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Amyotrophic lateral sclerosis Abnormalities of the tongue on magnetic resonance imaging.

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Amyotrophc Lateral Sclerosis:
Abnormahties of the Tongue on
Magnetic Resonance Imaging
Choon H. Cha and Bernard M. Patten, MD, FACP
We compared the magnetic resonance images of the tongues of 16 amyotrophic lateral sclerosis (ALS) patients with
those of 20 control patients and found the tongue in ALS patients is more frequently and more severely involved than
suspectedclinically, with major abnormalitiesof size, shape, position, and internal structure. The tongue size in ALS, as
measured in the sagittal plane, can be reduced by as much as two-thirds of normal. The shape of the tongue in ALS
tends to be rectangular or square rather than curved as is normal. As severity of the disease increases, the position of
the tongue changes so that the bulk of the muscle falls away from the incisors and no longer is in contact with the hard
or soft palate. The normal radial bands from the anterior floor of the mouth to the mucosal surface are often missing in
ALS as are the two curvilinear bands that run parallel to the mucosal surface and intersect the radial bands. Also, there
is a mottled disorganization of the internal structure of the tongue with areas of increased and decreased signal
intensity.
Cha CH, Patten BM. Amyotrophic lateral sclerosis: abnormalities of the tongue
on magnetic resonance imaging. Ann Neurol 1989;25:468-472
The disease process of amyotrophic lateral sclerosis
(ALS) affects hypoglossal motoneuron cells to a
greater extent and earlier than facial or trigeminal motoneuron cells. The same pattern is observed in bulbar
ALS and in patients with symptoms confined to the
limbs 111. Thus, ALS often involves the tongue, and
persons with the disease usually have characteristics of
spastic and flaccid dysarthria. Because degeneration of
the hypoglossal nucleus does not proceed uniformly,
flaccidity or spasticity may predominate at any given
time in a patient. Clinically, tongue involvement results in symmetrical weakness, slowing of movement,
fasciculations, and atrophy. In the early stages of ALS
the tongue may be only slightly weakened and articulation relatively preserved. Later a gradual and generalized weakness of the tongue occurs accompanied by
spasticity, which results in a reduced rate, range, and
force of articulatory tongue movements. In the terminal stage of ALS tongue movement is poor or absent,
and speech may be virtually impossible.
Mean anterior and lateral tongue strength in normal
adults is approximately 2,000 and 1,600 gm, respectively, whereas similar measures in adults with ALS are
1,000 and 700 gm [2}. Morphometry of the degenerative process in the hypoglossal nerves in ALS discloses
that progressive reduction of the large myelinated
fibers is the fundamental change 131. Mean myelinated
fiber diameters, reduced in ALS, correlate with the
atrophy of the tongue, and the total number of myelinated fibers in ALS hypoglossal nerves is always lower
than that of controls [3}.
Magnetic resonance imaging (MRI) provides a way
to assess structural changes in the oral cavity. It could
eventually surpass other diagnostic modalities in providing useful information about the tongue 14, 51.
With MRI we see that the oral cavity is composed of
various parts, with the hard and soft portions of the
palate constituting the roof, and a muscular diaphragm
consisting principally of the myohyoid muscle constituting the floor. The tongue, composed principally
of muscle covered by a specihzed mucosa, occupies a
very large portion of the oral cavity, and its internal
structure is apparent on sagittal scans (Fig 1).The free
margin of the tongue consists of the apex portion of
the inferior surface, the sides, and the dorsum. The
root is that portion by which the tongue is connected
by muscle and mucous membranes to the hyoid bone
and the epiglottis, to the soft palate, and to the
pharynx. The main substance of the tongue consists of
nine paired muscles that are separated by a median
septum. The paired muscles are considered either extrinsic or intrinsic according to their origins. The extrinsic set, which controls movement of the tongue, is
composed of five muscles and has its origin outside the
From the Baylor College of Medicine, Houston, TX.
Address correspondence to Dr Patten. 6501 Fannin. Houston. TX
77030.
Received Aug 22, 1988, and in revised form Oct 18. Accepted for
publication Oct 26, 1988.
468 Copyright 0 1989 by the American Neurological Association
patients as part of their hospitalization and compared
the results to images obtained in a group of 20 patients
suffering from other neurological conditions. The results of this study constitute the body of this report
and indicate that MRI is a useful way to appraise
tongue size, shape, position, and internal structure in
ALS.
Patients and Methods
Patient Characteristics
This series consists of 36 patients, 16 with ALS and 20 with
Fig I . TI -weighted magnetic resonance image, midsagittal
plane,fiom 60-year-old woman in horizontal,supine position,
head-jirst into machine. Norma( tonguefills virtually all of oral
cavity and has a rounded shape with mucosal (dorsal)su~ace
almost a circular arc, the center of which is at anteriorjoor of
mouth. Apex of tongue contacts posterior suvface of incisors, and
dorsum of tongue contacts hard and SOB
palates. Normal internal
structure shows two curvilinear bands parallel to mucosal sudace
(large arrows: superior and inferior curvilinear bands) and
multiple radial bands extending from anteroinferiorfloor of
mouth to mucosal suvfaces, intersecting both curvilinear bands
(small arrow: well-defined radial band).Superior curvilinear
band represents fat in septum separating superior longitudinal
muscle from transverse muscles and inferior longitudinal muscle.
Inferior curvilinear band separates inferiorlongitudinal muscle
fmm genioglossus. Radial bands represent fat within septa of
vertical genioglossus muscle fibers. High-intensity signalfrom
hard palate is normal, as is linear signal in center of soft palate.
(Magnetom machine at 0.5 Tesla, TR 0.5 sec, TE 25 msec, slice
thickness 6 mm, slice position 0.0, window width 1,472 mm,
and window center 552 mm. Acquisition and display matrixes
256 x 256 pixels each; spin echo measuring sequence.)
tongue; it includes the genioglossus (constituting the
bulk of the mass of the tongue), hyoglossus, chondroglossus, styloglossus, and palatoglossus muscles. The
intrinsic set of muscles consists of the superior and
inferior longitudinal, the transverse, and vertical
muscles. These muscles are mainly concerned with altering the shape of the tongue and have little role in
tongue movement. All muscles of the tongue, extrinsic
and intrinsic, are supplied by the hypoglossal nerve (41
and are affected in ALS 121.
To investigate the possible usefulness of MRI in
evaluating the tongue muscle of ALS patients, we evaluated the sagittal images routinely obtained from ALS
other neurological conditions. In each patient, the diagnosis
of ALS was made by at least 2 neurologists after a detailed
evaluation consisting of a history and physical examination,
neurological examination, electromyogram, muscle biopsy,
lumbar puncture, and multiple blood and urine tests to rule
out other conditions that might simulate ALS 161. All patients with ALS in this series had upper and lower motor
neuron dysfunction associated with progressive weakness
and atrophy of skeletal muscle, without significant sensory
involvement or cerebellar or sphincter dysfunction. The
diagnoses in the control group included multiple sclerosis (4
patients), peripheral neuropathy (3), stroke (2), vasculitis (2),
and stroke and Parkinson’s disease, stroke and sleep apnea,
complex partial seizures, myasthenia gravis, generalized seizure disorder (tonic-clonic type), cervical cord compression,
cervical radiculopathy, brachial plexus neuritis, pseudotumor
cerebri and syncope (1 each). For all, maximum right-hand
grip was measured in pounds using a force dynamometer.
Magnetic Resonance Imaging
MRI was done using the Siemens Magnetom with a superconductive magnet and rapid-array processor (BSPIVMR)
for rapid imaging and multiplanar reconstructions. Main
magnetic field strengths were 0.5 or 1.0 Tesla. Both the
acquisition matrix and the display matrix were 256 x 256
picture elements (pixels). The measuring field had a maximum diameter of 25 cm with resolution of 1 mm. The
repetition times (TR) for sagittal T1-weighted images ranged
from 50 to 600 msec, and the echo time (TE) ranged from 15
to 35 msec. The slice thickness in the sagittal plane was 5 to
6 mm. No special instructions were given to the patients
during the examination. They were not told to avoid swallowing or to position their tongue in their mouth in any
special location. Indeed, all of the scans were a routine part
of the patient’s initial evaluation and were not performed for
the purpose of this study. The area of the tongue was estimated by tracing the outline of the midsagittal magnetic resonance image on paper. The tracing was then cut out and
weighed on an analytical balance.
Statistical Analysis
We used SPSS PC Plus installed on an IBM-AT computer
equipped with the Math Coprocessor for descriptives, Student’s t tests on unpaired groups, and nonparametric correlations. Probability values of less than 0.05 were considered
significant; double-tail rule and separate group variances applied.
Cha and Patten: ALS Tongue Abnormalities on MRI
469
Table I. Characteristics and Findings in Amyotrophic Lateral
Sclerosis Patients
-~
~
Patient
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Age
(yr)
36
31
26
65
38
62
69
40
63
65
43
55
50
41
71
77
Sex
M
M
M
F
F
F
F
M
M
F
F
M
M
F
F
F
Tongue Trace
Weight (mg)
Right-Hand
Grip (Ib)
6.3
24
28.3
45
11.7
0
56.7
10.7
17.6
12.4
13.2
7.3
6.8
9.0
9.5
12.3
6.6
7.1
11.2
9.2
10.4
8.0
7.7
11
11
7
0
50
28
28
40.7
0
Table 2. Characteristics and Findings in Control Patients
~
Patient
Age
No.
(yr)
Sex
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
46
41
17
50
32
48
35
27
71
64
48
72
41
70
68
39
64
54
60
48
M
M
F
M
F
F
F
F
F
F
M
M
F
M
F
M
M
M
F
F
Tongue Trace
Weight (mg)
Right-Hand
Grip (Ib)
16.2
13.2
14.2
10.8
15.3
15.8
14.9
10.9
9.6
14.9
20.1
15.8
14.2
11.4
10.3
14.1
11.6
11.8
12.6
8.6
60.7
42
51
78
39
23
47.3
43.3
38
26
67.3
50
78
67
ND
60
60.1
10
45
18
ND = no data.
470 Annals of Neurology Vol 25
No 5 May 1989
Fig 2. TI weighted magnetic resonance imagefrom 71-year-old
woman with early amyotrophic lateral sclwosis and some mild
dysarthria. In midsagittal plane tonguefails to j I I upper anterior oral cavity and is no longer rounded in that region, nor is it
in diwct contact with posterior incisors or hard palate. Normal
curvilinear and radial bands are disrupted, and there is large
k g h t signal fmm root of tongue (arrow). (0.5 Tesla, TR 0.30
sec, TE 16 msec, slice position - 0.3 mm, window width 1,476
mm,and window center 436 mm. Acquisition and disphy matrixes 256 x 256 pixels each.)
Results
Patient Characteristics
The age, sex, tongue trace weight, and right-hand grip
of the ALS patients and the control patients are shown
in Tables 1 and 2, respectively. Comparing the ALS
patients to controls, there was no statistically significant
difference in sex distribution or age. The right-hand
grip (in pounds) of the ALS patients (mean, 21.8
19) was significantly reduced compared to controls
(mean, 47.6 2 19) ( p < 0.001). The size of the ALS
tongue was also reduced compared to controls, with a
mean value for ALS of 9.99
2.9 mg versus 13.3 +2.8 mg for controls ( p < 0.001). In neither group was
there a correlation of tongue size with age or grip.
Among the ALS patients the men were younger, on
average (mean age, 43 2 13 years), than the women
(59 f 14 years) ( p < 0.039). Also in the ALS group
the men had bigger tongues than the women, the mean
values being 11.8 .t 2.8 mg and 8.4 2 2.1 mg, respectively ( p < 0.02). There was no statistically significant
difference in the grips of ALS men compared to ALS
women, and in the control group there was no differ+_
+_
Fig 3. TI weighted magnetic resonance image, sagittal plane,
from 38-year-old woman with amyotrophiclateral sclerosis, dysphagia, and dysarthria. Tongue does notjill oral cavity and is
not in contact with incisors or hard or soft pakate. Rounded
shape has changed to a rectangle. Curvilinear and radial band
are missing, and multiple mottledfoci of bright signah are seen
in tongue's interior and at apex and base. (0.5 Tesla, T R 0.30
sec, TE 16 msec, slice position 3.8 mm, w i n a h width 1,012
mm, and w i n a h center 320 mm. Acquisition and display matrixes 256 X 256 pixels each.)
ence between men and women in regard to tongue
weight, age, or grip.
Magnetic Resonance Images
In ALS patients the MRI scans of the tongue are abnormal in size, shape, position, and internal structure.
As ALS progresses the tongue loses part of its bulk,
the shape becomes less curvilinear and more rectangular, and the position of the tongue retreats from the
posterior surface of the incisors and away from the
hard and soft palate toward the root of the tongue in
the posterior floor of the mouth (Figs 2-4). The internal tongue structure in ALS is interesting and abnormal. The characteristic feature that we observed was an
increased disorganization of the normal tongue's internal signal. The areas of increased signal have an intensity intermediate between the brightness of fat and the
brightness of normal soft tissue (see Figs 2-4). The
most common abnormality, present in 14 of 16 ALS
Pig 4. T 1-weighted magnetic resonance image, sagittal plane, of
65-year-Oldwoman unable to swallow or talk because of severe
amyotrophic lateralsclerosis of mwe than 3 years' duration.
Tongue is surrounded antm'dy, posteri'orly,and superiorly by
air,with signal void that outlinclr oral cavity and ompharynx.
Tongue apex is approximately 2 ma postm'or to central incisors
and I ma fmm pakate. Cuwed shape of tongue has been transformed to a kind ofsquare, and no trace of radial or curvilinear
band can be &tected. Tongue's interior is $Ued with abnormal
white signah. Inciahtally, signah fmnr sob pakate are abnormal
in this scan. N m l central b a d have been repkaced by superior and infm'orirregular bright signah. This patient died, and
one author (B. M. P.) obtained in v i m magnetic resonance imaging suns o f her tonguefolowed by histochemicalstaining of
multiple sections. OnIy jnding was dense collections of atrophic
musclej i k stained h r k on DPNH-TR, indicative of severe
neumgenic atrophy. Consiababk repkucement of tongue muscle
with connective tissue and fat had occumd. (0.5 Tesla, T R 0.5
sec, TE 30 msec, slice thickness 6 mm,slice position I0 mm,
window width 1,148 mm, and w i n a h center 340 mm. Acquisition matrix 256 x 512 pixels; display matrix 256 x 256
pixels.)
patients, was decreased tongue size. In addition, 12 of
the 16 had increased signal intensity in the tongue; 11
had patchy areas of different intensity; 6 had increased
signal intensities in palatal areas; 7 had thinning of the
soft palate; 8 had loss of apposition of the tongue and
the palate; and 5 had loss of opposition of the tongue
and the posterior surface of the incisors. No control
patient had similar abnormalities.
Discussion
Recently there has been some interest in the use of
imaging techniques to evaluate neuromuscular diseases
{ 5 , 7-10}. The conclusion that MRI can characterize
muscle diseases in terms of size of the muscle involved, the number of muscles, the distribution of diseased muscle, and the pattern of internal disorganiCha and Patten: ALS Tongue Abnormalities on MRI 471
neurons. Based on an MRI scan of a patient (not part
of our original series) with primary lateral sclerosis, we
assume that decreased tongue size, abnormal internal
signals, and rectangular shape of the tongue in ALS are
caused by lower motoneuron disease and that abnormal position can be attributed to upper motoneuron
disease alone (Fig 5).
Since the tongue can be visualized not only in midsagittal planes but in parasagittal, coronal, and axial
planes as well, and T2 weighting can be used 141, it is
clear that future studies of ALS tongues will probably
reveal more details than are reported here. MRI of
skeletal muscle is probably in its infancy. Further
refinements in technique and increased resolving
power coupled with clinical magnetic resonance spectroscopy might allow visualization of microscopic
structural details, thereby eliminating the need for
muscle biopsy. There might also be a use for MRI in
neuromuscular conditions other than ALS.
Fig 3 . TI weighted magnetic resonance image of 64-year-old
man in whom primary lateral sclerosis was diagnosed because of
anarthria, dysphagia, spastic quadripkgia, and bilateral Babinski signs, but no hervation on elertromyography or muscle
biopsy. On clinical examination his tongue had no atrophy or
fasciculation,yet he had lost all voluntary mwement of tongue.
Note on this midsagittal image that size and shape of tongue are
probably normal, with normal cuwilinear bands (large arrows)
and normal radial bands (smallarrows) and no intense internal
signals. Position of tongue is abnormal with t$ far from posterior incisors and mucosal sudace not in contact with hard or soft
palate. (Imagingparameters similar to those in Figure 4.)
zation of muscle is supported by the data presented
herein. The severity of involvement does not appear to
be directly related to disease duration, but it does parallel clinical severity of the condition.
The midsagittal T1-weighted scans reported here
were made to evaluate the craniocervical junction and
not to evaluate tongue size, shape, position, and internal structure. Nevertheless, significant abnormalities
were noted in the tongue of ALS patients compared to
controls, which in fully developed ALS resulted in a
marked reduction in tongue bulk, rectangular rather
than elliptical tongue shape, retreat of the tongue away
from the anterior and dorsal oral cavity structures, and
loss of the radial and curvilinear bands with a disorganization of internal signals and an increase in the T1
signal. Most of the abnormalities are easily explained
by the glossal atrophy in ALS due to the loss of hypoglossal neurons. The abnormal signal on the internal
scans of the tongue is due to fat replacement (see Fig
4 ) and may be increased by neurogenic atrophy of the
muscle itself. Since ALS involves upper and lower motoneuron loss, it would be helpful to know which abnormalities of the tongue are due to loss of which
472
Annals of Neurology Vol 25
No 5
May 1989
This paper was presented at the 113th Annual Meeting of The
American Neurological Association, Philadelphia, PA, October
1988.
George B. Lindler generously supported this project. Liz Reese
typed the manuscript. We thank Barry L. Horowitt, MD, for his
review of the figures and text, and Carlton F. Hazlewood, PhD, for
his many important suggestions. In vitro MRI of the tongue at autopsy was performed gratis by Houston Imaging, Inc.
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