ventral aspect of the vertebral canal on the left-ventral right-dorsal oblique. Final diagnosis is a suspected acute, traumatic atlanto-occipital (AO) luxation.
Same images as in Figure 1 . DV—Moderate soft tissue opaque swelling of the
The position of the incisor arcades, the movement of the mandible during extension and flexion of the atlanto-occipital joint, and the effects of routine dental floating on mandibular movement in horses have been previously described. 3,4 However, the
Na + , K + , Ca 2+ , glucose, and hemoglobin (data not shown).
Accurate characterization of the ICPVR is clinically helpful in indicating the margin of safety when obtaining CSF from the atlanto-occipital space in dogs in which
Objective—To evaluate CSF in horses with confirmed
West Nile virus encephalomyelitis.
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%,
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. (J Am Vet Med Assoc 2002;221:1303–1305)
radiographic views (A and B) as in Figure 1 and a lateral (C) xerographic image of the cervical portion of the vertebral column in a dog in which the atlanto-occipital articulation is considered normal for comparison. On the lateral (A) radiographic view, the
fracture of the right epihyoid bone. The diagnostic imaging modalities confirmed a diagnosis of atlanto-occipital (AO) luxation and atlanto-axial (AA) subluxation, with an associated dens avulsion fracture. Subsequent treatment was provided at the referral
appears partially fused to the occipital bone, resulting in an indistinct appearance of the atlanto-occipital (C1 and C2) articulation. The vertebral canal is poorly demarcated and has excessive angulation as it extends cranially through the atlanto-occipital
midazolam hydrochloride (0.05 mg/kg) administered over 30 seconds via the IV catheter. Once the horse was in lateral recumbency, an 18-gauge 8.75cm (3.5 in) spinal needle was placed in the atlanto-occipital cistern via the dorsal midline approach
, this was suspected to be a fibrous union given the time duration between radiographs. The atlanto-occipital joint appeared within normal limits. The owner was advised to slowly bring the horse back into ridden work but to continue to monitor for any
head and cranial cervical spine were obtained ( Figure 1 ) .
Left to right lateral (LeRtL) radiographic image of the atlanto-occipital (AO) joint and cranial cervical spine (A; cranial is toward the left) and longitudinal