Cervical spinal cord compression may affect anesthetic recovery quality and seizure incidence in horses after myelography.

Research Overview

• This study investigated how compression of the cervical spinal cord affects anesthetic recovery quality and the likelihood of seizures in horses undergoing cervical myelography, a diagnostic imaging procedure.
• It compared recovery and seizure incidence between horses with spinal cord compression and those without, analyzing medical records retrospectively from 2017 to 2022.

Background and Purpose

• Cervical myelography is a diagnostic technique used to evaluate spinal cord conditions in horses, which requires general anesthesia.
• Recovery from anesthesia can vary in quality, and seizures during or after recovery are a concern, especially in horses with spinal cord compression.
• The study aimed to understand whether cervical spinal cord compression influences:
  • the quality of anesthetic recovery
  • the incidence of seizures following the procedure

Methods

• Retrospective review of anesthesia and medical records of horses that underwent myelography from January 2017 to December 2022.
• Inclusion criteria:
  • Complete anesthetic records
  • Standardized anesthetic protocols
• Exclusion criteria:
  • Incomplete records
  • Diagnosis of equine protozoal myeloencephalitis (EPM), which could confound neurological outcomes
  • Non-standard anesthesia protocols
• Collected data included:
  • Demographics (age, breed, body weight)
  • Ataxia (neurological dysfunction) scores
  • Anesthetic management variables
  • Presence or absence of cervical spinal cord compression based on diagnostic results
• Two groups were formed:
  • Compression group (44 horses)
  • Noncompression group (150 horses)
• Statistical analysis involved comparing variables between groups and constructing regression models to identify factors associated with:
  • Quality of anesthetic recovery
  • Incidence of seizures

Key Findings

• An increase in body weight was significantly associated with poorer anesthetic recovery quality:
  • Each unit increase in body weight slightly elevated the risk of worse recovery scores.
• Cervical spinal cord compression was associated with a markedly higher risk (relative risk ratio ~8.89) of worse anesthetic recovery quality.
• Horses with compressive lesions exhibited more seizures during the late recovery period (up to 24 hours post-myeloography), but the difference was not statistically significant.
• No significant increase in seizure incidence was observed immediately after anesthesia recovery in horses with compression compared to those without.

Interpretation and Implications

• Heavier horses tend to experience more challenging recoveries after cervical myelography, regardless of age, breed, or neurological status.
• Cervical spinal cord compression potentially worsens anesthetic recovery quality and may predispose horses to seizures in the first 24 hours after the procedure.
• Seizures tend to occur later in the recovery process rather than immediately post-anesthesia in horses with spinal cord compression.
• Clinical recommendations include:
  • Giving special attention to heavier horses during the recovery phase to improve outcomes.
  • Implementing close monitoring protocols for seizures in the first 24 hours post-mylography in horses diagnosed with cervical spinal cord compression.

Study Limitations and Future Directions

• The study design was retrospective, which can introduce biases related to record accuracy and completeness.
• The incidence of seizures in horses with compression was not statistically significant, suggesting the need for larger sample sizes or prospective studies to confirm the association.
• Further research might explore mechanisms by which spinal cord compression influences anesthetic recovery and seizure susceptibility, and whether adjustments in anesthesia protocols could mitigate these risks.