Childs Nerv Syst (2004) 20:601–606DOI 10.1007/s00381-004-0990-7 S P E C I A L A N N U A L I S S U E

Scott Campbell Separation of craniopagus twins:the Brisbane experience

Received: 16 March 2004Published online: 28 July 2004� Springer-Verlag 2004

S. Campbell ())Kenneth G. Jamieson Neurosurgical Unit,Royal Brisbaneand Royal Children’s Hospitals,Brisbane, 4029, Australiae-mail: scott_campbell@health.qld.gov.auTel.: +61-7-36367470Fax: +61-7-36361563

Abstract Introduction: There aremany problems facing the neurosur-geon when separating craniopagustwins. The condition is rare, with anincidence of 1 in 2.5 million births.As such there is a paucity of infor-mation in the literature regardingstrategies for separation. Survivalrates: Over the last 20 years, therehas been a gradual improvement insurvival rates due to a combination ofimproved imaging, surgical/anaes-thetic techniques and postoperative

care. Currently, survival rates fol-lowing surgery are at 50–60%. Moreinformation regarding this conditionis needed to make surgical separationa safer event. Aim: The aim of thisarticle is to discuss the preoperativework-up, technical details of surgery,postoperative care and lessonslearned with respect to the separationof craniopagus twins.

Keywords Craniopagus · Conjoinedtwins · Surgical separation

Introduction

The author will discuss the perioperative and operativestrategies with respect to the separation of craniopagustwins. The information provided is based on a reviewof the literature and the personal experience gained fromthe separation of two sets of craniopagus twins bornin Brisbane, Australia. The first set of Brisbane twins(Fig. 1) were separated in October 2000 and the secondset (Fig. 2) in May 2001. The first case was published inthe Journal of Neurosurgery in October 2002 [2] and thesecond has recently been submitted for publication to thesame journal.

With regard to the first set of Brisbane twins separated,the operation was uncomplicated and both twins weredetached unscathed. One of the twins died approximately2 years later due to respiratory and renal failure, sec-ondary to cerebral palsy, which developed soon after birthand 6 months prior to surgical separation.

With regard to the second set of Brisbane twins, one ofthe twins developed malignant idiopathic hypertensionsoon after birth, which progressed to heart failure. Sepa-ration was attempted only when it was felt that the deathof that twin was imminent. The operation was performed

in an attempt to save the other twin’s life. At operation,the unhealthy twin died on the table. The other twinsurvived surgery despite requiring resuscitation due tohypovolaemia. She is alive and well and recently turned3 years of age. She commenced walking unaided at

Fig. 1 The first set of Brisbane twins separated in October 2000

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20 months of age. She has a good vocabulary, but walkswith a mild hemiparesis.

One of the main difficulties the Brisbane surgical teamfaced when separating the two sets of twins was that therewas very little current information in the literature re-garding the separation of craniopagus twins. O’Connell in1976 [5], Winston et al. in 1987 [9] and more recentlySpencer in 2000 [6] have provided detailed reviews of thesurgical planning and operative challenges, but regularupdates are required to review developing techniques andshare experiences if outcomes are to improve. The aim ofthis article is to report the information gained from theexperience of being involved with two craniopagus sep-aration operations and to review the current literature.

Discussion

Level of surgical expertise

Given the rarity of craniopagus and the high level ofexpertise that exists at individual centres around theworld, it is likely that most cases will be operated uponlocally by surgeons with little or no experience, apartfrom the day-to-day skills they have developed fromgeneral or paediatric neurosurgery. Adding to the problemof expertise, O’Connell [5] who had the opportunity tooperate on three cases of craniopagi, noted significantlydiffering anatomical and physiological difficulties witheach case. Therefore, as stated by Winston et al. in 1987,operating with lack of experience cannot be criticized, aslong as the surgical team has meticulously prepared,consulted widely and has modern resources available attheir hospital for appropriate preoperative investigationsand postoperative care [9].

Indications for operation

There are essentially three options for the treatment ofSiamese twins:

1. Leave the twins joined and let nature take its course2. As above, but perform an emergency separation should

one twin become critically ill or die3. Perform an elective separation

O’Connell [5] noted that with craniopagus twins, thereis no chance of a normal life whilst they remain con-nected, so separation is a reasonable proposition if there isa chance of success. The difficult part is deciding whetherthe twins can safely be separated, and if they survivesurgery, what degree of neurological impairment will bepresent. History to date has shown that about 50–60% ofpatients survive separation, but few survive unscathed [1].To make the decision process more problematic, the di-agnosis is mostly confirmed by antenatal ultrasound andMR scan, making a detailed assessment of the anatomydifficult. At this stage the mother and family requirecareful counselling as to the natural history of the con-dition and the risks of surgical separation. It is of interestthat despite pessimistic counselling during pregnancywith the two Brisbane cases, both sets of parents electedto go ahead with the pregnancy based on their own social,moral and ethical values. It can then mostly be assumedthat if the parents elect to go ahead with the pregnancy,they do so with a view to surgical separation after birth ifpossible.

Timing of surgery

With regard to the timing of operation, there are publishedopinions, but there is no firm evidence as to when cra-niopagus twins should be divided. It is generally felt thatdelaying surgery to approximately 6–12 months of age orlater is preferable in order to enable the babies to grow insize, develop their immune system and increase theirblood volume. This also allows adequate time to study thecomplex anatomy and canvass second opinions. The timecan be used to insert tissue expanders if needed. Withinreasonable limitations, all investigations should be doneearly, and repeated at a later date if needed, in order toprevent being caught unprepared should the need foremergency separation occur.

Risks of surgery

As craniopagus is such a rare condition and information todate is largely based on individual case reports, it is dif-ficult to give accurate morbidity/mortality figures, but theavailable published evidence is consistent with empiric

Fig. 2 The second set of Brisbane twins separated in Brisbane inMay 2001

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risks of a 33% chance of both babies dying as a result ofsurgery, a 33% chance of one dying and one surviving,and a 33% chance of both surviving. These figures needto be adjusted to fit the clinical picture if one twin isweaker than the other, which is often the case. It has beenobserved that worse surgical outcomes occur when onechild is already dead or the condition of one or bothchildren is steadily deteriorating [9]. The risks of surgerywill also vary depending on the site of the join and theextent of the shared brain and venous sinuses.

It should be noted that the 33% rule is for survival/mortality only and the parents need to be aware thatsurvival may be associated with neurological impairment,ranging from mild to severe. At present most case reportsappear focused on survival rates rather than morbidity. Itis hoped that as survival improves more focus will turn toquality of life issues.

Consultation

Separation of craniopagus twins presents a wide range ofclinical problems that will require solving. Local, nationaland international consultation is essential when tacklingthese difficult cases. Neurosurgical and plastic surgerycolleagues who have never had involvement with crani-opagus may have valuable suggestions to contribute thatcan both save time and avert neurological damage.

Conjoined twins have always attracted intense mediainterest, particularly those joined at the head, which addsto the pressure of separation. Wide and open consultationwill improve the chances of a favourable outcome andprotect from criticism against any adverse outcomes.

In general, the technical details of separation and risksinvolved are complex and often difficult to grasp forthe mother and family. So, in the course of planning forseparation, a number of case conferences should be at-tended by the surgical/anaesthetic team, radiologist, pae-diatrician, intensivist, nursing team and parents to facili-tate communication before consent is obtained. Addi-tional support for the parents may be needed from socialworkers and chaplains when survival cannot be guaran-teed for one or both twins.

A public relations department representative will berequired to facilitate appropriate communication with themedia. Legal advice may be required if any ethical issuesarise, especially if one twin is to be favoured over theother or one twin will die as a result of separation.

The role of the plastic surgeon

The role of the plastic surgeon is as essential as that of theneurosurgeon as skin, dura and bone coverage are vital toprevent postoperative wound breakdown, CSF leak andmeningitis. For large joins, preoperative tissue expanders

may be required in combination with flap rotations toenable adequate closure of the defects. Split thicknessskin grafts are an option if full closure is not possible.Ideally, both twins should share the available scalp tissueequitably, but if one twin is weaker or death is a proba-bility, then it is reasonable to give the healthier twin themajority of the scalp.

Following separation of the twins there will be a bonydefect of varying size. Options available to deal with thebony defect include:

1. Leave the defect with a view to closure at a later date.Small defects may heal completely with time. Largerdefects can be repaired with a split calvarial graft, ribgraft or titanium plate when the infant is older

2. Repair the defect at the time of surgery. This can beperformed using LactoSorb plates/sheets or a similarabsorbable material. Bone nibbles taken from the pe-rimeter of the join can be added to promote healing.Rib bone is another option, but can add to the overalllength of the operation and increase morbidity. Shouldone twin die during the operative procedure, it wouldbe appropriate (with parental permission) to use theavailable skin, dura and bone to cover the defect of thesurviving twin.

With regard to dural cover, the best material to use isfascia lata grafting. Unfortunately, problems arise when alarge surface area of exposed brain needs covering.Lyophilised dura is not an option in many countries due tothe risk of Jacob–Creutzfeldt disease. There are a numberof other artificial dura materials on the market that can beused, but there is an increased risk of infection with noguarantee of preventing CSF leak. Another option is tocover the defect with surgicel or similar material andinsert a drain to be left in until the wound has healed, say4–5 days, thus preventing leakage of CSF.

The role of the anaesthetist

Several authors [1, 9] have reported rapid and largeamounts of blood loss whilst attempting separation, oftenleading to cardiac arrest. With this in mind, the anaes-thetist may be called upon to treat the haemodynamicallyunstable patient and as such, the role of the anaestheticteam is vital, perhaps even more so than the surgical team.

Preoperative investigations

As craniopagus presents in diverse and complex ways thesurgical team will need to investigate thoroughly, firstlyto gather information as to whether the twins can beseparated and secondly to minimise morbidity once thedecision has been made to proceed with separation. Initial

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diagnosis will be made with antenatal ultrasound andmagnetic resonance (MR) scans (Fig. 3).

Computed tomography (CT) scanning and MR imag-ing remain the cornerstone of neurosurgical investigationand along with a skull X-ray (Fig. 4) should be the initialneurosurgical investigations performed after birth. TheCT scan best highlights the bony join whilst the MR scan(including MR venogram) best demonstrates the rela-tionship of the adjacent brains and shared venous sinuses.

In our institution, it was noted that the most usefulinvestigation for demonstrating the anatomy of the joinwas the use of an acrylic model. The model was made bystereolithographic biomodelling, a technology that allowsthree-dimensional CT and MR data to be used to manu-facture solid plastic replicas of anatomical structures(Fig. 5) [4].

The acrylic model has several advantages over con-ventional imaging techniques:

1. The anatomy is presented in three dimensions, clearlyshowing the relationship of the bony join and the majorshared sinuses and draining veins

2. The model can be used by the plastic surgery team inthe preoperative period to plan the surgical incisionsand skin flaps in order to provide the best possible skincoverage. To do this, a tailor-made pressure garment(e.g. Second Skin Pty., Ltd, Brisbane, Australia) can befitted around the acrylic model to simulate the scalpskin. This allows greater confidence that the plannedflaps are able to reconstruct the defect appropriately

3. The model can be sterilised and used intraoperatively

In our cases, two models were ordered for each set oftwins so that one of the models could be cut open at eachend to more closely view the anatomy of the venous si-nuses from the inside (rather than having a restricted viewfrom the outside via the anterior fontanel or foramenmagnum).

It should be noted that conventional cerebral angiog-raphy was not performed in the Brisbane cases, as it wasfelt that the procedure would carry an increased risk to thebabies with little additional information gained. However,it is acknowledged that angiography has been a mainstayof investigations in the past and is likely to remain pop-ular with surgeons in the future.

Image-guided navigation systems have been recentlyused intraoperatively to delineate the complex anatomyand avoid vital structures. It is to be expected that neu-roradiological advances in the future will give surgeonsa clearer understanding of the shared structures, withhopefully improved outcomes.

As a final note on investigations, it is important toremember that craniopagus has a high incidence of as-sociated congenital anomalies [8] and as such investiga-tions should extend to include other parts of the body,especially the heart, kidneys and spine.

Fig. 3 Antenatal T2-weighted magnetic resonance scan of thesecond set of Brisbane twins

Fig. 4 Skull X-ray of craniopagus twins

Fig. 5 Acrylic model of the first set of Brisbane craniopagus twins

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Planning the surgical procedure

One to 2 weeks prior to the operation it is recommendedthat a multidisciplinary planning day (or more if needed)be scheduled in theatre. A pair of life-sized mannequinsshould be joined in the exact cranial position to anticipateany potential problems that could occur during surgery.Numerous lines and tubes can be attached to the man-nequins so that the surgical, anaesthetic and nursing teamscan practise turning and transferring whilst maintainingsterility and preventing the lines/tubes from kinking orentangling. At the same time the operating room layoutcan be finalised. If the twins are medically stable, it maybe advantageous to take them to theatre for a practice runas well [7].

The extensive theatre and personnel utilisation in-volved in the separation of conjoined twins may lead to adecision for other elective surgery to be postponed on theday of the scheduled operation, depending on resourcesavailable. This strategy minimises traffic within the op-erating room suite, ensures sufficient nursing and supportstaff and services, facilitates patient safety and confi-dentiality, and generally minimises the potential for dis-turbances to the surgical separation. Postoperative inten-sive care bed availability should be confirmed prior tocommencing surgery.

The operation

Once the decision has been made to perform surgery anevaluation has to be made as to whether to do a one-stageprocedure or a two/three-stage procedure. The assessmentshould be made on an individual basis, with any sharedvenous sinuses as the major problem.

The options to deal with a common shared sinus in-clude:

1. Perform a staged operation with the aim of slowlyclosing down the shared sinuses over a period of time(weeks). This could be combined with radiological testocclusion

2. Perform a one-stage procedure and give the sinus toone twin and fashion a sinus from venous structureselsewhere (e.g. saphenous vein) for the other twin

3. Perform a one-stage procedure and give the sinus toone twin and let the other twin take its chances. Thisscenario would best suit a situation where one twin hada poorer prognosis

Bucholz et al. in 1987 reviewed 21 operative cases ofcraniopagus from 1928 to 1987 and noted that 9 out of the21 cases (43%) were staged procedures. He further notedthat twins who had been separated in stages uniformly didbetter than those separated in one-step procedures and hada significant reduction in operative mortality [1]. This

would seem to make sense, as shutting down shared ve-nous structures over a period of time would potentiallyallow the venous drainage an opportunity to re-channelback to the heart. Staged surgery would also allow theinfants to recoup any blood that may have been lost fromprevious surgery.

Separation of the Baragwanath twins in 1987 [3] in-volved the use of an external clamp on the common(shared) sinus, which was slowly tightened over a fewweeks until a collateral venous circulation had been es-tablished. Whilst this technique led to mixed results, onebaby died 18 months after surgery and the other is alivewith a mild neurological deficit (personal correspondencewith Dr P. Scott, December 2000), it does have potentialmerits. Winston et al. in 1987 also preferred a stagedprocedure [9]. Other institutions have tried to give theshared sinus to one twin, usually the stronger of the two,and fashion a second sinus from venous structures har-vested elsewhere in the body, again with mixed results.

At our institution, we were fortunate not have to facethe operative dilemma of the shared sinuses. In the firstcase, we were able to navigate through the join keepingthe abutting sinuses intact. In the second case, the death ofone of the twins was imminent so we “gave” the sinus tothe other twin (with parental and legal permission). De-spite the perceived advantages of staged operations, inrecent years there has been a trend towards one-stageprocedures. More case studies are needed to determine thebest practice.

During operation, the surgeon is faced with threemajor technical problems. First, as stated above, sharedvenous sinuses and brain must be separated leaving eachinfant with a functional residue when possible. Second,blood loss can cause the rapid demise of both twins, es-pecially if uncontrolled bleeding occurs through a largeshared sinus. The rapid loss of blood, often leading tocardiopulmonary resuscitation or death, has been wellreported in the literature. Efforts should be made toidentify potential difficulties and large troublesome si-nuses should be divided towards the end of the operation,thus reducing venous hypertension till the end.

When positioning the patients it is important to havegood exposure to any large shared sinuses. Slight ormoderate head elevation, if possible, will reduce venouspressure and blood loss. Air embolus is a risk that has tobe accepted, but generally has been unreported to date.

At some stage during separation the twins will have tobe turned over to allow an approach from the other side(side 2). It is important to gain meticulous haemostasisand reinforce the wound with packing prior to turning asfurther bleeding may occur from side 1 as venous hy-pertension builds with closure of each vein/sinus onside 2. The undersurface should be viewed at regular in-tervals to check for any occult bleeding.

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References

1. Bucholz R, Yoon K-W, Shively R(1987) Temporo-parietal craniopagus.J Neurosurg 66:72–79

2. Campbell S, Theile R, Stuart G et al(2002) Separation of craniopagus at theocciput. J Neurosurg 97:983–987

3. Drummond G, Scott P, Mackay D et al(1991) Separation of the Baragwanathcraniopagus twins. Br J Plast Surg44:49–52

4. D’Urso P, Thompson R, Atkinson R etal (1999) Cerebrovascular biomod-elling: a technical note. Surg Neurol52:490–500

5. O’Connell JEA (1976) Craniopagustwins: surgical anatomy and embryolo-gy and their implications. J NeurolNeurosurg Psychiatry 39:1–22

6. Spencer R (2000) Craniopagus con-joined twins: typical, parasitic, and in-tracranial fetus-in-fetu. Neurosurg Q10:60–79

7. Williams K, Callf N, Young J (2002)Surgical separation of conjoined twins:a perioperative nursing perspective.Aust Coll Operating Room Nurs J15:10–15

8. Winston KR (1987) Craniopagi: ana-tomical characteristics and classifica-tion. Neurosurgery 21:769–781

9. Winston KR, Rockoff MA, Mulliken JBet al (1987) Surgical division of cran-iopagi. Neurosurgery 21:782–791

Third, dura, bone and skin at the site of union must beclosed after separation is completed to prevent CSF leakand meningitis.

Postoperative care

Conjoined twins undergoing surgery are at greater risk ofexperiencing postoperative complications due to pro-longed anaesthesia and massive blood loss and transfu-sion. As a result, hypothermia, electrolyte imbalance andcoagulopathy may occur. As the twins have to be turnedat some stage during surgery, there is usually a varyingloss of sterility, which can cause infection. Seizure ac-tivity may require medication and CSF leakage can havedevastating consequences if it is not controlled.

Summary

Craniopagus is a rare and interesting multidisciplinarychallenge. The reduction of morbidity and mortality seenin the last decade can be attributed to a combination offactors, including better preoperative imaging, a greaterunderstanding of the venous anatomy and conjoined area

of brain, better control of venous haemorrhage and im-provements in anaesthesia and postoperative intensivecare facilities. However, the cornerstone to success islikely to remain teamwork, consultation and preoperativeplanning.

Conclusions

The lessons learned from reviewing the literature andseparating two sets of craniopagus twins include:

1. Consult widely: locally, nationally and internationally2. A team effort will give better results3. Perform all investigations early in anticipation that one

or both twins may suddenly deteriorate, necessitatingan urgent operation. Also, the anatomy of the join iscomplex and will take a considerable amount of timeto comprehend

4. Meticulous preoperative planning is required5. Look for co-morbidity, especially the heart and kid-

neys, which can lead to deterioration both before andafter separation

6. Keep the expectation of the parents, other colleaguesand the media low. Bad outcomes occur frequently