DIASTEMATOMYELIA
By Cohn B. Holman, M.D.,* Hendrik J. Svien, M.D.,t William H. Bickel, M.D.,44
and Haddow M. Keith, M.D.*
CLINICAL
NOTES
N
EUHAUSER, Wittenborg and Dehlinger,’in 1950, stimulated interest in an
un-common congenital malformation of the neural axis known as “diastematomyelia.”
Their contribution was of great value
be-cause they assembled the roentgenologic
criteria by which this lesion could be
recog-nized in patients who might be helped by operation. Previous to their report, this en-tity had not been reported to have been diagnosed correctly before operation. The case to be presented illustrates the applica-tion of diagnostic criteria in the
preopera-tive recognition of this malformation. According to Neuhauser and associates, diastematomyelia may be defined as a
“. . . congenital malformation of the neural
axis characterized by a sagittal division of a
segment of the spinal cord or cauda equina
and usually associated with anomalous
de-velopment of the vertebrae. The 2 lateral
portions of the cord are separated by an
os-seous or fibro-cartilaginous septum which is attached anteriorly to 1 or more vertebral bodies, posteriorly to the dura, and
oc-casionally to the deformed vertebral arches
as well.” Various degrees of this separation may be encountered, from complete
dupli-cation of the spinal cord at one extreme to
instances in which the spinal cord is di-vided for a short distance only.
REPORT OF CASE
An 8-year-old girl was seen in July, 1951,
because of an increasing curvature of the
From the Mayo Clinic and Foundation. The Mayo Foundation is a part of the Graduate School of the University of Minnesota.
0 ADDRESS: Section of Roentgenology, Mayo Clinic,
Rochester, Minnesota.
f Section of Neurologic Surgery.
00 Section of Orthopedic Surgery.
Section of Pediatrics.
thoracic and lumbar portions of the spinal column that had been observed for 5 years. At the time of birth, an area of discoloration of
the skin in the posterior thoracic region had
been noticed. The right lower extremity had appeared to the mother to be swollen as com-pared with the left when the patient was 1%
months of age. The child began to walk at the normal age but she did so with a limp and
with the right foot inverted. Control of bladder
and bowel was gained at the usual age. Other
aspects of the history seemed irrelevant. Examination disclosed pronounced thora-columbar scoliosis, the primary curve involv-ing the midthoracic portion of the spinal column. A growth of coarse hair was noted in
the midline in the thoracic region posteriorly
(Fig. 1). The right lower extremity was shorter and smaller than the left. Slight weakness of the right leg was present. The knee jerk reflex on the right was less active than that on the
left. Babinski’s sign was present on the right. No disturbance of sensation was detected.
Roentgenographic examination of the thora-columbar portion of the spinal column revealed pronounced midthoracic scoliosis, with the convexity toward the right. The center of the curvature was the ninth thoracic vertebra. The
neural canal was increased in width in the lower thoracic and lumbar regions. Anomalous development of the neural arches was pres-ent in the upper three lumbar vertebrae (Fig.
2).
Contrast myelography using ethyl
iodophe-nylundecylate (Pantopaque#{174}) was done. A
dia-mond-shaped defect in the middle of the opaque column opposite the body of the first lumbar vertebra was demonstrated (Fig. 3). A
diagnosis of diastematomyelia was made. A tiny opaque shadow was noted in the center
of the diamond-shaped defect; this was con-sidered to be a bony spicule in axial projec-tion.
thora-192 IIOLMAN - DIASTE\IATOMYELIA
colulnl)ar regH)Il, d SpiCUl( of bone ‘as
en-COIIIltere(l tltt aroSe from a base on the
Pst’II aspect of the hod of the first lumbar vcrtel)ra aIKl (‘XteIl(le(l s111)criorlv afl(l
p05-teriorly. The SpiILIl coid had ieen divided and transfixed l)v this bony sj)ur, vhich vas
re-IUOV(.’d l)\rongeur dfl(l curet (Fig. 4). The dura
\%‘as ClOSe(l vith a COfltiIlIlOlIS silk suture and a routine closure for laminecth)nly was (lone.
The 11tie1t returned for re-exaninatiou 1 1 moUths later. Sonic progression \VdS floteci ill
the degree of scoliosis; therefore, iiiltipic I)one
grafts were a1)1)lied l)ilaterailv to the spinal COIL1ITII1 from the level of the sixth thoracic to
the twelfth tlioracic vertel)ral segments. No increase as evident in the neurologic (leficits
Pre’itISlY (k’scrii)cd. The IItieIit
CLINICAL NOTES 19:3
1I(. 4. I)iagraniniatic sketch of findings at operation showing bony spicule (livi(ling spinal cori.
Note that each half of the spinal cord is enclosed by (hint.
dll(I tile veakness in the peroneal aixi aiiterior tibiai muscles as less pronounced.
COMMENT
Although diastematomvelia is an
uncom-fllOfl congenital abnormality, it is important that the diagnosis I)e niade early so that daniage to the s1)iflal cord may be halted. It is well known that at birth the caudal end of the spinal cord lies at the level of the
fourth lumbar vertebra and that by the time
full growth has been attained it lies at the
level of about the first lumbar interspace.
If tile C01(1 is prevellte(1 from accomplishing
its normal ascent relative to the vertebral
i)odieS, neurologic function is likely to be disturbed. In (Iiastematomyeha the spinal
cord is fixed to the spinal column in early
iiifancv, which makes the normal relative
ascent of tile spinal cord irfl1)Ossible.
Trac-tion occurs 011 the growing spinal cord and,
at tililes, scoliosis develops. The diagnosis is
suggestedi by tile occurrence of scoliosis, as
well as the presetice of midline dermal
de-fects, such as excessive hair or dimpling of the skin, t nevus or e1iaps a meningocele.
Other congenital abnormalities, such as
clubfoot, may l)e present.
Fixation of tile spiiial cord at this lower level may be tile result of faulty
develop-nient of the vertebrae themselves. It is
im-portant to recall that vertebrae ossify from
3 )rimary centers, 1 ill tile l)0(Iy aIld 2 ill
tile neural arch. The center of ossification ill
the vertebral body may be bibbed, in which
case 2 distinct centers of ossification are
PreseIlt. Asymmetric development of 1 of these centers may result in scoliosis, whereas
anomalous develo1)ment of both centers may
result in a deformity that is too small to be
recognized on routine physical examination. In such cases, the fixation of the spinal cord associated with subsequent
lengthell-illg of the sI)inal column results in scoliosis, whereas in other forms of scoliosis the curve may be dependent on an anomaly of 1 side of 1 or more vertebrae or on disease processes involving other systems.
Any element that goes to Illake up a
por-tion of a vertebral segment may be iiial-formed or fused to an adjacent vertebra.
194 HOLMAN - DIASTEMATOMYELIA
fusion of ribs, as well as countless
combina-tions or variations. Diastematomyelia may be associated with a decrease in the
antero-posterior diameter of the centrum, double
vertebrae or hemivertebra, unsegmented
vertebra, hypoplastic segments, bizarre arch
structures, such as abnormal fusion (spina
bifida), and with other less common
con-ditions, such as meningomyelocele, acrania
and cyclops.
Confirmation of the diagnosis of
chaste-matomyelia depends on the roentgenologic
criteria assembled by Neuhauser and
co-workers. There may be fusiform widening
of the interpedicular spaces over several
segments. The pedicles are not narrowed
but other vertebral anomalies may be noted. An osseous spur in the center of the
widened canal is present in some cases. This spur is rarely more than 1 to 1.5 cm. in length and is seen in the anteroposterior
view. Of the records of patients reviewed by
Herren and Edwards,2 only a fourth mdi-cated that an osseous spur was present. By the use of myelography, a filling defect in the opaque column is noted in the region of
the midline septum. Typical findings may be
masked in later childhood or early adult
life by rotation, curvature and shortening of the spinal column. Myelography is
par-ticularly important in those cases in which
the bony spicule cannot be demonstrated in routine projections. It is important to
differ-entiate this condition from arachnoiditis
with fibrous scarring about a normal spinal cord and from tumors arising within the neural canal. In arachnoiditis, the spinal canal is of normal width and the other
con-genital abnormalities are uncommon. In the case of tumors, if the interpedicular
dis-tance is increased the pedicles are usually narrowed and erosion of the posterior
por-tions of the vertebral bodies may be
demon-strated. No midline spur or septum is noted, but in the case of meningocele or lipoma there may be associated congenital
varia-lions in the vertebrae.
Since diastematomyelia involves
stretch-ing of the spinal cord, neurologic signs, such
as absence or decrease of the reflexes,
mus-cular weakness, urinary or fecal inconti-nence and possibly increasing enuresis, may be associated. Possible sequelae in cases in
which no treatment has been given include the development of the Arnold-Chiari
de-formity, hydrocephalus, atrophy of the lower extremities, increasing scoliosis and certain deformities of the foot. It is,
there-more, evident that the neurologic manifesta-tions must be corrected at once. In our
pa-tient the cord was dissected free. No
in-crease in the neurologic deficit was found
subsequently.
SUMMARY
Diastematomyelia is an uncommon con-genital malformation of the neural axis
manifested by separation of the lateral halves of the spinal cord. A case is
pre-sented in which the complaint was increas-ing curvature of the spine. Preoperative
diagnosis of this lesion was established by roentgenography. The condition is a serious congenital abnormality which is susceptible to treatment and, therefore, early diagnosis
is of practical importance.
REFERENCES
1. Neuhauser, E. B. D., Wittenborg, M. H., and Dehlinger, Klaus :
Diastemato-myelia; Transfixation of the cord or cauda equina with congenital anomalies of the
spine. Radiology, 54:659-664, 1950.
2. Herren, R. Y., and Edwards,
