1098940 case-report2022 JOR0010.1177/20551169221098940Journal of Feline Medicine and Surgery Open ReportsFarré Mariné et al Case Report Journal of Feline Medicine and Surgery Open Polysulfone tailor-made Reports 1­–7 © The Author(s) 2022 implant for the surgical Article reuse guidelines: sagepub.com/journals-permissions correction of a frontoparietal https://doi.org/10.1177/20551169221098940 DOI: 10.1177/20551169221098940 journals.sagepub.com/home/jfmsopenreports meningoencephalocoele in a cat This paper was handled and processed by the European Editorial Office (ISFM) for publication in JFMS Open Reports Alba Farré Mariné1, Martí Pumarola2 and Alejandro Luján Feliu-Pascual1 Abstract Case summary A 6-week-old entire female domestic shorthair cat was presented for evaluation of a soft bulge and a palpable skull defect on the forehead, present since adoption a few days earlier. The neurological examination revealed an absent menace response bilaterally and apparent blindness, localising the lesion to the occipital cortex. The main differential diagnoses were meningocoele (MC) and meningoencephalocoele (MEC). Surgical repair was proposed once the cat reached adult size. Meanwhile, the cat developed seizures and was treated with anticonvulsant therapy. At 6 months of age, CT confirmed a frontoparietal MEC with associated porencephaly. Based on a three-dimensional printed skull mould, a polysulfone implant was created. The meninges were dissected from the skin, a durectomy was performed and samples of the protruding brain were obtained. Part of the cerebrospinal fluid was drained until the size of the protruding brain decreased enough to be included below the implant that was anchored on top of the skull with cerclages. Histopathology confirmed the diagnosis of MEC. Three years and 7 months later, the cat had partially recovered vision but continued to seize monthly despite antiepileptic drugs. Relevance and novel information MC/MEC is a relatively uncommon disease reported in companion animals, and only four cases of surgical management have been described, and did not use a polysulfone tailor-made implant. In human medicine, surgical intervention is the treatment of choice. This case highlights a new implant option for surgical correction of MEC with good long-term result and no complications after 3 years and 7 months. Keywords: Meningoencephalocoele; polysulfone tailor-made implant; 3D reconstruction; frontoparietal Accepted: 19 April 2022 Introduction an option for dogs with MC/MEC and mild neurologi- Meningoencephalocoele (MEC) refers to a focal failure of cal signs,2 surgical intervention is considered the treat- the neuroectoderm and surface ectoderm to separate ment of choice in human medicine.13 during embryonic development. This induces a protru- The objective of this clinical report is to describe the sion of meninges and cerebral tissue through an opening use of a tailor-made polysulfone implant for the surgical in the calvaria (cranioschisis or cranium bifidum) that might be covered by skin.1 Numerous factors have been suggested as potential causes for this malformation, 1AUNA Especialidades Veterinarias-IVC Evidensia, Valencia, Spain including genetic defects, exposure to teratogenic agents 2Murineand Comparative Pathology Unit, UAB Veterinary School, during pregnancy and nutritional deficiencies.1–4 Barcelona, Spain Meningocoele (MC)/MEC is a relatively uncommon Corresponding author: disease reported in companion animals,1–12 and only Alba Farré Mariné LV, DipECVN, Aúna Especialidades four cases of surgical correction have been described.1,8,10,11 Veterinarias, Calle Algepser 22-1, Parque empresarial táctica, Although a multicentric retrospective study involving Paterna, Valencia 46980, Spain 22 dogs suggested that medical management could be Email: afm@aunaespecialidadesveterinarias.es Creative Commons Non Commercial CC BY-NC: This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (https://creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage). 2 Journal of Feline Medicine and Surgery Open Reports  correction of an extensive frontoparietal MEC in an 8-month-old cat and the long-term results. Case description A 6-week-old entire female domestic shorthair cat was presented for evaluation of a soft bulge and a palpable skull defect on the forehead since adoption a few days earlier (Figure 1). The physical examination did not reveal any other abnormalities. The only neurological deficit was an absent menace response bilaterally, which was attributed to the young age of the cat and the apparent blindness (see the video in the supplemen- tary material), localising the lesion to the occipital cortex. Differential diagnoses included congenital or traumatic MC or MEC. Echography through the cranial defect showed that the protruding tissue contained cer- ebral cortex and was associated with porencephaly. Therefore, a diagnosis of MEC and porencephaly was achieved. Surgical repair when the cat reached adult size was proposed. At the age of 4 months, the cat developed generalised tonic–clonic seizures and was initially treated with leve- tiracetam (20 mg/kg q8h PO gradually increased to Figure 1 Preoperative image of the cat at presentation 40 mg/kg q8h PO owing to poor seizure control [Keppra showing the large bulge in the forehead oral solution 100 mg/ml; UCB Pharma SA]). Then, when the cat was 6 months old, phenobarbitone (2 mg/kg For the surgical intervention, the cat was aseptically q12h PO gradually increased to 7.5 mg/kg q12h PO to prepared. The dorsal frontal region of the head was reach an acceptable serum level and seizure control shaved, from the dorsal limit of the nose to the second [Luminaletas 15 mg; Kern Pharma]) was added. At that cervical vertebra, including the lateral canthus of both stage, a CT study was performed under general anaes- eyes and the ears. The area was disinfected with 1% thesia with a 16-slice helical CT scanner (Brivo CT385; povidone-iodine (Braunosan H Plus Braun). The cat General Electric Healthcare). The CT images confirmed was positioned in straight sternal recumbency, with the the presence of severe cranioschisis with complete head placed on a sandbag and firmly fixed to the table. absence of the frontal bone, including the frontal sinuses A longitudinal incision was performed along the mal­ and part of the parietal bone. Both the meninges and cor- formation midline and extended 2 cm rostrally and cau- tical tissue protruded through the defect and porenceph- dally. The subcutaneous tissue was then carefully aly was also present. The caudal cranial fossa was dissected to separate the skin from the abnormally subjectively small, and the cerebellum appeared flat- thickened duramater, and the MEC was isolated. tened dorsoventrally (Figure 2). A three-dimensional Intravenous mannitol (0.25 g/kg [Mannitol 20%; Braun]) printed reconstruction of the cat’s skull helped to adapt and dexamethasone (0.05 mg/kg IV [Caliercortin 4 mg/ a polysulfone tailor-made implant (Beta Implants; ml Calier]) were administered as preventive treatment Pontevedra) for a perfect fit to cover the bone defect in case a subclinical increased intracranial pressure was (Figure 3). present, before performing the durectomy to remove the Surgical resolution was scheduled for 2 months later abnormal meninges and expose the protruded cerebral when the cat was 8 months old. Intramuscular pethi- cortex, whose macroscopic appearance was also abnor- dine (5 mg/kg IM [Dolantina 100 mg/2 ml; Kern mal. The resected meninges were sent for histopatho- Pharma]) and alfaxalone (0.5 mg/kg IM [Alfaxan 10 mg/ logical analysis. The exposed brain was hard and ml; Dechra]) were used as pre­ medication. Induction thickened, and no gyri were identifiable (Figure 4a). A was carried out with alfaxalone (0.5 mg/kg IV) and mida- 2 × 2 mm wedge biopsy of the protruding brain was also zolam (0.2 mg/kg IV [Midazolam 15 mg/3 ml; Normon]), submitted for histopathological study. Part of the cere- and an alfaxalone continuous rate infusion (CRI) was brospinal fluid lodged in the porencephalic cavity was used for anaesthetic maintenance at 10 mg/kg/h. drained with a 1 ml syringe until the volume of the pro- During surgery, a fentanyl (Fentanest Kern Pharma) truding brain decreased enough to be enclosed by the CRI was administered at 5 µg/kg/h and cefazolin tailor-made implant. Four holes were drilled in the (Cefazolin Normon) at 20 mg/kg every 1.5 h. No anaes- implant and another four at the edges of the cranial thetic complications were noted during the surgery. defect using a 1.5 mm drill bit so that they coincided Farré Mariné et al 3 Figure 2 (a) CT mid-sagittal reconstruction soft tissue algorithm showing severe cranioschisis with complete absence of the frontal bone, including the frontal sinuses and both meninges and brain tissue protruding through the defect consistent with meningoencephalocoele. Note a subjectively smaller-than-normal caudal cranial fossa and flattening of the cerebellum (black star); and (b) CT transverse plain of the same images at the level of the frontal lobe Figure 3 (a) Three-dimensional printed skull mould of the cranium of the cat at 6 months of age; and (b) the tailor-made polysulfone implant once the implant had been placed in the desired posi- Postoperative treatment included cefazolin (20 mg/kg tion. A haemostatic collagen mesh (Lyostyp; Braun) was q8h IV), dexamethasone (0.05 mg/kg q24h IV), pheno- placed between the brain tissue and the implant to barbitone (6.5 mg/kg q12h IV), levetiracetam (30 mg/kg replace the duramater. The implant was anchored to the q8h IV), maropitant (1 mg/kg q24h IV [Cerenia Zoetis]) skull with four 0.6 mm cerclages in the predrilled holes and a fentanyl CRI at 3 μg/kg/h, which was progressively (Figure 4b). The skin excess was removed using reduced over the first 24 h and replaced by buprenor- Metzembaum scissors to achieve a cosmetically ade- phine (10 µg/kg q8h IV [Buprecare Divasa-Farmavic quate appearance (Figure 5). The skin closure was per- SA DFV Group]). The cat was conscious and ambulatory formed in layers. within 12 h of surgery but showed ataxia and mild A postoperative CT revealed an acceptable congru- obtundation, which gradually improved during hos- ence between the implant and the skull with minimal pitalisation. The cat was discharged 3 days later with pneumocephalus (Figure 6). slight obtundation, mild ataxia and bilateral blindness. 4 Journal of Feline Medicine and Surgery Open Reports  Figure 4 (a) Intrasurgical image showing the exposed protruding brain tissue after durectomy; and (b) intraoperative image showing the implant placement and fixation with cerclages within predrilled holes Check-ups were carried out 1 week after surgery, 3 weeks later, then 2 months and 6 months after the intervention. At that time, the cat had partially recovered vision despite an absent menace response bilaterally. Otherwise, the neurological examination was normal, and the cat had no seizures since the surgery 6 months earlier. However, the cat started seizing again when a gradual decrease in levetiracetam was initiated and the treatment was reinstituted. One year after surgery, the cat was admitted for a conventional ovariohysterectomy that proceeded without complications. At that point, a recheck CT was performed observing that the implant was still in the same position and the pneumocephalus, present in the CT immediately postsurgery, had resolved (Figure 8). Three years and 7 months after surgery, the cat remained stable with a good quality of life and partial visual capacity, despite bilaterally absent menace Figure 5 Postoperative image of the cat a few months after response. At the time of final follow-up, 43 months surgery, showing acceptable cosmetic results postoperatively, the cat was seizing monthly despite receiving phenobarbitone (6.5 mg/kg q12h) and leveti- The histopathological and immunohistochemical racetam (30.5 mg/kg q8h). results showed disorganised nervous tissue and lepto­ meningeal thickness. The cerebral cortex was deprived of Discussion gyri and showed abnormal neural architecture with loss In human medicine, surgical intervention is considered of columnar and laminar organisation, a marked decrease the treatment of choice for MEC.13 This is based on the in the number of neuronal cell bodies and microspongi- potential for recurrent meningitis, brain damage from osis of the neuropil. Areas of neuronal pyknosis were herniation and refractory seizures, as MECs are thought observed along with reactive gliosis, astrocytosis, a large to act as seizure foci.2 Goals include removing the dural number of rod cells and activated macrophages contain- sac, preserving functional brain tissue and obtaining ing cytoplasmic dark material. The subcortical white adequate wound closure.1 matter showed loss of eosinophilia and excessive nerve Although MEC/MCs have been described in dogs fibre separation. The leptomeninges were accompanied and cats,1–12 and also occasionally reported in other by vascular proliferation and an increase in the fibrous species, including calves,14–18 pigs,19 a rabbit20 and a collagen-like component. The duramater was disorgan- raccoon,21 most of those animals were euthanased or ised, with abundant dense collagen bundles and calcifi- treated conservatively. Medical management has been cation. Inflammation was not a feature (Figure 7). These suggested for 22 dogs with MC/MEC and mild neuro- findings were all consistent with an MEC. logical signs.2 However, 73% of those dogs suffered an Farré Mariné et al 5 Figure 6 (a) Immediate postoperative CT mid-sagittal reconstruction soft tissue algorithm showing the tailor-made implant in place. Note the presence of postoperative pneumocephalus. (b) CT transverse plain of the same images at the level of the frontal lobe intranasal MEC and only 27% had the parietal bone affected; all of them with only meninges protruding through the parietal bone defect.2 On the other hand, surgical correction has only been described in two dogs,8,10 two cats1,11 and two calves.15,17 The scarce num- ber of MEC cases described in the veterinary literature precludes any conclusion regarding the best treatment option for this pathology, and needs to be evaluated on a case-by-case basis. Given the size of the bone defect and the large amount of protruding neural tissue in the pre- sent case, surgical repair was considered the best treat- ment for this cat. Both surgically treated dogs described previously,8,10 and one of the cats,11 suffered from an ethmoidal MEC and seizures, which were repaired after resection of the herniated tissue. In one of these dogs8 and the cat,11 seizures resolved after surgical resection; however, seizure frequency did not change after surgery in the other dog,10 which was attributed to the development of additional seizure foci as the dog had been seizing 36 months prior to the surgery. Finally, the sole cat reported with a parietal MEC had only a small amount of pro- truded brain tissue, and an abrupt resolution of aggres- siveness was also observed after surgical resection of the herniated tissue.1 The present case represents the Figure 7 (a) Microscopic transverse section of the abnormal largest surgically treated MEC; a complete resection protruding cerebral cortex (NeuN immunohistochemistry was not considered as it might have affected the cat’s counterstained with haematoxylin). Note the absence of sulci quality of life. This could have contributed to the fact and abnormal organisation of neuronal laminae with irregular that the cat continued seizing after surgery; however, density of neuronal cell bodies. (b) Microscopic transverse both concurrent malformations (porencephaly and an section of the abnormal protruding tissues (haematoxylin and eosin staining). Note leptomeningeal thickening (*) and cell abnormally small cranial caudal fossa present in our proliferation forming fibrous solid or concentric structures. The case) and a large volume of herniated neural tissue adjacent cortical cerebral tissue shows abnormal distribution have also been described as negative prognostic factors of neuronal cell bodies in human medicine.13 6 Journal of Feline Medicine and Surgery Open Reports  Figure 8 (a) Twelve-month postoperative CT mid-sagittal reconstruction soft tissue algorithm showing complete resolution of the postoperative pneumocephalus and correct implant positioning. (b) CT transverse plain of the same images at the level of the frontal lobe Regarding the different implant options available to and mechanical properties, volume to hold the tissue and close the MEC bone defect, described techniques in good aesthetic results. Recently, three-dimensional print- companion animals include dural substitutes and/or ing has become increasingly popular in the veterinary autologous fascia,8,10,11 and a titanium mesh covered by community as models for teaching purposes,22–24 and polymethylmethacrylate on both sides.1 Dural substi- also in clinical neurosurgery as three-dimensionally tutes and/or autologous fascia have only been used to printed titanium plates for cranioplasty in canine skull repair ethmoidal MEC;8,10,11 they were not considered in tumours;25 three-dimensionally printed patient-specific the present case owing to the location and extension of drill guides for spinal deformities,26 vertebral fractures27 the cranial defect. A hard implant was required to pro- and atlanto-axial ventral stabilisation;28 and imaging- tect the brain below. Comparing the implant used in our based three-dimensionally printed stereotactic brain case with the titanium mesh covered by polymethyl- biopsy devices in dogs.29 methacrylate,1 the latter is more voluminous as it requires a greater thickness to achieve the same resist- ance and rigidity; it is heavier (4.42 g/cm3 vs 1.31 g/cm3); Conclusions To our knowledge, the case described here is the first to more difficult to adapt intraoperatively; and it is radio- use a tailor-made polysulfone implant based on a three- paque, so it could interfere in future advanced imaging dimensionally printed mould to close an MEC defect, results. The tailor-made polysulfone implant was cho- sen for several reasons. First, given the extension of the and provided excellent cosmetic results. This case high- defect, we needed a more dome-shaped implant than lights a new implant option for surgical correction of commonly used, which would have been more difficult MEC with good long-term results and no complications to achieve with the titanium mesh and polymethyl- to date. methacrylate. Secondly, being able to tailor it before the surgery allowed the implant to perfectly fit in the defect. Acknowledgements The authors acknowledge the work Finally, having the implant ready at the time of surgery and effort of the referring veterinarian, all the veterinarians and allowed us to save surgical time that we would have nurses that were involved in the case, and the shelter that found spent adjusting the titanium mesh to the defect and the cat and fought to make this outcome possible. covering it with polymethylmethacrylate on both sides. Supplementary material The following file is available For the tailor-made implant design, a specific soft- online: ware for industrial three-dimensional design was used. Video 1: Neurological examination of the kitten at 6 weeks. First, a virtual three-dimensional model to simulate the surgery was generated from the CT images and the Conflict of interest The authors declared no potential surgeon’s indications. The implant was then created to conflicts of interest with respect to the research, authorship, fulfil adequate adaptation to the skull anatomy, physical and/or publication of this article. Farré Mariné et al 7 Funding The authors received no financial support for the 12 Günther C, Beckmann KM and Steffen F. Formation of a research, authorship, and/or publication of this article. meningoencephalocele after removal of a frontal lobe meningioma by transfrontal craniotomy in a cat. JFMS Ethical approval The work described in this manuscript Open Rep 2020; 6. DOI: 10.1177/2055116920957195. involved the use of non-experimental (owned or unowned) 13 Thompson D. Postnatal management and outcome for animals. Established internationally recognised high standards neural tube defects including spina bifida and encepha- (‘best practice’) of veterinary clinical care for the individual locoeles. Prenat Diagn 2009; 29: 412–419. patient were always followed and/or this work involved the 14 Buck B, Ulrich R, Whöhlke A, et al. Two rare brain mal- use of cadavers. Ethical approval from a committee was there- formations in black and white German Holstein calves. fore not specifically required for publication in JFMS Open Dtsch Tierarztl Wochenschr 2009; 116: 192–199. Reports. Although not required, where ethical approval was still 15 Krishna NVVH and Palli RK. Surgical management of obtained, it is stated in the manuscript. congenital meningo encephalocele in a new born Jersey calf : a case report. J Adv Vet Anim Res 2016; 7710: 192–194. Informed consent Informed consent (verbal or written) 16 Lee K, Yamada K, Tsuneda R, et al. Clinical experience of was obtained from the owner or legal custodian of all animal(s) using multidetector-row CT for the diagnosis of disorders described in this work (experimental or non-experimental in cattle. Vet Rec 2009; 165: 559–562. animals, including cadavers) for all procedure(s) undertaken 17 Ohba Y, Iguchi T, Hirose Y, et al. Computer tomography (prospective or retrospective studies). For any animals or diagnosis of meningoencephalocele in a calf. J Vet Med Sci people individually identifiable within this publication, 2008; 70: 829–831. informed consent (verbal or written) for their use in the 18 Zani DD, De Zani D, Morandi N, et al. Imaging diagnosis – publication was obtained from the people involved. split cord malformation. Vet Radiol Ultrasound 2010; 51: 57–60. 19 Cho IC, Park YS, Yoo JG, et al. Two cases of meningocele ORCID iD Alejandro Luján Feliu-Pascual https://orcid. and meningoencephalocele in Jeju native pigs. BMC Vet org/0000-0002-3555-9248 Res 2015; 11. DOI: 10.1186/s12917-015-0404-y. 20 Geelen JAG. A case of hydrocephalus and meningoenceph- References alocele in a rabbit, caused by aqueductal malformation. 1 Dewey CW, Brewer DM, Cautela MA, et al. Surgical treat- Lab Anim 1974; 8: 167–176. ment of a meningoencephalocele in a cat. Vet Surg 2011; 21 Render AJA, Kazacos EA, Kazacos KR, et al. Ocular, 40: 473–476. naso-maxillary, and neural anomalies in raccoons, Pro- 2 Lazzerini K, Gutierrez-Quintana R, José-López R, et al. cyon Lotor (L.). J Wildl Dis 1983; 19: 234–243. Clinical features, imaging characteristics, and long-term 22 da Silveira EE, da Silva Lisboa Neto AF, Sabino Pereira HC, outcome of dogs with cranial meningocele or meningo­ et al. Canine skull digitalization and three-dimensional encephalocele. J Vet Intern Med 2017; 31: 505–512. printing as an educational tool for anatomical study. J Vet 3 Sponenberg D and Graf-Webster E. Hereditary meningo- Med Educ 2021; 48: 649–655. encephalocele in Burmese cats. J Hered 1986; 77: 60. DOI: 23 de Souza Lima A, Machado M, de Cassia Ribeiro Pereira 10.1093/oxfordjournals.jhered.a110173. R, et al. Printing 3D models of canine jaw fractures 4 Parker A and Cusick P. Meningoencephalocele in a dog for teaching undergraduate veterinary medicine (a case history). Vet Med Small Anim Clin 1974; 69: 55–67. 1. Acta Cirúrgica Bras 2019; 34. DOI: 10.1590/s0102- 5 Rosenblatt AJ, Scrivani PV, Caserto BG, et al. Imaging 865020190090000006. diagnosis-meningoencephalitis secondary to suppurative 24 Suñol A, Aige V, Morales C, et al. Use of three-dimensional rhinitis and meningoencephalocele infection in a dog. printing models for veterinary medical education: impact Vet Radiol Ultrasound 2014; 55: 614–619. on learning how to identify canine vertebral fractures. 6 Jeffery N. Ethmoidal encephalocoele associated with J Vet Med Educ 2019; 46: 523–532. seizures in a puppy. J Small Anim Pract 2005; 46: 89–92. 25 James J, Oblak ML, Linden AR, et al. Schedule feasibility 7 Noden D and Evans H. Inherited homeotic midfacial and workflow for additive manufacturing of titanium malformations in Burmese cats. J Craniofac Genet 1986; 2: plates for ranioplasty in canine skull tumors. BMC Vet Res 249–266. 2020; 16. DOI: 10.1186/s12917-020-02343-1. 8 Martlé VA, Caemaert J, Tshamala M, et al. Surgical treat- 26 Elford JH, Oxley B and Behr S. Accuracy of placement of ment of a canine intranasal meningoencephalocele. Vet pedicle screws in the thoracolumbar spine of dogs with Surg 2009; 38: 515–519. spinal deformities with three-dimensionally printed 9 Woerde DJ, Hoffmann KL and Brown NL. Fronto­ patient-specific drill guides. Vet Surg 2020; 49: 347–353. ethmoidal encephalocele in a cat. JFMS Open Rep 2018; 4. 27 Oxley B and Behr S. Stabilisation of a cranial cervical DOI: 10.1177/2055116918783147. vertebral fracture using a 3D -printed patient-specific drill 10 Mojarradi A, Meervenne S Van, Bonnet AS, et al. Diagnosis, guide. J Small Anim Pract 2016; 57: 277. treatment and postsurgical complications in a dog with 28 Toni C, Oxley B and Behr S. Atlanto-axial ventral stabili- epileptic seizures and a naso‑ethmoidal meningoenceph- sation using 3D-printed patient-specific drill guides for alocele. Acta Vet Scand 2021; 63. DOI: 10.1186/s13028-021- placement of bicortical screws in dogs. J Small Anim Pract 00591-1. 2020; 61: 609–616. 11 Nozue Y, Yamazaki M, Nakata K, et al. Case report: 29 Gutmann S, Winkler D, Müller M, et al. Accuracy of a mag- surgical treatment for intranasal meningoencephalocele netic resonance imaging-based 3D printed stereo­tactic brain in a cat. Front Vet Sci 2020; 7. DOI: 10.3389/fvets.2020.00532. biopsy device in dogs. J Vet Intern Med 2020; 34: 844–851.