Effects of stylet-in versus stylet-out collection of cerebrospinal fluid from the cisterna magna on contamination of samples, sample quality, and collection time

OBJECTIVE

To evaluate safety of stylet-in and stylet-out techniques for collection of CSF from the cisterna magna and to assess whether there were differences between techniques with regard to contamination of samples, sample quality, and efficiency of collection.

ANIMALS

10 adult purpose-bred research Beagles.

PROCEDURES

A prospective crossover study was conducted. Preanesthetic physical and neurologic examinations and hematologic analyses were performed. Dogs were anesthetized, and collection of CSF samples from the cisterna magna by use of a stylet-in or stylet-out technique was performed. Two weeks later, samples were collected with the other sample collection technique. Samples of CSF were processed within 1 hour after collection.

RESULTS

Cellular debris was detected in higher numbers in stylet-in samples, although this did not affect sample quality. The stylet-out technique was performed more rapidly. No adverse effects were detected for either technique.

CONCLUSIONS AND CLINICAL RELEVANCE

Both techniques could be safely performed in healthy anesthetized dogs. The stylet-out technique was performed more rapidly and yielded a sample with less cellular debris. Both techniques can be used in clinical practice to yield CSF samples with good diagnostic quality.

INTRACRANIAL SUBARACHNOID HEMORRHAGE FOLLOWING LUMBAR MYELOGRAPHY IN TWO DOGS

Intracranial subarachnoid hemorrhage is a rare but serious complication of lumbar puncture in humans. Possible sequelae include increased intracranial pressure, cerebral vasospasm, or mass effect, which can result in dysfunction or brain herniation. We describe two dogs that developed intracranial subarachnoid hemorrhage following lumbar myelography. In both dogs, myelography was performed by lumbar injection of iohexol (Omnipaque). Both the dogs underwent uneventful ventral decompressive surgery for disk herniation; however, the dogs failed to recover consciousness or spontaneous respiration following anesthesia. Neurologic assessment in both dogs postoperatively suggested loss of brain stem function, and the dogs were euthanized. There was diffuse subarachnoid hemorrhage and leptomeningeal hemorrhage throughout the entire length of the spinal cord, brain stem, and ventrum of brain. No evidence of infectious or inflammatory etiology was identified. The diagnosis for cause of brain death was acute subarachnoid hemorrhage. Our findings suggest that fatal subarachnoid hemorrhage is a potential complication of lumbar myelography in dogs. The cause of subarachnoid hemorrhage is not known, but may be due to traumatic lumbar tap or idiosyncratic response to contrast medium. Subsequent brain death may be a result of mass effect and increased intracranial pressure, cerebral vasospasm, or interaction between subarachnoid hemorrhage and contrast medium.

Ultrasound-guided atlanto-occipital puncture for myelography in the horse

Complications of cervical myelography arising from the puncture of the subarachnoid space to collect the cerebrospinal fluid and to inject the contrast medium have been described in humans and animals. In this study, 2 ultrasound-guided procedures were developed for puncture of the atlanto-occipital subarachnoid space, collection of cerebrospinal fluid, and injection of contrast medium. Myelography was performed on 6 ataxic horses using these procedures. The first attempt to puncture the subarachnoid space was successful in 5 horses and in one horse, a second attempt was necessary. Collection of cerebrospinal fluid and injection of contrast medium were achieved without difficulty. Ultrasound-guided myelography allowed reduction of potential complications associated with blind percutaneous puncture of the subarachnoid space. Methods described in this study should be tried-at least initially in an experimental setting--to collect cerebrospinal fluid from the atlanto-occipital site in standing horses where it may represent an alternative method when lumbosacral cerebrospinal fluid collection has been unsuccessful or contaminated with blood.

Diagnostic techniques and clinicopathologic findings in ruminant neurologic disease

In ruminant species, cerebrospinal fluid (CSF) collection and analysis provide rapid (in some situations, instant) information to the veterinary clinician investigating a disease problem in the living animal. CSF analysis is particularly useful with respect to confirming the presence of an inflammatory lesion involving the leptomeninges,such as bacterial meningoencephalitis, and in investigating potential compressive lesions of the spinal cord. When correctly performed under local anesthesia, lumbar CSF collection in ruminants is a safe procedure and there are no harmful sequelae. Familiarity with the technique aids high extradural injection of lidocaine or xylazine, which has many applications in farm practice. There are few indications for cisternal CSF collection in food animals.

Findings in cerebrospinal fluids of horses infected with West Nile virus: 30 cases (2001)

OBJECTIVE

To evaluate CSF in horses with confirmed West Nile virus encephalomyelitis.

DESIGN

Retrospective study.

ANIMALS

30 horses.

PROCEDURE

Results of CSF analyses from horses with acute neurologic signs attributed to West Nile virus infection that was confirmed by immunoglobulin M antibody capture ELISA were reviewed and analyzed.

RESULTS

Among 30 CSF samples, findings in 8 (27%) were within reference ranges and in 22 (73%) were abnormal. Among the 22 abnormal samples, mononuclear pleocytosis was found in 16 (73%) and high protein concentration with nucleated cell count within reference range was found in 6 (27%) samples. A predominance of lymphocytes was found in 11 of 16 samples with mononuclear pleocytosis, and a predominance of large mononuclear cells was found in 5 of 16 samples. Sensitivities of analyses of CSF obtained from the lumbosacral and atlanto-occipital regions of the spinal cord were 89 and 50%, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that in horses with acute onset of neurologic signs caused by West Nile virus encephalomyelitis, findings in the CSF are likely to be abnormal, mononuclear pleocytosis with lymphocytic predominance may be most commonly observed, and CSF collected from the lumbosacral region may be abnormal more commonly than CSF collected from the atlanto-occipital region.

Differences in total protein concentration, nucleated cell count, and red blood cell count among sequential samples of cerebrospinal fluid from horses

OBJECTIVE

To examine total protein concentration and cell counts of sequentially collected samples of CSF to determine whether blood contamination decreases in subsequent samples and whether formulas used to correct nucleated cell count and total protein concentration are accurate.

DESIGN

Case series.

ANIMALS

22 horses.

PROCEDURE

For each horse, 3 or 4 sequential 2-ml samples of CSF were collected from the subarachnoid space in the lumbosacral region into separate syringes, and blood was obtained from the jugular vein. Total protein concentration, nucleated cell count, and RBC counts were determined in all samples.

RESULTS

Among 3 sequential samples, total protein concentration and RBC count were significantly lower in samples 2 and 3, compared with sample 1. Nucleated cell count was significantly lower in sample 3, compared with sample 1. Among 4 sequential samples, total protein concentration and RBC count were significantly lower in samples 2, 3, and 4, compared with sample 1. Nucleated cell count was significantly lower in samples 3 and 4, compared with sample 1. For 3 correction formulas, significant differences in corrected values for nucleated cell count and total protein concentration were detected between sample 1 and sample 3 or 4.

CONCLUSIONS AND CLINICAL RELEVANCE

Because iatrogenic blood contamination decreases in sequential CSF samples, a minimum of 3 samples should be collected before submitting the final sample for analysis. Formulas to correct nucleated cell count and total protein concentration are inaccurate and should not be used to correct for blood contamination in CSF samples.

Collecting diagnostic samples in avian patients

With the increasing owner demand of thorough medical evaluation of avian patients, clinicians are being required to collect meaningful diagnostic samples from bird species. The art of diagnosis stems from taking a complete medical history, performing a thorough physical examination, collecting appropriate diagnostics, and interpreting the collective information. This article focuses on methods of collecting diagnostic samples in avian patients.

Miniature pigs

Miniature pigs have become popular pets in North America, and veterinarians of a variety of clinical specialties may be called on for their care. Successful collection of blood from these animals requires familiarity with the location of sites for venipuncture and knowledge of adequate methods of restraint. In this article, restraint and techniques for venipuncture are described, as well as techniques for cerebrospinal fluid collection, semen collection, and vaginal cytologic examination. Interpretation of hematologic, serum biochemical, and urinalysis data are also discussed. Methods for diagnosis of skin diseases, gastrointestinal parasitism, and enteric infectious diseases are included in order to provide the practitioner with the essential knowledge and skills for a variety of clinical pathologic studies of this unique pet.

Clinical pathology of the domestic rabbit. Acquisition and interpretation of samples

Diagnostic laboratories are receiving increasing numbers of samples from practitioners as they strive to diagnose complex disease processes and manage rabbit cases. Proper acquisition of diagnostic samples and interpretation of results are key skills necessary for successful management of medical cases. This article reviews the collection and interpretation of clinicopathologic samples commonly used in rabbits.

Herpesvirus myeloencephalopathy in horses: 11 cases (1982-1996)

OBJECTIVE

To determine results of CSF analysis in horses with equid herpesvirus myeloencephalopathy (EHM) and to determine whether results of CSF analysis were associated with outcome.

DESIGN

Retrospective study.

ANIMALS

11 horses.

PROCEDURE

Medical records of all horses admitted to the veterinary teaching hospital between February 1982 and March 1996 in which EHM was diagnosed were reviewed.

RESULTS

7 horses were < or = 4 years old; 8 were admitted during January, February, or March. Six horses were febrile prior to admission, but none was febrile on the day of admission. Five horses had been stabled with other horses that had clinical signs of neurologic disease. All horses had had an acute onset of hind limb ataxia and paresis. Cranial nerve deficits were detected in 3 horses. Cerebrospinal fluid samples were collected on the day of admission from 10 horses. Protein concentration was high in 8 horses; nucleated cell count was normal in 8. Protein concentration and nucleated cell and RBC counts were not significantly different between horses that survived and horses that were euthanatized. Six horses were euthanatized, and 5 survived. All of the horses that survived remained standing or were able to stand with minimal assistance.

CLINICAL IMPLICATIONS

High CSF protein concentration and normal or only slightly high CSF nucleated cell count are common in horses with EHM; however, results of CSF analysis were not associated with outcome. Horses with EHM that become recumbent have a poor prognosis for survival.

Lumbar myelography in 79 dogs, using different puncture sites

Lumbar myelography was performed in 79 dogs either before spinal surgery or as part of an investigation of neurological disease. In small dogs the site of the puncture was between L1 and L5, avoiding the lumbosacral intumescence, whereas in large dogs the site was between T13 and L2. It was found that a lumbar puncture cranial to the lumbar intumescence was easier and caused no problems. The lumbar puncture was unsuccessful in three obese dogs. In 72 per cent of the cases the myelogram revealed a lesion, and the main cause of a non-diagnostic myelogram was epidural leakage.

A myelographic technique for avian species

A post-mortem myelogram was used to diagnose a vertabral fracture in a Red-tailed Hawk (Buteo jamaicensis). This diagnosis led the authors to believe that myelography would be useful in live birds. In a pilot study using live adult female chickens (Gallus domesticus), mammalian myelographic techniques were modified for avian anatomic differences. A thoracolumbar puncture site was used rather than the lumbar or cisternal site which is commonly used in mammals. The volume of contrast medium needed to produce a diagnostic myelogram in birds (0.8-1.2 ml/kg) was found to be approximately four times that needed in mammals. A 25 gauge spinal needle was used rather than a 23 gauge needle. Myelograms of diagnostic quality were obtained with normal subject recovery. Seizures, the most common post-myelographic complication in mammals, were not observed in any of the birds studied. Avian myelography was found to be a cost effective and humane technique with potential application to avian practice.

[Comparative determination of creatine kinase activity in the cerebrospinal fluid and in the blood of health cattle]

Cerebrospinal fluid (CSF) was obtained by puncture of the canalis vertebralis at the lumbosacral foramen. The activities of creatine kinase (CK) in CSF and plasma samples of 68 healthy cattle of different age and breeds were analysed. No significant correlation between CK activities of CSF and plasma was found. The obtained CSF were classified macroscopically into groups of clear-colourless, flaky-colourless, and bloody-flaky samples. The CK activities of clear-colourless CSF showed a normal distribution and were used for further analysis. The range of standard values of CK activities in CSF (0.2-18.7 U/I) was defined after identification of runaways and narrowing of random sample to 95%.

[The cerebrospinal fluid from healthy pigs and pigs with central nervous system diseases]

CSF samples were taken from 50 healthy pigs of both sexes and cytologically and biochemically examined. With the aid of regression calculations it was investigated, whether deep freezing of CSF samples influences the laboratory results. The parameters glucose, urea, creatinine, total protein, magnesium, anorganic phosphate, AST and AP were in good agreement with the values of the original samples exhibiting only slight variations. Minor age relationship was only seen with respect to the two enzymes LDH and HBDH. A linear relationship was found between values in CSF and in serum of the parameters urea, creatinine, sodium and potassium. CSF examination should include cell count, Pandy's test and bacteriological investigation as well as the determination of the levels of the enzymes LDH and HBDH. The activity of the enzymes AST and ALT increases along with the severity of the tissue damage (meningitis). The specific gravity increases similarly to the total protein level in cases of chronic compression of the spinal cord, and Pandy's test becomes positive. However, CSF glucose levels are partly reduced in animals with central nervous symptoms. The levels of the enzymes AP and CK are often increased in central nervous disturbances, but do not admit drawing a conclusion on the degree of damage.

A simple method for repeated sampling of lumbar cerebrospinal fluid in goats

A technique has been developed for repeated sampling of cerebrospinal fluid from conscious goats by means of a catheter placed surgically in the subarachnoid space between the sixth and seventh lumbar vertebrae. Uncontaminated cerebrospinal fluid in excess of 1.0 ml could be obtained readily from the cannulated goats several times daily for up to 6 weeks. Cannulated goats did not appear stressed during, and in between, sampling periods.

Ancillary tests for assessment of the nervous system

This article addresses the minimum data base needed to assist the clinician's diagnostic approach to neurologic diseases. The collection, storage, and processing of cerebrospinal fluid samples are discussed. Additional diagnostic tests are described under selected specific etiologies.

A review of the usefulness of myelography in 50 dogs

Fifty dogs showing clinical signs of spinal disease were investigated by myelography, using iopamidol. In 27 cases the technique was considered worthwhile. Of the 19 dogs not subjected to surgery or euthanasia as a result of the findings, three suffered seizures during recovery from anaesthesia, eight deteriorated in neurological condition and one suffered permanent respiratory arrest as a result of extensive subarachnoid haemorrhage.

Analysis of cerebrospinal fluid from field cases of some common ovine neurological diseases

Analysis of cerebrospinal fluid (CSF) samples from normal sheep and from cases of some common neurological diseases revealed a significant increase (P less than 0.05) in the group mean CSF protein concentration for meningitis, listeriosis and spinal abscess but not for scrapie, spinal injury, ovine pregnancy toxaemia or polioencephalomalacia. The CSF white blood cell count (WBC) was significantly increased (P less than 0.05) in the meningitis group and in those cases of listeriosis which failed to respond to antibiotic therapy. All cases of bacterial infection of the central nervous system (CNS) could be identified by the combined interpretation of the protein concentration and the differential WBC count. It is concluded that CSF analysis is useful clinically in differentiating traumatic from infective spinal lesions and toxic or metabolic lesions from bacterial meningitis in sheep.

A technique for serial sampling of cerebrospinal fluid from conscious swine and sheep

We devised a method for the atraumatic repeated collection of cerebrospinal fluid samples from conscious swine and sheep. Indwelling needles, with injection caps, were secured intracisternally and protected with plastic "crowns" attached to their skulls. The crowns permitted the animals freer movement with minimal risk of damage to the needles. With sheep, cerebrospinal fluid was withdrawn directly by puncturing the self-sealing injection caps attached to the hubs of the fixed needles. With the pigs, which are less amenable to handling, lengths of sterile polyethylene tubing inserted into the fixed needles enable collection without continuously disturbing the pigs. Serial samples were withdrawn from sheep (.10 to .30 ml) for up to 3 weeks with no problems, and from pigs (.05 to .15 ml) for 8 to 12 days, until the cannulae failed.

Lumbar subarachnoid catheterization in rats

An animal model was developed for the study of subarachnoid (spinal) anesthesia and analgesia under unanesthetized, unsedated and unrestrained conditions. Sprague-Dawley rats were anesthetized with intraperitoneal ketamine (75-100 mg.kg-1). A PE10 catheter was inserted under direct vision into the lumbar subarachnoid space, through partial laminectomy of L1 or L2 with or without removal of adjacent intervertebral ligament. One week after surgery, correct position of the catheter was verified by subarachnoid injection of 0.03-0.05 ml of 1.5% lidocaine, which produced temporary hind limb paralysis in all but one animal in 28 consecutive operations. There was neither mortality nor major complication, intraoperatively or postoperatively. Only 2 animals developed minor subcutaneous would infections which responded to incision, drainage and debridement.

Analysis of cerebrospinal fluid from the cerebellomedullary and lumbar cisterns of dogs with focal neurologic disease: 145 cases (1985-1987)

Data were obtained from 158 CSF samples from 145 dogs with focal, noninfectious/noninflammatory neurologic disease. The effect of lesion location and the duration and severity of clinical signs were studied. One hundred and twenty-five samples were obtained from the cerebellomedullary cistern (CMC), and 33 were obtained from the lumbar cistern (LC). Intracranial and cervical disease affected the CSF from the CMC more often than did thoracolumbar disease. However, lumbar CSF was more frequently affected by disease anywhere along the neuraxis. For compressive spinal cord disease, the protein concentration at both cisterns was more often high in acute, clinically severe lesions. Intracranial lesions consistently caused abnormalities in CSF from both the CMC (7 of 7; 100%) and LC (2 of 2; 100%). Abnormalities were identified in 16 of 38 (42%) and 5 of 7 (71%) CMC and LC samples, respectively, in dogs with cervical disease. In dogs with thoracolumbar lesions, only 22 of 80 (27.5%) CMC samples were abnormal, compared with 21 of 24 (87.5%) LC samples. These findings suggest that CSF collected cranial to the lesion may be normal or only mildly altered by focal neurologic disease. Fluid obtained caudal to the lesion presumably is more substantially altered because of the predominant caudal flow of CSF. To maximize the yield of diagnostic information from CSF analysis, the fluid should preferably be obtained caudad to the disease site; however, because of problems associated with lumbar puncture, we suggest that CSF from the CMC also be obtained.

Experimental infection of goats with Trypanosoma brucei ssp. and effects of treatment with suramin and Mel-B

A stock of Trypanosoma brucei ssp. isolated from a naturally-infected goat in the Lambwe Valley, Kenya, induced cerebral trypanosomiasis in experimentally-infected goats. Six of nine goats with cerebral trypanosomiasis induced by this stock were cured by a single high dose of suramin (50 mg kg-1). Two other goats appeared to be cured with this dosage of suramin but later developed abnormal central nervous system (CNS) signs and parasitaemia. Parasites first appeared in the cerebrospinal fluid (CSF) and then in the blood and lymph nodes. Mel-B was also effective against primary and relapse cerebral trypanosomiasis in goats.

Cerebrospinal fluid

It is hoped that we have demonstrated that collection, handling, and limited analysis of CSF samples from the dog and cat are relatively simple. No special equipment or handling is required, and the procedures are within the capabilities of any veterinarian interested in performing them. In addition, although this article was not intended to present a detailed discussion on the interpretation of the analysis of CSF, we have demonstrated some very practical interpretations to the various aspects of a routine CSF analysis. When combined with a signalment, complete history, and thorough general physical and neurologic examination, CSF analysis can prove invaluable in the workup of an animal with a neurologic disorder. Relatively simple laboratory procedures can be helpful in differentiating peripheral blood contamination from true intrathecal hemorrhage, in identifying an active inflammatory process, in potentially characterizing an etiologic agent, and, on rare occasions, in identifying primary or metastatic neoplastic disease involving the CNS. In many cases, the above is not directly possible, because the changes observed in our routine analysis are nonspecific. Yet, documenting and following these "nonspecific" alterations are helpful in determining if there is progression or regression of the disease process. In turn, these changes or lack of changes are helpful in identifying if the proper therapy has been instituted and if additional or different therapy is required.

Suboccipital puncture for cerebrospinal fluid in the common marmoset (Callithrix jacchus)

Cerebrospinal fluid (CSF) can be obtained routinely from the common marmoset (Callithrix jacchus) by suboccipital puncture. One field of research in which this method is applied is the detection of changes in the biogenic amine metabolism in CSF. The puncture technique is simple and rapid and does not injure the experimental animal.

Suboccipital puncture of guinea pigs

Cisternal cerebrospinal fluid (CSF) was tapped from anaesthetized guinea pigs by an improved technique. This method allowed repeated weekly punctures of the same animal without any cellular or neurochemical changes in CSF or changes in behaviour. About 60% of the punctures produced enough CSF (30-330 microliters) with no or a sufficiently low blood contamination for neurochemical analysis. The CSF space in the spinal canal, cisterna magna and basal cisterns was demonstrated by myelography.