- Email: [email protected]
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more than 5 years after the initial treatment involving radiotherapy. Chemotherapy was administered to 34 of 101 patients and various treatment regimens were used.3,4,12,18 However, no clinical evidence of an effective response was seen. Thus, the effective total radiation dose has been reported previously to be over 50 Gy;5 however, increased radiation did not improve the outcome.4 The incidence of recurrence is high in local boosts to the pineal lesion if the tumour is histologically benign.11,19,20 The target volume concepts varied and LINAC or gamma knife radiosurgery were performed in only five previously reported cases.3,4,14 In the present case, surgical resection was performed first, with accurate diagnosis. Postoperative adjuvant therapy using LINAC radiosurgery followed immediately by initial chemotherapy was added to the treatment regimen. Tumour shrinkage was most apparent during the month following this combination therapy and the effect was sustained for 2 years after the initial treatment. It is difficult to say whether this response was due to the effect of radiation alone, chemotherapy alone or a combined effect of the two. In all, local and spinal control was good. In a recently reported study, the prognosis of patients with residual tumour and disseminated disease was considered less favourable.4 In patients with PPTID, careful attention to future regrowth or dissemination is required if the visible tumour has been removed totally.3,6,10,11 The treatment strategy used in the present case is considered to be a reasonable and effective option. References 1. Mena H, Nakazato Y, Jouvet A, et al. Pineal parenchymal tumors. In: Kleiheus P, Cavenee WK, editors. The WHO Classification of Tumours of the Central Nervous System. Lyon: IARC Press; 2002. p. 115–22. 2. The Committee of Brain Tumor Registry of Japan. Special report of Brain Tumor Registry of Japan (1969–1990). Neurol Med Chir (Tokyo) 1999;39:59–107. 3. Fauchon F, Jouvet A, Paquis P, et al. Parenchymal pineal tumors: a clinicopathological study of 76 cases. Int J Radiat Oncol Biol Phys 2000;46:959–68. 4. Lutterbach J, Fauchon F, Schild SE, et al. Malignant pineal parenchymal tumors in adult patients: patterns of care and prognostic factors. Neurosurgery 2002;51:44–56.
5. Schild SE, Scheithauer BW, Schomberg PJ, et al. Pineal parenchymal tumors: clinical, pathologic, and therapeutic aspects. Cancer 1993;72:870–80. 6. Jouvet A, Saint-Pierre G, Fauchon F, et al. Pineal parenchymal tumors: a correlation of histological features with prognosis in 66 cases. Brain Pathol 2000;10:49–60. 7. Hassoun J, Grambarelli D, Peragut JC, et al. Specific ultrastructural markers of human pinealomas: a study of four cases. Acta Neuropathol (Berl) 1983;62:34–40. 8. Jouvet A, Fevre-Montange M, Besancon R, et al. Structural and ultrastructural characteristics of human pineal gland, and pineal parenchymal tumors. Acta Neuropathol (Berl) 1994;88:334–48. 9. Kleihues P, Burger PC, Scheithauer BW. Pineal parenchymal tumours. In: Kleihues P, Burger PC, Scheithauer BW, editors. Histological Typing of the Tumours of the Central Nervous System. second ed. Berlin: Springer; 1993. p. 26–7. 10. Tsunoda S, Sakaki T, Tsujimoto M, et al. Clinicopathological study on pineocytoma. Brain Tumor Pathol 1995;12:31–7. 11. Tsumanuma I, Tanaka R, Washiyama K. Clinicopathological study of pineal parenchymal tumors: correlation between histopathological features, proliferative potential, and prognosis. Brain Tumor Pathol 1999;16:61–8. 12. Brockmeyer DL, Walker ML, Thompson G, et al. Astrocytoma and pineoblastoma arising sequentially in the fouth ventricle of the same patient: case report and molecular analysis. Pediatr Neurosurg 1997;26:36–40. 13. Chang SM, Lillis-Hearne PK, Larson DA, et al. Pineoblastoma in adults. Neurosurgery 1995;37:383–91. 14. Kurisaka M, Arisawa M, Mori T, et al. Combination chemotherapy (cisplatin, vinblastin) and low-dose irradiation in the treatment of pineal parenchymal cell tumors. Childs Nerv Syst 1998;14: 564–9. 15. Matsumoto K, Higashi H, Tomita S, et al. Pineal region tumours treated with interstitial brachytherapy with low activity sources (192iridium). Acta Neurochir (Wien) 1995;136:21–8. 16. Nakamura M, Saeki N, Iwadate Y, et al. Neuroradiological characteristics of pineocytoma and pineoblastoma. Neuroradiology 2000;42:509–14. 17. Schild SE, Scheithauer BW, Haddock MG, et al. Histologically confirmed pineal tumors and other germ cell tumors of the brain. Cancer 1996;78:2564–71. 18. Ashley DM, Longee D, Tien R, et al. Treatment of patients with pineoblastoma with high dose cyclophosphamide. Med Pediatr Oncol 1996;26:387–92. 19. D’Andrea AD, Packer RJ, Rorke LB, et al. Pineocytomas of childhood: a reappraisal of natural history and response to therapy. Cancer 1987;59:1353–7. 20. Ito T, Takahashi H, Ikuta F, et al. Metastatic pineocytoma of the spinal cord after long-term dormancy. Pathol Int 1994;44:860–4.
doi:10.1016/j.jocn.2005.11.036
Separation of pyopagus conjoined twins: A New Zealand neurosurgical experience Mark Winder *, Andrew Law Department of Neurosurgery, Level 8, Auckland Hospital, Grafton Road, Grafton, Auckland, New Zealand Received 29 September 2005; accepted 10 November 2005 *
Corresponding author. Tel.: +64 09 379 7440; fax: +64 09 307 2897. E-mail address: [email protected] (M. Winder).
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Abstract Conjoined twins represent a rare form of incomplete embryonic separation. They are classified into eight different subtypes, with 18% representing pyopagus conjoints. History is scattered with accounts of the various types of conjoints and it is only recently that strategies have been devised to enable surgical separation of such twins. It is estimated that approximately 20 cases of separation of pyopagus twins have been performed. We provide a historical look at pyopagus conjoint twins and report our neurosurgical experience of Australasia’s first separation of pyopagus twin girls. 2006 Published by Elsevier Ltd. Keywords: Conjoined; Neurosurgery; Twins
1. Introduction Conjoined twins are identical same-sex twins that develop from a single fertilized ovum with a single placenta. There is a female preponderance, with a ratio of approximately 3:1. The actual incidence of conjoined twins is difficult to ascertain partly because of their infrequency, but also because of the fact that many are incompatible with life or have been born in underdeveloped countries where accurate historical and medical records are unavailable. The largest epidemiological study to date suggests an incidence of 10.25 per million births;1 however, many of these are incompataible with life. There are no defined aetiological factors, although there have been reports of geographical clustering.2 Conjoints can be separated into eight subtypes according to a dorsal or ventral conjoin: omphalopagus, thoracopagus, cephalopagus, ischiopagus, parapagus, craniopagus, rachipagus and pyopagus.3,4 The most common conjoins are thoraco-omphalopagus, thoracopagus and omphalopagus, with approximately 15–20% being pyopagus. Pyopagus twins represent the group of conjoints in which separation of the embryonic axis in the caudal region was incomplete, with resultant fusion of the sacral elements. There is usually a common dura and the neural elements can be fused, which may be mild, as in the case of distal elements of the cauda equina, or more severe, such as where there is fusion of the caudal part of the two spinal cords. Because the fusion is thought to occur at the caudal neuropore, the structures derived from the cloacal membrane, such as the anus, are normally affected. 2. History The medical literature is dispersed with accounts of conjoint twins. Hoyle5 provides an excellent review of all reports of conjoint twins, whereas Perlstein and LeCount6 have documented the chronology of reported pyopagus twins, albeit with some sparse details. Mentioned below is a chronological review of several of the more historically well-documented pyopagus twins. The first documented pyopagus twins were May and Eliza Chalkhurst, The Biddenden Maids, born in 1100 AD in Kent, England (Fig. 1A). They survived until the age of 34 years, leaving their entire fortune to the church. An annual celebration of their generosity still exists with ‘Biddenden cakes’.7
The Hungarian Sisters, Helen and Judith, (Fig. 1B) were born in Szony, Hungary in 1701. They were pyopagus twins who survived until the age of 22 years and became the subject of a poem by Alexander Pope. The advent of easier modes of travel brought many more conjoints to the eyes of the world. The most historically famous twins, Eng and Chang Bunker, were born in Siam in 1811. They were displayed around the world in the Barnum Circus as the Siamese Twins (Fig. 1C). The Bunkers lived to an age of 63 years, were successful businessman and fathered 19 surviving children. Chang is thought to have contracted pneumonia and died, with Eng dying in a matter of hours of his brother’s death. Millie and Christine McKoy (Fig. 1D) were born into slavery in 1851 in North Carolina and were bought by a showman. They were kidnapped by a rival showman and displayed over the country before being reunited with their mother at the age of 4 years. They became excellent performers, writing and performing their own songs. They died of tuberculosis at the age of 61 years. Other famous pyopagus conjoints include the Blazinek sisters, known as ‘The Bohemian Twins’ (Fig. 1E). They were born in Skreychov, Bohemia, in 1878. They shared a single introitus, with separate vaginae separated by a thin septum. They were examined extensively by physicians, phrenologists and surgeons. These details are thoroughly reported by Perlstein and LeCount.6 At 32 years of age, Rosa and Josefa consulted a physician regarding an abdominal swelling. Rosa was diagnosed as being pregnant and later gave birth to a healthy boy. The father of the child was denied the right to marry Rosa on moral grounds. Twelve years later, at the age of 44 years, Josefa developed an hepatitic illness, likely cholecystitis, with a concomitant severe bronchopneumonia. She died 5 days after the onset of the illness, with Rosa dying approximately 12 min later. The Hilton sisters (Fig. 1F) were a set of pyopagus twins born in 1908, Sussex, England. They were exhibited all over America, featured in several films, including Freaks, before being lost to public interest. They died in 1969 from the Hong Kong flu. As can be seen from the historical reports, the life expectancy of pyopagus twins is not unduly affected by their condition. However, the advent of surgical expertise and instrumentation has allowed the possibility of separation of conjoint twins, raising ethical and moral issues.
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Fig. 1. (A) The Biddenden Maids, (B) the Hungarian Sisters (C) Eng and Chang Bunker, (D) the McKoy Sisters, (E) the Blazinek Sisters with father and child and (F) the Hilton Sisters (reproduced with permission of www.phreque.com and www.mypage.direct.ca/c/csmason/multiples/conjoined).
The separation of conjoint twins was first reported in Switzerland in 1689 on xiphopagus twins.8 In more recent times, there have been many attempts to separate various types of conjoints, with variable success. The first cited report of a surgical separation of pyopagus twins was in 1700, where two female twins underwent separation but died 4 months later.9 The first modern report of the separation of pyopagus twins was in 1953 in Louisianna, where female twins fused at the base of the spines, with fused
neural elements, were separated without apparent neurological deficit.8 Reviewing the literature, it is estimated that approximately 19 cases of pyopagus conjoint separation have been attempted, with results confirming that pyopagus twins have a good prognosis because the fused structures are generally not life-threatening. McDowell et al.10 estimated survival rates for pyopagus separation to be 50% when performed in the neonatal period compared with 90% if the operation was delayed at least 6 months. Recent separations
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described by Hockley et al.11 and Feiggen et al.12 support this notion. Thus, if feasible, surgery should be delayed until physiological reserve can be maximised and the appropriate imaging and extensive operative planning formulated. Below, we report our neurosurgical experience in the separation of pyopagus conjoint twins, the first operation of its type performed in New Zealand. 3. Case report Conjoined twin girls, conjoined at the lower lumbar vertebrae and sacrum, with fused spinal cords, were diagnosed at 18 weeks gestation. The mother was 23 years old (gravida 1, para 1). The conjoin was identified through a standard screening ultrasound performed at 18 weeks gestation (the standard 12-week ultrasound was missed). Foetal magnetic resonance imaging (MRI) confirmed a conjoin of the pyopagus type, identifying four lower limbs, four ilia and fused distal spinal elements (Fig. 2). After extensive discussion with the family, a decision was made that separation would be the most likely avenue of treatment should the pregnancy proceed in an uncomplicated manner. The family was made aware that there was no urgency for surgical separation, with the ideal timeframe dependent on the twins’ development. The twins were delivered via Caesarean section at 34 weeks gestation. Initial Apgar scores for the twins were 10 and 10. Their combined birth weight was 4690 g. Initial examination revealed the twins to be fused at the distal spinal region, sharing a single anus, so that they faced away from one another in a partially oblique fashion. Twin B had evidence of talipes equinovarus of the left lower limb with some associated atrophy, but no other distinct neurological or muscoloskeletal abnormalities (Fig. 3). The children were discharged from hospital after 3 weeks to be cared for at home. During that time, their growth and neurological milestones were assessed. The literature provided valuable information as to the merits of certain imaging modalities,11,13–15 with subsequent imaging including repeat MRI, magnetic resonance angiography (MRA), three-dimensional computed tomography (CT) and ultrasonographic examinations (Fig. 4). Imaging revealed sacral fusion commencing at approximately the S2 level, with the majority of the sacrum mostly belonging to Twin A. A single sacral canal appeared up to the level of S2. Each twin had independently functioning lower limbs, with four separate ilia and separate sacroiliac joints. One of the most useful imaging adjuncts, for both the neurosurgical and orthopaedic teams, was the development of a three-dimensional acrylic model of the ilia, sacrum and lumbar spines (Fig. 5). This allowed a thorough appreciation of the site of fusion and orientation, aiding the operative planning. A management team was organized that consisted of general paediatric surgery, plastic surgery, neurosurgery, orthopaedic surgery, neonatology, anaesthesiology, urology and social work. We will focus on the aspects that pertain to the neurosurgical focus of the separation of the twins.
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Following extensive imaging and discussion among the relevant specialties, it was determined that a single operation would be the most appropriate strategy enabling separation of the twins, with the likelihood of further surgery required for functioning gastrointestinal and urological systems. Three months prior to separation, the plastic surgery team inserted tissue spacers on the back of each twin with the aim of increasing the circumferential expansion around the site of the conjoin. The tissue expanders were expanded serially over an 8-week period. The use of tissue spacers in the separation of conjoint twins has been documented previously on several occasions;16–18 however, it is only recently that the use of the formed pseudocapsule has been considered in the pre-operative planning of a tissue closure.
Fig. 2. Fetal magnetic resonance imaging at 18 weeks.
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Fig. 3. Talipes equinovarus in Twin B.
The operation was performed at a facility without paediatric intensive care or neurosurgical capabilities, requiring transportation of a Zeiss NC4 Operative Microscope, instrumentation and experienced operative staff. A date was chosen to accommodate all surgical specialties, which corresponded to the twins’ age of 14 months. Immediate pre-operative preparation included standard bowel preparation with clear fluids 24 h prior to anaesthetic, with a fasting time of 4 h. Standard blood profiles were performed with cross-matched blood available at request, because expected blood loss was estimated at two blood volumes. Anaesthetic considerations for the conjoint separation had been well rehearsed with models. The patients were each intubated with central, arterial and peripheral lines placed. Positioning of the patients had been rehearsed assuming sterile fields as required. Initially, the patients were positioned in an anterolateral manner, prepared and free draped to enable the plastic surgeons to remove tissue expanders and mark out appropriate skin flaps. At the time, a pseudocapsule from the deep surface of the tissue-expanded cavity was mobilised to enable its use in the dural repair as required. The general paediatric surgeons then divided the single anus, with separation of the two rectums, enabling an initial approach to the anterior aspect of the sacrum. The conjoint twins were then repositioned, enabling the orthopaedic team to expose the posterior elements of the lower lumbar spine and sacrum. There was a single plate of posterior element at the fused junctional segment, with an open canal distally over the sacrum, which extended to the fifth lumbar vertebrae. Under microscopic vision, the posterior and lateral aspects of the laminae were carefully resected, enabling identification of the dura. A modified laminectomy of the distal components and a segmental laminoplasty of the more proximal segments were performed. The periosteum and overlying fascia were kept intact, where possible, to allow layered closure following dural repair. The dura of each twin’s spinal cord was clearly identified revealing the Y-shaped dura at the site of fusion (Fig. 6). The posterior elements of the lower lumbar vertebrae and upper
Fig. 4. Fose-natal three-dimensional computed tomography (top), magnetic resonance imaging (bottom).
sacral elements were moderately deficient in certain areas, allowing relatively easy exposure of the more proximal and distal dura, using Kerrison punches through the ligamentum flavum. At this time, it was apparent that the single dural sac of the distal spinal canal was not symmetrical, increasing the likelihood of tethered distal cauda equina components in one of the twins and neurological asymmetry. The dura was completely exposed in an extradural fashion to the distal limits, identifying the sites of major attachment. A durotomy was performed in the midline and carefully extended both proximally in each cord and distally in the conjoin, allowing identification of the conjoint’s spinal canal contents (Fig. 7). The cords were identified, confirming posterolateral fusion of the cords, which tapered into a single, mildly asymmetric conus and filum terminale. Multiple nerve rootlets
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Fig. 6. Dural exposure, showing clear exposure of the Y-shaped dural sac with obvious filum terminale. Fig. 5. Acrylic three-dimensional computed tomography model.
arising at the anterolateral and inferior aspects were interspersed with small intradural vessels (Fig. 7). There were abnormal rootlets arising from the midline of the conjoin and passing forwards, which inevitably would need sacrificing. In order to define the intradural contents and allow for a primary dural repair following cord separation, the dura was exposed as far distally as possible. Sites of adhesions were identified, with the cord and distal elements tethered in one of the twins. These adhesions were carefully released. The lateral aspects of the cords were identified to determine the degree of dura available for primary closure without compromising the canal contents. Once the dura was clear cicumferentially, a decision as to the most appropriate site of cordotomy was made. As shown in Fig. 6, fusion of the distal cord was not completely symmetrical. The main concerns were the nerve rootlets arising at the distal and lateral aspects of the fused cord, which passed distally and contralaterally. It was clear that it would be impossible to separate the cord without nerve root damage to some degree. Previous reports of the separation of pyopagus twins highlighted the degree to which the spinal cords retracted upon detethering and separation.12,19,20 Having been aware of this possibility, we wanted to ensure that no intradural vessels would be subject to forces causing haemorrhage. Therefore, we carefully ensured that the cords were free of communicating vessels and associated pial and arachnoid adhesions such that should retraction occur, haemorrhagic risk would be minimal. Having carefully released the cords proximally, a vertical cordotomy was performed starting lateral to the filum terminale and extending proximally in a midline position, assuming separation between the dorsal columns of each twin’s cord. At the distal site, several of the small nerve roots, which crossed contralaterally, were sacrificed to enable cord separation. Once separated, the cords retracted marginally, allowing excellent exposure of the arachnoid and dura around the cords.
The flium was then separated from the single cord. The posterior aspect of the dura was able to be freed from the underlying extradural soft tissues. The dura was then mobilised and a primary dural closure with 5/0 nylon performed, made possible in one of the twins due to the asymmetry of the dural sac. A primary closure was not entirely possible on the other twin and an autologous dural repair was required, with harvested fascial layer, also using 5/0 continuous nylon. Upon completion, there was no evidence of obvious cerebrospinal fluid (CSF) leak. The spinal canals were then packed with thrombin-soaked pledgelets, with salinesoaked patties placed to afford protection of the cords while the sacral separation was performed. The orthopaedic team then identified the site of the sacral conjoin and performed a separation of the posterior aspect through a plane of cartilage where possible. Once performed, the canal contents were protected and the conjoints were repositioned to enable the general surgical team to deal with the genitourinary and anorectal issues. Once completed, the orthopaedic team was able to approach the anterior aspect of the sacrum. This was divided carefully and separation of the
Fig. 7. Conjoint exposure.
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twins performed. Haemostasis was achieved carefully and the twins moved to separate operating fields. The twins were repositioned to allow exposure of the spinal canal and dural repair. Of the reported cases of separation of pyopagus conjoint twins, the risk of CSF leak is clearly highlighted. Aware of this fact, Duragen (Medtronic, Gladesville, NSW, Australia) was also placed over the sites of possible compromised dural integrity, together with fibrin glue along the length of the durotomy and site of repair. There was no evidence of CSF leak on valsalva manoeuvre. Once we were satisfied of dural integrity, a carefully layered closure occurred, commencing with the paraspinal fascia and lumbar fascia. A fascial rotation flap was performed using the previously exposed pseudocapsule from the tissue spacer, aiming to ensure a watertight closure and to minimise the likelihood of a pseudomeningocoele. The layered closure used 4/0 vicryl dissolvable sutures and an extremely secure closure was achieved, completing the operative neurosurgical involvement (Fig. 8). Over the following days, it was clear that the twins were progressing well under the care of the multidisciplinary team. There were no obvious new neurological deficits, particularly of lower limb function or bladder or bowel dysfunction. Approximately 1 week postoperatively, despite the care of dural closure, a small pseudomeningocoele was thought to have developed in Twin A. The wound appeared infected around the site and a decision was made to return the child to theatre for wound debridement. The general paediatric surgeons performed a washout and debridement with removal of a Goretex implant used for urogenital closure, noting no evidence of CSF leak. The wound healed well and no further complications have yet been seen. At 1-year follow-up, the twins were progressing well. Neurological milestones were normal in Twin A, with Twin B maintaining persistent unilateral leg atrophy and subsequent weakness, despite successful correction of talipes equinovarus. Twin A is walking independently, whereas Twin B mobilises with the assistance of a rolling frame. Colostomies remain in place because it is unlikely that faecal continence will be achieved. A repeat MRI confirmed evidence of distal cord tethering and syrinx (Fig. 9). There is no evidence of pseudomeningocoele. Both twins show evidence of herniated cerebellar tonsils, which will necessitate further neurosurgical involvement.
of tissue spacers, as an additional autologous layer, to enhance the integrity of the surrounding tissues when performing a dural closure.10 We found the use of the pseudocapsule an extremely advantageous tool, especially because primary dural closure was only possible in one of the twins. Subsequently, dural integrity was mildly affected in the other twin. Preventing a CSF leak is of paramount importance in ensuring adequate wound healing, and even more so in the context of a child that has had gastrointestinal surgery because the risk of sepsis is markedly increased.19,20 We used synthetic and autologous dural patches, with overlying fascial closures, in an attempt to prevent pseudomeningocoele formation and CSF leak. Despite this, there was some evidence of a small pseudomeningocoele in Twin B (in whom primary dural closure was not possible) and an overlying wound infection. It is questionable whether the psedomeningocoele was the cause of the wound infection because CSF was not identified at the time of debridement, but also no further treatment with the exception of antibiotics, afforded a complete cure. However, CSF leak has been reported to occur in 37.5% of separated pyopagus twins with conjoined cords.19,20 We were mindful, having read previous neurosurgical insights into separation of pyopagus twins, of the possibility of retraction of the twins’ cords following separation and detethering. Ensuring careful visualization of adhesions and vessels, with adequate exposure proximally, appeared to prevent this, despite there being some tension with the twins’ cords. Undertaking a major surgical operation such as separation of pyopagus twins requires a well-rehearsed, multidsiciplinary communicative approach. Owing to the rarity of conjoint separation, it is clear that these procedures need to be performed in a unit that has access to all specialties involved with the procedure, including a paediatric intensive care unit. Because no operation on pyopagus twins will ever be the same, we hope that our experience from a neurosurgical perspective will provide some assistance to prospective operations, just as the literature aided our experience.
4. Discussion Conjoint twins have fascinated the medical fraternity for centuries and only recently has the potential for separation been feasible. The outcome of separation of pyopagus twins in the modern era is very successful owing to the nature of the fusion. The primary neurosurgical goals are to define a spinal cord separation that minimises neurological deficit and enables dural closure with the integrity to prevent CSF leak. Previous accounts in the separation of pyopagus twins have noted the use of the pseudocapsule from the insertion
Fig. 8. Separation.
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Fig. 9. Twelve month follow up sagittal T2-weighted MRI. Twin A: Distal syrinx and evidence of cerebellar tonsillar herniation (left, top and bottom). Twin B: Tethered cord, smaller syrinx and cerebellar tonsillar herniation (right, top and bottom).
Acknowledgement The authors acknowledge the help of Dr Askar Kukkady and the staff of Waikato Hospital for their excellent planning in the execution of a complicated procedure. References 1. Edmonds LD, Layde PM. Conjoined twins in the United States 1970– 1977. Teratology 1982;25:301–8. 2. Kaplan M, Eidelman AI. Clustering of conjoined twins in Jerusalem, Israel. Am J Obstet Gynaecol 1983;145:636–7. 3. Spencer R. Anatomic description of conjoined twins: a plea for standardized terminology. J Paedatr Surg 1996;31:941–4. 4. Spencer R. Theoretical and analytical embryology of conjoined twins. Part 1. Embryogenesis. Clin Anat 2000;13:36–53. 5. Hoyle RM. Collective review: surgical separation of conjoined twins. Surg Gynaecol Obstet 1990;170:549–58. 6. Perlstein MA, LeCount ER. Pyopagus twins. The history and necropsy report of the Bohemian Twins, Rosa–Josepha Blazek. Arch Pathol Lab Med 1926;3:171–92. 7. Adolph F. Ein menschlinger Pyopagus, Inaugural Dissertation. Marburg: Pathologic Institute; 1894. 8. Votteler TP. Conjoined twins. In: Welch KJU, Randolph JG, Ravitch MM, et al., editors. Paediatric Surgery. 4th ed. Chicago: Year Book Medical Publishers; 1986. p. 829–36. 9. Treyling JJ. Gemelac mediantibus ossibus coccyges sibi invicern connatae. Acta Physico-Med Acad 1740;5:445.
10. McDowell BC, Morton BE, Janik JS, et al. Separation of conjoined pygopagus twins. Plastic Reconstruct Surg 2003;111: 1998–2002. 11. Hockley AD, Walsch AR, Gornall P, et al. Management of pyopagus conjoined twins. Childs Nervous Syst 2004;20: 635–9. 12. Fieggen AG, Dunn RN, Pitcher RD, et al. Ischiopagus and pygopagus conjoined twins: neurosurgical considerations. Childs Nervous Syst 2004;20:640–51. 13. Spiegel DA, Ganley TJ, Akbarnia H, et al. Congenital vertebral anomalies in ischiopagus and pyopagus conjoined twins. Clin Orthop Relat Res 2000;381:137–44. 14. Kingston CA, McHugh K, Kumaradevan J, et al. Imaging in the preoperative assessment of conjoined twins. Radiographics 2001;21: 1187–208. 15. Fieggen AG, Peter J, Millar A, et al. Conjoined spinal cords in pyopagus twins. Lancet 2002;360:1934–40. 16. Manders EK. Soft tissue expansion in the lower extremities. Plastic Reconstruct Surg 1988;81:208–19. 17. Zubowicz V, Ricketts R. Use of skin expansion in separation of conjoined twins. Ann Plastic Surg 1988;20:272–6. 18. Zuker R, Filler R, Lalla R. Intra-abdominal tissue expansion: an adjunct in the separation of conjoined twins. J Pediatr Surg 1986;21: 1198–200. 19. Fieggen G, Millar A, Rode H, et al. Spinal cord involvement in pygopagus conjoined twins: case report and review of the literature. Childs Nervous Syst 2003;19:183–7. 20. Fieggen G, Peter J, Millar A, et al. Conjoined spinal cord in pyopagus twins. Lancet 2002;360:1934.
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more than 5 years after the initial treatment involving radiotherapy. Chemotherapy was administered to 34 of 101 patients and various treatment regimens were used.3,4,12,18 However, no clinical evidence of an effective response was seen. Thus, the effective total radiation dose has been reported previously to be over 50 Gy;5 however, increased radiation did not improve the outcome.4 The incidence of recurrence is high in local boosts to the pineal lesion if the tumour is histologically benign.11,19,20 The target volume concepts varied and LINAC or gamma knife radiosurgery were performed in only five previously reported cases.3,4,14 In the present case, surgical resection was performed first, with accurate diagnosis. Postoperative adjuvant therapy using LINAC radiosurgery followed immediately by initial chemotherapy was added to the treatment regimen. Tumour shrinkage was most apparent during the month following this combination therapy and the effect was sustained for 2 years after the initial treatment. It is difficult to say whether this response was due to the effect of radiation alone, chemotherapy alone or a combined effect of the two. In all, local and spinal control was good. In a recently reported study, the prognosis of patients with residual tumour and disseminated disease was considered less favourable.4 In patients with PPTID, careful attention to future regrowth or dissemination is required if the visible tumour has been removed totally.3,6,10,11 The treatment strategy used in the present case is considered to be a reasonable and effective option. References 1. Mena H, Nakazato Y, Jouvet A, et al. Pineal parenchymal tumors. In: Kleiheus P, Cavenee WK, editors. The WHO Classification of Tumours of the Central Nervous System. Lyon: IARC Press; 2002. p. 115–22. 2. The Committee of Brain Tumor Registry of Japan. Special report of Brain Tumor Registry of Japan (1969–1990). Neurol Med Chir (Tokyo) 1999;39:59–107. 3. Fauchon F, Jouvet A, Paquis P, et al. Parenchymal pineal tumors: a clinicopathological study of 76 cases. Int J Radiat Oncol Biol Phys 2000;46:959–68. 4. Lutterbach J, Fauchon F, Schild SE, et al. Malignant pineal parenchymal tumors in adult patients: patterns of care and prognostic factors. Neurosurgery 2002;51:44–56.
5. Schild SE, Scheithauer BW, Schomberg PJ, et al. Pineal parenchymal tumors: clinical, pathologic, and therapeutic aspects. Cancer 1993;72:870–80. 6. Jouvet A, Saint-Pierre G, Fauchon F, et al. Pineal parenchymal tumors: a correlation of histological features with prognosis in 66 cases. Brain Pathol 2000;10:49–60. 7. Hassoun J, Grambarelli D, Peragut JC, et al. Specific ultrastructural markers of human pinealomas: a study of four cases. Acta Neuropathol (Berl) 1983;62:34–40. 8. Jouvet A, Fevre-Montange M, Besancon R, et al. Structural and ultrastructural characteristics of human pineal gland, and pineal parenchymal tumors. Acta Neuropathol (Berl) 1994;88:334–48. 9. Kleihues P, Burger PC, Scheithauer BW. Pineal parenchymal tumours. In: Kleihues P, Burger PC, Scheithauer BW, editors. Histological Typing of the Tumours of the Central Nervous System. second ed. Berlin: Springer; 1993. p. 26–7. 10. Tsunoda S, Sakaki T, Tsujimoto M, et al. Clinicopathological study on pineocytoma. Brain Tumor Pathol 1995;12:31–7. 11. Tsumanuma I, Tanaka R, Washiyama K. Clinicopathological study of pineal parenchymal tumors: correlation between histopathological features, proliferative potential, and prognosis. Brain Tumor Pathol 1999;16:61–8. 12. Brockmeyer DL, Walker ML, Thompson G, et al. Astrocytoma and pineoblastoma arising sequentially in the fouth ventricle of the same patient: case report and molecular analysis. Pediatr Neurosurg 1997;26:36–40. 13. Chang SM, Lillis-Hearne PK, Larson DA, et al. Pineoblastoma in adults. Neurosurgery 1995;37:383–91. 14. Kurisaka M, Arisawa M, Mori T, et al. Combination chemotherapy (cisplatin, vinblastin) and low-dose irradiation in the treatment of pineal parenchymal cell tumors. Childs Nerv Syst 1998;14: 564–9. 15. Matsumoto K, Higashi H, Tomita S, et al. Pineal region tumours treated with interstitial brachytherapy with low activity sources (192iridium). Acta Neurochir (Wien) 1995;136:21–8. 16. Nakamura M, Saeki N, Iwadate Y, et al. Neuroradiological characteristics of pineocytoma and pineoblastoma. Neuroradiology 2000;42:509–14. 17. Schild SE, Scheithauer BW, Haddock MG, et al. Histologically confirmed pineal tumors and other germ cell tumors of the brain. Cancer 1996;78:2564–71. 18. Ashley DM, Longee D, Tien R, et al. Treatment of patients with pineoblastoma with high dose cyclophosphamide. Med Pediatr Oncol 1996;26:387–92. 19. D’Andrea AD, Packer RJ, Rorke LB, et al. Pineocytomas of childhood: a reappraisal of natural history and response to therapy. Cancer 1987;59:1353–7. 20. Ito T, Takahashi H, Ikuta F, et al. Metastatic pineocytoma of the spinal cord after long-term dormancy. Pathol Int 1994;44:860–4.
doi:10.1016/j.jocn.2005.11.036
Separation of pyopagus conjoined twins: A New Zealand neurosurgical experience Mark Winder *, Andrew Law Department of Neurosurgery, Level 8, Auckland Hospital, Grafton Road, Grafton, Auckland, New Zealand Received 29 September 2005; accepted 10 November 2005 *
Corresponding author. Tel.: +64 09 379 7440; fax: +64 09 307 2897. E-mail address: [email protected] (M. Winder).
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Abstract Conjoined twins represent a rare form of incomplete embryonic separation. They are classified into eight different subtypes, with 18% representing pyopagus conjoints. History is scattered with accounts of the various types of conjoints and it is only recently that strategies have been devised to enable surgical separation of such twins. It is estimated that approximately 20 cases of separation of pyopagus twins have been performed. We provide a historical look at pyopagus conjoint twins and report our neurosurgical experience of Australasia’s first separation of pyopagus twin girls. 2006 Published by Elsevier Ltd. Keywords: Conjoined; Neurosurgery; Twins
1. Introduction Conjoined twins are identical same-sex twins that develop from a single fertilized ovum with a single placenta. There is a female preponderance, with a ratio of approximately 3:1. The actual incidence of conjoined twins is difficult to ascertain partly because of their infrequency, but also because of the fact that many are incompatible with life or have been born in underdeveloped countries where accurate historical and medical records are unavailable. The largest epidemiological study to date suggests an incidence of 10.25 per million births;1 however, many of these are incompataible with life. There are no defined aetiological factors, although there have been reports of geographical clustering.2 Conjoints can be separated into eight subtypes according to a dorsal or ventral conjoin: omphalopagus, thoracopagus, cephalopagus, ischiopagus, parapagus, craniopagus, rachipagus and pyopagus.3,4 The most common conjoins are thoraco-omphalopagus, thoracopagus and omphalopagus, with approximately 15–20% being pyopagus. Pyopagus twins represent the group of conjoints in which separation of the embryonic axis in the caudal region was incomplete, with resultant fusion of the sacral elements. There is usually a common dura and the neural elements can be fused, which may be mild, as in the case of distal elements of the cauda equina, or more severe, such as where there is fusion of the caudal part of the two spinal cords. Because the fusion is thought to occur at the caudal neuropore, the structures derived from the cloacal membrane, such as the anus, are normally affected. 2. History The medical literature is dispersed with accounts of conjoint twins. Hoyle5 provides an excellent review of all reports of conjoint twins, whereas Perlstein and LeCount6 have documented the chronology of reported pyopagus twins, albeit with some sparse details. Mentioned below is a chronological review of several of the more historically well-documented pyopagus twins. The first documented pyopagus twins were May and Eliza Chalkhurst, The Biddenden Maids, born in 1100 AD in Kent, England (Fig. 1A). They survived until the age of 34 years, leaving their entire fortune to the church. An annual celebration of their generosity still exists with ‘Biddenden cakes’.7
The Hungarian Sisters, Helen and Judith, (Fig. 1B) were born in Szony, Hungary in 1701. They were pyopagus twins who survived until the age of 22 years and became the subject of a poem by Alexander Pope. The advent of easier modes of travel brought many more conjoints to the eyes of the world. The most historically famous twins, Eng and Chang Bunker, were born in Siam in 1811. They were displayed around the world in the Barnum Circus as the Siamese Twins (Fig. 1C). The Bunkers lived to an age of 63 years, were successful businessman and fathered 19 surviving children. Chang is thought to have contracted pneumonia and died, with Eng dying in a matter of hours of his brother’s death. Millie and Christine McKoy (Fig. 1D) were born into slavery in 1851 in North Carolina and were bought by a showman. They were kidnapped by a rival showman and displayed over the country before being reunited with their mother at the age of 4 years. They became excellent performers, writing and performing their own songs. They died of tuberculosis at the age of 61 years. Other famous pyopagus conjoints include the Blazinek sisters, known as ‘The Bohemian Twins’ (Fig. 1E). They were born in Skreychov, Bohemia, in 1878. They shared a single introitus, with separate vaginae separated by a thin septum. They were examined extensively by physicians, phrenologists and surgeons. These details are thoroughly reported by Perlstein and LeCount.6 At 32 years of age, Rosa and Josefa consulted a physician regarding an abdominal swelling. Rosa was diagnosed as being pregnant and later gave birth to a healthy boy. The father of the child was denied the right to marry Rosa on moral grounds. Twelve years later, at the age of 44 years, Josefa developed an hepatitic illness, likely cholecystitis, with a concomitant severe bronchopneumonia. She died 5 days after the onset of the illness, with Rosa dying approximately 12 min later. The Hilton sisters (Fig. 1F) were a set of pyopagus twins born in 1908, Sussex, England. They were exhibited all over America, featured in several films, including Freaks, before being lost to public interest. They died in 1969 from the Hong Kong flu. As can be seen from the historical reports, the life expectancy of pyopagus twins is not unduly affected by their condition. However, the advent of surgical expertise and instrumentation has allowed the possibility of separation of conjoint twins, raising ethical and moral issues.
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Fig. 1. (A) The Biddenden Maids, (B) the Hungarian Sisters (C) Eng and Chang Bunker, (D) the McKoy Sisters, (E) the Blazinek Sisters with father and child and (F) the Hilton Sisters (reproduced with permission of www.phreque.com and www.mypage.direct.ca/c/csmason/multiples/conjoined).
The separation of conjoint twins was first reported in Switzerland in 1689 on xiphopagus twins.8 In more recent times, there have been many attempts to separate various types of conjoints, with variable success. The first cited report of a surgical separation of pyopagus twins was in 1700, where two female twins underwent separation but died 4 months later.9 The first modern report of the separation of pyopagus twins was in 1953 in Louisianna, where female twins fused at the base of the spines, with fused
neural elements, were separated without apparent neurological deficit.8 Reviewing the literature, it is estimated that approximately 19 cases of pyopagus conjoint separation have been attempted, with results confirming that pyopagus twins have a good prognosis because the fused structures are generally not life-threatening. McDowell et al.10 estimated survival rates for pyopagus separation to be 50% when performed in the neonatal period compared with 90% if the operation was delayed at least 6 months. Recent separations
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described by Hockley et al.11 and Feiggen et al.12 support this notion. Thus, if feasible, surgery should be delayed until physiological reserve can be maximised and the appropriate imaging and extensive operative planning formulated. Below, we report our neurosurgical experience in the separation of pyopagus conjoint twins, the first operation of its type performed in New Zealand. 3. Case report Conjoined twin girls, conjoined at the lower lumbar vertebrae and sacrum, with fused spinal cords, were diagnosed at 18 weeks gestation. The mother was 23 years old (gravida 1, para 1). The conjoin was identified through a standard screening ultrasound performed at 18 weeks gestation (the standard 12-week ultrasound was missed). Foetal magnetic resonance imaging (MRI) confirmed a conjoin of the pyopagus type, identifying four lower limbs, four ilia and fused distal spinal elements (Fig. 2). After extensive discussion with the family, a decision was made that separation would be the most likely avenue of treatment should the pregnancy proceed in an uncomplicated manner. The family was made aware that there was no urgency for surgical separation, with the ideal timeframe dependent on the twins’ development. The twins were delivered via Caesarean section at 34 weeks gestation. Initial Apgar scores for the twins were 10 and 10. Their combined birth weight was 4690 g. Initial examination revealed the twins to be fused at the distal spinal region, sharing a single anus, so that they faced away from one another in a partially oblique fashion. Twin B had evidence of talipes equinovarus of the left lower limb with some associated atrophy, but no other distinct neurological or muscoloskeletal abnormalities (Fig. 3). The children were discharged from hospital after 3 weeks to be cared for at home. During that time, their growth and neurological milestones were assessed. The literature provided valuable information as to the merits of certain imaging modalities,11,13–15 with subsequent imaging including repeat MRI, magnetic resonance angiography (MRA), three-dimensional computed tomography (CT) and ultrasonographic examinations (Fig. 4). Imaging revealed sacral fusion commencing at approximately the S2 level, with the majority of the sacrum mostly belonging to Twin A. A single sacral canal appeared up to the level of S2. Each twin had independently functioning lower limbs, with four separate ilia and separate sacroiliac joints. One of the most useful imaging adjuncts, for both the neurosurgical and orthopaedic teams, was the development of a three-dimensional acrylic model of the ilia, sacrum and lumbar spines (Fig. 5). This allowed a thorough appreciation of the site of fusion and orientation, aiding the operative planning. A management team was organized that consisted of general paediatric surgery, plastic surgery, neurosurgery, orthopaedic surgery, neonatology, anaesthesiology, urology and social work. We will focus on the aspects that pertain to the neurosurgical focus of the separation of the twins.
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Following extensive imaging and discussion among the relevant specialties, it was determined that a single operation would be the most appropriate strategy enabling separation of the twins, with the likelihood of further surgery required for functioning gastrointestinal and urological systems. Three months prior to separation, the plastic surgery team inserted tissue spacers on the back of each twin with the aim of increasing the circumferential expansion around the site of the conjoin. The tissue expanders were expanded serially over an 8-week period. The use of tissue spacers in the separation of conjoint twins has been documented previously on several occasions;16–18 however, it is only recently that the use of the formed pseudocapsule has been considered in the pre-operative planning of a tissue closure.
Fig. 2. Fetal magnetic resonance imaging at 18 weeks.
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Fig. 3. Talipes equinovarus in Twin B.
The operation was performed at a facility without paediatric intensive care or neurosurgical capabilities, requiring transportation of a Zeiss NC4 Operative Microscope, instrumentation and experienced operative staff. A date was chosen to accommodate all surgical specialties, which corresponded to the twins’ age of 14 months. Immediate pre-operative preparation included standard bowel preparation with clear fluids 24 h prior to anaesthetic, with a fasting time of 4 h. Standard blood profiles were performed with cross-matched blood available at request, because expected blood loss was estimated at two blood volumes. Anaesthetic considerations for the conjoint separation had been well rehearsed with models. The patients were each intubated with central, arterial and peripheral lines placed. Positioning of the patients had been rehearsed assuming sterile fields as required. Initially, the patients were positioned in an anterolateral manner, prepared and free draped to enable the plastic surgeons to remove tissue expanders and mark out appropriate skin flaps. At the time, a pseudocapsule from the deep surface of the tissue-expanded cavity was mobilised to enable its use in the dural repair as required. The general paediatric surgeons then divided the single anus, with separation of the two rectums, enabling an initial approach to the anterior aspect of the sacrum. The conjoint twins were then repositioned, enabling the orthopaedic team to expose the posterior elements of the lower lumbar spine and sacrum. There was a single plate of posterior element at the fused junctional segment, with an open canal distally over the sacrum, which extended to the fifth lumbar vertebrae. Under microscopic vision, the posterior and lateral aspects of the laminae were carefully resected, enabling identification of the dura. A modified laminectomy of the distal components and a segmental laminoplasty of the more proximal segments were performed. The periosteum and overlying fascia were kept intact, where possible, to allow layered closure following dural repair. The dura of each twin’s spinal cord was clearly identified revealing the Y-shaped dura at the site of fusion (Fig. 6). The posterior elements of the lower lumbar vertebrae and upper
Fig. 4. Fose-natal three-dimensional computed tomography (top), magnetic resonance imaging (bottom).
sacral elements were moderately deficient in certain areas, allowing relatively easy exposure of the more proximal and distal dura, using Kerrison punches through the ligamentum flavum. At this time, it was apparent that the single dural sac of the distal spinal canal was not symmetrical, increasing the likelihood of tethered distal cauda equina components in one of the twins and neurological asymmetry. The dura was completely exposed in an extradural fashion to the distal limits, identifying the sites of major attachment. A durotomy was performed in the midline and carefully extended both proximally in each cord and distally in the conjoin, allowing identification of the conjoint’s spinal canal contents (Fig. 7). The cords were identified, confirming posterolateral fusion of the cords, which tapered into a single, mildly asymmetric conus and filum terminale. Multiple nerve rootlets
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Fig. 6. Dural exposure, showing clear exposure of the Y-shaped dural sac with obvious filum terminale. Fig. 5. Acrylic three-dimensional computed tomography model.
arising at the anterolateral and inferior aspects were interspersed with small intradural vessels (Fig. 7). There were abnormal rootlets arising from the midline of the conjoin and passing forwards, which inevitably would need sacrificing. In order to define the intradural contents and allow for a primary dural repair following cord separation, the dura was exposed as far distally as possible. Sites of adhesions were identified, with the cord and distal elements tethered in one of the twins. These adhesions were carefully released. The lateral aspects of the cords were identified to determine the degree of dura available for primary closure without compromising the canal contents. Once the dura was clear cicumferentially, a decision as to the most appropriate site of cordotomy was made. As shown in Fig. 6, fusion of the distal cord was not completely symmetrical. The main concerns were the nerve rootlets arising at the distal and lateral aspects of the fused cord, which passed distally and contralaterally. It was clear that it would be impossible to separate the cord without nerve root damage to some degree. Previous reports of the separation of pyopagus twins highlighted the degree to which the spinal cords retracted upon detethering and separation.12,19,20 Having been aware of this possibility, we wanted to ensure that no intradural vessels would be subject to forces causing haemorrhage. Therefore, we carefully ensured that the cords were free of communicating vessels and associated pial and arachnoid adhesions such that should retraction occur, haemorrhagic risk would be minimal. Having carefully released the cords proximally, a vertical cordotomy was performed starting lateral to the filum terminale and extending proximally in a midline position, assuming separation between the dorsal columns of each twin’s cord. At the distal site, several of the small nerve roots, which crossed contralaterally, were sacrificed to enable cord separation. Once separated, the cords retracted marginally, allowing excellent exposure of the arachnoid and dura around the cords.
The flium was then separated from the single cord. The posterior aspect of the dura was able to be freed from the underlying extradural soft tissues. The dura was then mobilised and a primary dural closure with 5/0 nylon performed, made possible in one of the twins due to the asymmetry of the dural sac. A primary closure was not entirely possible on the other twin and an autologous dural repair was required, with harvested fascial layer, also using 5/0 continuous nylon. Upon completion, there was no evidence of obvious cerebrospinal fluid (CSF) leak. The spinal canals were then packed with thrombin-soaked pledgelets, with salinesoaked patties placed to afford protection of the cords while the sacral separation was performed. The orthopaedic team then identified the site of the sacral conjoin and performed a separation of the posterior aspect through a plane of cartilage where possible. Once performed, the canal contents were protected and the conjoints were repositioned to enable the general surgical team to deal with the genitourinary and anorectal issues. Once completed, the orthopaedic team was able to approach the anterior aspect of the sacrum. This was divided carefully and separation of the
Fig. 7. Conjoint exposure.
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twins performed. Haemostasis was achieved carefully and the twins moved to separate operating fields. The twins were repositioned to allow exposure of the spinal canal and dural repair. Of the reported cases of separation of pyopagus conjoint twins, the risk of CSF leak is clearly highlighted. Aware of this fact, Duragen (Medtronic, Gladesville, NSW, Australia) was also placed over the sites of possible compromised dural integrity, together with fibrin glue along the length of the durotomy and site of repair. There was no evidence of CSF leak on valsalva manoeuvre. Once we were satisfied of dural integrity, a carefully layered closure occurred, commencing with the paraspinal fascia and lumbar fascia. A fascial rotation flap was performed using the previously exposed pseudocapsule from the tissue spacer, aiming to ensure a watertight closure and to minimise the likelihood of a pseudomeningocoele. The layered closure used 4/0 vicryl dissolvable sutures and an extremely secure closure was achieved, completing the operative neurosurgical involvement (Fig. 8). Over the following days, it was clear that the twins were progressing well under the care of the multidisciplinary team. There were no obvious new neurological deficits, particularly of lower limb function or bladder or bowel dysfunction. Approximately 1 week postoperatively, despite the care of dural closure, a small pseudomeningocoele was thought to have developed in Twin A. The wound appeared infected around the site and a decision was made to return the child to theatre for wound debridement. The general paediatric surgeons performed a washout and debridement with removal of a Goretex implant used for urogenital closure, noting no evidence of CSF leak. The wound healed well and no further complications have yet been seen. At 1-year follow-up, the twins were progressing well. Neurological milestones were normal in Twin A, with Twin B maintaining persistent unilateral leg atrophy and subsequent weakness, despite successful correction of talipes equinovarus. Twin A is walking independently, whereas Twin B mobilises with the assistance of a rolling frame. Colostomies remain in place because it is unlikely that faecal continence will be achieved. A repeat MRI confirmed evidence of distal cord tethering and syrinx (Fig. 9). There is no evidence of pseudomeningocoele. Both twins show evidence of herniated cerebellar tonsils, which will necessitate further neurosurgical involvement.
of tissue spacers, as an additional autologous layer, to enhance the integrity of the surrounding tissues when performing a dural closure.10 We found the use of the pseudocapsule an extremely advantageous tool, especially because primary dural closure was only possible in one of the twins. Subsequently, dural integrity was mildly affected in the other twin. Preventing a CSF leak is of paramount importance in ensuring adequate wound healing, and even more so in the context of a child that has had gastrointestinal surgery because the risk of sepsis is markedly increased.19,20 We used synthetic and autologous dural patches, with overlying fascial closures, in an attempt to prevent pseudomeningocoele formation and CSF leak. Despite this, there was some evidence of a small pseudomeningocoele in Twin B (in whom primary dural closure was not possible) and an overlying wound infection. It is questionable whether the psedomeningocoele was the cause of the wound infection because CSF was not identified at the time of debridement, but also no further treatment with the exception of antibiotics, afforded a complete cure. However, CSF leak has been reported to occur in 37.5% of separated pyopagus twins with conjoined cords.19,20 We were mindful, having read previous neurosurgical insights into separation of pyopagus twins, of the possibility of retraction of the twins’ cords following separation and detethering. Ensuring careful visualization of adhesions and vessels, with adequate exposure proximally, appeared to prevent this, despite there being some tension with the twins’ cords. Undertaking a major surgical operation such as separation of pyopagus twins requires a well-rehearsed, multidsiciplinary communicative approach. Owing to the rarity of conjoint separation, it is clear that these procedures need to be performed in a unit that has access to all specialties involved with the procedure, including a paediatric intensive care unit. Because no operation on pyopagus twins will ever be the same, we hope that our experience from a neurosurgical perspective will provide some assistance to prospective operations, just as the literature aided our experience.
4. Discussion Conjoint twins have fascinated the medical fraternity for centuries and only recently has the potential for separation been feasible. The outcome of separation of pyopagus twins in the modern era is very successful owing to the nature of the fusion. The primary neurosurgical goals are to define a spinal cord separation that minimises neurological deficit and enables dural closure with the integrity to prevent CSF leak. Previous accounts in the separation of pyopagus twins have noted the use of the pseudocapsule from the insertion
Fig. 8. Separation.
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Fig. 9. Twelve month follow up sagittal T2-weighted MRI. Twin A: Distal syrinx and evidence of cerebellar tonsillar herniation (left, top and bottom). Twin B: Tethered cord, smaller syrinx and cerebellar tonsillar herniation (right, top and bottom).
Acknowledgement The authors acknowledge the help of Dr Askar Kukkady and the staff of Waikato Hospital for their excellent planning in the execution of a complicated procedure. References 1. Edmonds LD, Layde PM. Conjoined twins in the United States 1970– 1977. Teratology 1982;25:301–8. 2. Kaplan M, Eidelman AI. Clustering of conjoined twins in Jerusalem, Israel. Am J Obstet Gynaecol 1983;145:636–7. 3. Spencer R. Anatomic description of conjoined twins: a plea for standardized terminology. J Paedatr Surg 1996;31:941–4. 4. Spencer R. Theoretical and analytical embryology of conjoined twins. Part 1. Embryogenesis. Clin Anat 2000;13:36–53. 5. Hoyle RM. Collective review: surgical separation of conjoined twins. Surg Gynaecol Obstet 1990;170:549–58. 6. Perlstein MA, LeCount ER. Pyopagus twins. The history and necropsy report of the Bohemian Twins, Rosa–Josepha Blazek. Arch Pathol Lab Med 1926;3:171–92. 7. Adolph F. Ein menschlinger Pyopagus, Inaugural Dissertation. Marburg: Pathologic Institute; 1894. 8. Votteler TP. Conjoined twins. In: Welch KJU, Randolph JG, Ravitch MM, et al., editors. Paediatric Surgery. 4th ed. Chicago: Year Book Medical Publishers; 1986. p. 829–36. 9. Treyling JJ. Gemelac mediantibus ossibus coccyges sibi invicern connatae. Acta Physico-Med Acad 1740;5:445.
10. McDowell BC, Morton BE, Janik JS, et al. Separation of conjoined pygopagus twins. Plastic Reconstruct Surg 2003;111: 1998–2002. 11. Hockley AD, Walsch AR, Gornall P, et al. Management of pyopagus conjoined twins. Childs Nervous Syst 2004;20: 635–9. 12. Fieggen AG, Dunn RN, Pitcher RD, et al. Ischiopagus and pygopagus conjoined twins: neurosurgical considerations. Childs Nervous Syst 2004;20:640–51. 13. Spiegel DA, Ganley TJ, Akbarnia H, et al. Congenital vertebral anomalies in ischiopagus and pyopagus conjoined twins. Clin Orthop Relat Res 2000;381:137–44. 14. Kingston CA, McHugh K, Kumaradevan J, et al. Imaging in the preoperative assessment of conjoined twins. Radiographics 2001;21: 1187–208. 15. Fieggen AG, Peter J, Millar A, et al. Conjoined spinal cords in pyopagus twins. Lancet 2002;360:1934–40. 16. Manders EK. Soft tissue expansion in the lower extremities. Plastic Reconstruct Surg 1988;81:208–19. 17. Zubowicz V, Ricketts R. Use of skin expansion in separation of conjoined twins. Ann Plastic Surg 1988;20:272–6. 18. Zuker R, Filler R, Lalla R. Intra-abdominal tissue expansion: an adjunct in the separation of conjoined twins. J Pediatr Surg 1986;21: 1198–200. 19. Fieggen G, Millar A, Rode H, et al. Spinal cord involvement in pygopagus conjoined twins: case report and review of the literature. Childs Nervous Syst 2003;19:183–7. 20. Fieggen G, Peter J, Millar A, et al. Conjoined spinal cord in pyopagus twins. Lancet 2002;360:1934.