Cytology of equine cerebrospinal fluid

Comparison of Fluid Analysis and Cytologic Findings of Cerebrospinal Fluid Between Three Collection Sites in Adult Equids With Neurological Disease

Cerebrospinal fluid (CSF) is routinely collected from three sites in the horse, the atlanto-occipital (AO), atlantoaxial (AA), and lumbosacral (LS) space. A comparison between fluid analysis parameters [total protein, total nucleated cell count (TNCC), red blood cell (RBC) count, and morphologic analysis] from samples obtained at each of the three sites has not previously been performed. A retrospective analysis was performed to evaluate the differences in fluid analysis of CSF between the AO, AA, and LS sites in equids presented to a referral service for evaluation of suspected neurological disease. A total of 113 equids aged ≥1 year that underwent CSF collection between 2008 and 2020 were included. Total nucleated cell count, RBC concentration, total protein (TP), and morphologic evaluation between CSF samples obtained from the three sites were compared. When comparing all samples, LS centesis was associated with higher RBC compared to other sites (p < 0.05); TP was lower in the AA group than in the LS group (p < 0.05). Within a subset of cytologically unremarkable samples, RBC concentration was highest in LS samples (p < 0.01); TP was higher in LS samples compared to AA samples (p < 0.05) and TNCC was higher (p < 0.01) in AA and LS groups compared to the AO. In cytologically abnormal samples, there were no significant differences between sites in any parameter. Abnormal cytology was correlated with non-survival (p = 0.0002). Non-survival was associated with higher TNCC (p < 0.01). The receiver operating characteristic (ROC) curve for TNCC had an area under the curve of 0.67 (95% CI, 0.55-0.79) and indicated that a cutoff value of 24 cells/μL maximized specificity (72%) and sensitivity (54%) to predict non-survival in all horses. Positive predictive value was 45%; negative predictive value was 78%. The concentration of RBC was higher in samples from the LS site. This has clinical implications due to the importance of comparative diagnostics and its potential impact on cytologic evaluation. There were minimal differences in multiple other parameters between sites, which are likely clinically insignificant.

Collection of cerebrospinal fluid in 50 adult healthy donkeys (Equus asinus): clinical complications, and cytological and biochemical constituents

Background

Diseases of the central nervous system are a well-recognized cause of morbidity and mortality in equine. Collection and analysis of cerebrospinal fluid (CSF) give information about the type and stage of degenerative and inflammatory diseases in central nervous system (CNS). The present research aimed to assess the clinical complications of CSF collections and to establish range values of cytological and biochemical parameters of CSF in adult healthy donkeys (Equus asinus). The CSF samples were collected from fifty healthy donkeys at the lumbosacral (LS) and atlanto-occipital (AO) sites.

Results

Hypothermia, tachycardia, ataxia and recumbency may develop post-puncture. Erythrocytes were noticed in 35 of 50 CSF samples. Total nucleated cell counts ranged from 0 to 6 cells/μL, and lymphocytes predominated the cells (61%). The concentration of glucose (1.2 to 5.3 mmol/L) was lower than that of serum (P < 0.05). The CSF sodium concentration (123 to 160 mmol/L) was approximately like that of serum, but potassium (1.5–3 mmol/L) was lower than that of serum (P < 0.01). Urea concentrations (1.1–2.9 mmol/L) were markedly lower than serum (P < 0.001). Concentrations of CSF total proteins, and albumin ranged from 0.1 to 0.6 g/dL, and from 0.002 to 0.013 g/dL, respectively. The albumin quotient ranged from 0.06 to 0.56.

Conclusions

Transient hypothermia, tachycardia, ataxia and recumbency may develop as clinical complications of CSF puncture procedures. The collection site has no impact on the constituents in CSF. Furthermore, this study presented the range values for normal cytological and biochemical constituents of CSF in donkeys (Equus asinus) that can provide a basis in comparison when evaluating CSF from donkeys with neurologic diseases.

Characterisation of the cerebrospinal fluid of horses with West Nile virus neuroinvasive disease

West Nile virus (WNV) is a zoonotic arbovirus transmitted by mosquitoes between wild birds (natural hosts) and other vertebrates. Horses and humans are incidental, dead-end hosts, but can develop severe neurological disorders. Owing to the close contact of cerebrospinal fluid (CSF) with the extracellular fluid of the brain, the analysis of CSF composition can reflect central nervous system (CNS) impairments enabling the diagnosis and understanding of various neurodegenerative CNS disorders. Our objective was to compare the findings from the CSF samples of horses with neuroinvasive WNV infection with those of healthy controls. We compared findings from fifteen CSF samples of 13 horses with acute WNV encephalomyelitis with those of 20 healthy controls. Protein, particular enzymes and ions, glucose and lactate showed abnormal levels in a significant number of WNV cases. None of the six horses with elevated glucose concentrations survived. Rather neutrophilic than mononuclear pleocytosis was identified with WNV infection. Neutrophils probably play a role in the development of inflammatory response and brain damage. Although elevated glucose levels reliably predicted the outcome, they might be the consequence of increased plasma levels and reflect general stress rather than CNS pathophysiology. The CSF findings of WNV encephalomyelitis patients are non-specific and variable but facilitate the differential diagnosis.

Examination of cerebrospinal fluid in the horse

The examination of cerebrospinal fluid (CSF) is often part of the diagnostic work-up of a patient exhibiting signs of disease involving the central nervous system. Awareness of the capabilities and limitations of these laboratory tests is important in assessing the benefit-to-risk ratio of performing such procedures. Collection of CSF is a relatively simple procedure, and together with a thorough history, physical examination, and other diagnostic tests, may be a valuable aid in arriving at a diagnosis or prognosis.

Clinical pathology of bovine neurologic disease

This article describes the general and specific interpretations of common laboratory tests used to evaluate bovine neurologic disease. Cerebrospinal fluid analysis is emphasized. Comments are made about general conclusions such as hemorrhage, inflammation, infection, and neoplasia as well as specific diseases like thromboembolic meningoencephalitis. Tests in commonly available serum chemistry profiles like total calcium concentration and aspartate aminotransferase activity are described in terms of their usefulness in diseases such as parturient paresis or hepatic encephalopathy. The indications for more specific tests like ionized calcium, blood ammonia concentration, or erythrocyte transketolase are included.