, . 17:4: 384–388 (1997)

SHORT COMMUNICATION

PRENATAL DIAGNOSIS OFCEPHALOTHORACOPAGUS JANICEPS

MONOSYMMETROS

- *†, - §, - †, - †, - * - ‡

Departments of *Obstetrics and Gynecology, †Medical Research, and ‡Pathology, Mackay Memorial Hospital,Taipei, Taiwan, Republic of China; §Department of Pathology, Shin Kong Wu, Ho-Su Memorial Hospital, Taipei,

Taiwan, Republic of China

Received 24 June 1996Revised 4 October 1996

Accepted 3 November 1996

SUMMARY

We report a case of cephalothoracopagus janiceps monosymmetros that was diagnosed prenatally by ultrasoundat 23 weeks’ gestation. Obstetric ultrasound demonstrated conjoined female twins with a single fused cranial vaultirregular in contour, duplicated cerebra, one face, two eyeballs, a fused thorax, two hearts, two thoracic spines, eightlimbs, and polyhydramnios. The pregnancy was terminated and all the features described prenatally were observedat necropsy. The asymmetrical fused faces consisted of a ventral humanoid face with micrognathia, microphthalmia,low-set ears, a normal nose, and an opposite reduced face with partial facial features of a central narrowed fissureand paired synotic ears. The conjoined twins had fused umbilical cords, omphalocoele, and a single oesophagus,stomach, and duodenum, but duplicated pancreases, spleens, and central nervous, cardiopulmonary, hepatic,and genito-urinary systems. The common gastrointestinal tract bifurcated at the level of the jejunum. Ourcase documents a very uncommon variety of asymmetrical cephalothoracopagus janiceps with duplicated centralnervous systems. ? 1997 by John Wiley & Sons, Ltd.

: cephalothoracopagus; janiceps; monosymmetros; conjoined twins; ultrasound

INTRODUCTION

Conjoined twinning is a rare congenital malfor-mation that occurs once in 100 sets of monozygotictwins (Jones, 1988) and once in 50 000–100 000births (Edmonds and Layde, 1982). Twins with afused head and thorax but two separate spines,limbs, and pelves are known as cephalothoracopa-gus. Cephalothoracopagus is a rare form of con-joined twinning occurring once in 3 million birthsand once in 58 sets of conjoined twins (Slager

et al., 1981). With the advent of obstetric ultra-sound, the prenatal diagnosis of various forms ofconjoined twins is now possible. In this paper, wereport a case of cephalothoracopagus janicepsmonosymmetros that was diagnosed prenatally byultrasound at 23 weeks’ gestation. This case docu-ments a very uncommon variety of asymmetricalcephalothoracopagus janiceps with duplicatedcentral nervous systems.

CASE REPORT

A 24-year-old Chinese primigravida wasreferred for sonographic examination at 23 weeks’gestation because of fetal abnormalities. The

Addressee for correspondence: Chih-Ping Chen, MD,Departments of Obstetrics and Gynecology, and MedicalResearch, Mackay Memorial Hospital, 92, Section 2, Chung-Shan North Road, Taipei, Taiwan, Republic of China.

CCC 0197–3851/97/040384–05 $17.50? 1997 by John Wiley & Sons, Ltd.

paternal age was 27 years. The parents involved inthis pregnancy were unrelated and there was nohistory of diabetes mellitus, twins, or congenitalmalformations. The mother denied any exposureto drugs for ovulation prior to conception, orteratogenic medications, irradiation, or infectiousdiseases during this pregnancy. Sonographicexamination performed at 23 weeks’ gestationdemonstrated polyhydramnios, a single placentawith no separating membrane, two fused umbilicalcords with a total of six vessels, and conjoinedtwins with a fused head and a fused thorax,omphalocoele, a stomach, but two separate spines,hearts, pelves, bladders, and eight limbs. Therewas a single cranial vault irregular in contour withone face, two eyeballs, and an enlarged headcircumference of 24 cm equivalent to 27 weeks’gestation. The intracranial structures included twocerebra, each of which had a single separate lateralventricle (Fig. 1) and a low-lying common spacerepresenting the fused medial ventricle (Fig. 2).Both twins had female genitalia. Because of thelethality and inseparability, termination of preg-nancy was offered. The 23-week malformedtwins weighing 1280 g were delivered per vaginamwithout any difficulty. Chromosome analysiswas compatible with a normal female, 46,XX.The maternal serum alpha-fetoprotein level at23 weeks’ gestation was 2·23 MOM.Necropsy demonstrated a monoamniotic,

monochorionic pregnancy and confirmed all thesonographic features described prenatally. Therewas a single placenta with two umbilical cords

which fused together from placental insertion tothe omphalocoele. The fused umbilical cordsmeasured 25 cm in length. Each umbilical cord hadone umbilical vein and two umbilical arteries. Theasymmetrically fused faces consisted of a ventralhumanoid face with micrognathia, microphthal-mia, low-set ears, and a normal nose (Fig. 3), andan opposite reduced face with partial facialfeatures of a central narrowed fissure and synoticpaired ears (Fig. 4). The conjoined twins had asingle oesophagus, stomach, and duodenum, butduplicated pancreases, spleens, and central nerv-ous, cardiopulmonary, hepatic, and genito-urinarysystems. The gastrointestinal structures that werefused and shared by both twins were the commonoropharynx, oesophagus, stomach, and duo-denum. Bifurcation of the bowel occurred at thelevel of the jejunum. In the skull, there were twoanterior, middle, and posterior cranial fossae andtwo great occipital foramina. The central nervoussystems (Fig. 5) included duplicated cerebra, cer-ebella, pituitary glands, pontes, medullae oblon-gata, and spinal cords. Each cerebrum had oneseparate lateral hemisphere and one medial fusedhypoplastic hemisphere. Two side-by-side adher-ent medial hypoplastic hemispheres from differentcerebra were fused coronally. The other two lateralhemispheres were not fused. Each brain containedtwo separate occipital and parietal lobes. Therewere two optic nerves on the humanoid side but noolfactory bulbs were found. Post-mortem radi-ography of the twins showed one fused skull andtwo complete vertebral columns (Fig. 6).

Fig. 1—A transverse scan of the skull showing an enlarged headwith irregularity of the external contour and a central septum(arrows), two orbits (O), one nose (N), and two separate lateralventricles (V) of two brains

Fig. 2—A low-lying transverse scan of the skull showing acommon space representing the fused medial ventricle (MV)and two separate lateral ventricles (LV)

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DISCUSSION

The term cephalothoracopagus janiceps isreferred to twins with a fused head and thoraxwhose single fused head has two faces each lookingin opposite directions. The term janiceps is derivedfrom Janus, the two-faced Roman god. When thetwo faces are identical and symmetrical, it is calledjaniceps disymmetros (Wedberg et al., 1979; Slageret al., 1981; Nolan et al., 1990). In the case ofsymmetrical janiceps disymmetros, the orien-tations of the two notochordal axes are perfectlyventroventral; therefore, the two faces on oppositesides of the head are identical and surprisinglynormal (Machin and Sperber, 1987). When the twofaces become dissimilar and only one normal facecan be seen with a second reduced face showingvarying degrees of differences in the completenessof a face, it is called janiceps monosymmetros

(Slager et al., 1981; Sperber and Machin, 1987). Incases of cephalothoracopagus janiceps monosym-metros, the duplicated axial orientations convergein the plane of the lesser partial face, whereas thegreater face remains normal (Machin and Sperber,1987). The incomplete facial features of the secondface include a single naris, cyclopic eyes, synoticears, a proboscis, or two small eyes in a singlepalpebral fissure. Many kinds of incompleteopposite face show varying degrees of reductionthrough holoprosencephalic configurations tosimply a single fused ear, e.g., one cyclopic eyeand synotic ears (Abbott and Kaufmann, 1916;Ishida and Koga, 1990); two small eyes in a singlepalpebral fissure surmounted by a proboscis(Slager et al., 1981); only one fused ear (Bartlett,1959; Brenbridge et al., 1987); and paired synoticears (Plumer and Scheffer, 1916; Grundfest andWeisenfeld, 1950; Jawa, 1972; Delprado andBaird, 1984). Our case is a rare occurrence of the

Fig. 3—Anterior view of twins showing a fused thorax, ompha-locoele, a single umbilical cord, and a single head with ahumanoid face having micrognathia, microphthalmia, low-setears, and a normal nose

Fig. 4—Posterior view of twins showing a narrowed centralfissure and synotic paired ears

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last variety, also known as cephalothoracopagussyncephalus, in which the reduced face is repre-sented by ears only, but with a variable cerebralcomponent to the reduced face (Sperber andMachin, 1987). Most reported cases of cephalo-thoracopagus janiceps monosymmetros havedescribed asymmetrical facial and prosencephalicstructures, especially one single cortex, butsymmetrically duplicated brainstems, cerebella,and spinal cords (Slager et al., 1981; Delprado andBaird, 1984; Sperber and Machin, 1987). Our caseof cephalothoracopagus janiceps monosymmetrospresented symmetrical prosencephalic structuresthat were detected correctly by prenatal ultra-sound. As for the symmetrical facial features, wedetected one face with two eyeballs and one nose,but were unable to find the synotic-type ears on theopposite face.Prenatal ultrasonography permits accurate diag-

nosis of conjoined twins and allows a detailedanalysis of the degree of fusion. In this presenta-tion, absence of a separating amniotic membranebetween the twins, the fusion of body parts at thehead and thorax with two hearts and two spines,fused umbilical cords with more than three vessels,an enlarged cranial vault with irregularity of theexternal contour, one identifiable face and twobrains, and polyhydramnios act as markers forcephalothoracopagus janiceps monosymmetros inprenatal ultrasound. However, we emphasize that

Fig. 6—Post-mortem radiograph showing one fused skull andtwo complete vertebral columns

Fig. 5—Rostral view of two brains showing two cerebra, cerebella, brainstems, and two optic nerves (arrows). Each brain contains one medullaoblongata (MO), one cerebellum (C), one pons (P), two separate occipitallobes (O), one temporal lobe (T), one frontal lobe (F), one fused frontallobe, and one fused temporal lobe. L: left-sided; R: right-sided

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further efforts should be made to search for thecyclopic-type eye or synotic-type ears in suchcircumstances.

REFERENCES

Abbott, M.E., Kaufmann, J. (1916). Double monster ofJanus type: cephalothoracopagus monosymmetroscyclopos synotus, Bull. Int. Assoc. Med. Museums, 6,95–101.

Bartlett, R.C. (1959). Cephalothoracopagus: report of acase, Arch. Pathol., 68, 292–298.

Brenbridge, A.N., Kraft, J.L., Teja, K. (1987). Sono-graphic findings in the prenatal diagnosis of cephalo-thoracopagus syncephalus. A case report, J. Reprod.Med., 32, 59–62.

Delprado, W.J., Baird, P.J. (1984). Cephalothoracopa-gus syncephalus: a case report with previously unre-ported anatomical abnormalities and chromosomalanalysis, Teratology, 29, 1–9.

Edmonds, L.D., Layde, P.M. (1982). Conjoined twinsin the United States, 1970–1977, Teratology, 25,301–308.

Grundfest, T.H., Weisenfeld, S. (1950). A case of ceph-alothoracopagus, NY State J. Med., 50, 576–579.

Ishida, T., Koga, M. (1990). Cardiovascular anomaliesof cephalothoracopagus synotus. A case report and

review of the literature of 23 Japanese autopsied cases,Acta Pathol. Jpn., 40, 128–136.

Jawa, F. (1972). A case of cephalothoracopagus,Sb. Ved. Pr. Lek. Fak. Univ. Karlovy, 15 (Suppl.),417–420.

Jones, K.L. (1988). Smith’s Recognizable Patterns ofHuman Malformation, 4th edn, Philadelphia: W. B.Saunders, 594.

Machin, G.A., Sperber, G.H. (1987). Invited editorialcomment: lessons from conjoined twins, Am. J. Med.Genet., 28, 89–97.

Nolan, R., Ling, F., Langlotz, H., Fletcher, A. (1990).Cephalothoracopagus janiceps disymmetros twinning,J. Ultrasound. Med., 9, 593–598.

Plumer, J.S., Scheffer, C.J. (1916). Report on a case ofcephalothoracopagus monosymmetros, Bull. Int.Assoc. Med. Museums, 6, 101–107.

Slager, U.T., Anderson, V.M., Handmaker, S.D.(1981). Cephalothoracopagus janiceps malformation.A contribution to the pathogenesis of cerebralmalformation, Arch. Neurol., 38, 103–108.

Sperber, G.H., Machin, G.A. (1987). Microscopic studyof midline determinants in janiceps twins, BirthDefects: Orig. Artic. Ser., 23, 243–275.

Wedberg, R., Kaplan, C., Leopold, G., Porreco, R.,Resnik, R., Benirschke, K. (1979). Cephalothoracopa-gus (janiceps) twinning, Obstet. Gynecol., 54, 392–396.

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