Non-compressive Nucleus Pulposus Extrusion Research Articles

Presumptive acute non-compressive nucleus pulposus extrusion in 11 cats: clinical features, diagnostic imaging findings, treatment and outcome.

Objectives The aim of the study was to describe the clinical features, diagnostic imaging findings, treatment and outcome in cats diagnosed with presumptive acute non-compressive nucleus pulposus extrusion. Methods Medical records and imaging studies of cats diagnosed with presumptive acute non-compressive nucleus pulposus extrusion were retrospectively reviewed. Information on long-term outcome was acquired from patient records and from either owners or referring veterinary surgeons via a telephone questionnaire. Results Eleven cats met the inclusion criteria. All cats had a peracute onset of clinical signs, with eight cats experiencing witnessed (n = 6) or suspected (n = 2) external trauma based on imaging findings. Neuroanatomical localisation included C1-C5 (n = 1), T3-L3 (n = 7) and L4-S3 (n = 3) spinal cord segments. MRI revealed acute non-compressive nucleus pulposus extrusions located at C3-C4 (n = 1), T12-T13 (n = 1), T13-L1 (n = 1), L1-L2 (n = 1), L3-L4 (n = 3), L4-L5 (n = 1) and L5-L6 intervertebral disc spaces (n = 3). Treatment included supportive care and 10 cats were discharged with a median hospitalisation time of 10 days (range 3-26 days). One cat was euthanased during hospitalisation owing to complications unrelated to neurological disease. All cats that presented as non-ambulatory regained an ambulatory status with the median time to ambulation of 17 days (range 6-21 days). Overall, the outcome for cats diagnosed with acute non-compressive nucleus pulposus extrusion was successful, with almost 90% returning to ambulation with urinary and faecal continence. Conclusions and relevance The majority of cats diagnosed with acute non-compressive nucleus pulposus extrusion had good outcomes. Acute non-compressive nucleus pulposus extrusion should be considered as a differential diagnosis for cats presenting with peracute onset of spinal cord dysfunction, particularly if there is a clinical history or evidence of trauma.

Assessment of interobserver agreement and use of selected magnetic resonance imaging variables for differentiation of acute noncompressive nucleus pulposus extrusion and ischemic myelopathy in dogs.

OBJECTIVE To evaluate interobserver agreement for features used in presumptive diagnosis of acute noncompressive nucleus pulposus extrusion (ANNPE) or ischemic myelopathy by MRI, compare findings on postcontrast T1-weighted (T1W) MRI sequences with fat saturation (FS) for the 2 conditions, and determine whether length and directional patterns of hyperintensity of the intramedullary spinal cord on T2-weighted (T2W) fast spin echo (FSE) MRI sequences differ between dogs with these diseases. DESIGN Retrospective, observational study. ANIMALS 20 dogs with clinical signs compatible with ANNPE (n = 14) or ischemic myelopathy (6). PROCEDURES 3 observers evaluated MRI data (including T2W FSE, T2W single-shot FSE, and T1W FS sequences) for dogs with a presumptive diagnosis of ischemic myelopathy or ANNPE. Interobserver agreement for variables of interest including presumptive diagnosis was assessed by κ statistic calculations. Associations between diagnosis and variables of interest were assessed with Fisher exact or Cochran-Mantel-Haenszel tests. RESULTS Perfect interobserver agreement (κ = 1 for all comparisons) was found for the presumptive diagnosis of ischemic myelopathy versus ANNPE. Meningeal enhancement on postcontrast T1W FS MRI images and nonlongitudinal directional pattern of intramedullary hyperintensity on T2W FSE images were significantly associated with a diagnosis of ANNPE. Greater length of intramedullary hyperintensity was significantly associated with a diagnosis of ischemic myelopathy. CONCLUSIONS AND CLINICAL RELEVANCE Directional pattern and length of intramedullary hyperintensity on T2W FSE MRI images and enhancement patterns in postcontrast T1W FS sequences may provide important contributions to the criteria currently used in the presumptive diagnosis of ischemic myelopathy versus ANNPE.

Prevalence, clinical presentation, prognosis, and outcome of 17 dogs with spinal shock and acute thoracolumbar spinal cord disease.

To describe the prevalence, signalment, clinical features, etiology, and outcome in dogs with acute thoracolumbar disease and suspected spinal shock. Retrospective clinical case study (2005-2010). Private specialty practice. Medical records of 263 dogs with thoracolumbar spinal magnetic resonance imaging were reviewed. If decreased or absent withdrawal reflexes were present in 1 or both pelvic limbs, in the absence of a spinal lesion in the lumbosacral intumescence, dogs were diagnosed with spinal shock. Dogs with suspected or confirmed spinal neoplasia, myelomalacia, or meningomyelitis were excluded. Seventeen of 263 dogs (6%) met inclusion criteria. None. Thoracic lesions were significantly more likely to result in spinal shock when compared to lumbar lesions (P = 0.03). Fibrocartilaginous embolism was the most commonly diagnosed etiology (7 of 17 dogs), and was more common in the thoracic spine compared to in the lumbar spine (P = 0.10). Six of 17 dogs (35%) were diagnosed with intervertebral disk herniation; 4 of 17 dogs (24%) with suspected acute noncompressive nucleus pulposus extrusion. Two dogs were lost to follow-up. Fourteen of 15 (93%) dogs had improved or normal reflexes by 60 days post injury. Although the prevalence of spinal shock was low, it should be considered in any dog presenting with an acute history of thoracolumbar spinal injury with reduced or absent reflexes in the pelvic limbs. The presence of spinal shock should not dissuade a veterinarian from pursuing appropriate diagnostic testing and therapy for the underlying etiology.

INTER- AND INTRAOBSERVER AGREEMENT FOR DIAGNOSING PRESUMPTIVE ISCHEMIC MYELOPATHY AND ACUTE NONCOMPRESSIVE NUCLEUS PULPOSUS EXTRUSION IN DOGS USING MAGNETIC RESONANCE IMAGING.

Ischemic myelopathy (IM) and acute noncompressive nucleus pulposus extrusion (ANNPE) are common spinal emergencies in dogs with similar clinical presentations. Magnetic resonance imaging (MRI) criteria for a presumptive antemortem diagnosis have been reported, however inter- and intraobserver agreement for use of these criteria has not been established. The aim of this retrospective, descriptive, cross-sectional study was to describe inter- and intraobserver agreement for using previously published MRI criteria to diagnose presumptive IM and ANNPE in a sample dogs. Dogs with a presumptive diagnosis of IM or ANNPE and available MRI scan data were retrieved from medical record archives during the period of 2009 and 2013. A total of 127 dogs were identified. From this sample, MRI scans for 60 dogs were randomly selected and duplicated for intraobserver analysis, giving a total of 187 anonymized studies that were presented to two blinded assessors (one board-certified veterinary neurologist, one board-certified veterinary radiologist). Assessors were asked to diagnose lesions as IM or ANNPE based on previously published MRI characteristics. Interobserver agreement in diagnosing IM or ANNPE was moderate (Kappa = 0.56) and intraobserver agreement was moderate to good (Assessor 1 Kappa = 0.79, Assessor 2 Kappa = 0.47). Agreement was strongest for detecting presence of lesions overlying a vertebral body (94% of lesions that were diagnosed as IM) or overlying an intervertebral disk (85% of lesions that were diagnosed as ANNPE). Findings indicated that use of previously published MRI criteria yields moderate inter- and moderate to good intraobserver agreement for a presumptive diagnosis of IM or ANNPE in dogs.

A Review of Fibrocartilaginous Embolic Myelopathy and Different Types of Peracute Non-Compressive Intervertebral Disk Extrusions in Dogs and Cats.

This review discusses terminology, pathological, clinical, and magnetic resonance imaging (MRI) findings, treatment, outcome, and prognostic factors of fibrocartilaginous embolic myelopathy (FCEM), acute non-compressive nucleus pulposus extrusion (ANNPE), and intradural/intramedullary intervertebral disk extrusion (IIVDE). FCEM, ANNPE, and IIVDE have a similar clinical presentation characterized by peracute onset of neurological dysfunction that is generally non-progressive after the initial 24–48 h. Differentiating between these conditions can be challenging, however, certain clinical and imaging findings can help. FCEM can occur in both adult and immature animals, whereas ANNPE or IIVDE have been reported only in animals older than 1 year. In dogs, ANNPE and IIVDE most commonly occur in the intervertebral disk spaces between T12 and L2, whereas FCEM has not such site predilection. In cats, FCEM occurs more frequently in the cervical spinal cord than in other locations. Data on cats with ANNPE and IIVDE are limited. Optimal MRI definition and experience in neuroimaging can help identify the findings that allow differentiation between FCEM, ANNPE, and IIVDE. In animals with ANNPE and IIVDE, the affected intervertebral disk space is often narrowed and the focal area of intramedullary hyperintensity on T2-weighted images is located above the affected intervertebral disk space. In dogs with ANNPE signal changes associated with the extruded nucleus pulposus and epidural fat disruption can be identified in the epidural space dorsal to the affected intervertebral disk. Identification of a linear tract (predominantly hyperintense on T2-weighted images, iso to hypointense on T1-weighted images and hypointense on T2*-weighted gradient recall echo images) extending from the intervertebral disk into the spinal cord parenchyma is highly suggestive of IIVDE. Treatment of FCEM and ANNPE is conservative. Dogs reported with IIVDE have been managed either conservatively or surgically. Prognostic factors include degree of neurological dysfunction (particularly loss of nociception) and disease-specific MRI variables.

SUSCEPTIBILITY ARTIFACTS ON T2*-WEIGHTED MAGNETIC RESONANCE IMAGING OF THE CANINE AND FELINE SPINE.

The T2*-weighted gradient recalled echo sequence is a sensitive means to detect blood degradation products. While not a routine sequence in magnetic resonance imaging of the spine in small animals, it can provide additional valuable information in select cases. The goal of this retrospective, cross-sectional study was to describe findings when acquiring this sequence during magnetic resonance imaging examination of the spine in small animals. The University of Tennessee's veterinary radiology database was searched for dogs and cats that underwent magnetic resonance imaging for suspect spinal disease in which a T2*-weighted gradient recalled echo sequence was acquired and susceptibility artifact was identified. The following information was recorded: signalment, clinical signs, location and appearance of susceptibility artifact, and final diagnosis. Thirty-nine cases were included in the study. Extradural susceptibility artifacts were observed in cases of intervertebral disc herniation with or without associated hemorrhage (n = 28), extradural hemorrhage associated with spinal trauma (n = 2), hemophilia (n = 1), and in a cystic extradural mass (n = 1). Remaining lesions displaying susceptibility artifact were intramedullary and included presumptive acute noncompressive nucleus pulposus extrusion (n = 2), hematoma (n = 1), hemangiosarcoma metastasis (n = 1), intramedullary disc extrusion (n = 1), presumptive meningomyelitis (n = 1), and a mass of undetermined etiology (n = 1). Inclusion of a T2*-weighted gradient recalled echo sequence may be helpful in spinal magnetic resonance imaging when standard imaging sequences are ambiguous or intramedullary lesions are observed.

Association of clinical and magnetic resonance imaging findings with outcome in dogs with presumptive acute noncompressive nucleus pulposus extrusion: 42 cases (2000–2007)

To assess associations of severity of neurologic signs (neurologic score), involvement of an intumescence, and findings of magnetic resonance imaging (MRI) with interval to recovery and outcome in dogs with presumptive acute noncompressive nucleus pulposus extrusions. Retrospective case series. 42 dogs with presumptive acute noncompressive nucleus pulposus extrusions. Medical records and magnetic resonance (MR) images of dogs evaluated from 2000 through 2007 were reviewed. Inclusion criteria were acute onset of nonprogressive myelopathy following trauma or strenuous exercise, MRI of the spine performed within 7 days after onset, MRI findings consistent with acute noncompressive nucleus pulposus extrusions, and complete medical records and follow-up. Clinical neuroanatomic localization of lesions was to the C1-C5 (n = 6), C6-T2 (6), T3-L3 (28), and L4-S3 (2) spinal cord segments. Median neurologic score was 3.5. Median duration of follow-up was 804 days (range, 3 to 2,134 days) after onset of neurologic signs. Outcome was successful in 28 (67%) dogs and unsuccessful in 14 (33%) dogs. Severity of neurologic signs, extent of the intramedullary hyperintensity on sagittal and transverse T2-weighted MR images, and detection of intramedullary hypointensity on GRE images were all associated with outcome on univariate analysis. Results of multivariate analysis suggested that maximal cross-sectional area of the intramedullary hyperintensity on transverse T2-weighted MR images was the best predictor of outcome. Clinical and MRI findings can help predict outcome in dogs with acute noncompressive nucleus pulposus extrusions.