VACUUM PHENOMENON OF THE CANINE SPINE: CT FINDINGS IN 3 PATIENTS

Evaluation of vacuum phenomenon in dogs with coxofemoral degenerative joint disease using computed tomography

Background

Degenerative joint disease (DJD) is a common orthopedic lesion in the coxofemoral joint of canine patients. Concurrent with the sign of degeneration, the vacuum phenomenon (VP), or intra-articular gas, has been observed in several locations in both human and canine patients. A cadaveric study described VP in small breed dogs without DJD but with hip laxity. However, none of the canine VP reports mentioned coxofemoral DJD. Therefore, the aim of this retrospective study was to describe the distribution of coxofemoral VP revealed on computed tomography (CT) imaging in canine patients with DJD.

Results

A total of 282 dogs (564 coxofemoral joints), comprising 142 small, 85 large, and 55 medium breeds, were included in the present study. DJD was found in 31.02% of all dogs. The incidence of DJD was highest in large breed dogs (50%), followed by medium (31.81%) and small (19.36%) breed dogs. In addition, VP was detected with CT using the pulmonary window in 31 joints of 25 dogs that received a diagnosis of hip degenerative disease. VP was found most frequently at the laterodorsal area of the acetabulum. The incidences of VP in large, small, and medium breed dogs were 35.94%, 17.14% and 8.33%, respectively. The presence of coxofemoral VP was significantly and positively correlated with DJD (odds ratio = 17.58, 95% CI 2.32–133.42).

Conclusions

The presence of coxofemoral joint DJD and VP was more likely to be detected in large breed dogs, especially in those with established DJD. CT is an advanced diagnostic imaging modality that can be used to reveal VP lesions, most of which are reported at the laterodorsal acetabulum. Further studies, including comparisons of different patient positions, may reveal more information regarding coxofemoral VP.

[Diagnostic imaging of changes of the canine intervertebral disc]

Intervertebral disc degeneration can cause intervertebral disc herniation. Diagnostic imaging, including radiography, computed tomography and magnetic resonance imaging, is the most important tool in diagnosis. Firstly, an overview of macroscopic and biochemical physiology and pathology of the intervertebral disc will be given. Subsequently, the physics of diagnostic imaging and the appearance of intervertebral disc degeneration and displacement in several imaging methods are described.

The vacuum phenomenon in intervertebral disc disease of dogs based on computed tomography images

OBJECTIVES

Vacuum phenomenon is suspected to be indicative of disc degeneration and subsequent herniation. The objective of this study was to assess the reliability of vacuum phenomenon for identification of herniated discs causing neurological signs. Prevalence of vacuum phenomenon and influencing factors in dogs with disc herniation were determined.

METHODS

Retrospective review of computed tomography scans from dogs with suspected disc herniation for the presence of gas within intervertebral disc space with subsequent comparison of vacuum phenomenon and herniated disc as confirmed by surgery. Subgroups were created (chondrodystrophic, non-chondrodystrophic and unknown classification) to analyse prevalence and influencing factors (age, breed and gender) for vacuum phenomenon and agreement with herniated disc.

RESULTS

Prevalence of vacuum phenomenon in all dogs, chondrodystrophic, non-chondrodystrophic dogs and those with unknown classification was 19·8, 14·9, 35·7 and 24·5%, respectively. Corresponding correlation rate between vacuum phenomenon and herniated disc was 64, 67, 40 and 82%. Prevalence of vacuum phenomenon was significantly higher in nonchondrodystrophic dogs (P=0·04). Age was the only factor influencing prevalence of vacuum phenomenon (P=0·04).

CLINICAL SIGNIFICANCE

In dogs with intervertebral disc disease, vacuum phenomenon is a frequent but inconsistent finding. Although helpful to identify degenerated discs, it is not suitable to identify currently herniated disc with sufficient accuracy.

Computed tomography in small animals – Basic principles and state of the art applications

Since its clinical introduction, computed tomography (CT) has revolutionized veterinary medicine and is considered to be one of the most valuable tools for the imaging work-up of neurological, oncological and orthopaedic canine and feline patients. In small animals with acute trauma, particularly those involving complex anatomic areas such as the head, spine or pelvis, CT has been established as a standard imaging method. With the increasing availability of radiation therapy in veterinary medicine, CT has also become the principal tool to stage a tumour, assess response, and guide radiation therapy. The increasing availability of helical CT in veterinary medicine has allowed novel techniques such as spiral CT angiography and high-resolution CT. This review provides a brief overview of the historical and technical development of CT and literature reviews of the major clinical CT applications in small animals such as intracranial and extracranial lesions, the spine, the appendicular skeleton, and abdominal and thoracic diseases.

Agreement between computed tomography, magnetic resonance imaging, and surgical findings in dogs with degenerative lumbosacral stenosis

OBJECTIVE

To assess the extent of agreement between computed tomography (CT), magnetic resonance imaging (MRI), and surgical findings in dogs with degenerative lumbosacral stenosis.

DESIGN

Observational study.

ANIMALS

35 dogs with degenerative lumbosacral stenosis.

PROCEDURES

Results of preoperative CT and MRI were compared with surgical findings with respect to degree and location of disk protrusion, position of the dural sac, amount of epidural fat, and swelling of spinal nerve roots.

RESULTS

A lumbosacral step was seen on radiographic images from 22 of 32 (69%) dogs, on CT images from 23 of 35 (66%) dogs, and on MR images from 21 of 35 (60%) dogs. Most dogs had slight or moderate disk protrusion that was centrally located. There was substantial or near perfect agreement between CT and MRI findings in regard to degree of disk protrusion (kappa, 0.88), location of disk protrusion (0.63), position of the dural sac (0.89), amount of epidural fat (0.72), and swelling of spinal nerve roots (0.60). The degree of agreement between CT and surgical findings and between MRI and surgical findings was moderate in regard to degree and location of disk protrusion (kappa, 0.44 to 0.56) and swelling of spinal nerve roots (0.40 and 0.50).

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicate that there is a high degree of agreement between CT and MRI findings in dogs with degenerative lumbosacral stenosis but that the degree of agreement between diagnostic imaging findings and surgical findings is lower.

Vacuum disk and facet phenomenon in a dog with cauda equina syndrome

A 7-year-old castrated male Rottweiler was evaluated for an 18-month history of bilateral hind limb lameness, signs of pain on rising, and mild ataxia. A gas-filled lumbosacral disk space (vacuum disk phenomenon) was revealed by use of computed tomography. Additional smaller gas bubbles were in the periphery of the disk and between the degenerated L5-L6 dorsal articular facets (vacuum facet phenomenon). Vacuum disk and facet phenomena have been described in humans with degenerative disk and vertebral articular facet joint disease; gas attracted from surrounding tissues accumulates within clefts of the degenerated disk or in unstable facet joints. Vacuum disk phenomenon has been reported in dogs and indicates degenerative disk disease. The phenomenon is more commonly observed by use of computed tomography, compared with conventional radiography, and can be elicited by hyperextension of the vertebral column.

Association between postoperative outcome and results of magnetic resonance imaging and computed tomography in working dogs with degenerative lumbosacral stenosis

OBJECTIVE

To determine whether results of magnetic resonance imaging (MRI) and computed tomography (CT) are associated with postoperative outcome in working dogs with degenerative lumbosacral stenosis.

DESIGN

Prospective cohort study.

ANIMALS

12 dogs treated surgically for degenerative lumbosacral stenosis.

PROCEDURE

The lumbosacral vertebral column was examined before surgery by use of MRI and CT and after surgery by use of CT. Outcome, based on performance in standardized training exercises, was assessed 6 months after decompressive surgery. Associations between imaging results and postoperative outcome were determined by use of a Fisher exact test and logistic regression.

RESULTS

None of the dogs were able to perform their duties before surgery. By 6 months after surgery, 8 of 12 dogs had been returned to full active duty. Nerve tissue compression was effectively localized by use of CT and MRI. Significant associations between results of imaging studies and postoperative outcome were not identified.

CONCLUSIONS AND CLINICAL RELEVANCE

Surgical intervention is justified in high-performance working dogs with degenerative lumbosacral stenosis. However, results of imaging studies may be less important than clinical or surgical factors for predicting outcome in affected dogs.

Magnetic resonance, computed tomographic and radiologic findings in a dog with discospondylitis

Magnetic resonance (MR), computed tomographic and radiographic imaging were conducted in a dog with discospondylitis. The MR findings were increased T2 and decreased T1 signal intensity of the soft tissues ventral to vertebral bodies, the end plates of the same vertebral bodies and the intervertebral disc, and are similar to those described in human with discospondylitis.

Intervertebral disk disease

Neurologic dysfunction is the most common clinical manifestation of intervertebral disk disease. This article is a comprehensive review of intervertebral disk disease emphasizing clinical features, diagnosis and treatment of cervical and thoracolumbar disk disease. Clinical signs are determined by neuroanatomic localization and severity of spinal cord injury. Myelography is most commonly used for determining the location and extent of the disk protrusion/extrusion; however, computed tomography and magnetic resonance imaging are also common adjunctive and primary diagnostic techniques. Summaries from recent studies will give the clinician an improved understanding on how to confront controversial issues regarding prophylactic and therapeutic management and prognosis.

The spine

Computed tomography (CT) and magnetic resonance imaging (MRI) are becoming increasingly accessible in veterinary medicine. Because of their ability to image the bony spine and spinal cord noninvasively and with exceptional detail, these techniques have revolutionized the way spinal disorders are diagnosed in both people and animals. Although the veterinary literature on this topic is limited, interpretation of CT and MR images of the spine are facilitated by the similarity of human and animal disease processes. This article provides an overview of imaging strategies, normal anatomy, and the CT and MRI features of degenerative, infectious, neoplastic, and vascular diseases of the spine.