Cerebrospinal Fluid (CSF)

Full Title: Cerebrospinal Fluid (CSF)

Author: Kathy Mayher

Date of Publication: December 30, 2011

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Research Paper Text:

Cerebrospinal fluid (CSF) is fluid found in the subarachnoid space, surrounding the brain and spinal cord. The subarachnoid space is the area between the tough outermost membrane layer (dura mater) and the softer innermost layer ( pia mater) that covers the brain and spinal column. The brain and the spinal cord are the two organs that form the central nervous system (CNS) (“Cerebrospinal Fluid Tap in Dogs”).

According to PetPlace, a website with a library of articles written by veterinarians and specialist, “The fluid resembles serum, and its purpose is to maintain equal pressure within the brain and spinal cord” (“Cerebrospinal Fluid Tap in Dogs”). A cerebrospinal fluid tap is the collection of this fluid for diagnostic purposes. Veterinarians collect a sample of this fluid to diagnose brain or spinal cord diseases. It is often performed after imaging techniques, such as computed tomography (CT scan) and magnetic resonance imaging (MRI) to detect some abnormality in the central nervous system (“Cerebrospinal Fluid Tap in Dogs”).

Abnormalities may include inflammation, viral or bacterial infection, bleeding or suspected tumors (“Cerebrospinal Fluid Tap in Dogs”).

A cerebrospinal fluid tap may also be performed to deliver pain-relieving medication before a surgical procedure. It may also be performed to inject dye in the spinal column to detect an abnormal position of the spinal cord. After the dye is injected, x-rays are taken, this is known as a myelogram (“Cerebrospinal Fluid Tap in Dogs”).

There are two different types of taps: a cisternal tap and a lumbar tap (“Cerebrospinal Fluid Tap in Dogs”).

According to PetPlace, the process to performing a cisternal tap is, “the back of the top of the neck is shaved and sterilized. A needle is inserted at the base of the skull, and into the spinal column, passing through the dura mater and arachnoid membranes to the subarachnoid space” (“Cerebrospinal Fluid Tap in Dogs”). Then a syringe is attached to the spinal needle to draw out the fluid. The fluid can also be allowed to drip into a tube. Rapid withdraw of the spinal needle may result in rupture of vessels in the subarachnoid space causing the sample to be contaminated with blood (Vernau, “Cerebrospinal Fluid Assessment in Dogs and Cats”).

A lumbar tap, also known as a lumbar puncture, occurs on the lower back. The lower back is first sterilized, and then a spinal needle is inserted. A syringe is attached to the needle and fluid is withdrawn or the fluid is allowed to drip into a collection tube (“Cerebrospinal Fluid Tap in Dogs”).

The cerebrospinal fluid pressure is measured before and after the withdraw of fluid. The device used for measurement is called the manometer.

When the cerebrospinal fluid is under abnormally high pressure it will sometimes stream out of the needle hub and in spite of the attachment of the manometer, a large volume of fluid is lost. This result is an accurate reading of pressure (Palumbo, “The Role Of The Cerebrospinal Fluid Tap In The Neurological Examination Of The Dog”).

When the initial pressure is high and the final pressure is low it indicates a small reservoir of fluid. A tumor or lesion that is occupying space within the cranial cavity could be responsible. If there is interference with reabsorption of cerebrospinal fluid (meningitis or communication hydrocephalus) there will be a large fluid reservoir and a smaller difference between the initial and final readings (Palumbo, “The Role Of The Cerebrospinal Fluid Tap In The Neurological Examination Of The Dog”).

General anesthesia is necessary to perform the procedure. Pets undergoing this procedure usually receive a pre-anesthetic sedative and or analgesic drug to encourage relaxation. Because the procedure is performed under anesthesia, no pain is involved. There may be some discomfort following the procedure. The pain will vary among individual dogs (“Cerebrospinal Fluid Tap in Dogs”).

After the cerebrospinal fluid is obtained the color and character should be recorded. And due to the fragile cellular elements of this fluid, if smears (samples) are to be made, this should be done within 20 minutes of the collection. The two most important procedures are the cell counts and the protein concentration. The analysis of cerebrospinal fluid has been described as the central nervous system equivalent of the complete blood count. The primary function of CSF analysis in most cases is to assist in the diagnostic process by excluding the likelihood of certain diseases (Palumbo, “The Role Of The Cerebrospinal Fluid Tap In The Neurological Examination Of The Dog”). Dr. Vernau, an Assistant Professor at the School of Veterinary Medicine at the University of California states, “As is the case with all tests, CSF analysis is only useful when the results are used in conjunction with the history, clinical findings, imaging studies and laboratory test” (“Cerebrospinal Fluid Assessment in Dogs and Cats”).

Measurement of total protein concentration in cerebrospinal spinal fluid is important in the diagnosis of neurologic disease; the protein concentration of CSF in normal dogs is 0.3g/L. A normal CSF analysis does not exclude the presence of disease. However abnormal CSF findings always indicate the presence of pathologic abnormality. An increase in the cellularity of CSF is called pleocytosis. The proportions of the different cell types present in CSF in disease vary according to the nature of the disease process and provide useful information for the diagnosis of neurologic disease (Vernau, “Cerebrospinal Fluid Assessment in Dogs and Cats”). Due to the accurateness of the CSF, it proves to be a useful diagnostic tool for veterinarians.

Works Cited

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