7, 8). Since

perform gadolinium or histologic analysis,

Radiology

#{149}

to

enwe

in prevalence

nisms of RDH In conclusion,

that

in patients

between and the

important disease

MR role as well

#{149}

research.

We thank all the friends Primavera Neuroradiologica

especially

Giovanni

Ruggiero,

pres-

References SaalJA,

SaalJS,

history

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sion

treated

Herzog RJ. intervertebral nonoperatively.

The

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15:683-686. 2.

3.

or mecha-

as regards its site. our findings show

undergoing

the

ident of the club, for their helpful suggestions and Elena Vinci for assistance in manuscript preparation.

live treatment for lumbar spine disk hernialion, there is a high frequency of regression of herniated material and a low frequency of progression

of digesting

hernialion). is thought

between

disease.

play an of this

Acknowledgments: of the “Club Della

that was markedly low-up MR imaging

be capable

disk

tissue

(nonsurgical)

as in future

4.

with

and

interval

in

this finding could be that the larger the disk hernialion, the more extensive is the active scar around it. This could facilitate digestion of disk mate-

rial. No relationship was found the location of the herniation

herniation

the

imaging could in management

the largest

are the ones that tend to decrease

disk

and

two MR imaging examinations; a positive correlation was found between the size of the disk hernialion and the amount of regression. We believe our findings may support the theory that lumbar disk hernialion is primarily a

substantially improve our knowledge of the process. Statistically significant correlations were niation RDH

process

between

RDH

differences

Gadolinium enhancement greatly improves identification of this tissue, as reported by Ross et al (21) (in six of

patients

axial

of the

disk material (7) as well as other epidural fragments, such as displaced bone grafts (22). In our study, we occasionally observed epidural tissue

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(a) Initial

were the location

1.

seven

herniation.

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The

disk

later.

is related

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were

is lo-

in the

to the lack of nutrients supplied the disk; desiccation is due to of hydrophilic proteoglycans, phagocytosis is stimulated by flammatory response present study,

in

material

anulus

dural space, resorption, tosis of the

acute

and

or months of the close correla-

weeks obtain

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cated

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is thought

in

5.

conserva6.

of

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