Dermoid sinus in Burmese cats

Sacral Spina Bifida Occulta: A Frequency Analysis of Secular Change

Substantial relaxation of natural selection beginning around 1900 changed the mutation/selec­tion balance of modern genetic material, producing an increase in variable anatomical structures. While multiple structures have been affected, the temporal increase in variations of the sacrum, specifically, ‘Sa­cral Spina Bifida Occulta,’ have been reliably demonstrated on a localised scale. Calculation of largescale frequency has been hindered by the localised nature of these publications, the morphological variability of this variation, and potential pathological associations, which have produced divergent classifications, and conflicting reported rates of occurrence. A systematic review of the reported literature was conducted to provide an objective analysis of Sacral Spina Bifida Occulta frequency from 2500 BCE to the present. This review was designed to compensate for observed inconsistencies in reporting and to ascertain, for the first time, the temporal trajectory of this secular trend. A systematic review of Sacral Spina Bifida Occulta lit­erature was conducted through the strict use of clinical meta-analysis criteria. Publications were retrieved from four databases: PubMed, Embase, the Adelaide University Library database, and Google Scholar. Data were separated into three historical groups, (1 = <1900, 2 = 1900 to 1980 and 3 = >1980), and frequency outcomes compared, to determine temporal rates of occurrence. A total of 39/409 publications were included in the final analysis, representing data for 16,167 sacra, spanning a period of 4,500 years. Statistically significant results were obtained, with total open S1 frequen­cy increasing from 2.34%, (79 to 1900CE), to 4.80%, (1900 to 1980CE) and to 5.43% (>1980CE). These increases were significant at p<0.0001, with Chi-squared analysis. A clear secular increase in the global frequency of Sacral Spina Bifida Occulta has been demonstrated from 1900 to the present. This research provides a novel and adaptable framework for the future assessment of variation distribution, with impor­tant implications for the fields of biological anthropology and bioarchaeology.

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.

Cystic Abnormalities of the Spinal Cord and Vertebral Column

Cystic lesions of the vertebral column and spinal cord are important differential diagnoses in dogs with signs of spinal cord disease. Synovial cysts are commonly associated with degenerative joint disease and usually affect the cervical and lumbosacral regions. Arachnoid diverticulum (previously known as cyst) is seen in the cervical region of large breed dogs and thoracolumbar region of small breed dogs. This article reviews the causes, diagnosis, and treatment of these and other, less common, cystic lesions.