Post anaesthetic myopathy/neuropathy in horses undergoing magnetic resonance imaging compared to horses undergoing surgery.
BACKGROUND
Patient positioning and long anaesthetic duration required for magnetic resonance imaging (MRI) may result in a higher frequency of post anaesthetic myopathy/neuropathy syndrome (PAMNS) as compared to horses undergoing anaesthesia for surgery.


OBJECTIVE
Equine anaesthesia for MRI is associated with a higher frequency of PAMNS than anaesthesia for nonemergency, nonabdominal surgery.


METHODS
Anaesthetic and medical records of horses (n = 633) undergoing MRI or surgery between January 2001 and January 2005 (inclusive), were reviewed. Information obtained included patient details (breed, sex, age, bodyweight), area of body scanned or involved in surgery, body position, anaesthetic and inotropic agents administered, anaesthetic duration, adverse events during anaesthesia and outcome at 7 days. Data were examined by cross tabulation and Chi-square or Fisher's exact test of association. The influence of individual variables was examined by univariant and multivariant analysis models.


RESULTS
There were no statistically significant differences between the 2 groups in parameters examined, except that horses in the MRI group were heavier (P<0.0001) and anaesthetic duration longer in the surgery group (P<0.004). Eight horses (2.3%, 95% Confidence interval [CI]: 1.1-4.2) in the MRI group had clinical signs of PAMNS in the post anaesthetic period, whereas only 2 horses (0.98%, 95% CI: 0.2-2.8) in the surgery group were affected. This was not statistically significantly different (odds ratio = 2.7, 95% CI: 0.8-13, P = 0.3). Two horses undergoing MRI were subjected to euthanasia due to the severity of PAMNS.


CONCLUSIONS
There was no difference in the occurrence of PAMNS between the 2 groups.


CONCLUSIONS
The risk of performing general anaesthesia for diagnostic procedures such as MRI may not be greater than that for a surgical procedure. However, the benefits should be carefully weighed against the risks involved.
Franci
P
P
Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, CB8 7UU, UK.
Leece
E A
EA
Brearley
J C
JC
D000704:Analysis of Variance; D000762:Anesthesia Recovery Period; D000768:Anesthesia, General / Q000009:adverse effects / Q000662:veterinary*; D000818:Animals; D001835:Body Weight / Q000502:physiology; D016009:Chi-Square Distribution; D016001:Confidence Intervals; D005260:Female; D006734:Horse Diseases / Q000209:etiology* / Q000601:surgery; D006736:Horses; D008279:Magnetic Resonance Imaging / Q000009:adverse effects / Q000662:veterinary; D008297:Male; D009135:Muscular Diseases / Q000453:epidemiology / Q000209:etiology / Q000662:veterinary*; D009422:Nervous System Diseases / Q000453:epidemiology / Q000209:etiology / Q000662:veterinary*; D016017:Odds Ratio; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors