Diastematomyelia in Two Sisters

Sevim Balcı,1* Kudret Caglar,1 and Muzaffer Eryilmaz2

1Department of Clinical Genetics, Department of Pediatrics, Hacettepe University Faculty of Medicine,Ankara, Turkey

2Department of Radiology, Hacettepe University Faculty of Medicine, Ankara, Turkey

Diastematomyelia is a rare spinal cordanomaly that usually occurs in a non-syndromal, sporadic manner; however, fewfamilial cases have been reported. We re-port on diastematomyelia in 2 sisters withvariable expressivity. The spinal column isdivided by osseous or fibrous tissue. Thismay be responsible for the variable expres-sivity. Most cases previously reported werefemales. This suggests X-linked dominantinheritance with lethality in hemizygousmales or female sex limitation of a multifac-torial trait. Am. J. Med. Genet. 86:180–182,1999. © 1999 Wiley-Liss, Inc.

KEY WORDS: diastematomyelia; X-linkeddominant inheritance; arach-noidal cyst; spina bifida; teth-ered cord; pilonidal sinus;variable expressivity

INTRODUCTION

Diastematomyelia is a rare condition characterizedby a congenital longitudinal fissure through the spinalcord in the anteroposterior plane with fibrous or bonytissue. This is usually a non-syndromal, sporadic dis-order; however a few familial cases have been reported

Fig. 1. Posterior view of Patients 1 and 2 at the age of 3 and 9 years, respectively, with hairy lumbar region, asymmetrical gluteal clefts, and piloninaldimple/sinus (Patient 1 post-surgery).

*Correspondence to: Dr. Sevim Balcı, Department of Pediatricsand Clinical Genetics, Hacettepe University Faculty of Medicine,06100 Ankara, Turkey. E-mail address: caglar@tr-net.net.tr

Received 13 May 1997; Accepted 28 April 1999

American Journal of Medical Genetics 86:180–182 (1999)

© 1999 Wiley-Liss, Inc.

[Gardner, 1973; Kapsalakis, 1964]. We present a newfamily whose two daughters had diastematomyelia todraw attention to the familial occurrence of this mal-formation.

CLINICAL REPORTS

The proposita was a 3-year-old girl who was the sec-ond child of non-consanguineous parents, the motherwas 29 and the father 30 years old when she was born.The chief complaint was difficulty in walking withouturine or fecal incontinence. The first child in the sib-ship, a 9-year-old girl, had the same complaint andlumbar hypertrichosis; the third pregnancy was spon-taneous abortion (Fig. 1).

The proposita’s weight was 15 kg (50–75th centile),height was 93 cm (25–50th centile). She had an area ofhypertrichosis between T3 and T10; the left leg wasslightly atrophic and she had a pilonidal sinus.

Vertebral radiographs demonstrated spina bifida be-tween the thoracic 10th and lumbar 3rd vertebrae andthe vertebral column was enlarged below the lumbarregion. CT demonstrated that vertebrae T9 and T10were normal but at and below T11 the entire medullarycanal was filled with spinal cord (Fig. 2). At T12 thespinal cord was divided by a bony septum, suggestingthe presence of diplomyelia (Fig. 3).

The spinal cord extended to L2. The amount of con-nective tissue was increased at L2 but there was noneural tissue below L2. The spinal cord was evaluatedusing sagittal and axial T1- weighted series with eithera 1.4 and 1.3T magnet MRI (Siemens). This showedthat the medullary vertebral signals were homogenous;a “butterfly” vertebra was noted at T10 (Fig. 4). Thus,the diastematomyelia extended from T11-T12 to L2with a posterior fusion defect in this region. The osse-ous septum gave an increased signal intensity cen-trally at the level of T12 and the spinal column wasseparated by this structure. A syrinx extended fromT11 to the upper lumbar vertebrae with enlargement of

anterior subarachoidal space. There was a perineuralcyst with a diameter 13 × 13 × 10 mm at the sacralvertebral region.

The signal intensity of this cyst is similar to that ofcerebrospinal fluid. At surgery there was a spina bifidabetween T10-L3 and the osseous septum was con-firmed at the level of T11-T12. A total laminectomy wasperformed at T11 and T12; arachnoidal adhesions werereleased by microneurosurgical technique. The patientdischarged with normal neurologic function of thelower limbs.

Fig. 2. Patient 1: Horizontal MRI image through T11 showing posteriorfusion defect and wide spinal cord filling the medullar cavity.

Fig. 3. Patient 1: Horizontal MRI image through T12 showing bonyseptum through spinal cord and 2 vertebral species.

Fig. 4. Patient 2: Sagittal MRI showing malformed (“butterfly”) verte-bra at T10. The posterior vertebral fusion defect between T11-L2.

Diastematomyelia in Two Sisters 181

The 9-year-old sister with similar clinical findingswas asymptomatic. Plain X-ray films showed a spinabifida at L5. Her spine was evaluated using sagittaland axial series with MRI. T1 weighted series with a1.0 T magnetic MRI (Picer) showed the presence ofspina bifida at the level of L5 and extension of theconus medullaris at the level of L3 with the diastema-tomyelia extended from L2 to the conus medullaris butan osseous, fibrous or cartilaginous septum was notobserved. The filum terminale was thicker than normal(2.5 mm) and contained a small lipoma. A neurosurgi-cal procedure will be performed in the future.

DISCUSSION

In 1964 Kapsalakis reported on diastematomyelia in2 sisters; Gardner [1973] described 3 sisters with dias-tometamyelia and related manifestations in variouscombinations. Advanced imaging techniques (CT, MRI)can provide detailed information about spinal cordanatomy such as arachnoidal cyst, lipoma, or other le-sions. Breningstall et al. [1992] examined 45 patientswith myelomeningocele in this manner and found twocases of additional diastematomyelia.

All reported individuals with diastometamyelia, in-cluding our patient, are female. This may indicate X-linked determination with lethality in hemizygousmales or female sex-preference of a multifactorial trait.No cases of X-linked diastematomyelia pedigrees areknown to date.

The McKusick Catalog [1994] lists diastematomyeliaas an autosomal recessive trait because of sib occur-rence with normal parents; however, a hypothesis ofX-linked dominant inheritance with limitations to fe-males because of lethality in hemizygous male cannotbe excluded formally at this time.

Winter et al. [1989] drew attention to the prenataldiagnosis of diastematomyelia and recently Sepulvedaet al. [1997] reported on 2 cases of prenatally diagnoseddiastematomyelia by routine 2nd-trimester sonogra-phy. For these reasons, parents should be counseledabout the possible recurrence of diastematomyelia insibs.

REFERENCES

Breningstall GN, Marker SM, Tubman DE. 1992. Hydrosyringomyelia anddiastematomyelia detected by MRI in myelomeningocele. Pediatr Neu-rol 8:267–271.

Gardner WJ. 1973. The dysraphic states from syringomyelia to anen-cephaly. Amsterdam: Excerpta Medica, p 89–94.

Kapsalakis Z. 1964. Diastematomyelia in two sisters. J Neurosurgery 21:66–77.

McKusick VA. 1994. Mendelian Inheritance in Man, a catalog of humangenes and genetic disorders. Baltimore and London: Johns HopkinsUniversity Press. p 1766.

Sepulveda W, Kyle PM, Hassan J, Weiner E. 1997. Prenatal diagnosis ofdiastematomyelia: case reports and review of the literature. PrenatDiagn 17:161–165.

Winter RK, McKnight L, Byrne RA, Wright CH. 1989. Diastematomyelia:prenatal ultrasonic appearances. Clin Radiol 40:291–294.

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