Equis ISSN 2398-2977

CSF: collection - ultrasound-guided standing cervical

Synonym(s): Ultrasound-guided standing cervical collection of cerebrospinal fluid

Contributor(s): Graham Munroe, Rachael Conwell

Introduction

  • The collection of cerebrospinal fluid (CSF) in horses is a well recognized additional aid in the investigation of neurological disease.
  • It can be collected from the cisternal or the lumbosacral site.
  • Until recently it has been usually obtained via lumbosacral centesis in the standing horse, with or without ultrasound guidance CSF: collection. Limitations include: the need to use a very long needle (15 cm/6 in); the potential for contamination with blood (this may be decreased by using ultrasound-guidance); the potential for a non-representative sample when assessing cranial disease due to the long distance between the sampling point and disease source; and finally, the potential for injury to the clinician, who is close to the hind limbs when carrying out the procedure, if the horse reacts violently.
  • Obtaining a CSF sample from more cranially has some advantages and both cerebellomedullary, atlanto-occipital and cervical C1/C2 centesis have been described. Cerebellomedullary centesis has been reported in standing horses but is technically difficult. Standing cervical C1/C2 collection was reported in 2012. Atlanto-occipital centesis, with or without ultrasound-guidance, had only been reported in patients under general anesthesia up until 2014, when it was described in the standing horse.
  •  The use of general anesthesia is of major concern in ataxic and intracranial lesion patients as there is an increased risk of injury upon recovery, therefore standing collection techniques avoid this risk.
  • Ultrasound-guidance has been used to allow the proper placement of contrast medium into the subarachnoid space for myelography Myelography and to minimize the risk of needle placement into the subdural space or within the spinal cord.

Uses

  • Collection of CSF samples in standing patients from between C1-2.

Advantages

  • Can be used to obtain CSF in standing patients with no reported detrimental effects.
  • Blood contamination is minimized with increased practice. This is particularly important where EPM testing is to be undertaken as small amounts of blood contamination can interfere with the test. Experience at placing the needle (reduced attempts) plus discarding the initial 5 ml of CSF sample may decrease the blood contamination.
  • Rapid technique with increased accuracy of needle placement into the dorsal aspect of the subarachnoid space. Normally only one attempt to enter the space is required.
  • Penetration of the spinal cord, nerve roots and vertebral vessels is avoided by the orientation of the needle and the ultrasound-guidance.

Disadvantages

  • Risk of blood contamination.
  • A sudden drop in CSF pressure created during the withdrawal of CSF can result in tentorial herniation and subsequent convulsions.
  • May be contraindicated if there are clinical signs of brain herniation.

Requirements

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Preparation

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Procedure

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Aftercare

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Outcomes

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Prognosis

  • Determined by underlying neurological problem.

Further Reading


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