Spina Bifida, Meningomyelocele, and Meningocele

The most common congenital malformations in dogs: Literature review and practical guide

Congenital malformations can affect almost 7% of canine newborns. The increase of commercial dog breeding and inbreeding used to maintain the striking characteristics of each breed, the appearance of malformations has become increasingly common, especially in brachycephalic dogs. The causes are diverse, and include genetic, nutritional, iatrogenic, and infectious factors, often making it difficult to establish a cause-consequence relationship. The high mortality associated with malformations comes not only from the fact that some are incompatible with life, but also because even if many undergo surgical treatment or correction, they require specific management, monitoring, and clinical treatment for an indefinite period of time. The most common malformations such as cleft lip and palate, hydrocephalus and anasarca have been studied for a long time, and it is currently known that brachycephalic dogs have a greater predisposition, however, for other less common conditions as gastroschisis and hypospadias, there is only a few case reports. The appearance of congenital defects in a litter leads to financial losses for the breeder, emotional losses for the owner and the veterinarian and harms the well-being of that individual. For this reason, the aim of this review article is to gather relevant information on the characteristics, diagnosis, and management of the main malformations in puppies. It is essential that the veterinarian is prepared to diagnose and treat these conditions, reducing negative impacts on animals and owners.

Vertebral and spinal malformations in small brachycephalic dog breeds: Current knowledge and remaining questions

Small brachycephalic dog breeds, such as the French bulldog, English bulldog and pug have become increasingly popular. These breeds are predisposed to a variety of vertebral and spinal malformations, including hemivertebra, caudal articular process dysplasia, transitional vertebra, cranial thoracic vertebral canal stenosis, spinal arachnoid diverticulum and meningeal fibrosis. Recent studies have provided new insights into the prevalence, anatomical characteristics, pathophysiology and treatment of these conditions. Thoracic hemivertebra, caudal articular process dysplasia, transitional vertebra, and cranial thoracic vertebral canal stenosis occur commonly in neurologically normal dogs. Although the clinical relevance of these vertebral anomalies has therefore been questioned, severe kyphosis and hemivertebra in pugs have been associated with an increased likelihood of neurological signs. Meningeal fibrosis is characterised by the formation of dense intradural fibrotic adhesions, constricting the spinal cord. This condition has been heavily associated with the pug breed. It is in pugs further common to observe multiple concurrent spinal disorder in association with chronic progressive pelvic limb gait abnormalities. This clinical presentation has been referred to as 'pug dog thoracolumbar myelopathy' and potential genetic risk factors have recently been identified. Despite our increased knowledge, many questions remain currently unanswered. This review discusses our current understanding and controversies surrounding vertebral and spinal malformations in small brachycephalic dog breeds.

Profile of a Multivariate Observation under Destructive Sampling-A Monte Carlo Approach to a Case of Spina Bifida

A biodegradable hybrid polymer patch was invented at the University of Cincinnati to cover gaps on the skin over the spinal column of a growing fetus, characterized by the medical condition spina bifida. The inserted patch faces amniotic fluid (AF) on one side and cerebrospinal fluid on the other side. The goal is to provide a profile of the roughness of a patch over time at 0, 4, 8, 12, and 16 weeks with a 95% confidence band. The patch is soaked in a test tube filled with either amniotic fluid (AF) or phosphate-buffered saline (PBS) in the lab. If roughness is measured at any time point for a patch, the patch is destroyed. Thus, it is impossible to measure roughness at all weeks of interest for any patch. It is important to assess the roughness of a patch because the rougher the patch is, the faster the skin grows under the patch. We use a model-based approach with Monte Carlo simulations to estimate the profile over time with a 95% confidence band. The roughness profiles are similar with both liquids. The profile can be used as a template for future experiments on the composition of patches.

Case report: Sacral agenesis in two boxer dogs: clinical presentation, diagnostic investigations, and outcome

Two boxer dogs from the same litter were presented at 3 months of age for urinary and fecal incontinence. Both dogs had an abnormal tail consisting of a small stump, an atonic anal sphincter, and absent perineal reflex and sensation. Neurological evaluation was indicative of a lesion of the cauda equina or sacral spinal cord. Radiology and CT scan of the spine displayed similar findings in the two dogs that were indicative of sacral agenesis. Indeed, they had 6 lumbar vertebrae followed by a lumbosacral transitional vertebra, lacking a complete spinous process, and a hypoplastic vertebra carrying 2 hypoplastic sacral transverse processes as the only remnant of the sacral bone. Caudal vertebrae were absent in one of the dogs. On MRI, one dog had a dural sac occupying the entire spinal canal and ending in a subfascial fat structure. In the other dog, the dural sac finished in an extracanalar, subfascial, well-defined cystic structure, communicating with the subarachnoid space, and consistent with a meningocele. Sacral agenesis-that is the partial or complete absence of the sacral bones-is a neural tube defect occasionally reported in humans with spina bifida occulta. Sacral agenesis has been described in human and veterinary medicine in association with conditions such as caudal regression syndrome, perosomus elumbis, and Currarino syndrome. These neural tube defects are caused by genetic and/or environmental factors. Despite thorough genetic investigation, no candidate variants in genes with known functional impact on bone development or sacral development could be found in the affected dogs. To the best of the authors' knowledge, this is the first report describing similar sacral agenesis in two related boxer dogs.

Postnatal Surgical Correction of Myelomeningoceles: Preoperative and Intraoperative Risk Factors Associated with Postoperative Neurologic Outcomes

OBJECTIVE

Open spina bifida or myelomeningocele (MMC) is a congenital defect that results from failure of caudal neurulation. We present a case series of patients who were treated with postnatal surgical correction for MMC, evaluating the possible preoperative and intraoperative risk factors associated with neurologic outcomes.

METHODS

A retrospective chart review of patients who underwent postnatal surgical correction for MMCs over 11 years at our institution was performed. MMCs were classified based on their morphologic configuration into 3 types. Type I includes defects without a sac and there is cerebrospinal fluid (CSF) leak. Type II includes where there is a sac ≤4 cm, with or without CSF leak. Type III includes defects with a sac that are greater than 4 cm.

RESULTS

Fifty patients were included. The median age of gestation at surgery was 37.4 weeks. There were 30 females (60%). All mothers received adequate folate supplementation. All patients underwent surgical correction in the first 48 hours. Lower extremity motor function at the last clinical follow-up was normal in 34 patients (68%). CSF leak, infection, and mortality were 8%, 2%, and 0%, respectively. Twenty-one patients (42%) underwent ventriculoperitoneal shunt for hydrocephalus.

CONCLUSIONS

Despite there being no statistically significant associations with a timely closure, all cases were treated within the first 48 hours and this could influence the low complication rate. Individuals of Hispanic background who received appropriate folate supplementation still had high rates of MMC and we posit that this may be caused in part by a genetic/molecular predisposition.

Postnatal surgery for myelomeningocele in neonates: neurodevelopmental outcomes

BACKGROUND

The study aims to evaluate the neurodevelopmental outcomes of neonates with myelomeningocele (MMC) operated in the postnatal period.

METHODS

This is a prospective follow-up study in a tertiary neonatal intensive care unit. Neurodevelopmental outcomes of term neonates operated for MMC and healthy term newborns were compared with the Bayley Scales of Infant and Toddler Development -Third Edition (BSID III) at 12-18 months.

RESULTS

A total of 57 cases were included in the study (patient group = 27; control group = 30). Demographic data between the groups were similar. Cognitive, linguistic, and motor composite scores of the patient group were lower than those of the control group (p < 0.001). In the patient group, those who underwent ventriculoperitoneal shunt had lower cognitive, language and motor scores than those without shunt (p < 0.05). The cognitive, linguistic, and motor composite scores in the patient group who underwent surgery before 72 h were better than those who underwent surgery after 72 h.

DISCUSSION

In our study, it was found that the neurodevelopmental prognosis of MMC cases requiring ventriculoperitoneal shunt in the postnatal period was significantly worse than those without shunt. It is the first study in which the neurodevelopment of patients with MMC who were operated in the postnatal period was evaluated with BSID III evaluated and delays in all areas were shown in cases with MMC compared to normal cases. Better neurodevelopmental outcomes in patients operated in the first 72 h suggest that early surgery will improve neurodevelopmental outcomes in patients with MMC.

Neurogenic Bladder in Dogs, Cats and Humans: A Comparative Review of Neurological Diseases

Lower urinary tract disease (LUTD) includes abnormalities in the structure and function of the bladder and the urethra. LUTD caused by neurological disease is defined neurogenic bladder (NB). The integrity of the central nervous system (CNS) and peripheral nervous system (PNS) is required to explicate normal micturition, maintaining the proper function of bladder and urethra. The location and type of neurological lesions influence the pattern of clinical manifestations, potential treatment, and prognosis. Though, in dogs and cats, spinal cord injury is considered mainly responsible for bladder and/or urethra incompetence, other disorders, congenital or acquired, involving CNS or PNS, could play a role in NB. In veterinary medicine, the information about the epidemiology, prevalence, etiopathogenesis, diagnosis and treatment of NB are scattered. The aim of this study is to provide an overview of the epidemiology, prevalence, clinical findings, diagnosis and prognosis for NB in dogs and cats compared with humans.

Case Report: Surgical Treatment of Type IV Spinal Dermoid Sinus in a Shiba Inu

A 2-year-old spayed female Shiba Inu was presented with progressive non-ambulatory bilateral paraparesis, back pain, and urinary incontinence. CT and MRI revealed multiple vertebral malformations and type IV dermoid sinus. Hemilaminectomy was performed in T1–T5 to remove the dermoid sinus and granulomatous lesion that infiltrated into the spinal cord parenchyma. Histopathological examination of the excised tissue revealed type IV dermoid sinus with granulomatous meningomyelitis. After surgery, back pain was resolved, and the dog recovered ambulation and voluntary urination at the time of follow-up 4 months after surgery.

Comparison of inherited neural tube defects in companion animals and livestock

Neural tube defects (NTDs) are congenital malformations resulting from the improper or incomplete closure of the neural tube during embryonic development. A number of similar malformations of the protective coverings surrounding the central nervous system are also often included under this umbrella term, which may not strictly fit this definition. A range of NTD phenotypes exist and have been reported in humans and a wide range of domestic and livestock species. In the veterinary literature, these include cases of anencephaly, encephalocele, dermoid sinus, spina bifida, and craniorachischisis. While environmental factors have a role, genetic predisposition may account for a significant part of the risk of NTDs in these animal cases. Studies of laboratory model species (fish, birds, amphibians, and rodents) have been instrumental in improving our understanding of the neurulation process. In mice, over 200 genes that may be involved in this process have been identified and variant phenotypes investigated. Like laboratory mouse models, domestic animals and livestock species display a wide range of NTD phenotypes. They remain, however, a largely underutilized population and could complement already established laboratory models. Here we review reports of NTDs in companion animals and livestock, and compare these to other animal species and human cases. We aim to highlight the potential of nonlaboratory animal models for mutation discovery as well as general insights into the mechanisms of neurulation and the development of NTDs.

Limited dorsal myeloschisis in three cats: a distinctive form of neural tube defect

Case series summary

The aim of this case series was to describe the clinical presentation, imaging findings and histopathology of three cats with limited dorsal myeloschisis (LDM). The history, examination and MRI sequences were reviewed in three cases presented to a single referral hospital. The surgery report and histopathology were described in two cases. All cats were young (10 weeks old, 5 months old, 4 years old), presenting with varying degrees of progressive paraparesis. All had a midline skin defect overlying the spinal column that was either sunken or saccular, containing fluid thought to be cerebrospinal fluid. MRI sequences demonstrated tissue extending from the dura through an overlying bifid spinous process and attached to the dermis, with associated spinal cord tethering, atrophy and syringomyelia. Lesions were located at L2–L3, T8–T9 and L4. Histopathology described a fibroneural stalk with a glio-ependymal lining, surrounded by glial nests and nerve fibres. The youngest and most severely affected was euthanased, while the other two underwent surgery. Both regained independent ambulation with persistent paraparesis; however, one required ongoing management of urinary incontinence.

Relevance and novel information

LDM is a primary neural tube defect that may result in neurological deficits, including bladder dysfunction, and is characterised by a fibroneural stalk between the dermis and the spinal cord. Distinct MRI features, such as a visible intrathecal tract, dorsally tethered cord and syringomyelia, help distinguish this condition from the clinically similar dermoid sinus. The presence of progressive neurological signs, with a palpable midline defect overlying the affected spinal cord segment, may raise suspicion for this clinical entity in veterinary patients.

Surgical outcomes of six bulldogs with spinal lumbosacral meningomyelocele or meningocele

OBJECTIVE

To report the surgical treatment and outcome of six bulldogs with spina bifida (SB) and meningocele (MC) or meningomyelocele (MMC).

STUDY DESIGN

Case series.

ANIMALS

Five French bulldogs and one English bulldog with MC or MMC.

METHODS

Medical records of dogs with spinal MC or MMC diagnosed by MRI at two institutions between 2013 and 2016 were reviewed for surgical treatment and outcomes.

RESULTS

Meningocele was diagnosed in two dogs, and MMC was diagnosed in four dogs. A lumbosacral dimple was noted in all dogs along with neurological deficits most commonly consisting of urinary and fecal incontinence (n = 6) and mild/moderate paraparesis (n = 3). Dorsal laminectomy was performed in all dogs to allow dissection of the meningeal sac to the vertebral column defect. In dogs with MMC, nerves were repositioned and protruded meninges were removed prior to suturing remaining meninges. Adhesions and filum terminale were resected in two dogs with suspected tethered cord syndrome. Urinary and fecal incontinence improved in two dogs and remained unchanged in four. Paraparesis improved in two dogs.

CONCLUSION

Surgical treatment resulted in partial improvement of the urinary and fecal incontinence (2/6 dogs) and paraparesis (2/3 dogs) or stable neurological condition (3/6 dogs), with only minor temporary complications.

CLINICAL SIGNIFICANCE

In the absence of published data comparing surgical and conservative treatment of puppies affected by SB and MC or MMC, early surgical treatment can be considered to prevent deterioration of neurological signs and, eventually, facilitate improvement of neurological signs.

Dermoid sinus type VI associated with spina bifida and tethered cord syndrome in a French Bulldog

A 4-mo-old French bulldog was presented with acute onset pain and reluctance to move. A tubular structure arising in the dorsal thoracic midline and extending from a cutaneous orifice into deeper tissues was palpated on physical examination. Computed tomography with sinography revealed a dermoid sinus associated with spina bifida at the level of T3-T4. On surgical exploration, the dermoid sinus was found to communicate with the dura. Histology confirmed the diagnosis and classification as a type VI dermoid sinus. The pain response and hyperesthesia were suspected to be the result of tethered cord syndrome. Complete resolution of clinical signs was appreciated post-surgery, with the patient still free of clinical signs 3 mo later.

Consequences and Management of Canine Brachycephaly in Veterinary Practice: Perspectives from Australian Veterinarians and Veterinary Specialists

This article, written by veterinarians whose caseloads include brachycephalic dogs, argues that there is now widespread evidence documenting a link between extreme brachycephalic phenotypes and chronic disease, which compromises canine welfare. This paper is divided into nine sections exploring the breadth of the impact of brachycephaly on the incidence of disease, as indicated by pet insurance claims data from an Australian pet insurance provider, the stabilization of respiratory distress associated with brachycephalic obstructive airway syndrome (BOAS), challenges associated with sedation and the anaesthesia of patients with BOAS; effects of brachycephaly on the brain and associated neurological conditions, dermatological conditions associated with brachycephalic breeds, and other conditions, including ophthalmic and orthopedic conditions, and behavioural consequences of brachycephaly. In the light of this information, we discuss the ethical challenges that are associated with brachycephalic breeds, and the role of the veterinarian. In summary, dogs with BOAS do not enjoy freedom from discomfort, nor freedom from pain, injury, and disease, and they do not enjoy the freedom to express normal behaviour. According to both deontological and utilitarian ethical frameworks, the breeding of dogs with BOAS cannot be justified, and further, cannot be recommended, and indeed, should be discouraged by veterinarians.

A novel proximal 3q29 chromosome microdeletion in a Chinese patient with Chiari malformation type II and Sprengel's deformity

Background

Chiari malformation type II (CM-II) is mainly characterized by elongation and descent of the cerebellum through the foramen magnum into the spinal canal. Moreover, CM-II is uniquely associated with myelomeningocele. Sprengel’s deformity refers to the malposition of the scapula, i.e. scapular elevation which is sometimes accompanied with scapula dysplasia. Although few familial cases of CM-II and Sprengel’s deformity have been previously reported, both of these defects are considered to be sporadic, thus the exact etiology and causative genes have largely remained unknown.

Case presentation

The patient was diagnosed with CM-II accompanied with Sprengel’s deformity. Further genetic investigation revealed a novel 666 kb microdeletion located in 3q29 (chr3:194,532,035–195,198,585; Hg19). Subsequently, genes within the affected region were summarized, and XXYLT1 and ACAP2 were identified as the candidate genes.

Conclusion

We reported a case of a patient with CM-II and Sprengel’s deformity harboring a microdeletion in 3q29. This case highlights the importance of 3q29 in early neural and skeletal development, as well as expands the phenotype spectrum of this rare disorder.